Machsupport Forum

G-Code, CAD, and CAM => G-Code, CAD, and CAM discussions => Topic started by: OCNC on February 12, 2011, 06:26:47 PM

Title: G41/42 question
Post by: OCNC on February 12, 2011, 06:26:47 PM

I'm trying to generate a g-code program that zig-zags.  In order to keep the tool on the correct side of the cut I need to change the cutter offset at the end of each x axis motion.  The change from G41 to G42 and back again seems like it might be happening at maximum rapid speed.  What speed is used for the cutter compensation move and is there any strategy that applies to making a smooth transition between G41 and G42?
Thanks.

Chris

Title: Re: G41/42 question
Post by: ger21 on February 12, 2011, 09:44:22 PM

You can't change from G41 to G42 without first canceling whichever is in effect with a G40.

The best way is to probably do the offsets in CAD and not use G41/G42

Title: Re: G41/42 question
Post by: OCNC on February 12, 2011, 10:58:56 PM

Thanks Ger,

I was hoping to keep the CAD side of it as simple as possible.  I drew the centerline paths in Rhino and used Rhinoscript to generate the g-code.  I failed to use the G40 word before changing the compensation so I'll have to try inserting that tomorrow to see what the effect is.  It was suggested to me on the cnczone g-code forum that I would have to use leadins with the cutter compensation change so if that is in fact a necessity it may make changing the CAD the easier solution.

Chris

Title: Re: G41/42 question
Post by: ger21 on February 13, 2011, 08:45:18 AM

Yes, a lead in move is required, as that is where the comp is applied.

Title: Re: G41/42 question
Post by: OCNC on February 13, 2011, 10:04:22 AM

Is there any particular preferred path for the leadin move?

Chris

Title: Re: G41/42 question
Post by: ger21 on February 13, 2011, 10:10:45 AM

Probably depends on the application, but it should be a G0 or G1 move, and not an arc.