Messages

371

General Mach Discussion / Re: run from here takes forever

« on: March 31, 2012, 10:21:21 AM »

Servos don't "correct" errors.  They can simply make you aware of them.  But a properly designed and operated stepper system should never be off-position.  This is not an inherent characteristic of steppers, but rather an indicator that the stepper system (motors, drivers, power supplies) were either poorly matched to the requirements, or are being operated outside their capabilities.  Under those conditions, servos will fare no better.  How would you "correct" for a 1/2" position error anyway?  The part is long since scrap by the time that happens.

Regards,
Ray L.

372

General Mach Discussion / Re: run from here takes forever

« on: March 31, 2012, 10:05:07 AM »

BTW - Mine typically run less than 20 counts error (0.001") on all axes in actual use.

Regards,
Ray L.

373

General Mach Discussion / Re: run from here takes forever

« on: March 31, 2012, 08:39:55 AM »

You must have pretty slack following error Ray, mine is set to 20 counts max so at 8000 per 5mm that equates to 0.0125mm or just under 0.0005inch.
Hood

Hood,

I'm running Geckos, which allow up to 128 counts, which is 0.0064".  Doesn't help if you're in a rapid....

Regards,
Ray L.

374

General Mach Discussion / Re: run from here takes forever

« on: March 31, 2012, 12:12:04 AM »

If your axis are light and dont have much momentum then it may be you wont lose position too much. How much is too much will depend on the type of work you do and the accuracy needed. If for example it is a wood working machine then a few hundredths of a mm or thousands of an inch will likely not matter, on a metal cutting machine such as a lathe it may well be enough to scrap your part.
Hood

Also helps to have servos.  If you're moving slowly enough that the axis coasts to a stop before you exceed the max following error, there will be no position loss, and the servo will bring it back to where Mach3 wants it to be.

Regards,
Ray L.

375

General Mach Discussion / Re: Program a stepper motor for a sinusoidal movement

« on: March 27, 2012, 09:27:50 AM »

Probably the simplest way to do it is to program a two-axis circular move, with one axis being a "dummy" that isn't really driving anything.  The remaining axis will them move sinusoidally (after it gets accelerated up to speed).  The basic command is either G2 or G3.  Assuming Y is the "dummy" axis, and you want a 2" diameter motion at 10 IPM about x3.000 y5.000:

F10.0 (Set feedrate to use)
G0 X4.000 Y5.000 (Move to start point on circle 4.000,5.000)
M98 P001 L10 (Call subroutine 001 to do one circle, L10 calls subroutine 10 times)
M30 (Program End)

O001 (Subroutine ID)
G2 X3.000 Y5.000 I-1.000 J0.000  (Do one complete circle in XY plane, with center at X3.000, Y5.000)
M99 (Return)
M30

Regards,
Ray L.

376

General Mach Discussion / Re: kennametal .5" indexable mill cutter

« on: March 22, 2012, 06:31:25 PM »

Those look more expensive than a standard endmill!

I have a ihcnc mill (rf45) no toolchanger. I design my parts (aluminum) to work with one cutter when possible. I use the endmill for a lot of drilling operations when I can. It's been driving me crazy when I ding a corner of my standard carbide endmills.

I'm still learning and know this will continue to happen for awhile.

I also know that finish may suffer a bit going indexable.

I question why you bother with carbide for a '45.  The spindle speed is so low, you really can't get any benefit from carbide.  You'll get the same removal rate, and longer tool life (for less money), using HSS.  If you're using it right, a single HSS tool will last a loooooong time.  Though straight plunges are murder on ANY tool, and probably is why you're breaking so many corners.

Regards,
Ray L.

377

General Mach Discussion / Re: Need break out board suggestions

« on: March 17, 2012, 01:15:23 AM »

The second DB25 just give you access to the same signals as the first one, if you want to pass some unused I/Os to some other device.  I've never used them on mine.  I've used them with the parallel port, both USB and Ethernet SmoothSteppers, and now a KFlop.  Never a problem with any of them.  I don't recall the shipping cost, but it was quite reasonable, and delivery was always quick.  I've also used their spindle control boards - very nice! 

You can contact Peter Homann directly at peter@homanndesigns.com.

Regards,
Ray L.

378

General Mach Discussion / Re: Need break out board suggestions

« on: March 16, 2012, 09:03:10 PM »

The Homann Designs (www.homanndesigns.com) breakout boards are dirt cheap (US$30), and work flawlessly.  I've got four of them, and never had a single problem.

Regards,
Ray L.

379

General Mach Discussion / Re: Encoder Problem

« on: March 16, 2012, 10:40:25 AM »

What you want is home switches, not encoders....

380

General Mach Discussion / Re: Tool table DRO´s

« on: March 12, 2012, 10:44:56 AM »

Why not just use G10L1 to update the tool table on-the-fly?

Regards,
Ray L.