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Author Topic: New to Mach3- Problem with Corners  (Read 2887 times)

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New to Mach3- Problem with Corners
« on: August 27, 2009, 09:48:31 PM »
Hi All:
Name here is Jim and I have just completed an 8020 CNC Router. I am in the first testing stages and most is going very well. I am using VCarve V5 for my machine codes and it, like Mach3, is a great program. I have noticed one small thing that I am sure is the result of my ignorance. I cut out a simple sign on scrap pine with a rectangle of about 5 inches square around the out side. It was done in 2 passes. The first pass cut in the counter clockwise direction and the corners were very square and sharp. When it made the second pass, this time in the clockwise direction it cut one corner in a more rounded way, and on a second it overcut one little spot. If I can figure out how I will add a couple of pictures.

Any one have any idea as to what I should check?

Thanks--
Jim

Offline budman68

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Re: New to Mach3- Problem with Corners
« Reply #1 on: August 28, 2009, 05:02:33 AM »
Hi Jim,

Have you checked your machine for backlash? If so, how much do you have?

Just the fact that it took more material going the opposite way would tell me something is "loose" in the axis drivetrain somewhere along the way.

Just a thought for you.
Dave
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Re: New to Mach3- Problem with Corners
« Reply #2 on: August 28, 2009, 10:33:43 PM »
Hi Dave:
Thanks for the idea. I had already checked that and found no problem. The machine is very tight. I did seem to find the solution though. In searching the forum I found that having the acceleration too low can cause a problem in the corners. I doubled the acceleration and also set CV off at 86 deg. The corners now come out 100%. It looks like I am now ready to really make some sawdust.  Thanks again- and I will post a picture of my creation. It is really not my own design, but rather a unit created through the ideas from CNC Zone. Ahren for the guides, Dumpster CNC for some great parts, Gecko for the 540 drive, Keling for the motors, 8020 Surplus, etc, etc.

The computer is a whole other story. I started out trying EMC2 and after upgrading two old computers to find one that met the latency needs of EMC2. Then only to have the latency go sky high after UBUNTU updates. After the second time I stole my wife's XP machine, put in the video card I bought for the EMC2 failure, purchased MACH3, and never looked back. I did have to get my wife a new computer though. I should have just bought MACH3 from the start-- it is one heck of a nice piece of software. If anything the price is way too low for what it offers, and the support is second to none.

Thanks again for the help.
Jim