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Mach Discussion => General Mach Discussion => Topic started by: Hood on August 11, 2010, 05:29:30 PM

Title: High speed spindle recommendations
Post by: Hood on August 11, 2010, 05:29:30 PM
Anyone know of a small high speed spindle that would be suitable for attaching to my mills quill. Only for engraving so doesn't have to be that powerful and small size and reasonable cost would be a big advantage. Looking for around 20,000 rpm and variable speed is not needed.

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 11, 2010, 06:45:07 PM
For engraving?  For straight line engraving I use a non spinning spring loaded engraving point.  There are several on Ebay.  Used to be there was only one for about $179 USD, but there is now another cheaper one.  I got mine from one of the guys on the Zone.  Now that I have seen his I could make one on my lathe easily enough.  The hard part is finding just the right spring.  Depending on the point chosen (or made) it works on a variety of things.  I have even used it to engrave the curved side of relatively large sockets to see how far I could push it.  

What are you engraving?  I found this type worked very well with a sharp carbide point on steel or hard aluminum, but for plastics a rounded point worked better and "pressed" or embossed in the marks.  You can also get diamond tips for engraving really hard stuff like glass.  

If you are routing out you can get a Harbor Freight flex shaft tool with a handpiece with chuck that will handle .125 shaft bits for about $50 USD and it only has a couple thousandths side play.  I can't feel it in mine.  It free spins about 15,000 rpm, but if you load it down with deep passes it slows down.  I have two of them and I sometimes use them in my mill with a home made bracket that holds two of them so I can destroy two work pieces at a time.  I hang the motor on the wall and clamp in the handpieces.  They actually have less sideplay than the $50 Foredom (no motor included) hand pieces, but for a lot of work the $135-$150 Foredom 25 continuous duty handpiece would be better because it has bigger bearings and sideplay down around .0015.  

If you are hogging out larger lettering in wood then the cheapest thing that's halfway decent is probably a Makita Router and your own mounting bracket.  Thei trim router turns about 28,000 RPM.
Title: Re: High speed spindle recommendations
Post by: Hood on August 11, 2010, 06:56:41 PM
Thanks Bob,
What I am doing is I suppose V Carving in Alu and possibly stainless and also want it for PCB prototyping.
So spring loaded is not wanted and end float in the spindle has to be minimal as the max depth I am going is 0.5mm.
Will have a look at the flexi stuff you mentioned. A router was my first thought but really its too bulky, would prefer something small, preferably that I could fit half way into a 40 taper spindle.
Below is the type of thing I am wanting to do, this took 3hrs and if I could get the spindle up to 20,000rpm it would take under half an hour.

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 11, 2010, 07:07:29 PM
Side play and runout can be a much bigger issue when using smaller bits.  That looks almost like lithograph type work there.  I think I would be tempted to go with the Fordom 25 with one of their motors.  It only claims 1/5 HP, but its a true 1/5 HP and it turns 18,000 rpm.  Either that or there is a guy selling a high speed spindle and motor on ebay that claims very low runout and side play.  He claims people are using it with bits and mills so small you might break one just looking at it.  

Do not get a Foredom 44T or 43T handpiece thinking to save a few bucks and compromise.  They are intended strictly as a hand carving tool holder and they have looser tolerances and looser bearings to reduce heat build up.  I know.  I already tried them and I was unhappy with them for a spindle on my machine.  Go with the 25 if you go that way.  If you want to go cheap the HF ones are tighter tolerance than the 44 or 43, and yes they do build up some heat at full speed.  

Also, the Foredom 25 comes with self centering collets instead fo a chuck.  Slightly better consistency that way. 
Title: Re: High speed spindle recommendations
Post by: budman68 on August 11, 2010, 08:42:52 PM
I've heard great things about the Kress spindles, but I don't think it's as small as what you're after though  ???

Dave
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 04:35:13 AM
Thanks guys,
 cant seem to find anything decent in the UK for the flexi type but have found some Kress ones which look promising but a bit expensive. Then again the only place I have found so far that has them is well known for top flight prices.

Will keep searching.

Hood
Title: Re: High speed spindle recommendations
Post by: M250cnc on August 12, 2010, 05:35:55 AM
Have found some Kress ones which look promising but a bit expensive. Then again the only place I have found so far that has them is well known for top flight prices.

Will keep searching.

Hood

Welcome to the World Of CNC  ;D

Have you though about a die grinder, they can be bought quite cheaply on that well know auction site
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 05:46:14 AM
Hi Phil,
yes have thought about die grinders but not sure what the end float and runout would be, any ideas?
 Suppose if the worst came to the worst I could make up a short spindle  and just use the grinder for  driving it.


Hood
Title: Re: High speed spindle recommendations
Post by: M250cnc on August 12, 2010, 07:08:22 AM
Hi Hood,

I think i paid £20 for mine from that well know auction site it has no discernible end float.

It is quality Taiwan not cheap Chinese rubbish. ::)
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 08:02:13 AM
LOL,
 link? Name?

Hood
Title: Re: High speed spindle recommendations
Post by: bill-the-cat on August 12, 2010, 09:03:48 AM
Hi Hood,

You might want to take a look at Wolfgang Engineering on eBay.

http://shop.ebay.com/wolfgang314/m.html?_nkw=tb&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313

Sounds like just what you're looking for.
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 09:12:54 AM
Thanks bill, looks good but the 3mm cutter size is a killer as the nine9 engraving cutter I use has a 6mm shank :(

Hood
Title: Re: High speed spindle recommendations
Post by: bill-the-cat on August 12, 2010, 09:40:19 AM
I don't know how much he would charge, but I'm pretty sure he could/would make a custom collet for you.

At least it wouldn't cost you anything to ask ;)
Title: Re: High speed spindle recommendations
Post by: ASC on August 12, 2010, 10:26:25 AM
I've had good results with NSK spindles.  They're small, powerful, run up to 50,000 rpm no problem with less than 5 micron runout!  Price tag is the killer in that case though!  I could afford to put them on machines for customers but never afford to keep one for myself lol.
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 12, 2010, 11:29:30 AM
Are import duties and wait times that bad in the UK?  I bought some fishing tackle from a Chinese company in Hong Kong a couple years ago and it seemed to arrive a lot faster than I expected. I'm in the USA. 
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 01:22:03 PM
Bill,
 may do that :)

ASC
 I think NSK is out of my price range as well due to the limited use it would be put to.

Bob
 Times are usually not to bad from the USA but certainly longer than from Asia. Added to that is items from Asia usually slip through unnoticed by customs where I dont think I have ever had anything from the USA that has not been grabbed by UK Customs.
The charges involved are a flat fee of £12 per package for customs handling and 17.5% VAT (soon to be 20%), occasionally I have also been charged import duty which I think was around 10% so it can end up being expensive.

