Messages

1641

General Mach Discussion / Re: Want to run multiple toolpaths in succession

« on: September 01, 2008, 10:18:30 AM »

Bill,

    Here's an alternative you might consider - While you could do what you want with a Mach3 macro, if you're not a programmer, that may be a daunting task.  I use SheetCAM for G-code generation.  SheetCAM has the ability to save "parts", and call them up by name.  If you prepared a separate SheetCAM "part" for each sign in each of its three possible positions on the machine, you could then simple run SheetCAM, load the three parts you want to fab, and it will generate the G-code.  For example, you'd have three different "parts" for a "Home Sweet Home" sign, the only difference between them being where they are located on the machine.  Once you've created all the parts, actually picking the ones you want to use for a run and generating the G-code would only take seconds.  You can get a free eval copy of SheetCAM if you want to give it a try, and Les Newell, the author, provides first-rate support.

Regards,
Ray L.

1642

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 10:52:10 PM »

Kristin,
    Put lotsa capacitance on whatever you use.  I would think you'd want 10,000 uF at an absolute minimum, so you don't get voltage sag under heavy load.

Regards,
Ray L.

1643

General Mach Discussion / Re: VFD and noise questions

« on: August 31, 2008, 10:24:21 PM »

Also, how do you have things grounded?  It's important to have a single, common ground point that everything connects directly to.  You don't want to have grounds daisy chained.  Each device should have its own ground wire, which runs directly to the single common ground point, ideally a big lug on the metal chassis.  Doing otherwise can create all kinds of flaky, mysterious problems.

Regards,
Ray L.

1644

General Mach Discussion / Re: VFD and noise questions

« on: August 31, 2008, 10:22:16 PM »

What revision is your C11 board?  It should be screened on to the board somewhere.

Regards,
Ray L.

1645

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 10:20:41 PM »

Questions, questions...

It's a Taig mill, motors are 205 Oz unipolar, HobbyCNC Pro driver board (hey for $25 on eBay I couldn't pass it up), 20TPI leadscrews & adjustable nuts (new a couple of weeks ago). I think you hit it with supply voltage, think I am only getting about 20 VDC @ 10A out of the gutted Astron PS I am using, got to dig out another transformer and build another for 30-32 Volts I can run the board up to 42VDC but don't have a transformer on hand with 36V output.

I have adjusted the gibs, adjusted the leadscrew nuts and it's not mechanicaly binding anywhere, really not trying to run fast(6 IPM) or take more than .01/cut with a sharp USA made four flute 3/8"end mill. Could just have been the heatsink was pretty soft aluminum and was giving me fits?

Kristin

Kristin,

    OK, well you've got several things working against you.  Unipolar motor controllers, and low supply voltage.  The motors and drivers are probably OK for such a small machine, however.  I'd beef up the power supply - get as close as you can to the 42V limit, and you'll see MUCH better performance.  At 20V, your performance will be very poor.
    You do have to be careful with soft aluminum, as it gets "gummy" and will really clog the cutter.  Using a good lubricant will help a lot.  WD-40 works pretty well.  Also, don't go too high in RPM.  You're far better off keeping RPM low, and increasing feedrate.  Excessive RPM creates a lot of heat, which will tend to clog the cutter, as well as dulling it much faster.
    Good luck, and let us know how you make out!

Regards,
Ray L.

1646

General Mach Discussion / Re: VFD and noise questions

« on: August 31, 2008, 09:22:46 PM »

"Is it possible these are acting as an antenna of sorts picking up stray RF ?" - Not really. 

Is the *only* difference between the configuration that works and the one that doesn't that you've added the control cable from the VFD to the electronics enclosure?

Regards,
Ray L.

1647

General Mach Discussion / Re: VFD and noise questions

« on: August 31, 2008, 09:14:32 PM »

It's generally not a good idea to ground a shield at both ends.  That encourage the shield to become a conductor, which is *really* not what you want.  I would connect the shield only at the VFD end, since the VFD is providing the power for the signals.  What BOB are you using, and how is it connected?

Regards,
Ray L.

1648

General Mach Discussion / Re: Microstepping & Torque

« on: August 31, 2008, 09:10:46 PM »

Kristin,
    Yes, microstepping will reduce torque somewhat.  But, if you're having problems with the motors stalling, your real problem is that either:
a) You're pushing the machine too hard or,
b) Your motors are too small or,
c) Your controllers are not very good, or are limiting current (Geckos are highly recommended) or,
d) You're not running high enough power supply voltage or,
e) Any combination of the above

   What kind of machine is this?  What size motors?  What, if any reduction (including leadscrew pitch)?  What stepper controllers are you using?  What is your power supply voltage, storage, curring capability?

Regards,
Ray L.

1649

General Mach Discussion / Re: MPG Signal requirements

« on: August 29, 2008, 10:39:29 AM »

Sage,

    Yes, you need a quadrature signal.

Regards,
Ray L.

1650

General Mach Discussion / Re: Progressive Move Error with X and Y

« on: August 29, 2008, 09:57:59 AM »

Ray,

I'm using shielded cables for the steppers and my limit/home switches and I have a good case ground which uses equipment ground. My CNC4PC board is the C11 Multifunction Board Rev 3.1. Not sure if that's good or bad.

I justed completed testing and eliminated pins 4 and 5 on the breakout board. So X used 2 and 3, Y used 8 and 9, and Z used 6 and 7 where even is step and odd is dir. After 5 full runs of the program there was no error!! So it appears that I either have a bad breakout board or a bad parallel cable. It appears that when both pins 2/3 and and pins 4/5 are connected, there is some type of coupling or cross talk.

I tried to wire direct and am unable to get things to work. I wired the pins from the parallel cable for step and dir directly to the Gecko driver. I then tried to use the USB 5V for the common connection on the Gecko driver but no luck. I even connecting to pin 18 on the parallel cable. I certainly don't understand how the 5v reference is suppose to be wired in regard to the parallel pins.

Sage, yes, my troubleshooting skills are lacking in regard to electronics. Way over my head but I do thank you for the suggestions along with everyone else that has helped. This has been an invaluable source for me.

Best Regards.

Carl

Carl,

    You should get in touch with Arturo at CNC4PC, and tell him of your problems, and make sure he knows how old your board is.  Rev 3.1 is pretty old (the new one I just got it Rev 7.0), and the problems you're having are very much like the ones I had with my old Rev 2.0 board.  The Rev 7.0 has been very solid.  The Rev 7.0 boards have a large number of design improvements, over the earlier ones.  I was unable to get my Rev 2.0 board to work reliably, even after doing a large amount of rework to correct its design shortcomings.
    I'm not sure I understand how you tried to directly wire the Geckos.   There should be no pin 18 connection.  No ground connection at all, in fact.  The +5V from the USB port shoudl go directly to the Common terminals of the Geckos.  The signal pins (any of 2-9) should go directly to the step/dir pins of the Geckos.  Those are the only connections you should have.

Regards,
Ray L.

Regards,
Ray L.