Machine Slow on Curves

More
09 Apr 2014 07:05 - 09 Apr 2014 07:06 #45728 by swisscheese
Hi everyone, new and have come here on advice from others who cant seem to crack the problem yet :P

Im having a problem on my machine when it does curves. It only has the problem when the curves are specifically made up of lots of smaller straight lines. It works fine on circles and it works fine when a curve is made up of lots smaller different radiuses.

What happens is the machine accelerates and deccelerates when doing the curve. I haven't got G61 activated. It is in G64 mode. I have also tried several P and Q parameters from 0 to 0.5 for each. this affects it minimally.

This wouldn't be a problem if cambam could output curves as radiuses but it seems cambam can only output a curve as lots of small straight lines.

Here is a video of what it is doing



Thanks for your help!
Last edit: 09 Apr 2014 07:06 by swisscheese.

Please Log in or Create an account to join the conversation.

More
09 Apr 2014 10:39 #45736 by Todd Zuercher
If you feel up to it. Try out the new trajectory planner.
linuxcnc.org/index.php/english/forum/10-...stersprograms-wanted
It is being created specifically to address this problem.

Please Log in or Create an account to join the conversation.

More
09 Apr 2014 18:39 #45750 by BigJohnT
Replied by BigJohnT on topic Machine Slow on Curves
What is the maximum velocity and acceleration settings for the X and Y axis?

JT

Please Log in or Create an account to join the conversation.

More
09 Apr 2014 19:57 #45755 by swisscheese
Replied by swisscheese on topic Machine Slow on Curves

If you feel up to it. Try out the new trajectory planner.
linuxcnc.org/index.php/english/forum/10-...stersprograms-wanted
It is being created specifically to address this problem.


Hi,
well unfortunately I'm not very good at linuxcnc software and find following the above quite hard.

Cheers

Please Log in or Create an account to join the conversation.

More
09 Apr 2014 20:00 - 09 Apr 2014 20:00 #45756 by swisscheese
Replied by swisscheese on topic Machine Slow on Curves

What is the maximum velocity and acceleration settings for the X and Y axis?

JT


x, y and z are all about 800mm/s^2

Max velocity about 6m/min for both. I already had some one suggest that i may have these setting set to slow, or one too slow compared to the others but it works fine with circles so this isn't the problem.
Last edit: 09 Apr 2014 20:00 by swisscheese.

Please Log in or Create an account to join the conversation.

More
25 Apr 2014 03:58 #46292 by photomankc
Replied by photomankc on topic Machine Slow on Curves
CamBam can easily output curves and circles that are arcs. What post-processor are you using?

Please Log in or Create an account to join the conversation.

More
25 Apr 2014 18:15 #46306 by BigJohnT
Replied by BigJohnT on topic Machine Slow on Curves

What is the maximum velocity and acceleration settings for the X and Y axis?

JT


x, y and z are all about 800mm/s^2

Max velocity about 6m/min for both. I already had some one suggest that i may have these setting set to slow, or one too slow compared to the others but it works fine with circles so this isn't the problem.


Max acceleration is usually 10-20 times max velocity and if it is lower that is the problem. For more info see

linuxcnc.org/docs/html/common/User_Concepts.html

I think in inches so changing from m/min and mm/s is confusing to me and it's too early in the morning...

JT

Please Log in or Create an account to join the conversation.

More
25 Apr 2014 21:02 #46312 by andypugh
Replied by andypugh on topic Machine Slow on Curves

This wouldn't be a problem if cambam could output curves as radiuses but it seems cambam can only output a curve as lots of small straight lines


There is an option in CamBam to approximate line segments to arcs.

If you import an STL file then it is made up of very many small triangles. When the software creates a tool path it joins points on the edges of the triangles, and this becomes a sequence of little straight lines.
The more accurate you make the STL file (smaller triangles) the shorter the line sections become.

Cambam can convert these short lines to arcs if you turn on arc fitting, see page 44 here:
www.cambam.info/doc/CamBam-0.9.8N.pdf

Please Log in or Create an account to join the conversation.

Time to create page: 0.139 seconds
Powered by Kunena Forum