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 12, 2010, 03:01:01 PM
12 pounds plus 30%.  WOW! 
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 04:32:42 PM
12 pounds plus 30%.  WOW! 

WOW is not the word I use ;D

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 12, 2010, 04:39:08 PM
That's the Ebay guy I was thinking of. 

Hi Hood,

You might want to take a look at Wolfgang Engineering on eBay.

http://shop.ebay.com/wolfgang314/m.html?_nkw=tb&_sacat=0&_odkw=&_osacat=0&_trksid=p3911.c0.m270.l1313

Sounds like just what you're looking for.
Title: Re: High speed spindle recommendations
Post by: derekbpcnc on August 12, 2010, 05:40:54 PM
Hi Hood,

I was looking at using a router...
Not sure if the spindle bearings are up to it, but maybe possible to retrofit an additional bearing??.

Bosch do a nice little palm router 600W about 30k RPM
http://www.powertools2u.co.uk/routers-and-trimmers/bosch-gkf600-professional-palm-router.htm (http://www.powertools2u.co.uk/routers-and-trimmers/bosch-gkf600-professional-palm-router.htm)

Just an idea????

ATB
Derek
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 12, 2010, 05:46:05 PM
I'm considering using a router (with speed reduction pullies) to drive a precision hand piece myself.  The only issue I have with the handpiece spindles is they bog down on a heavy cut. 
Title: Re: High speed spindle recommendations
Post by: Hood on August 12, 2010, 06:02:39 PM
Thanks Derek/Bob, spindle speed would be too high with that for Alu or Stainless and the cutter I use, 20,000 I think is tops. But Bobs idea about using it as a motor to drive a spindle may be worth considering. Then again the Kress are not that much dearer  (I found a few other places to get them in the UK :) ) so it will likely be the way I go.

Hood
Title: Re: High speed spindle recommendations
Post by: alenz on August 12, 2010, 10:31:37 PM
Hood,

Another option might be an air spindle. There are pros and cons. I designed and fabed a Sherline air spindle adapter (which I was rather proud of <grin>) and posted it to one of the hobby sites.

http://groups.yahoo.com/group/sherline/photos/album/1116381707/pic/list

 For my purpose it turned out to be less than acceptable. My hobby mill is inside the house (need to be inside the AC here in southern Louisiana) and the air spindle noise would wake the dead, or in my case a sleeping wife. Also the air requirement exceeds the capacity of the small ‘quiet’ hobby compressors and dragging an air hose from the garage into the house wasn’t convenient.  In the end, even tho it worked very well, I gave up on it.

In a shop environment where you have plenty of air and noise isn’t such an issue, an air spindle might be worth considering.

Al Lenz

Title: Re: High speed spindle recommendations
Post by: Hood on August 13, 2010, 03:01:17 AM
alenz
 Yes I had considered air but a few  problems, two of which you have mentioned, are making me hesitant. First is the noise, probably not a huge problem though. Second is the air demand. This in itself shouldn't be an issue as I have a medium sized compressor but air is actually a quite expensive way of driving things as the large three phase motor on the compressor would be constantly running just to turn a small air motor.
Having said all that it is still worth considering as it wouldn't be getting used day in day out, or at least not at this point in time.
Tried to look at the link you supplied but afraid it needs membership of the Sherline group :(

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 13, 2010, 11:48:02 AM
Hood,

Another option might be an air spindle. There are pros and cons. I designed and fabed a Sherline air spindle adapter (which I was rather proud of <grin>) and posted it to one of the hobby sites.

http://groups.yahoo.com/group/sherline/photos/album/1116381707/pic/list

 For my purpose it turned out to be less than acceptable. My hobby mill is inside the house (need to be inside the AC here in southern Louisiana) and the air spindle noise would wake the dead, or in my case a sleeping wife. Also the air requirement exceeds the capacity of the small ‘quiet’ hobby compressors and dragging an air hose from the garage into the house wasn’t convenient.  In the end, even tho it worked very well, I gave up on it.

In a shop environment where you have plenty of air and noise isn’t such an issue, an air spindle might be worth considering.

Al Lenz

Hood,  Sorry for the thread jack. 

Al,

I'm curious which factor or component decided you to move your machine into the house.  I've been able to keep my motors and controller within the heat specs by putting fans on the machine, and with my newer motors and controller heat sinks have done the trick.  Its not uncommon for temps to get close to 100F inside my shop.  The only part I really worry about for heat is the computer iteself.  I'm in Southwest Arizona where outdoor summer temps often hit 110-115 in the shade and occassionally hit the low 120s.  We normally do not have anywhere your humidity however so air cooling does work better.  5-20% most of the time and maybe 40% in late summer. 

When I get some time and the urge it is in my plan to put my machine next to the communications closet in my office, put the LPT cable through the wall, and place the computer in the air conditioned closet. 

Bob
Title: Re: High speed spindle recommendations
Post by: alenz on August 13, 2010, 03:25:43 PM
Bob, the air conditioning is a requirement for my comfort, nothing to do with the equipment. :)
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 13, 2010, 03:48:12 PM
Bob, the air conditioning is a requirement for my comfort, nothing to do with the equipment. :)
At 99% humidity and 99F in the shade I can understand that.  I'ld rather experience 110F in the southwest desert than anything over 90 in the midwest or south. 
Title: Re: High speed spindle recommendations
Post by: RICH on August 13, 2010, 06:00:57 PM
Quote
small high speed spindle that would be suitable for attaching to my mills quill. Only for engraving so doesn't have to be that powerful and small size and reasonable cost would be a big advantage. Looking for around 20,000 rpm and variable speed is not needed.

HOOD,
I have a few air driven and electric motor driven ones for engraving.
Probably the best bang for the buck was the Flexible Shaft Grinder from "Grizzly model WA300" since  it was 1/4 HP and 1800 rpm.
 I bought the associated handpieces also ( one uses a collet and other has a small chuck ). After a simple modification they were better than a lot of the expensive handpieces. Just make a holder for the handpieces and a holding plate for the quill and your good to go at very reasonable cost.
They work fine for engraving and small milling and also as a pecking drill when using a foot controlled pedal to vary the speed.

I prefer the electric ones to the air ones, still noisy but not as bad as the air ones.

If you want more info,like how to modify the handpieces, just ask.

RICH
Title: Re: High speed spindle recommendations
Post by: Hood on August 13, 2010, 06:06:00 PM
Rich, is that 18,000 or 1,800? need the higher of the two
Will look at the ones you mentioned.

