[usage] tilting heights

[ajmendez]

Got an interesting question about some transforms:

• tilting gcode?
• PROBE?

[ajmendez]

probe_surface.py generates a simple matrix of heights by triggering the z limit axis to soft alarm the system. When correcting the gcode file, the "estimate_surface_z_at_pozition()" method triangulates the offset at any given gcode location. Large movements can break this as it will linearly interpolate between the z locations.

For a relativally linear offset you could create your own probe_test result:

PyGRBL/probe_surface.py

Line 122 in 5049476

np.savetxt('probe_test.out', Surface_Data, delimiter=',',header='X_STEP:,{:.4f}, Y_STEP:,{:.4f},'.format(X_STEP,Y_STEP))

to sweep along the x axis, you need to define your res by the step sizes and then you could sweep along an axis using a np.linspace() call. Here is the schema.

Surface_Data = np.empty([len(arange(0, X_MAX+X_STEP/2.0, X_STEP)),len(arange(0, Y_MAX+Y_STEP/2.0, Y_STEP))])

[pip9ball]

Thanks for the information Alex. If I understand you correctly, creating my own probe result like:

#x_step:,.5000, y_step:,.5000,
0,-.004,-.007,-.011,-.014,-.018
0,-.004,-.007,-.011,-.014,-.018
0,-.004,-.007,-.011,-.014,-.018
0,-.004,-.007,-.011,-.014,-.018
0,-.004,-.007,-.011,-.014,-.018

I'm assuming at X0Y0, Z=0. At X=0.5,Y=0,Z=-.004, X=1, Y=0, Z=-.007. And so on. Basically I'm defining a .4 degree line.

To give some background: I'm a computer engineer (Hardware) and part time custom cue builder. When generating toolpaths for intricate and tiny inlays, the CAM program assumes that the surface is flat.

When clamping the cue between centers on my Rotary Axis, due to the taper of the cue, it is not sitting flat anymore.

Some workarounds are:

1.) Manually tilt the cue between centers by shimming the tailstock.
2.) Some CAM programs have the ability to "project" a TP to a surface. One's I can't afford :-)
3.) post-process the G-code and tilt. This is where I came across your code.

Example design of cue: Large end is 1.25", small is .840". Length is 29". This equates to roughly 0.4 degree taper

I'll play around with this later this week and see if I can get this working as I can see some real benefit in my workflow.

Cheers!

-Phil

[ajmendez]

@pip9ball I think it would make it a bunch easier if you were to invest into a rotating fourth axis (e.g. https://www.youtube.com/watch?v=jkgmjIlOVKc). This should be supported be some grbl boards, but it has been a while since I was actively working on hardware stuff. I would think having the cue rotate so that the top surface would be parallel to one of your cartesian axes (with your shim setup), so it would be just rotating and moving along the length of the cue for the inlay. As I write this, and depending on your machine you may be able to use reuse one of your axis steppers as the fourth axis.

Great to see the mockup -- would love to see the end product!