Topics

1

General Mach Discussion / dro and gcode don't match

« on: July 21, 2011, 11:16:24 PM »

While trying to fix another issue I happend to notice that the dro doesn't match the gcode when I stop the program during a run.  They are all off by a small amount.  A search of the web only turned up a suggestion to check backlash settings.  I have backlash compensation turned off so I don't think that's my problem.

I did some air runs of old jobs and now see that those files had dro / gcode mismatch as well.  The pieces cut fine, but I cut artwork not jet engine components and I don't measure the finished project. 

Is this normal behavior for Mach?  Is a setting(s) I should be checking?

Thanks.

Ed

2

General Mach Discussion / Large Toolpath and Mach Pauses every couple hundred lines

« on: July 21, 2011, 11:08:45 PM »

I have a large rotary toolpath with about 1.2 million lines of gcode.  When I run the file Mach3 pauses for a couple of seconds every couple hundred lines of code.  As a test I deleted a bunch of the code so that I only have the first 10,000 lines in the file.  Lines 1 to 10,000 are exactly the same as the first 10,000 lines of the large file.  This smaller file runs perfectly with no pauses.

I have look ahead set to 200.  Looking at diagnostics I don't see any indication that the machine is overloaded.  It's a pretty fast computer.

I see that the limit for Mach3 is 10,000,000 lines of code.  I'm nowhere near that.  Any suggestions on what I should be looking at to get rid of these pauses?  It's a 12 hour job if it runs smoothly.  The pauses will add a lot more time.  Not to mention the problem of having the bit turn in place every couple of inches while Mach is doing whatever it's doing while it pauses.

Thanks.

Ed

3

General Mach Discussion / Rotary + CV + G00 = Clunk

« on: July 04, 2011, 11:52:32 PM »

Running a CNC Router with a rotary axis.

Running a vcarve toolpath (lots of short movements and moves up to safe z for rapids) that carves on a cylinder.

Using CV I get a clunk from the motor on the z-axis (probably losing steps) on a lot of the G00 moves to up safe z which preceedes a G00 move to a new A.  Sample code that clunks:

N680 G1 X0.0965 A-19.6482 Z0.1927
N690 G00 X0.0965 A-19.6482 Z0.4050
N700 G00 X0.0965 A-30.9263 Z0.4050

I get the clunk from the z motor on line 690.

If I switch from CV to Exact Stop, I don't get any clunking.  This toolpath runs very smooth with exact stop set.  Changing motor tuning (velocity / acceleration) makes no difference with CV, unless I drop to super low levels that would be crazy to use.  Tried different values for CV distance tolerance and angle, but it didn't help CV run this toolpath smoothly.

If I take the exact same toolpath and run it on a flat surface (using y instead of the rotary A), I can run with CV and it is completely smooth.  No clunking on the G00s. 

I don't have any long arcs (with multiple segments) in this particular toolpath so I can run it with exact stop.  But that may not always be the case.

Is there some setting somewhere when using A as a rotary axis that will allow CV to work like it does in the flat world?

It's almost like Mach3 is picking up the acceleration from the A axis (which is really high) and using it for the z axis when it is doing the G00 move to safe z with CV on.

My A Axis (rotary) is velocity 18810 and acceleration 3151.

My Z Axis is velocity 200 (inch per min) and 50 acceleration.

I could see where slamming the z motor with an acceleration of 3151 might result in a clunk or two.

I'm new to Mach and still learning the ropes, so I apologize if I didn't explain things clearly.  I tried searching the forums but didn't find anything that helped me.

Any and all help welcome.

Thanks,

Ed