Hood
Title: Re: High speed spindle recommendations
Post by: RICH on August 13, 2010, 06:21:37 PM
Oops that's  18,000 rpm. I just looked and Grizzly dosn't have that model listed, but if you search under Flexible Shaft Grinders you will see one which looks like mine / has a handle with a small drill chuck. If you tweak the handle by taking out the end play it works quite well. I replaced the chuck
( which wasn't bad at all ) with one from Albretch and also Jacobs.

I wouldn't spend the money for Foredom ( say $300+ or Dumore say $700 ) or some other brand when $100 one works just as well!

RICH

Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 13, 2010, 06:35:03 PM
This one from Grizzly:
http://www.grizzly.com/products/Flex-Shaft-Grinder/G9928
$64.95

Looks exactly like this one from Harbor Freight:
http://www.harborfreight.com/flexible-shaft-grinder-and-carver-40432.html
$44.95  (On sale from 49.95)

They both claim 15,000 RPM.  I have not been able to find the older ones that used to claim 18,000 RPM since I started looking at these for mill spindles a few weeks ago. 

I found the handpiece that came with the Harbor Fright one to be surprisingly good.  I highly doubt the motor puts out a true 1/4 HP however.  On an agressive cut or sudden turn when cutting surface increases it bogs down and makes the motor jump all over the place on its hook.  That's why I was considering trying to adpat the flexshaft to a router that definitely produces much more horsepower.  With apporpiate speed reuction pulley of course. 

A fixed solid mount for the motor instead of a hanging mount might help of course, but then it might just snap the shaft. 

Title: Re: High speed spindle recommendations
Post by: RICH on August 13, 2010, 07:54:10 PM
Thanks for the links Bob.
I would try the Harbor Freight one. For engraving work your only doing very light cuts so HP is not a problem , any way even if it is not a true 1/4 HP. At least the motor dosen't work as hard as my Dumore and that one isn't cheap. I just flood the area with fluid, slow feedrates and let the cutter make slush....

I will add that before purchasing mine, i called them and asked if they had other handpieces and when they looked they found that you could order one with collet or chuck and i got both.

To fix the play you just lightly heat the end of the handpiece to loosen the epoxy / locktight / crazy glue and screw the end off. Then you shim
the play out by adding spacers. You test the handpiece by running it and if the bearings get hot reduce the spacer. I would guess that i have .0005" of end play. You need to reduce it or your engraving will look like crap or you'll break those nice graving cutters.

RICH
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 13, 2010, 10:58:57 PM
Just use your existing cutter to make yourself a set of mounts for the HF handpiece.  That's what I did.  Actually twice.  Once for a single cutter, and one to hold two of the HF handpieces so I could destroy work pieces two at a time.  
Title: Re: High speed spindle recommendations
Post by: Hood on August 14, 2010, 08:41:58 AM
Thanks Rich, Bob et al, I have found a similar looking one here, lot more expensive than the USA but thats the way things are here :(
http://www.axminster.co.uk/axminster-axminster-heavy-duty-flexible-drive-unit-prod20091/

Hood
Title: Re: High speed spindle recommendations
Post by: RICH on August 14, 2010, 09:06:18 AM
Hood,
Looks like a good choice and would recommend you get both hand pieces ( collet and drill ).
The drill chuck on mine was just as good as the Jacobs collet ( about .002"  runout at the jaws ) but it had a rough /bad / tight feel when tightening a the cutting bits in it.

Here is a link to a few holders i made for the hand peices. This way i can easily mount  them on the lathe , mill , and engraving machine.
http://www.machsupport.com/forum/index.php/topic,12484.msg88231.html#msg88231

RICH
Title: Re: High speed spindle recommendations
Post by: RICH on August 14, 2010, 09:33:52 AM
HOLDER COMMENTS:
- Drill and ream block for holder OD
- make the holder such that it "springs" some to insert the holder ( the bearings are at the ends of the holder)
 that's why there are relief cuts in the block on mine
- with the holder mounted in the block, set up to machine the block so the base, sides, front & back are parallel with the handle center line
- do the base first and check with a piece of small ground stock inserted into the collet / chuck and check for runout at the tip of the bit /
  want it to be as good as possible ( match mark the handle and block for repeatable insertion of the handle into the block)

Just want to make later setup easy ie; can use a master square to set the holder.
If not done right you'll break small drills and end mills in a heart beat.
Naturally the less run out the better. Engraving line width will be determined by the runout, and should you do real fine stuff it becomes important.

FWIW,
RICH
Title: Re: High speed spindle recommendations
Post by: Hood on August 14, 2010, 09:36:13 AM
Looks good Rich, will have to study when I get home, doing a dozen things at once here today ;D

Hood
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 14, 2010, 12:56:53 PM
The drill chuck on mine was just as good as the Jacobs collet ( about .002"  runout at the jaws ) but it had a rough /bad / tight feel when tightening a the cutting bits in it.

I had that with my HF chuck keys.  One was better than the other so I took a look at them.  The center pin on one was longer than the other.  I ground it off and now both feel better.   I may grind it a little more and see if it feels perfect or not. 
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 18, 2010, 04:42:03 AM
I am using a Dumore 1/4HP flex shaft die grinder (22,000 RPM) mounted in an aluminum block that bolts to the side of the head. I have had this tool for about 30 years. It was expensive back when I purchased it new and now is somewhere around US$ 1,000 methinks. You might find one used, but I'll be taking mine to my grave as would most owners. Shown in operation here:
http://www.youtube.com/watch?v=r9Zf_5yHB1I

If runout and longevity are concerns, you would want to avoid the hobby level stuff like Fordome, etc. Use something that is intended for high speed grinding in a shop environment. An interesting thought would be to get a used Dumore tool post gringer and mount a 1/2"-20 mounted ER-16 collet holder on the end of the shaft. These grinders are pretty common on ebay. Runout would be the challenge with such a setup, I would imagine. Runout and dynamic balance are the critical issues in this application.

I built a mount and drive setup for a fellow to drive an industrial engraving spindle using a laminate trimmer motor thru a round belt setup, but I think that air turbines are the best solution. Note that these tools are very different from a vane type air die grinder or similar tools that are extremely noisy and require oiled air.

If I were inclined to go the 'mount-an-inexpensive-die-grinder' rout, I would probably use this one: http://cgi.ebay.com/Metabo-GE700-3-7-000-27-000rpm-6-2Amp-Die-Grinder-NEW-/330461681654?pt=LH_DefaultDomain_0 It has good reviews, a steel nose for mounting (very important), good speed and power (electronic torque comp), and comes with a 1/4" collet and most importantly for engraving, it has a factory 1/8" collet option available for it.
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 18, 2010, 05:19:15 AM
Here is a link to a promo video of turbine tools:

http://www.youtube.com/watch?v=SWovmvEwPR4

It seems to me that you would need to use a lot of shop air for engraving anyway to keep the tool cool and the swarf cleared away. It would be convenient if the turbine exhaust could be directed at the cutting tool. I don't know if that scheme is acceptable, but it would be zero cost air if it was.

