Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Spencer m on May 18, 2012, 04:27:18 PM
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I'm using solidworks with solid cam and mach3 as my programs. I drew a part that is a simple shape with a straight cut and some curve cuts. The piece is 1/8 inch flat wood stock. The pattern is one profile cutting 5 passes stepping down till it cuts through. My question is when it cuts the curved parts it's not supper cleanness, it looks slightly scalloped. I was wondering if this is some kind of motor tuning thing or if my machine is not tuned properly, or for that matter built properly. Is this normal. How clean of parts do you get right off the mill. Am I expecting too much. Can anyone help. Thank you.
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Could be lots of things.
What kind of machine are you using?
Can you post a picture of the cuts?
5 passes is a bit excessive for 1/8" wood. It should come off the machine very smooth and clean, if you use the right tooling at proper feedrates and rpm's.
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I made my own cnc router mill. I'm new with forums I don't now how to post pictures. My computer is not hooked up to Internet, I use my I phone. Can you tell me how real quick. So if I slow down the feed rate on the main screen that should help. I was just hoping to get the part milled faster it already takes a min and a half.
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I tried slowing the feed down really really slow it helped a tiny bit but still not super clean. When it comes to the part that has the tightest radius that's when I here the motors step mimicking those little scallop marks and as it tapers off the tight radius to the lesser it gets better. Any thoughts.
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I had a very similar problem with my router. I fixed it by going into the Config/General config page and changing the "IJ" mode from ABS to INC. You will find it in the second column from the left about half way down in the box for "Start up Modals"
Hope this helps.
Stuart
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Is the code an arc or is it tiny wee steps?
Hood
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It's just a curved line that takes the X and Z axis to perform its sounds like little steps and when it does that I think that's what causes it to be uneven
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I was meaning is the code an arc or is it lots of short lines, also is it really the X and Z? Just thought by your initial secription it would have been X and Y .
Hood
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Oh ya your right x and y. It's an arc or a spline not short lines
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Spencer,
Can you post the gcode, or a portion of it if it is a large file?
Will help to diagnose your problem.
Regards,
John Champlain
www.picengrave.com
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Is there a way to post the gcode with my I phone I don't have Internet on that computer. I've never posted any files what's the easiest way to do that
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Sorry,
Can't help with that - I don't have an I phone.
On your machine, can you detect any movement when you try to "wiggle" a bit in the spindle by hand? Also, are you climb-cutting?
These two things may explain your issue.
Regards,
John Champlain
www.picengrave.com
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My machine has about 1/32 of an inch of movement but that takes I bit of pressure just to move it that tiny little bit. Everything is pretty darn tight. With zero backlash. I'm positive that it is NOT clime cutting. Just from the sound of the motors and watching them it seems like that's issue.
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Ok I see exactly what's going on but can't fix it. The uneven cuts are caused by the motors speeding up and slowing down on the curves. The steeper the curve the faster it sputters, as the curve gets less steep the motors sputter slower. Every time it does that which is through out the entire curve you can see the correspondence on the part of how poorly it moves and cuts. It's got to be something in the way the motors are working. Because every now and then when I stop the feed and restart it, it does this big loop around and then back on course. When it does that loop it actually sounds really really smooth like how I wished it would cut my part. I've tried adding the g64 in the code but it does nothing I've tried tweaking motors and the IJ mode to INC. still no luck. All my settings say constant velocity on.
I don't know how to post my gcode but I will figure it out so you guys can see it. Thank you so much for helping me. Give me a few days to figure it out.