Hello Guest it is December 16, 2019, 03:08:06 AM

Author Topic: Backlash compensation for a rotary axis ?  (Read 16813 times)

0 Members and 1 Guest are viewing this topic.

Offline jimpinder

*
  •  1,233 1,233
  • Wakefield, West Yorks, UK
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #20 on: March 29, 2008, 06:21:48 AM »
Nice job, Greg.

I can see where you are going now.

As far as backlash is concerned, I don't know if Andrews program keeps the axis as a rotary axis or converts it to a linear one.

If it keeps it as a rotary axis, then I cannot see you having any trouble with backlash compensation, since it clearly auto compensates for the diameter you are working at. The "thrust" of the tool will be taken by the gearbox, and if it reverses to "write" the other way, backlash comes on first and takes up the movement.

I wish I could get down to 4 thou of backlash - I dare not tell you how much my lathe has ( I am working on it, with new ball type leadscrews on the horizon) but I find Mach 3 compensation both accurate and reliable (although to listen to it working is sometimes a bit concerting. I was cutting brass handrails - a pole with a ball at the top and centre and half ball at the bottom - something you cold not do manually - as the z axis came to the ball, the x axis had to come out and back, describing the arc. When it changed direction at the apex, you could not see any distortion in the brass. This, I thought, was excellent.

Best of luck.
Not me driving the engine - I'm better looking.

Offline Chaoticone

*
  • *
  •  5,634 5,634
  • Precision Chaos
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #21 on: March 29, 2008, 06:36:23 AM »
Good job Greg. I like it. I want to build a 4th axis soon (relative term you know :) ) for the Hurco.

Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!

Offline Greolt

*
  •  956 956
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #22 on: March 29, 2008, 07:27:37 PM »


As far as backlash is concerned, I don't know if Andrews program keeps the axis as a rotary axis or converts it to a linear one.



Yes Andrew's little conversion program uses degrees.  It does not simply convert to  linear code.  So as you say the backlash setting stays constant at different diameters.

In my one test so far I set Backlash Speed at 100% and Shuttle Accel. at 0.01 seconds.  I have no idea why it is called "Shuttle Wheel Setting"

Greg

Offline Greolt

*
  •  956 956
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #23 on: April 01, 2008, 07:01:46 PM »
Just for fun I made a little video.  ;D

http://www.youtube.com/watch?v=Kd2jyn8l0I4

I don't know how to make it show on this post like others do.
« Last Edit: April 01, 2008, 07:16:57 PM by Greolt »

Offline Greolt

*
  •  956 956
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #24 on: February 23, 2009, 04:19:32 AM »
Finally got off my butt and made a mount and tailstock for this 4th axis.   :D

Greg

Offline RICH

*
  • *
  •  7,382 7,382
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #25 on: February 23, 2009, 06:21:56 AM »
Greg,
Seems like a year has passed by. Your doing good. Got a few here that i have even forgot
why the project was  started in the first place!  ;)
RICH

Offline olf20

*
  •  318 318
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #26 on: February 23, 2009, 07:37:25 AM »
Very nice! I'm also working on one. Slow but sure.
What bit did you use to cut your work??
Thanks olf20
Mach3, Atlas Knee Mill, 4th Axis, VcarvePro, ESS, Super PID.
Been Heating with corn since 1998

Offline docltf

*
  •  353 353
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #27 on: February 23, 2009, 07:46:47 AM »
greg
what program did you use to cut that wooden figure.

thanks bill

Offline Greolt

*
  •  956 956
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #28 on: February 25, 2009, 06:44:33 AM »
Rich

Yeah I usually get things finished eventually.  Sometimes takes a while.  :)

Olf20

1/4" and 1/8" ballnose endmills.

Bill

Therein lies my problem.  I don't have CAM software to do these sort of toolpaths.

A friend provided this one.  He does have some industrial CAM.  I can't afford it.  :(

All I can do so far is convert 2D toolpaths to 4th axis with a Wrapper program.  A bit limited.

Greg

Offline docltf

*
  •  353 353
    • View Profile
Re: Backlash compensation for a rotary axis ?
« Reply #29 on: February 25, 2009, 08:08:14 AM »
Greg

I would like to have a copy of that figure you were cutting and give it a go.could you post the g-code.

thanks bill