Below is a link to the spindle that I made the mount and drive pulley setup for as mentioned in the previous post. The spindle was beautiful. Pure mechanical art:

http://www.artcotools.com/nsk-nakanishi-pulley-spindle-c-327-p-1-pr-17011.html
Title: Re: High speed spindle recommendations
Post by: Hood on August 18, 2010, 07:50:53 AM
Thanks for the info Simpson, that stuff does look good but for my small scale needs the cost is too much I am afraid. As for using the air to cool the tool I use flood coolant so no air consumed at the moment.

Hood                                                           
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 18, 2010, 08:07:11 AM
I am planning to add flood myself and that was one of the attractions of flex shaft or air turbine  . . . immunity to water.  I know you have flood already, but you planning to use that for engraving? That seems like it would be a bit uncommon for engraving.

An economy approach to an engraving spindle would be an even less inexpensive (or used) die grinder mounted on your mill head. That's really the quick and dirty, but besides the end play issue you already mentioned, I do think that most consumer level products are only going to last a few hours in production.

I am making a permanent engraving head from a new surplus 30,000 RPM tool motor (ebay) to belt drive a straight shank ER16 coller holder running on hgh speed bearings in a simple casing made from DOM tubing and mounted on the mill head. This will satisfy three objectives in my application:

1) save the wear and tear on my poor much abused Dumore flex shaft grinder. (the replacement shaft costs more than many complete die grinders)

2) allow me to use 3/8" shank tool bits as well as the normal 1/4" and 1/8"

3) provide for easy ratio changes should I need more RPM or more torque for a particular job.

I have no doubt you could fab up someting similar if that sounds like it would be a useful approach. If you want to feally fast, a drop to ER-11 or 'universal' double taper would be mo' better
Title: Re: High speed spindle recommendations
Post by: Hood on August 18, 2010, 08:44:46 AM
Use flood for everything I do ;D Well except inserted cutters as they tend to like to cut  dry, especially  on the 316.

If this was going to be production I would definitely be buying something of high quality but its likely to be only a few a year so no point in splashing out, after all I am a Scot ;D
Have been toying with the idea of making a small spindle and driving with one of the model aero DC motors but I have found out someone I talk to on Skype is about to do the same so I will wait and see how his turns out :)

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 18, 2010, 09:41:17 AM
Flood cooling at 22K RPM will make a big mess. Hope you have a full mill enclosure . . .  ;)  I have this funny mental image of the operator standing there in one of those huge yellow 'lighthouse keeper' type of rain suits.

Below is the 'spindle' I am thinking about. I already have a 1" shaft ER32 version that I bought some time ago and have never used, but that was not intended for engraving speeds. For 22K, you could use this, methinks:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=150477898066&ssPageName=STRK:MEWAX:IT

Also at 'only' 22K you can use a GT3 tooth belt, or a small v-belt or a flat belt. Belts are rated in linear FMP, so just keep the pulley diameter small and you'll be good to go.   
Title: Re: High speed spindle recommendations
Post by: Hood on August 19, 2010, 02:23:41 AM
Not a full enclosure but the table has a guard round  three sides, the front having a removable perspex door, so no oil skins required :)

I have a DA pencil collet that I was contemplating using as a spindle but that ER is a great price.

Did make up a spindle speeder of sorts which was geared via a toothed belt but it got too hot to touch after about 3 mins running and the heat seemed to be coming from the belt friction on the pulleys, was thinking of directing some coolant through the body but not sure how the bearings would like it, would have to filter it and may give it a go.



Hood
Title: Re: High speed spindle recommendations
Post by: RICH on August 19, 2010, 05:52:20 AM
A friend made something similar to what you show in the pic. He basicaly took the hand grinder added a pulley to it and used a small motor and was belt driven. Works fine, but would have been just as easy to use the flex shaft. I have run the flex shafted one on my end for 4 hours continously at one time
( say worst case ) and the handle just got warm, motor got hot though. My friend had the heat problem with his setup. I guess it all depends
on how roburst you want to make it and what your going to do with it. Some of the high speed expensive spindles have around 1000 hrs life max before they must be sent back and rebuilt and purchase and rebuild is not cheap.

As far as the using the ER, not worth making the holder unless you can grind the shaft if making it. Even if puchased you will have additional runout due to length. Again depends on what you intend to due with it.

RICH
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 19, 2010, 07:37:30 AM
Not a full enclosure but the table has a guard round  three sides, the front having a removable perspex door, so no oil skins required :)

I have a DA pencil collet that I was contemplating using as a spindle but that ER is a great price.

Hood, beware of these Chinese collet holders. Bought few BT30 holders (from another Chinese seller though) and accuracy is not something these were built for. The quoted 0.01mm runout appeared to be not the worst case like you'd expect, but the best tolerance they can achieve. Actual runout measured on 5 holders ranged from about 0.02mm to 0.25mm (I didn't miss a zero there)!!!

Did make up a spindle speeder of sorts which was geared via a toothed belt but it got too hot to touch after about 3 mins running and the heat seemed to be coming from the belt friction on the pulleys, was thinking of directing some coolant through the body but not sure how the bearings would like it, would have to filter it and may give it a go.



Hood

Round tooth profile belts perform better at higher speeds. They engage better with the pulley, with less friction, and thus less heat (and noise) is produced. But I assume this is what you already have... What speed are you running the driving pulley at? And what diameter is it? I have 75mm diameter pulley that would run for hours at 3500RPM without getting that hot. I am sure I could run it even at 5000RPM much more than 3 minutes and not get that hot. May be check the tension?

Anyway, the best choice for a high speed application is a V-belt, or any belt other than timing belts. Or put it another way, timing belts are least suitable for high speed applications because their teeth engagement and disengagement with the pulley teeth produce a lot of noise and heat at high speeds. You don't really need a timing belt there - no angular positioning needed and no big moments to be transferred - so may be put a V-belt or even an O-ring belt and see if it helps. It really should, unless there is another source for the heat.

Daniel
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 19, 2010, 09:33:41 AM
There is an amusing engineering expression: 'A Camel is a horse designed by a committee'.

In engineering a mechanical assembly, you should start with objectives and parameters and then design to satisfy your targets. For example, you don't make a soup spoon out of titanium just because titanium is 'better'. Running hot is not automatically bad, either. Heat is actually beneficial in many cases. Just don't exceed the specs.

