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Author Topic: inconsistent cuts  (Read 5271 times)

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Offline lee

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inconsistent cuts
« on: December 11, 2006, 04:22:54 PM »
Hi there,  ???
I have been using the Mach 2 software for just about 7 months on a plasma table.  I have been cutting the same pieces for since then, and just in the last month have noticed alot of problems.  First curves came out flat, circles were not round, straight lines cut in funny and getting alot of jagged not very smooth cuts.  I have cleaned, tuned motors, checked backlash, checked drivers, checked files and resent them, redone the installation of the software to double check things, I have callibrated and referenced the table.  So here I am stuck on what to check next.  What am I missing or doing wrong? What should I recheck?
If anyone can help it would be much appreciated, I've been down for a week now!
I have also noticed that I have to re-tighten the head of the torch all the time.  Shouldn't it stay snug, I have put some locktight but still comes loose after awhile.
I was just starting to enjoy this machine and was getting the hang of it till now, I am out of idea :-\
Hope to hear soon
A

ynneb

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Re: inconsistent cuts
« Reply #1 on: December 11, 2006, 04:50:05 PM »
Please give us more details of the machine.  Servo or stepper motors? It sounds like you bought the machine professionally built? Who made it. Have you changed the program you use to draw your designs with, or the CAM program ?
Is there any reason why you are not using Mach 3 ?
What software have you recently installed on that computer? There are some incompatible softwares that dont get along with mach, quicktime for example.
« Last Edit: December 11, 2006, 04:53:37 PM by ynneb »

Offline Chaoticone

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Re: inconsistent cuts
« Reply #2 on: December 11, 2006, 04:55:39 PM »
Hi Lee,
    Do you use ballscrews? Any chance the mechanical end is getting dirty, hard to turn, key ways wearing, set screws on pulleys loosening up? Are you using servos or steppers?
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline lee

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Re: inconsistent cuts
« Reply #3 on: December 11, 2006, 05:05:49 PM »
It is a plasma cutter with which we cut all 4x8 sheets of parts with, with stepper motors, we bought it from precision cutting systems, we use corel draw right now, which eventually would like to change but is not available to me right now.  I have had someone check the drawings at precision cutting syst. also.  Seemed to work there.  
There is no reason we are not using Mach 3, was told to wait till kinks were worked out, is it available now, I just asked and was told a bit longer still.
I have a sepereate computer just for that machine and don't use any other programs on it. I will check and make sure there is nothing on it that has been used.  
Thanks for the prompt response.
A
In response to other post, we do not use ballscrews, I have checked every screw I can see and I have cleaned the rails and greasers, and everything else I could think of.

Offline Chaoticone

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Re: inconsistent cuts
« Reply #4 on: December 11, 2006, 05:33:32 PM »
Sounds like you are either skipping steps because of mechanical trouble, your motor tuning which you have already checked, or good old noise. Just my first thoughts. Still lots of possibility's. Can you get it to repeat the problem and if so, where, and what is it doing?
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

ynneb

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Re: inconsistent cuts
« Reply #5 on: December 11, 2006, 05:43:30 PM »
I presume the straight lines you are talking about are only jagged when cut diagonal using two axis, and the lines are cut straight using single axis ?
What mode are you using Constant velocity or exact stop ? This could make some difference.
Another idea is to check the voltage going to the steppers. Find out what the voltage should be and compare the two. If the voltage is too small this might cause problems.
Also the acceleration and decceleration settings for each motor can cause slight variations too.

Offline chad

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Re: inconsistent cuts
« Reply #6 on: December 11, 2006, 10:18:54 PM »
flattened circles and arcs usually are a backlash symptom. first thing I would check is look for any slop on the x and y. Grab the head with your hand and yank it back and forth in the x and y ( boy after re reading that, i realized that could be taken totally the wrong way) . if it moves then you will want to try to tighten the belts, rack or ball screw (man i just can't win). get the head as tight as possable without any binding. 


Never mind, just look for any slop or stick in the system.

Chad
 
« Last Edit: December 11, 2006, 10:30:34 PM by chad »

Offline Chaoticone

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Re: inconsistent cuts
« Reply #7 on: December 12, 2006, 08:28:48 AM »
LOL
What a perv. ;D
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline lee

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Re: inconsistent cuts
« Reply #8 on: December 12, 2006, 09:23:48 AM »
ok I am attaching just a sample of what we are making mostly.  I do cut other pieces but this is the one giving me the most grief and is the most important.  I am going to try some of these things right now. Thanks for the help I will let you know if it works or doesn't work.
 :)

Offline Chaoticone

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Re: inconsistent cuts
« Reply #9 on: December 12, 2006, 09:29:00 AM »
Lee,
    Post your GCode here on the forum.
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!