Hello Guest it is May 20, 2019, 01:00:23 PM

Author Topic: First cut always in the air - how to get rid of it  (Read 2366 times)

0 Members and 1 Guest are viewing this topic.

First cut always in the air - how to get rid of it
« on: September 29, 2013, 03:23:43 PM »
Hey folks.  Someone out there knows the simple answer I'm sure

I've been having good luck with Mach3 on my BlackToe 2' x 4' machine, but there is one semi-annoying (note really) issue I've been having, and that is, after setting X,Y, Z DRO's to zero at the top face and lower left corner of my work piece and starting the first G-code run, the Z axis ALWAYS does an air cut and resets the Z DRO to zero - so its doing what it thinks it should - just 1.5 inches above the work.  When I again re-zero and start again, its fine, but not knowing how to avoid those first air cuts is getting to be a drag.

Any good suggestions?

cheers


Derrick

Offline Hood

*
  •  25,811 25,811
  • Carnoustie, Scotland
    • View Profile
Re: First cut always in the air - how to get rid of it
« Reply #1 on: September 29, 2013, 05:03:07 PM »
Cant think of anything that would reset zero unless its something in your code.
If you attach your code and your xml I will see what happens here.
Hood

Offline Vogavt

*
  •  258 258
    • View Profile
Re: First cut always in the air - how to get rid of it
« Reply #2 on: October 14, 2013, 08:16:54 PM »
Would you happen to be running Mach2010 screenset?
I have run into a similar problem with it doing the same thing.
I set the Z to zero at the surface of the work piece and it always go up and comes down to 0.200" above the work piece and starts cutting in the air.
Reset the Z to zero again and it works fine.

Haven't been able to track that down yet either.

I've briefly looked through the macros for the tool change routines but not found anything yet.

Offline ger21

*
  • *
  •  6,231 6,231
    • View Profile
    • The CNC Woodworker
Re: First cut always in the air - how to get rid of it
« Reply #3 on: October 14, 2013, 09:47:35 PM »
Are you zeroing in one offset (like G54) and your g-code is using another (G55, G56, ...)? That's the only thing I can think of that could cause what you're seeing.
In 3 years, I haven't had anyone else have this issue.
Can you post some g-code and your xml?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline Vogavt

*
  •  258 258
    • View Profile
Re: First cut always in the air - how to get rid of it
« Reply #4 on: October 14, 2013, 10:11:05 PM »
@ger21
If you're talking to me, I think you nailed it. Yes, I am using different offsets. Will look at that and try to report back in the next few days.

Offline ger21

*
  • *
  •  6,231 6,231
    • View Profile
    • The CNC Woodworker
Re: First cut always in the air - how to get rid of it
« Reply #5 on: October 14, 2013, 10:40:15 PM »
Yes, I was talking to you.
There's a modified auto zero on my website that sets the Z zero in all 6 of the standard offsets. Try it and see if it works for you.
If you're doing toolchanges, though, you'll need to modify the M6End with the same code that does the offsets.
« Last Edit: October 14, 2013, 10:41:54 PM by ger21 »
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html