If there is an unlimited budget, then the smart move here it to simply plunk down the cash and purchase a high speed spindle, electric or air, as desired. However, the primary parameter here has been stated by the 'customer' as cost, so living with the tolerances offered by 'cost effective' solutions is simply a necessary part of this particular project. It is unrealistic to expect .000000000001" runout for 25 bucks.  ;)

A good example is the heat issue. Aluminum is obviously better at getting rid of the heat, so you would want to make the body from aluminum . . .  but only if you can tolerate the accuracy loss generated by the clearance you would need to design into the bearings to accommodate the expansion difference between the aluminum casing and the steel shaft within. If you are using high clearance ball bearings, probably not a problem over 4" distance. On the other hand, if you have a precision angular contact set, the expansion difference will erase your pre load . . not good.

Bearings have a temp spec. Hybrid ceramics can take a lot more heat and are not nearly as expensive as full ceramic. Simply using a cutoff tool to make  . . oh, say 20 or so radial grooves .100" x.100" cut into the casing OD may provide adequate cooling for hybrid ceramics, which run hot, but thats perfectly OK.  Clamping aluminum mounting blocks right at the bearing sites will draw off a great deal of heat as well. Then you could get fancy and cut cooling fins in the mounting blocks . . etc, etc.

A left a question unanswered some time back, so here is the answer: For my previous little X2 mill, in order to run the spindle at 7,500 RPM, I simply attached an old Pentium 3 aluminum heat sink to the side of the head. That was enough to keep the beargins in spec. Low tech, cheap, ugly, but completely effective.
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 19, 2010, 10:02:52 AM
A left a question unanswered some time back, so here is the answer: For my previous little X2 mill, in order to run the spindle at 7,500 RPM, I simply attached an old Pentium 3 aluminum heat sink to the side of the head. That was enough to keep the beargins in spec. Low tech, cheap, ugly, but completely effective.

Thanks Steve.

Daniel
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 19, 2010, 10:49:14 AM
May be worth a try:

http://cgi.ebay.com/Water-Cooled-CNC-Spindle-Motor-1-5KW-2HP-Engraving-ER11-/170513456929?pt=BI_Tool_Work_Holding
Title: Re: High speed spindle recommendations
Post by: Bob La Londe on August 19, 2010, 11:00:03 AM
Just FYI....  I have over 100 hours on one of the Harbor Freight tools at continuous duty at maximum speed (15K).  The handpiece is starting to exhibit noticeable side play.  I would no longer trust it with high feedrate for the smaller tools, but its still fine for rough work with a 1/8" ( 3mm apx ) ball cutter.  I have not tried to adjust it yet.  That being said it still has less side play than the stock setting for  Foredom 44T.  I now have a Foredom 25 hand piece which Foredom reccomended for continuous duty production work.  They claim side play is about .00015" ( .004 mm apx ) and that it has much larger bearings to hold up to continuous duty and reduce heat buildup.  It is slightly larger diamter so I need to make a new set of mounting clamps for it before I can test it.  I know these are not as fast as you are looking for at 15K with the HF motor or upto 18K with some of the Foredom motors, but I figured since its what I have direct recent experience with I'ld keep you posted for background information.  
Title: Re: High speed spindle recommendations
Post by: Hood on August 19, 2010, 05:49:40 PM
Rich,
 I wanted to do it the way I did as it meant I just had to pt it in the spindle and the spindle would do the driving, just a stabiliser bar needed and full quill travel would be preserved.

Dan
 It was belts and pulleys I had lying around, so not sure what the profile of the teeth was and cant took as its at the workshop. Think the belt is spec'd at 100 deg C but it was the housing and bearings getting that heat that worried me more. Maybe should borrow my friends laser temp gauge and see if it gets hotter on extended runs, maybe just gets to that temp and sticks there.

Belt is 2.5mm pitch and I was running 3000rpm at the spindle and the output would be 11250 at that spindle speed.

Vee belt probably would have been my choice but as I already had the belts and pulleys I decided to use them, not sure how an o ring would do, may give it a go as pulley would be simple to make up. Wont use the cutter I have though for the testing as at  £22 an insert I dont want to break it until I am sure it works.


Simpson

My design process starts usually with what I have lying around or can get cheap ;D   I had a  1/3 sheet of 19mm thick 5083 alu left from a job and the belt and pulleys so that's where I started my design. Not the best way I know but........
The body was made of Alu and this may actually be the reason I feel the heat so quickly and as said above I really need to test a bit more as its possible that it ma not get much hotter with time, or is that a stupid thing to hope for?

Water cooled spindle looks good and I know a few that have them and seem to think they work well but will wait and see what my needs for the high speed are in the future as at the moment it doesn't really justify any more that £100 with the amount I do.

Hood



Title: Re: High speed spindle recommendations
Post by: simpson36 on August 19, 2010, 06:51:13 PM
My design process starts usually with what I have lying around or can get cheap ;D   I had a  1/3 sheet of 19mm thick 5083 alu left from a job and the belt and pulleys so that's where I started my design. Not the best way I know but........
Actually, you have just described probably THE most common design criteria. GM used the same front suspension and steering in full size cars from I think 1955 or so until 1965 and then continued the same setup on the Corvette all the way to 1982. Somebody somewhere was definitely saying "use what we have!". I just finished a very large project that had the same criteria up front. It takes an act of congress to get approval for a new component.
Quote
The body was made of Alu and this may actually be the reason I feel the heat so quickly and as said above I really need to test a bit more as its possible that it ma not get much hotter with time, or is that a stupid thing to hope for?

Not at all. The aluminum getting hot is exactly what you want. That means it is drawing the heat out of the part. All you need to do then is take the heat off the aluminum, hence my comments about the exterior arrangement. Fins, fans or fluid, as they say.




[/quote]
Title: Re: High speed spindle recommendations
Post by: Hood on August 19, 2010, 07:21:45 PM
Well I used to be into overclocking computers and got quite handy with the cooling, even had one CPU cooled down to -15 deg C ;D
Going to borrow the thermometer and do some more testing, maybe a waterjacket of some sort will be the easy way, seeing as how I use flood  :)
Hood
Title: Re: High speed spindle recommendations
Post by: Sam on August 20, 2010, 01:04:35 AM
Might as well throw my two cents in, I suppose. If it were me, and I already had a method of driving the spindle, I would go with the collet extender. Everything is pretty simple to make/repair. If a bearing goes out, no biggie, spend a few bucks and get a new set. Better yet, get a few and save on shipping, and when they need replaced, your back in action in a short time. You also have a wide range of collet sizes to choose from. You've already got a lathe and more than enough "know how" to make it, and with your expertise, you can produce a spindle MUCH better than any cheap engraver on the market. If something goes wrong with one of those, your most likely just stuck with replacing it, and putting your project on hold until a new one arrives.
Here's one on the zone Henrik made. http://www.cnczone.com/forums/showthread.php?t=41200&highlight=spindle+design&page=4 (http://www.cnczone.com/forums/showthread.php?t=41200&highlight=spindle+design&page=4)
Have you thought about using link belting? I've never used them, but have heard great things about them from several sources. Swede from 5 bears is where I got the idea for them. http://www.5bears.com/vfd02.htm (http://www.5bears.com/vfd02.htm) If I had to take a guess, since there's less contact area, they probably produce less heat.
Title: Re: High speed spindle recommendations
Post by: Hood on August 20, 2010, 03:56:02 AM
Sam
 not quite sure what you are meaning by a collet extender? Making a spindle wouldnt be a big issue for me, its the increasing of the speed that seems to be my problem although after the last few posts maybe just changing the pulley/belt type will solve that problem.

