Messages

1261

General Mach Discussion / Re: Routing Acrylic!!! Please Help!

« on: April 15, 2009, 04:09:44 PM »

If by 0 flute, you mean a burr type cutter (for fiberglass/carbon fiber. etc) definately not.

I would suggest for acrylic that you use high speed steel straight single flute.

You can use a two flute spiral cutter if your stock is thick enough to not try and climb up the cutter. It will be really tricky if you have a high speed spindle. When I have to cut plastic, I use the fastest feed that does not check up the edge and the fastest spindle speed that won't melt the plastic . .  which is usually still pretty slow.

I much prefer Polycarbonate as it is harder, stronger, and cuts fine with two flut end mills. Best again to use high speed steel made for aluminum which are high helix and poilshed.

Avoid carbide insert or brazed carbide cutters for soft plastics like acrylic unless you have some method of putting a razor edge on the carbide.

No matter what cutter, the best thing I have found for success is LOTS of very high velocity compressed air to keep the tool and the plastic cooled down and keep the chips from recutting or sticking to the tool. I've never used fluid on plastic so other than the caveat I mentioned previously, I can't comment on it's effectivness compared to air. 

1262

General Mach Discussion / Re: Opinion and advice - explain relationship of encoder to kernel speed

« on: April 15, 2009, 03:45:39 PM »

I'm a new kid on the block, so I'm afraid I don't know all the players around here, but I think I recall the name Greg being associated with the smooth stepper.

Just so I have this straight in my mind (I'm easily confused  )  . . .

The hold up is with implimenting something in smooth stepper, not in MACH, and the operation at issue here is hard tapping on a lathe. Is that correct?

If so , could someone elaborate on this a little for those of us who are newbies?

Thanks.

1263

General Mach Discussion / Re: 3.042.026 Fixtures broken

« on: April 15, 2009, 03:36:59 PM »

I'm not using anything special and I didn't dig into it at all . ..  primarily because I would not know what to look for as I'm a novice at this stuff.

Since I am just starting to mess with saved fixtures and tools, it jumped out at me when .026 worked differently and I thought I'd throw a heads up out there in case somebody wanted to look into it.

1264

General Mach Discussion / Re: Can two 36v power supplies be used in series to get 72v?

« on: April 15, 2009, 03:30:07 PM »

My apologies to all if I misdescribed the power supply. Not intentional . . . as I said, I'm not well versed in this stuff which is why I thought I should link to what I have.

Unfotunately I can only make an uneducated observation of things like a PC power supply which has several voltages supplied and assume there must be some simple way it does this.

I'm an engineer, but when it comes to electronic design, I'm at 'Electrons for Dummies' level, but I'm not afraid to risk asking stupid questions . . . . like . .

What is the difference between unregulated and switching? Are these mutually exclusive? Why would one be better over another.

1265

General Mach Discussion / Re: Opinion and advice - explain relationship of encoder to kernel speed

« on: April 15, 2009, 12:51:25 PM »

You mentioned you were in a hurry.

In a hurry + waiting on software guys = how old are you now . .  you may not live long enough . . .

If you did rig a DPDT switch, you could prove the theory, get your immediate need satisfied, and it would not interfere with any miracles that come down the road from the programers.

Just a thought . . .

1266

General Mach Discussion / Re: Routing Acrylic!!! Please Help!

« on: April 15, 2009, 12:46:18 PM »

Just general stuff:

Definately test any coolants on the acrylic before use. Some oils can cause permanent discoloration, clouding or even micro stress cracking in certain plastics . . . including arcylic.

Constant stream of high velocity compressed air, single flute cutter (two flute at most)

Consider using polycarbonate instead of acrylic.

1267

General Mach Discussion / Re: Can two 36v power supplies be used in series to get 72v?

« on: April 15, 2009, 12:37:23 PM »

THANKS guys!

This is exactly the sort of caveats I was looking for.

A wise man once said it is more important to know what you don't know than what you do know. I'm not good with electrons, so I appreciate the help.

I am capable of checking the items cautioned about. I am using a separate power supply for the electronics side of things and the Keling 36v goes only to the Gecko 203V drives, which are 'unkillable' per Gecko, so hopefully I can't do too much damage if I go ahead with this scheme.

However, I'm thinking it might be wise for me to buy the Gecko 320 and a little NEMA23 36v servo motor to play with first. I have the stepper thing pretty well figured out, but this will be my first taste of servos. Objective is to get some experience under my belt doing a usefull project (repowering my stepper driven indexer) before I do my next mill conversion . .  which will be 100% servo powered.

Thanks for the advice, much appreciated.

1268

General Mach Discussion / Re: Opinion and advice - explain relationship of encoder to kernel speed

« on: April 15, 2009, 09:31:40 AM »

Now, here is a new idea that occurred to me for a possible 'swap' method:

My spindle irection is changed by a Mach controlled relay on the DC power to the motor and it workes fine. I don't see why a similar setup could not switch the source of the power as well. Position 1 to the VFD (controlled by Mach) and then Position 2 to the  A axis output from the servo drive?

With this scheme, You would need only one Mach setup and could even switch the motor's power source with a Mach controlled relay. You would have speed control for turing and and indexing for single point threading when you run as a spindle and then switch the motor to A axis power for the other functions.

In my case, the servo drive yould be a Geckodrive 320 that is limited to 80v 20A which is probably not nearly enough for Hood's big motor, but for appropriate servo motors, unless there is something I'm missing, this seems like a workable solution.

Note that the above is for a lathe. For my purpose, I need both the mill spindle and 4th axis active at the same time.

1269

General Mach Discussion / Re: Can two 36v power supplies be used in series to get 72v?

« on: April 15, 2009, 09:06:39 AM »

Thanks for the replies.

The power supply: (KL-320-36 36V/8.8 or 9.6A) http://www.kelinginc.net/SwitchingPowerSupply.html

 . . have 3 sets of terminals, but internally they are all connected together, so it is actually only one output from one rectifier/transformer. There are three caps, but again they are in parrallel and connected to the same trace on the output.

So, refining the question a bit; using two of these powere supplies, can I use a 36v terminal from each power supply to drive steppers @ 36v  and then also series wire a set of terminals to get the 72v for the servo motor?

1270

General Mach Discussion / Re: Opinion and advice - explain relationship of encoder to kernel speed

« on: April 14, 2009, 12:01:49 PM »

Yes that is doable and is what I will be doing to get rigid tapping if the SS doesnt support it when I eventually get the mill finished. It would however be a lot of working out and coding. The easiest option would be to set up two profiles, one a mill and the other a Turn and when you wanted to do lathe work just start up the Turn profile, the A axis would be set as a spindle in it.
Hood

Again, I don't know who Terri is, but I was remebering the above comment from earlier in this thread from 'Hood'

Two profiles seems like a viable solution to me. What would make that solution impractical in your opinion?

As to the axis swap, I have written one program that does this sucessfully, but it was a real mind bender to get it right. Up is down, left is up, right no longer exists, that type of thing . . LOL!

Art is hard at work modifying the threading code for Machturn, so maybe the objective can be met more easily with whatever new capabilities he manages to stuff in there.