Wildly incorrect dimensions of pocket in g-code?

[Franciscus]

Newbie with a vexing conundrum:

I've specified a cylindrical pocket, 20 mm diameter, 18 mm deep (see attached CamBam file and generated g-code, as well as a photo of the finished part).
What is generated is a pocket, exactly 19 mm diameter and 23 mm deep.

I've verified that the end mill truly is 8 mm dia and that the mill is not skipping steps.
I've searched this forum and examined the various settings, both in CamBam as well as in Axis on LinuxCNC.
Postprocessor used is that for LinuxCNC. The resulting part has a perfectly smooth pocket with (nearly to the 1/100 mm exactly 1 mm too narrow hole that is 4 mm too deep?
What could have caused this?

Thank you in advance for any suggestions!

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[mactec54]

Newbie with a vexing conundrum:

I've specified a cylindrical pocket, 20 mm diameter, 18 mm deep (see attached CamBam file and generated g-code, as well as a photo of the finished part).
What is generated is a pocket, exactly 19 mm diameter and 23 mm deep.

I've verified that the end mill truly is 8 mm dia and that the mill is not skipping steps.
I've searched this forum and examined the various settings, both in CamBam as well as in Axis on LinuxCNC.
Postprocessor used is that for LinuxCNC. The resulting part has a perfectly smooth pocket with (nearly to the 1/100 mm exactly 1 mm too narrow hole that is 4 mm too deep?
What could have caused this?

Thank you in advance for any suggestions!

Have the Steps / Per Rev, been set accurately!

The code for the depth is correct if your Tool offset was set to the top of your work.

Check that the cutter has not come out of the collet, this is a common problem, with incorrect collet torque.

Check the cad / Cam Hole dia, Check the Tool setup for I & J use center of Tool or edge of Tool.

[servtech]

Newbie with a vexing conundrum:

I've specified a cylindrical pocket, 20 mm diameter, 18 mm deep (see attached CamBam file and generated g-code, as well as a photo of the finished part).
What is generated is a pocket, exactly 19 mm diameter and 23 mm deep.

I've verified that the end mill truly is 8 mm dia and that the mill is not skipping steps.
I've searched this forum and examined the various settings, both in CamBam as well as in Axis on LinuxCNC.
Postprocessor used is that for LinuxCNC. The resulting part has a perfectly smooth pocket with (nearly to the 1/100 mm exactly 1 mm too narrow hole that is 4 mm too deep?
What could have caused this?

Thank you in advance for any suggestions!

Cutter compensation and tool type could be an issue, given the depth is too deep by half the cutter diameter is it programmed as ball end ?

[mactec54]

Newbie with a vexing conundrum:

I've specified a cylindrical pocket, 20 mm diameter, 18 mm deep (see attached CamBam file and generated g-code, as well as a photo of the finished part).
What is generated is a pocket, exactly 19 mm diameter and 23 mm deep.

I've verified that the end mill truly is 8 mm dia and that the mill is not skipping steps.
I've searched this forum and examined the various settings, both in CamBam as well as in Axis on LinuxCNC.
Postprocessor used is that for LinuxCNC. The resulting part has a perfectly smooth pocket with (nearly to the 1/100 mm exactly 1 mm too narrow hole that is 4 mm too deep?
What could have caused this?

Thank you in advance for any suggestions!

Now I see your program, this could be your problem G91.1 have you programmed in incremental or absolute. remove this G91.1 and see if this helps, if you have programed in Incremental then use a G91

You should be using Absolute for your programing though which is G90.

[mactec54]

Cutter compensation and tool type could be an issue, given the depth is too deep by half the cutter diameter is it programmed as ball end ?

You seem fixated on cutter compensation when it is not being used, in the program