Messages

751

General Mach Discussion / Re: High speed spindle recommendations

« 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.   

752

General Mach Discussion / Re: Switched out my PC and now Mach3 is unhappy

« on: August 18, 2010, 08:37:22 AM »

It may well be the built in parallel port. The computer I am using now has similar behavior if the built in parallel port is used at anything over 25K driver speed.

A MACH3 compatible dual PCI parallel port solved the issue completley for me. I posted here a while back the exact card that I am using, source for the card, where to get the drivers, etc. Just do a search and it should show up.  My computer tops out at 86K pulse rate, but the card seems to handle it fine. I run stable at 75k.

The card as I recall is something like $15 or less.

753

General Mach Discussion / Re: RPM readout showing negative numbers . . suddenly . . . WTF??

« on: August 18, 2010, 08:24:53 AM »

Never seen or heard about this before except with the driver a few revisions back and certain computers but unless you ave changed Mach Rev or Computer mobo then afraid I dont know
Hood

Thanks for the comment. Same computer, same sensor, same wiring, same operator (likely will prove ot be the problem ultimately). It is quite the mystery.

The only thing new is that I have introduced AC servo motors and 220V power, but even with all of that switched off, the DRO is still jazzed I went back to an older version of Mach and reinstalled including the pulse driver. Problem is still there. Next I guess I will delete the XML and reinstall again and reconfigure fro scratch.

My concern is that it is an interference issue and if so it may effect other more critical functions.

Incidentally, I am now an industrial AC servo drive convert. I just put an AC servo motor on my 4th axis that is about 1/3 the size of the DC servo and still has slightly more continuous torque rating. A little 200 watt AC servo motos on my X axis has more than twice the torque of the slightly bigger NEMA23 DC servo motor it replaced. Pretty impressive so far . . . .

Two words . . . AUTO . . .TUNING . . . 

754

General Mach Discussion / Re: High speed spindle recommendations

« 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

755

General Mach Discussion / Re: RPM readout showing negative numbers . . suddenly . . . WTF??

« on: August 18, 2010, 07:47:03 AM »

Thanks for the response.

Motor type is irrelevant in this instance. I am referring to Machs RPM screen readout (DRO) which is driven by a sensor (photointerruptor and shutter disk in my case) which is independent of the motor or drive type.

756

General Mach Discussion / Re: High speed spindle recommendations

« 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

757

General Mach Discussion / RPM readout showing negative numbers . . suddenly . . . WTF??

« on: August 18, 2010, 05:08:48 AM »

I did a search on this and have not found and answer, but I am sure it must be something simple.

Currently I am  installing Mistubishi industrial AC servo drives and therefor have beed tinkering around in the control box and reconfiguring Mach, but I did not change the BOBs  nor any of the sensors or wiring related to the spindle speed. I don't know when the RPM readout went south so I can't say exactly what I was messing with that affected it.

The signal from the sensor shows strong and clean on a scope and the BOB has indicator LEDs  that are flashing regularly as the spindle rotates. The readout is not only negative, but the readings are low  . . no pun intended . . for example it reads -750 when the spindle is actually running about 2,000 RPM. The readout does change and follows the spindle speed, albeit inaccurately.

758

General Mach Discussion / Re: High speed spindle recommendations

« 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.

759

General Mach Discussion / Servo Drive Review - Granite VXD-XE added. New TOP CHOICE drive.

« on: June 24, 2010, 08:27:06 AM »

Since the original review was done, the granite Devices VSD drives have undergone significant upgrades which brought the product into competition with the Dugong drive. Additionally, new firmware allows the Granite drive to control two motors (DC brush) which also makes the product price competitive with the lower powered drives.

I have had a continuous stream of requests to look at the Granite Devices product, but until the drive was further developed, it was not suitable for my application, and was too expensive to just purchase and review as a 'favor' to people.

Two issues have converged to make the Granite drive not only attractive, but necessary for my application. First was a very significant upgrade in the drives specs to 160V 40A. Second was CNCdrive's inability to add the needed features to the Dugong.

My 4th axis project has been at a standstill for months now waiting on promissed new Dugong features. With the Granite drive already having the feature set I need and now with the higher power that I also need, the higher cost of the Granite drive was more palatable.

Here is the link to the review: http://www.thecubestudio.com/ServoDriveReview.htm

As it turns out, while I was mostly interested in the feature set of the Granite drive, the exceptional performance alone would easily justify the higher cost in some applications. The same features that make the VSD suitable for the 4th axis also make it suitable for a servo powered spindle, either for a mill or a lathe. On balance, below are two excerpts from the updated review which summarize my findings:

UPDATE: 06/24/2010: the Whale3 remains the ”BEST CHOICE” among the smaller (100V/20A or less) drives in this lineup, but after adding and reviewing the recently upgraded Granite VSD-XE, it is now the TOP CHOICE .

While the Ganite VSD-XE is my TOP CHOICE for this review, that choice is weighted heavily with performance and features of the VSD-XE that the competing products simply cannot match in their current configurations. However, users requiring a 100+V/35A drive who do not need the features of the Granite product, and are not gong to use step multipliers, would most likely be happy with the less expensive previous winner, the Dugong from CNCdrives in Hungary.

760

General Mach Discussion / Re: 3D acceleration problems and choppy cuts

« on: June 23, 2010, 06:56:46 AM »

For comparison sake, here is a tiny chunk of the code for rotary engraving a fairy character, and the video showing the cut (done with a pen only). Cutting starts 40 seconds into the video. Note the size of the segments in the code and the smoothness of the resulting curves on the workpiece.

http://www.youtube.com/watch?v=sC2urdg_bqg

G01 A-1.2137 X-1.8734
G01 A-1.2185 X-1.8782
G01 A-1.2235 X-1.8829
G01 A-1.2283 X-1.8871
G01 A-1.2331 X-1.8908
G01 A-1.2375 X-1.8941
G01 A-1.2420 X-1.8972
G01 A-1.2465 X-1.8997
G01 A-1.2507 X-1.9020
G01 A-1.2552 X-1.9039
G01 A-1.2591 X-1.9056
G01 A-1.2633 X-1.9067
G01 A-1.2675 X-1.9076
G01 A-1.2714 X-1.9081
G01 A-1.2754 X-1.9084
G01 A-1.2793 X-1.9084
G01 A-1.2832 X-1.9081
G01 A-1.2868 X-1.9076
G01 A-1.2908 X-1.9067
G01 A-1.2983 X-1.9039
G01 A-1.3056 X-1.9006
G01 A-1.3132 X-1.8961
G01 A-1.3207 X-1.8905
G01 A-1.3283 X-1.8843
G01 A-1.3361 X-1.8776
G01 A-1.3440 X-1.8697
G01 A-1.3479 X-1.8658
G01 A-1.3490 X-1.8647
G01 A-1.3496 X-1.8641
G01 A-1.3499 X-1.8641
G01 A-1.3513 X-1.8647
G01 A-1.3566 X-1.8667
G01 A-1.3619 X-1.8689
G01 A-1.3734 X-1.8734
G01 A-1.3852 X-1.8773
G01 A-1.3908 X-1.8790
G01 A-1.3966 X-1.8804
G01 A-1.4022 X-1.8812
G01 A-1.4076 X-1.8812
G01 A-1.4126 X-1.8810
G01 A-1.4176 X-1.8798
G01 A-1.4221 X-1.8776
G01 A-1.4244 X-1.8762