As to the link belt, I use that all the time on the fishing boats I repair, its great stuff and much better than the older style that had metal pins. With the corrosive environment, especially in the smaller craft (under 10m), the steel pins would rust and soon chew their way through the links but the new style has no steel pins so lasts well. For my application though it wouldnt be much use as the pulley diameter is too small :(

Hood
Title: Re: High speed spindle recommendations
Post by: rcaffin on August 20, 2010, 06:07:25 AM
PreciseBits have a nice ER16 collet chuck on their front page - exactly what you want. 20 mm shaft on it, and TIR very small - 0.0002". Put good bearings top and bottom and drive with a decent motor and a speed-up belt.

Cheers
Title: Re: High speed spindle recommendations
Post by: Hood on August 20, 2010, 06:34:20 AM
Did a wee bit of testing this morning, first thing I did was open the box up and replace the toothed belt with an 'O' ring, not ideal as it was driving on the toothed pulleys but was fine for my testing purposes. I never put the mid section back in so I could see what was going on. Spun it up and let it run for 15 mins and there was only a slight increase in the temp. That got me doing a dangerous thing, I did some thinking ;D I was wondering if the air was helping things cool as the pulleys were basically acting as inefficient fans and I could feel the air flow if I put my hand near it. Replaced the 'O' ring with the toothed belt and again gave it a run for 15 mins and it did increase in temp but was nothing like before, I could comfortably keep the back of my hand on it.
I am now thinking I should be able to incorporate some cooling channels in the housing and put the coolant into the top and let it run through the Alu and out at the bottom and direct it via some lok-line onto the cutter, wish me luck ;D

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 20, 2010, 07:06:48 AM
Round belts ('O'-ring, doughnut, etc) are very good for extreme speed, but I would be hesitant to use them where any swarf or cutting fluid could get on them. The newer tooth belts with curvilinear teeth (GT3, etc) run quiet and cool and have stupidly high power ratings for their size. i.e. you can use a belt that looks (to my old eyes, anyway) far too small to handle the power, but it clocks along for years even with exposure to contaminants. The older trapezoid teeth are a different matter and I don't recommend them for high speed.

The terms 'collet extender' 'collet adapter' and 'collet holder' seem to be used somewhat interchangeably. The item on PreciseBits appears to be 1/2" and not 20mm and also looks too short to use the shaft as an axle . . .  unless I missed something.

O1111 (off topic rant)  >:(
Something that was impossible to miss on the PreciseBits site was the prominent blurb on the company's Christian roots and belief in equality of all people and in the US constitution . . . . . on the same page with a big red banner supporting the new Arizona immigration law which is being challenged as unconstitutional and which clearly presumes all Mexican people to be fundamentally inferior, unwelcome and having criminal intent. Arizona will undoubtedly next pass another new law bringing back the Inquisition.
M99 (End of Rant)
%  
Title: Re: High speed spindle recommendations
Post by: rcaffin on August 20, 2010, 07:46:48 AM
The item on PreciseBits appears to be 1/2" and not 20mm and also looks too short to use the shaft as an axle . . .  unless I missed something.
Oops on the 1/2" bit - I was thinking of another collet chuck. Sorry!

The shank on the PreciseBits one is maybe a bit short, but I have seen others which are longer - up to 160 mm long shank. That might do?
Mind you, with good bearings, even the short one sold by PB would do for anything without huge side-loads.

Cheers
Title: Re: High speed spindle recommendations
Post by: Hood on August 20, 2010, 08:35:56 AM
Ha ha I think I will leave American politics to Americans so no comment from me regards that :)

I have a DA pencil chuck so if I go down that route it is what I will use but thanks all he same.

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 20, 2010, 08:49:20 AM
Hood,

It's going to be an interesting project with the cooling channels ;)

I would still replace the timing belt with a V-belt or O-ring. Timing belts are just not designed for such high speeds. What matters for a belt is not the RPM, but rather the linear speed it runs at. A 20mm diameter timing pulley carrying a belt and revolving at 3000RPM would probably have no issues, but a 100mm pulley rotating at the same speed would mean a much higher linear speed of the belt and wouldn't be OK.

I have a grinder which I built few years ago and it uses O-Rings for driving the shafts. Have never had an issue with them, and they transfer quite a moment compared to the spindle speeded you built. The pulleys have a round profile to match the O-ring. Was pretty easy to make them. I ground a HSS tool bit to the appropriate radius.

Dan
Title: Re: High speed spindle recommendations
Post by: Hood on August 20, 2010, 09:07:27 AM
Daniel
 The driver pulley I am using is about 45mm OD and will be spinning at about 3000 to 3800rpm, the driven pulley is approx 12mm OD so will be going 3.75 times faster.
'O' ring or vee may be the way to go but as drilling cooling holes will probably be done whichever way I go I will try it first with the timing belt.
Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 20, 2010, 09:48:01 AM
Hood,

Oh... so speed is not really an issue I would say. You could get by with the timing belt and the cooling. Another thing is that if you wanted a quieter and smoother operation, then an O-ring would be beneficial. Unless you've already made your decision about drilling cooling holes in whatever case or you have other reasons for it than the heat generated by the belt, I am pretty confident that an O-ring configuration wouldn't need them.

Daniel
Title: Re: High speed spindle recommendations
Post by: Sam on August 20, 2010, 10:13:35 AM
Quote
not quite sure what you are meaning by a collet extender?
Same thing Simpson is talking about.
Good to hear about the link belting, as I'm planning on using some of it.
Title: Re: High speed spindle recommendations
Post by: Hood on August 20, 2010, 01:46:21 PM
Daniel
 holes bored will be the quickest and easiest, if it doesnt work then I will look at vee or 'O' ring.
On that subject, how tight do you need the 'O' ring, does it need stretched a bit or just enough to not have  any slop?

