Messages

1

General Mach Discussion / Re: Precipitous Loss of Zero

« on: December 21, 2012, 09:02:04 PM »

That's a good thought. If it were sticky in the up direction, the motor might stall and loose steps.

2

General Mach Discussion / Re: Precipitous Loss of Zero

« on: December 21, 2012, 11:40:59 AM »

When I try to set the speed higher than 369, Mach will default back to this number. The result is that I can never get the motor to stall.

3

General Mach Discussion / Re: Precipitous Loss of Zero

« on: December 21, 2012, 10:13:57 AM »

Is there a definitive test for checking stepper speed and acceleration? Mostly what you find for advice is, "Does it sound right?" Since my problem only show us after many cycles, I need to be sure about speed and acceleration.

4

General Mach Discussion / Re: Precipitous Loss of Zero

« on: December 19, 2012, 10:26:45 AM »

I have had a loose bit before (operator error!) and that usually results in the gradual loss of depth as the bit is pushed further and further into the collet. This was sudden and in the opposite direction, so I think we can rule that out.

How can I check for the second possibility? The motor sounds smooth, and the fact that it had done 70,000 repititions already makes me think it might be something else. Or is this kind of error cumulative over time?

Could it be a glitch in the AC power (240 volt)? Like you said, the X and Y still look good all the way through the project.

5

General Mach Discussion / Precipitous Loss of Zero

« on: December 18, 2012, 11:13:12 PM »

After pecking 70,000 small holes, my Z axis suddenly decided to lose 0.05 of throw and started dragging the bit around. Has anybody seen this before?

The photo shows the pattern going from bottom to top, and left to right in small strips. The red arrow shows where the Z it lost it and started to not be able to clear the material. Clearance ablove the material was only 0.03, but like I said, it had done plenty of holes before it went south.

Having looked at this particular line in the program, the g-code seems really solid.

6

General Mach Discussion / Re: Backlash strangeness

« on: December 09, 2012, 10:14:45 AM »

Rich, Tweakie and all,

Problem solved. After some testing, all I had to do was move the Shuttle Wheel Acceleration to 0.03 instead of 0.01.

Many thanks for your help. I'm off to the races.

--Ansen
http://ansenseale.com

7

General Mach Discussion / Re: Backlash strangeness

« on: December 08, 2012, 12:17:53 PM »

One more thing: to drill this pattern, I use a v-groove bit with a 53 degree angle. This make the Z axis plunge depth the same as the hole diameter at the surface of the material.

8

General Mach Discussion / Re: Backlash strangeness

« on: December 08, 2012, 12:14:21 PM »

Rich,

I ran the pattern several times with and without backlash compensation. The results were always the same. Gaps and (even missing holes) in the same locations with BC on.

My machine uses steppers on all axis.

Attached is the XML.

Thanks for your help.

9

General Mach Discussion / Re: Backlash strangeness

« on: December 07, 2012, 08:18:13 AM »

Rich,

I am absolutely sure that the 1/4" gaps are due to backlash compensation. Here's that file. If you want to, run it once with BC on and once with it off. I would be interested to see if you get the same results.

As for the banding, I fixed a farly significant "hardware" issue last night which brought my backlash down considerably. X=0.003, Y=0.001, Z=0. I'm going to try the face file again this morning with BC off.

Thanks for your help, guys!

10

General Mach Discussion / Re: Backlash strangeness

« on: December 06, 2012, 01:51:56 PM »

That image looks great.

I'm really more interested in the sculptural quality of the image. I create four different layers in acrylic and paint each layers' holes in a different color--typically cyan, magenta, yellow and black. These are the four colors used in almost all color printing.

Regardless of my original problem, so far the cure has been worse than the disease! The gaps in the original test image are completly software generated. All I did was turn backlash comp on. This pattern of holes is totally repeatable.

I obviously have some kind of hardware issue with 0.009 of backlash, but that doesn't explain why I would get giant 1/4" gaps in the output.