Cutter Compensation

[Terry G]

I had asked the question about cutter compensation when using re-sharpened end mills. I guess this is more of a question about how to use this feature in DeskCNC, but not much support there.

DeskCNC does support work coordinate offsets, and the G41/42 commands. I just don't see any place to program the machine with a cutter compensation value.

The only place is when generating my g-code. I can have it automatically offset the tool by telling it what diameter I am using and which direction I want it to cut. Or I can select 'machine compensation', which does not offset the toolpath in the gcode.

This would mean there should be a way to offset the toolpath within the machine based on the tool diameter.

Is this a not so common approach to machining? I have always automatically generated my tool paths based on the cutter diameter I am using.

Thanks.

[fastflyer]

"Is this a not so common approach to machining?"

Yes it is a very common way to machine. But you would need to use G41 or G42. So if
deskcnc does not support these codes then no you cant, which seems odd.
I can only suggest using 'machine compensation' when you output the gcode and running some tests to see if the profile you programmed changes when you input different dia's in your tool offset page.

HTH

Richard

[Terry G]

Yes, DeskCNC supports G41/42 codes.

I did generate some simple g-code (a 3" square) using "machine compensation G41/G42" option.

N10 G00 X0.0000 Y0.0000 Z0.5000
N20 G00 X0.0000 Y3.0000
N30 G01 X0.0000 Y3.0000 Z0.1000 F4
N40 G01 X0.0000 Y0.0000 F10
N50 G01 X3.0000 Y0.0000
N60 G01 X3.0000 Y3.0000
N70 G01 X0.0000 Y3.0000
N80 G00 X0.0000 Y3.0000 Z0.5000

It put the tool dead center on the perimeter of the square. At this point would I need to do anything else in my gcode besides call out the tool ID?

In the DeskCNC tool library, I guess I would simply setup the tool parameters with the exact diameter of the tool I am using. (no tool offset page) Don't know if this would be enough to compensate the tool path with my particular diameter. I just don't see any G41/G42 commands initially being generated.

I really need to read up on this more, and experiment a bit.

But thanks for the info, it really helps.

[fastflyer]

Hello again,

Sorry, I misread what you wrote, it was late, past my bedtime!

The code that was posted does not show any tool calls or pre-positioning, could it be a problem with the post-processor?

You could add the compensation manually, but you would need to add feed in and feed out lines as well. I cant really help more without knowing your cam system.

Richard

[Terry G]

Ya, I understand what you mean.

I need to read up on it some more and do a bit more research. AT that point I may be able to ask some better questions. I think I jumped into it to quickly thinking there was a simple answer.

Thank you for your replies.

Terry

[fastflyer]

No problem. Just post anymore questions to this thread and I will try to help.

Richard

[fastflyer]

Just had a quick look through the deskcnc manual, and can suggest you repost the profile with all the cutter info input. Also make sure the cutter info is in the tool library. I also spotted the "entry and exit" function for contouring, that will do the feed in and out lines. Also suggest you have a play with setting up your post processor, this obviously has an effect on how the gcode is output. For example, you can make your linear moves modal, this will stop the post putting out G01 on every line. Like so:-

N10 G00 X0.0000 Y0.0000 Z0.5000
N20 X0.0000 Y3.0000
N30 G01 X0.0000 Y3.0000 Z0.1000 F4
N40 X0.0000 Y0.0000 F10
N50 X3.0000 Y0.0000
N60 X3.0000 Y3.0000
N70 X0.0000 Y3.0000
N80 G00 X0.0000 Y3.0000 Z0.5000

Not essential, but it tidies up the program.

Richard