Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: MIDDEN1 on February 17, 2012, 12:30:44 PM
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hi
i have a k2cnc with gecko g540 running with mach3 2ghz cpu and 1 gig of memory
i am trying to v carve a harley davison emblem was programmed with bobcad looks good in graphics and look good on mach3 graphics but when i run on router the tool path looks
good and then it will totally go off course and cut letters away and will just end up with pocket it will repeat the same every time. I can just do regular 2d engraving with no problem.
any help would be very much appreciated
:(bob
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Sounds like you may be having issues with the motors stalling but if you want to attach the code and your xml I will check them over to see if I can find a config issue.
Hood
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hood thanks for reply i will attach my xml file and the code i am using
i have i guy i am doing this for and it has been driving me crazy
thanks
bob
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One thing I see in the xml is you have MPG 1 2 and 3 set up and have them as the same pins as your limits. Best to disable the MPG's if you dont have any or if you do then you will need to set to other pins.
Dont see anything obvious that would be an issue other than the above, and that shouldnt really make motors stall. I do notice the X axis is on the max for velocity at the 25KHz kernel so might be worth trying at 35KHz.
Hood
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hood
i turned off the mpg no change as you thought but before i had adjusted the volocity i just thought i would
try some of my old vcarve programs and they work without any problem,the only diffence they were lot bigger
parts aprox 3inchx5inch the harley logo is about 1.2inch x .900inch i am thinking mach3 won't handle the smaller
arks what do you think.
bob
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Mach handles arcs no problem.
Try reducing your vel and accel by half for a test, did you try at the 35KHz kernel?
Hood
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i have not yet tried 35khz kernal but i will and also try adjusting vol and accal now that you say mach3 will handle arcs
midden1
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i finnally got caught on my prodjects
andi tried 35k kernal but was no help if i made the drawing 2 times larger it worked fine
midden1
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Think your steppers are skipping. So lower your velocity and accel as Hood suggested.....50% to start.
If it skips, is it random or rather consistant? ie; same line in the program, during a rapid move, once during the program, etc.
If stepper skips the end result is usualy some lost position ( it seems to recover ) OR complete loss of position in that it goes off on its owne.
RICH
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skips in different places all the time this part has a lot of code with .001 or less move in both directions but it will run bigger parts no problem all the time but i will try adjusting accel and velocity
midden1
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If you could try air cutting at the reduced vel and accel to see what happens.
Even at 80% reduction. There is a reason for my asking.
RICH
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looks like that did the trick i lowered velocity from 75 to 40 and accel from 4 to 1 kernal speed at 25000 and it looks good ran 5 times and was good everytime but now i am getting random miscuts only some parts starts out good then will cut thru some letters and then go back to cutting normal on same part.frustrating
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Sounds like your stilll skipping.
I would have thought that after skipping and have cut through the letter that the position would be lost and the piece trashed.
RICH
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working at lot better now since i adjusted volocity from 75 to 40 and excel from 4 to 1 kernal set to 25000 i ran part 5 times or more with no problem but now it will randomly cut through some letters and then will recover itself and finish engraving
fine.getting frustrated
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sorry posted same thing twice
it always corrects and goes back to the correct position every time that is why i am confused
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it always corrects and goes back to the correct position every time
The axis will go to where it is instructed to go by the Gcode. CV can create rounding. If the stepper skips the axis will loose position
and it doesn't recover. If during a roughing stage, and more cutting to go, then may seem like it recovered ...but it didn't...just had
enough to work with to finish the piece.
RICH
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when it goes off on cut it will zig zag all over aprox .500 inch area then after it picks up and moves it appears to be cutting right on also i have dual shaft steppers with knobs on them
and they have white line and when i home out they come back to same place on white line every time after i run part if they lost steps shouldn't that white line be off
midden
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Can you post a pic of of the spoiled work?
Mach will handle the small arcs and moves of the file. You didn't mention what you changed the tuning to. Since it works at 5x the scale,
lower your max velocity to something like 1/5 of the max and drop the velocity down accordingly. So the max velocity would be in the range of
6-10 IPM and accel is 1 or 2 and see what the tuning ramp looks like and if it won't skip ....and also drop you velocities in the program.
Since you making very small moves, your asking the stepper motors to accelerate almost instantaneously, and i donlt think your motors are capable of doing it.
So you can try lowering the vel and accel to allow enough time for the motors to react to what they need to do or you can provide motors with enough torque
at the desired velocity to accomplish the task. The lowered velocity on big files will increase the machining time.
RICH
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here is what the cut looked like
midden
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midden,
My suggestions in reply 17 still apply.
Your choice to try them or not. No other thoughts on the matter.
RICH
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Rich
finnaly finnished my big engraving jobs running full speed then i slowed vol down to 15 and accel to 2 and you are right it did work thier lt was quite slow but that is ok ony doing one piece
thanks alot for your time
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Glad you got some favorable results.
RICH