Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Erik G. on September 11, 2008, 05:48:06 PM
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Hello all,
I am Erik in Albuquerque, New Mexico. We have just set up a new Vortech 5' X 10' stepper controlled router using machIII controller and the latest version of ArtCam. We are able to 2.5D straight lines & circle/arc toolpaths perfectly using the ArtCam post {machIII arc (inch)} however when attempting to do 3D toolpaths, the movement in X & Y is jerky and leaves tool marks in the material. It appears that the machine is pausing between each line of code. I have tried changing the ramping speeds for the steppers, but when it is slow enough to have some effect on the problem, my machine times (time to do the job) get way out there. (loosing money). Is there any way to string the code together so the tool runs smoothly? Is this a switch in Mach? Config is set to absolute for lines & incremental for arcs. Also where do I set the rapid (out of material) speeds? Any help will be very much appreciated.
Thanks for your help.
Erik
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Run the machine in CV mode and see if that helps, you can do this by going to the MDI line and typing in G64, also make sure there are no G61 in your code as that will just switch Exact Stop back on.
Hood
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Tried CV mode, no joy. Could it be the accel & deccel rates for the steppers? Somehow I don't think this is the whole problem.
Erik
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Can you attach a sample of the code that gives you problems?
Hood
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I will try to do so. I have to break the code out of the job file as all I have with me are ArtCam files which are composite files. I will do that today & send it to you tomorrow or Monday.
Thanks for your help.
Erik
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I'm getting the same problems with my 3d files. anything that requires x and y movement together results in grooves in the profile. It's more noticeable the higher the speed. They aren't random either. I was cutting an angled curved wall with a .005 overlap and there was noticeable grooves running down the wall at an angle. It seems like the slower the feed rate the less angle on the grooves. I'm cutting another part with a slower feed rate and the grooves are running straight up and down.
I'm running servos by the way.
Derek
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Hey Eric I don't mean to hijack your thread but I think we're suffering the same type of problem.
Here's a pic I just shot of the area I'm talking about. This was cut with a .005" overlap at 50 ipm. You can easily see the chops on the right of the picture but they go all the way around the curved area to the left. When the curve goes straight the chopping stops. If I was to cut this at 100 ipm the chops would lead out at more of an angle.
Here's a link to the picture I couldn't figure out how to embed it in the post
http://www.machsupport.com/forum/index.php?action=gallery;sa=view;id=27
Derek
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derek
What motion is your cutter moving, is it going round the arc or is it coming down from the top?
Hood
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Hi Hood
I'm using a horizontal finishing pattern. Round and round it goes!!!
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Could it be your code is made up of many short lines when its going round in the arc?
Hood
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Hi Hood
Yes it is most definitely made up of many line segments. but their deviation off of an arc is slight. I just cut out a section of the code on that area and inputted the coordinates as points. I then connected the points with a poly line. I fitted an arc to that line and the deviation was less than .00003 Then I projected a line against the surface at the same z level as the tool path and the deviation was less than .003. This last measurement really doesn't mean much as we're concerned with deviation off of the arc as in a choppy cut. The tool paths all look nice and smooth as well.
Derek
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Do you have CV Distance Tolerance enabled? If try without and see what its like.
Hood
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I'm about 99 percent sure that it's turned off but I'll double check tomorrow and let you know.
Thanks
Derek
Do you have CV Distance Tolerance enabled? If try without and see what its like.
Hood
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Yep CV tolerance is disabled. G100 Adaptive NURBS is enabled though. Not sure if this matters or not.
Derek
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G100 setting should not affect it but switch it off as its not used anymore (I think ;) ) and even if it was you dont have a G100.
Are you definitely in CV mode? Make sure your code isnt switching it to Exact Stop (G61)
Try doing an G2 or G3 on a piece of scrap and see if its good.
Hood
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Hi Hood
It's absolutely in CV. One thing I would mention is I'm handling huge amounts of code. The piece in the picture had over 500,00 lines loaded into Mach. As soon as I finish this piece I'll do some tests and post the results here. I'm going to cut that same section that has the chops but try it at a few different speeds and cutting strategies. I really need to get to the bottom of this.
Thanks
Derek
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try setting the lookahead down a bit or even turning the toolpath off, maybe the computer is just bogging down a bit with the amount of data its processing?
Hood
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Hello Hood, Erik here.
I managed to get a continuous path (circular & straight) by turning on the "laser" mode, but when it is not in "laser" mode the path reverts to a stop/start with each line of code. Also it seems to have "stuttering" in the Z axis movements and still has a noticeable series of marks in the machined material at every new line of code and a noticeable hesitation at the line where the X/Y motion meets a Z axis movement. Even though the X/Y motion appears and sounds to be continuous the machine still leaves a noticeable mark in the material (Z axis or vertical) that appears to be coincident with the progression of code line to line. Most of the code (85%) is made up of an XYZ command in each line. Do you think this is motor tuning (accel/deccel) or could it be a backlash compensation issue? I tried various feed speeds, but the frequency of the surface inconsistencies remained the same, so I don't think it is mechanical harmonic vibration. I set the look ahead to 500 lines and it did help some. Should not CV mode work even when not set to "laser"? Thanks for your help.
Erik
PS: the the angular stop in CV mode is set to 90 Deg.
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Hi Hood, Erik here.
Sorry, I meant to say "plasma" mode in my previous post. Do you want to see the whole toolpath perhaps just a chunk out of the middle somewhere? I checked the settings in Mach today and I do not have the backlash compensation on. Could it be that part of the problem occurrs because the Z axis command is a 90 deg fise that happens with each complete X/Y execution? Thanks again.
Erik
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Not sure what plasma mode does, will have to do a bit of reading and see what exactly it does. I need some sleep now (2:30am) but bump this thread if I havent got back to you tomorrrow.
Hood