Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: bruno76 on March 13, 2008, 01:33:48 PM

Title: Mach3 "cuts corners" toolpath not respected
Post by: bruno76 on March 13, 2008, 01:33:48 PM

I have a solsylva machine that I highly upgraded so I can cut up to 170 IPM and travel at 225 IPM.
I am having a little problem: If I cut at 100IPM everything is fine and all dimensions are respected.
At 150 IPM the toolpath is no longer respected and mach3 seems to "cut the corners". For example
if you cut a square  mach will round the path on corners.
Is anyone can help me  understand?
Bruno

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: Chip on March 13, 2008, 03:24:32 PM

Hi, Bruno

In Config, General Configuration, Is it in Exact Stop mode.

Thanks, Chip

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: Whacko on March 13, 2008, 03:34:07 PM

Check page 5.24 of the M3M1_84.pdf. It has a good explanation of what you need to check.

Whacko

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: bruno76 on March 13, 2008, 04:13:12 PM

Hi Chip,
Well if I do that 1/ I got an abnormal condition 2/ the movement of X and Y is extremely choppy.
Bruno

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: bruno76 on March 13, 2008, 04:24:12 PM

Hi Whacko
I got a blank page on page 5.24

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: jimpinder on March 13, 2008, 04:47:47 PM

We had a good discussion on the forum a short time ago about this very thing.

There are two modes - Constant Velocity - and Exact Stop.

Constant Velocity is adjustable, but basically the computer reads forward and computes the next move ( i.e. the next change of direction). As it slows down from the present one, it also accelerates into the next one. This obvious results in the "rounding" of corners.
There are parameters you can alter to make the corners more "square" but you need to experiment with the setting that suit you.

On Exact Stop the axis must do just that - come to an exact stop. The problem is, travelling at 150' per minute, it takes some time to slow down and stop exactly on the button - and then from stop, the carriage that has to accelerate back up to speed. If you have a lot of changes, this will appear to be very jerky, but something you will have to live with I'm afraid, if you want to travel at light speed.

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: Overloaded on March 13, 2008, 04:47:56 PM

Hello Bruno,
Here is the whole scoop.....with all of the poop.  http://www.machsupport.com/documentation/Mach-3CVsettings%20V2.pdf
RC

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: Whacko on March 13, 2008, 06:47:25 PM

Hi Bruno, is the filename the same? But anyways, the link RC posted is even better reading. Thanks RC!

Whacko

Title: Re: Mach3 "cuts corners" toolpath not respected
Post by: bruno76 on March 14, 2008, 12:19:48 AM

Issue resolved with this document who really help me. I did not know it's existence as it was recently added> Now I can understand the implications of the acceleration.
Thank to everyone.
Bruno