Sam
 Ok thanks and yes the belts are good in boats where the bilges are full of salt water, diesel oil and all sorts of other nasties so should be fine almost any other place :)

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 20, 2010, 05:38:13 PM
"Timing belts are just not designed for such high speeds"   This statement is inaccurate. For those who prefer observation over engineering specs, note the black thing on the front a blown top fuel dragster engine  . . . 10,000 RPM 6" dia pulley . . do the math . . . or the primary drive of a custom Chopper (motorcycle), or the dry sump oil pump on indy cars or perhaps just the cam drive on many modern automobile engines. In machine tools, some surface grinders have 'timing belt' drives on the grinding wheels.

And . . .  all of these real world examples use the OLD trapezoid tooth profile. The newer curvilinear profiles are far better. Flat belts have been used for years for high speed applications like tool post grinders and so on because they are less prone to whipping like V belts which have a much larger tangential cross section. A 'timing belt' is similar to a flat belt in dynamics, except that there is no slippage, which coincidentally is actually where the heat comes from in v-belts, round belts and flat belts.

Round belts come in two types; elastic and corded. Example of elastic are vacuum cleaner belts. Belts with chords don't stretch (much) and you must follow the manuf specs for the type of belt . . specifically the type of chord.

In any case, no matter what belt drive setup is chosen, the amount of heat contributed by the belt is minuscule. The heat comes from the bearings.
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 21, 2010, 06:56:06 AM
Hood,

Yes, extra cooling sure wouldn't hurt in any case. Especially if it's so easy to do ;)

An O-ring is stretchable by nature and I don't know of any 'scientific' recommendations for its tension. And here is its advantage, I think, you don't need any tensioning mechanism. I designed my drives so that the O-ring is a bit stretched - about 5mm shorter than required (if memory serves me well) worked fine for me. But it would depend on the overall length of the belt. Mine were made from long stock O-ring, cut to size and melt joined the ends.

Steve,

Correction: V-belts work better at high speeds. Much better in most cases! Timing belts produce noise (and heat) as the speed increases - this is a fact! As the speed increases you have to consider for precise aligning of the timing belt. As the speed increases the teeth wear becomes more of an issue. For high speed application not requiring positive belt grip don't use timing belts. There are big industrial lathes with spindle speeds to 18,000RPM capable of rigid tapping which use poly V belts - NOT timing belts.

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 21, 2010, 07:58:51 AM
Thanks for the info Daniel, will see how the cooling goes and decide from there, may even make a wee gearbox up as I found some nice gears from an old encoder drive thing ;D
Cooling holes have been drilled and seem to be fine, just have to dismantle and rebuild with the shafts/pulleys/belt in place and test it out, only problem is I need to replace the driveshafts in the van today so wont get a chance to test it out.

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 21, 2010, 08:39:02 AM
"Wee Gearbox"... hmm... sounds good, but what is it anyway :D

Daniel
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 21, 2010, 08:51:15 AM
Timing belts produce noise (and heat) as the speed increases - this is a fact!

I agree with you on this point, although it also applies to belts of all types.

Since we cannot agree on v-belt vs timing belt, perhaps we should compromise on a grooved belt . . . a.k.a.  'serpentine' as it is commonly called in automotive applications.

This would avoid the single disadvantage of timing belts . . they cost several times more than v-belts.

In this way, I can be satisfied with it's 'flatness' and you can find joy in it's  . .  'V' ness.  ;)

Seriously, a groove belt is an alternative worth considering because it fall in price between the 'timing' belt and the 'V'-belt and the pulleys are stupid easy to make and since the grooves are shallow, the pulley can be small in dia . . . . so long as it stays within the flex radius spec so we can be scientific.  8)
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 21, 2010, 09:09:42 AM
I agree on the Poly V-belt (or a grooved belt like you say) ;) Already mentioned it being used on industrial lathes. Not sure about the pricing though - was getting mine for ridiculously low prices - something like $5 for a 17" XL belt. Much cheaper than the polyurethane reinforced V-belts I've been buying - about $20 for about the same size belt. But then it may be just my supplier ;)

Daniel
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 21, 2010, 11:23:03 AM
Seems we are on the same page, albeit in different scales and with some symantics. I recall you are in the middle east and I am in the USofA.

Big multiple V-belts as one would find on a machine tool are called 'banded' or 'ganged' in my world. Also big V-belts can be had in 'matched sets' (matched for exact length, but separate belts.)

The little brother is called 'grooved' or 'ribbed' and in automotive speak is a 'serpentine' belt, although that desribes the arrangment and not the belt structure. A difference, (other than the obvious  . . . size) is that the grooved belt has traction material on the smooth side which is intended as a drive surface in a serpentine arrangement.

I'm not clear on which belt type 'poly v' refers to, but it seems that you used the term for both a big machine tool and Hood's little engraving spindle, so it seems the term is somewhat universal. And yes, your are right about suppliers also. A 'grooved' belt purchased from an industrial supply house might be $10. But the identical 'Serpentine' belt from an automotive store is $38.  :-X    Go figure.
Title: Re: High speed spindle recommendations
Post by: Hood on August 21, 2010, 11:52:16 AM
"Wee Gearbox"... hmm... sounds good, but what is it anyway :D

Daniel

Well I will assume you know what a gearbox is so it must be the "wee" bit you don't understand ;D
Wee is small  :)
Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 21, 2010, 01:41:48 PM
Thanks Hood ;D

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 23, 2010, 05:11:49 PM
Did a bit of testing today with the coolant running through. Alu was cold after half an hour at 3000 rpm input. Output shaft was a bit warmer but nothing like it was before, I could quite comfortably hold the back of my hand against it :)

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 24, 2010, 02:11:06 AM
Good results :)

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 08:12:09 AM
Well its actually not ;D
Decided to let it run while I was welding up a stainless anchor, after about half an hour I heard the sound change, went over to the mill and the output was not turning very fast. Felt for heat and it was ok on Alu and shaft like yesterday so removed from spindle and hauled it apart. Belt was all stretched and misshapen like it has had too much heat.
 Going to think about things and decide the next move.

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 24, 2010, 08:21:57 AM
Oh... sorry for that. It's strange. Must be something wrong with that particular belt you used or the pulleys. May be they were not meshing correctly... may be didn't have same tooth profile. Otherwise, I think, the speed was not that high to cause what you described. Could be a bad alignment of the pulleys...?

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 10:09:37 AM
Ha ha no sorry thoughts needed. Its been put down to experience :) Its how we learn, if you dont make mistakes or fook ups you are doing something wrong, secret is to move on and learn from the mistakes :)

Belt and pulleys I think are matched but as I never bought I cant be sure, they do look ok though. Pulleys were running true and tension seemed fine.
Gears sound like they may be my next move as it will hopefully allow me to keep things more in line with the spindle.

