Hello Guest it is May 11, 2021, 09:25:33 AM

Author Topic: lumps & bumps  (Read 5665 times)

0 Members and 1 Guest are viewing this topic.

lumps & bumps
« on: May 30, 2013, 01:38:55 PM »
I've just been making my first cuts on my recently finished CNC router. I cut a small table top earlier today, and had 3 small bumps in a profile cut (g-code attached). The timber is maple, I did 15 x 1.5mm passes and each pass had the bump in the same place. I'm confident there are no lost steps as the rest of the geometry was smooth. There is no uniformity to where these bumps are in relation to the rest of the geomtery, and I would expect if there was mechanical culprit for these bumps to be elsewhere in the toolpath. I've taken a close look at the g-code toolpath and this seems to be fine.  I don't think there is any backlash, and the bump positions don't seem to be on curves. Any insight would be much appreciated!
Re: lumps & bumps
« Reply #1 on: May 30, 2013, 01:40:07 PM »
g-code attached

Offline Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: lumps & bumps
« Reply #2 on: May 30, 2013, 02:17:09 PM »
Looks like it may be flex or slackness in your machine that is causing that.
Hood
Re: lumps & bumps
« Reply #3 on: May 30, 2013, 04:57:21 PM »
Looks like every instance is near what looks like "Tabs" along combined X,Y moves.
Out of curiosity, I'd try setting all of the tabs along single x and y axis moves to eliminate X,Y,Z combined moves.
What did you generate the code with ? (just curious) These tabs have basically 0 length .... just ramping up, then dwn.

Russ
 :)
and ... Welcome to the group ! :)
Re: lumps & bumps
« Reply #4 on: May 30, 2013, 05:18:17 PM »
Also, even the upper passes that do not change the Z for the tabs, still break the otherwise "straight" move into segments un-necessarily.
This could be the area of your problem.
Possibly ::)

dang ... I was in machine coords, disregard the dro's  :D
Russ
Re: lumps & bumps
« Reply #5 on: May 30, 2013, 05:39:51 PM »
Thanks for the suggestion overloaded, it could explain 2 of the three bumps. I will run the same code tomorrow without tabs and see if this makes a difference. FYI the tabs are 3D tabs in VCarve Pro.

 Hood, I have run other geometry without these bumps , I would expect machine flex to be more consistent. Even with this tool path, there's a similar feature that has been cut blemish free.

Thank you both for your input.

Offline Chaoticone

*
  • *
  •  5,626 5,626
  • Precision Chaos
    • View Profile
Re: lumps & bumps
« Reply #6 on: May 30, 2013, 06:02:25 PM »
If its tabs is it raising in those positions?  Have you trammed your spindle by chance?

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 Hood

*
  •  25,838 25,838
  • Carnoustie, Scotland
    • View Profile
Re: lumps & bumps
« Reply #7 on: May 30, 2013, 06:29:18 PM »
Are these bumps present before the last few passes? If they are then dont think its tabs.

Hood
Re: lumps & bumps
« Reply #8 on: May 30, 2013, 09:44:54 PM »
....... each pass had the bump in the same place.

If each pass followed the same path, then there would be the same jog (bump) on the opposite side of the cut.
At least ONE path is different. Maybe a finish pass ? ? ?
Re: lumps & bumps
« Reply #9 on: May 30, 2013, 11:38:13 PM »
Cv settings?