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Author Topic: Jerky Motion & Poor Quality in Curves  (Read 10218 times)

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Offline MJR

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Jerky Motion & Poor Quality in Curves
« on: July 16, 2006, 11:36:15 PM »
Howdy all:
Recently purchased V-Carve Pro from Vectric.  Great program.  I seem to be getting Jerky Motion & Poor Quality in Curves.  Mach3 has never done this to me on it's own when I have converted dxf files.
Just wondering if anyone may have some suggestions as to what might be going on.
If I slow the feedrate down to about 10 inches/min as less the quality greatly improves and the jerkiness is to a minimum, but now it takes forever to cut.
I have the Constant Velocity already selected.
Thanks.

ynneb

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Re: Jerky Motion & Poor Quality in Curves
« Reply #1 on: July 17, 2006, 01:00:01 AM »
I have had this problem in the past. There was a few issues. Curves in exact stop mode were jumpy, or smooth in constant velocity mode. The problem with constant velocity mode then meant that the corner was lopped off squares etc.
One of the problems on my machine was the gearing down of the motors was not enough. I seem to remember a temporary solution was to lower the acceleration and deceleration setting on each motor helped.
I also wonder if the resolution setting in VCarve is very high and is causeing this http://machsupport.com/forum/index.php?topic=621.msg3461#msg3461 to happen. It may pay to reduce the Vcarve resolution setting.
« Last Edit: July 17, 2006, 01:07:33 AM by ynneb »
Re: Jerky Motion & Poor Quality in Curves
« Reply #2 on: July 17, 2006, 08:51:13 PM »
i have an answer and a question.....


MJR: there is a new post processor in VCarve Pro that outputs true arcs instead of lots of little linear moves. i spoke with Brian and he allowed me to download a beta. it seems to help me. i am having other issues on my mill so i cant tell you for sure if it will be a total cure for you.

Mach experts: it seems that you can select constant velocity for the "soft" curves and set a limit to CV for "hard" corners. the Setting tab looks like it allows this, but the actual values are not clear to me and the mach document help was not much help. can anybody clear up what each of those settings do? the default angle is 180 which seems odd, and there seems to be a multiplier of some sort, defaulted to 1. any help would be great.

Ben

Offline MJR

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Re: Jerky Motion & Poor Quality in Curves
« Reply #3 on: July 17, 2006, 09:44:28 PM »
FastCote:
I was directed by a V-Carve Pro user to look into exactly what you are talking about.  I am just waiting to get verifcation from that person to tell me if that box in question should be green & what values should be entered.
Go to this post on Vectrics forum:
http://www.vectric.com/forum/viewtopic.php?p=2694#2694
Does that make sense?
Thanks.
Re: Jerky Motion & Poor Quality in Curves
« Reply #4 on: July 18, 2006, 06:14:23 AM »
ya, i read that already, but i figured this was a more appropriate place to get good Mach Answers. As far as i can tell, you enable constant velicity ono the STATE page from the CONFIG menu. Once enabled, that page you showed (from the SETTINGS Tab) allows you to restrict how sharp an angle before the CV is suppressed. What the numbers actually mean are a mysetry to me. 180 degrees does not make sense, and the number below it??????
Re: Jerky Motion & Poor Quality in Curves
« Reply #5 on: July 18, 2006, 11:20:30 PM »
If the angle of the two lines is less  then 180 (the angle in the box) it will do the CV. this is for the plasma users and router users...
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com

Offline MJR

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Re: Jerky Motion & Poor Quality in Curves
« Reply #6 on: July 18, 2006, 11:34:58 PM »
FastCote:
Thanks for that.  I seem to be getting conflicting opions about the CV settings.  I quess I will just have to experiment.
I did go into Motor Tuning & reduce me acceleration numbers.  That made some differenence to the good until I decided to up the feedrate.  Anything over 30 inches/min starts the jerking motion again.  Very eratic & extremely jerky at 100 inches/min.  This is only happening when I use V-Carve Pro, not when I use Mach3 by itself.  To get a good finish really adds to my cutting time.
Why does no one know exactly what those CV settings mean? 180 & that mysterious number below.
I am hoping that Vectric will soon solve this problem.  Is this problem only affecting Mach users or does it also affect other post processors?
Talk to you later.

Just read Brians post.
Does that mean we should change that 180 to something else?  Don't quite understand.
Re: Jerky Motion & Poor Quality in Curves
« Reply #7 on: July 18, 2006, 11:44:38 PM »
Set it to about 60 and that should do you...
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com

Offline MJR

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Re: Jerky Motion & Poor Quality in Curves
« Reply #8 on: July 18, 2006, 11:47:28 PM »
Thanks Brian, I will try that tomorrow.
So, why is it that I have no problems when running just Mach3 on it's own?  Can cut very fast with smooth/clean results.
What is the number below the 180?
Later.
Re: Jerky Motion & Poor Quality in Curves
« Reply #9 on: July 18, 2006, 11:50:49 PM »
That is the feedrate that the machine will slow down to when it goes around a corner
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com