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 24, 2010, 11:16:27 AM
Wasn't this project for a 22,000 RPM spindle?
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 11:32:50 AM
20,000 it was  but 1475 would have been fine for a start, especially as that was what the pulleys in stock would give ;D

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 24, 2010, 11:44:19 AM
Sorry to be dense, but I'm not following this at all. How do you engrave at 1,475 RPM   ???
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 11:55:09 AM
Sorry to be dense, but I'm not following this at all. How do you engrave at 1,475 RPM   ???

easy, you put a zero at the end of that ;D should be 14750
Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 24, 2010, 11:59:19 AM
So where does the 3,000 RPM fit into the puzzle  ???. . .  3,000 at the motor and 14,750 at the spindle? Is that what you have?
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 02:21:51 PM
My spindle on the Beaver Mill has 3800rpm top speed the way I have it connected. The gearing in the speeder I made is 3.75 times so that gives me the 14250 (14750 was another typo ;D ). I have been testing out at 3000 rpm spindle speed so output was 11250.

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 24, 2010, 02:46:37 PM
Hood,

Are those gears you found ground? Otherwise don't think it would be a good idea to spin them at the speeds you like...

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 03:08:11 PM
They are very nice quality anti backlash gears from an old Bullard lathes encoder/switch housing. They are possibly a bit on the light side but time will tell :) Not sure what speed they would originally have done, will have to put them back in order and see if I think they will do.

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 24, 2010, 05:18:06 PM
Wow :o  I did not realize you were trying to drive the high speed engraver off the main mill spindle. Almost 4:1 speed increase with a single belt is pretty optimistic.  Going the other way is a whole different animal. If you are now thinking about using gears, you would be well advised to seek out a planetary set. Consider yourself so advised  ;)

In my setup, I am shooting for 40k to 50k rpm, but I'm starting with a pre-balanced 30,000 RPM tool motor.  In any case, good luck and please keep posting your results. This is interesting to follow.
Title: Re: High speed spindle recommendations
Post by: Hood on August 24, 2010, 05:37:32 PM
Wow :o  I did not realize you were trying to drive the high speed engraver off the main mill spindle. Almost 4:1 speed increase with a single belt is pretty optimistic.  Going the other way is a whole different animal. If you are now thinking about using gears, you would be well advised to seek out a planetary set. Consider yourself so advised  ;)
Ok I will take that onboard :) Now what about this idea, this was actually my first but it ended up going by the wayside. I have some small Alpha in line planetary gearboxes that are meant for servo reduction. I was planning on driving it arse for tit and then I discovered the Input (which would be the output) relied on being clamped to the motor shaft. No probs I thought, housing, angular contacts and job done. I then looked up the spec and it says 6000rpm input speed so I decided against it. I am thinking it may be worth a shot, have a couple of angular contacts and would be simple to make up a housing and shaft. If the box screws up its no big deal as I got 2 of them for £12 :)
So what do you think?


In my setup, I am shooting for 40k to 50k rpm, but I'm starting with a pre-balanced 30,000 RPM tool motor.

Thats quite a bit faster than I need, tool I have is rated to 20,000rpm in stainless I think so anywhere between 15 and 20K would suit me.

In any case, good luck and please keep posting your results. This is interesting to follow.


Interesting as in funny watching me screw up? ;D

Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 24, 2010, 08:03:43 PM
I am thinking it may be worth a shot, have a couple of angular contacts and would be simple to make up a housing and shaft. If the box screws up its no big deal as I got 2 of them for £12 :)
So what do you think?
Hard to say without knowing the ratio, but if I am thinking correctly, the original input shaft should be the center pinion and the output would be the planets, so 'arse for tit' the high speed would be the center pinion driven by the planets, which is a good arrangement for a speeder. The gear set will *probably* hold up if the planets are on (or can be put on) needle rollers. I'd say go for it. You are likely to have vibration issues, it will just depend on how bad they are and what kind of effect they have on your finish.
Quote
[50,000 RPM is] quite a bit faster than I need, tool I have is rated to 20,000rpm in stainless I think so anywhere between 15 and 20K would suit me.
The point I was making here is that the speed change ratio is minimized if you start with a source closer to the target speed.
Quote
Interesting as in funny watching me screw up? ;D
We all get a 'turn in the barrel' so to speak. I specialize in frying electronic components. I get paid to know about things mechanical, so it is more embarrassing when I break the hard stuff.
Title: Re: High speed spindle recommendations
Post by: Hood on August 25, 2010, 06:26:29 PM
 Been a busy day but I did get a chance to look at the gearbox, its a 3:1. I put the output shaft in a collet holder and spun up the spindle, first a few hundred RPM to make sure the body was easy to hold still then 1000 then 3000. After about 3 mins the body was too hot to hold so looks like its back to the drawing board.
Best option is obviously a motor that can spin at that speed whether its a separate motor or one of the various spindle that have been mention in this thread.
Think the project will go on the back burner for the time being and will just keep my eyes open for a deal :)

Hood
Title: Re: High speed spindle recommendations
Post by: Dan13 on August 26, 2010, 01:13:25 AM
I am sure you'll find a good deal - it often looks like they are looking for you ;) Seems you trashed the O-ring idea though...

Daniel
Title: Re: High speed spindle recommendations
Post by: Hood on August 26, 2010, 03:00:24 AM
I am just a bit scared that the "O" ring would not have enough power, it would be fine for something like a grinder but for the cutters I use the slightest slippage would snap the carbide insert and at £22 each I wouldnt want that.
Hood
Title: Re: High speed spindle recommendations
Post by: simpson36 on August 30, 2010, 07:39:12 AM
I have acquired a spindle to build my high speed head. It has a 150mm long 12mm OD shaft, .0005" runout and ER11 chuck. The whole shaft has a 5mm thru hole.

This will ride on sealed hybrid ceramic bearings rated for 100,000 RPM.  I'm thinking I will make the casing from a piece of steel DOM tubing so that there will not be expansion issues. I may try an alternate design with an aluminum casing incorporating a spring washer on the upper bearing.  :-\

I have a dynamic balance now, but if it is not fast enough to deal with this spindle I have located a local motor shop that has a professional commercial dynamic balancer and will do a high speed armature or spindle balance for $150. With ER11 and a hollow spindle, I am not anticipating a problem . . unless the thru hole is off center . .  in which case the balance will be hopelessly bad and I will take advantage of the return privilege most likely.

Drive will probably be a flat belt for 50,000 RPM 1/8" bits and tooth belt for 25,000 RPM 1/4" bits.

Anybody else making progress?

Title: Re: High speed spindle recommendations
Post by: Hood on August 30, 2010, 09:41:17 AM
No not done anything and probably wont for a while.
Hood