Milling test generator : advice needed

Mostly Printed CNC - MPCNC Advice
1

i’m doing a little test job generator to test feed and plunge speeds.

as a template i have something like this as a plunge speed test (as now it will imply no speed control)

G90 // absolute
G21 // sorry, metric :stuck_out_tongue:
G1 Z5.000 F500 // safe height, constant
G1 Z-4.000 F{testPlungeSpeed} //i think of -4mm depth as a constant, as i think of it as a quick test.
G0 Z5.000 F500 // safe height again

and this as a feed test

G90
G21
G0 Z5.000 //safe heigth
G0 X-{diameter/2 +startOffset} Y-{diameter*stepover} F2000.0 // start test position at safe heigth
G0 Z-{cutDepth} F500 // cut depth set
G0 X{diameter/2 +cutOffset} F{testFeedSpeed} // the spindle will just go fully in the material
G0 Z5.000 F500 // safe heigth

the problem is, i’m quite ignorant in milling :smiley: i’m a programmer and i’m doing this test generator also to understand better the concepts.

the question is… a test like this make sense? :thinking:

2

That makes some sense. You will need to make sure you zero your Z first.

The plunge on both of them is just straight down. A lot of times, you will get better results if you ramp down, or peck to drill a hole.

The ramp would be something like

G1 Z-4 X10 F500

So it would go down to Z=-4, but only on a slope to X=10. Or:

G1 Z-2 X5 F500
G1 Z-4 X0 F500

To have a shorter ramp, at the same angle.

3

I agree with Jeff that a straight down plunge is uncommon. I use Fusion 360, and the default settings are always ramping into the wood in some fashion. Often the bit follows a helix path into the wood. The only time I use a straight down plunge is cutting foam where the speed of the plunge does not matter. I’d probably just punt on the plunge test.

As for cutting, to start with what you care about is that for any given wood, bit and toolpath, what depths of cut (DOC), RPMs, and cutting rates work well. Creating a test for these parameters is pretty easy in an any CAD/CAM setup. You can also modify the cutting rate on the fly using a M220 g-code, or some displays allow you to make the the change with a turn of the rotary encoder. And if your router has variable RPM, you can make changes there on the fly as well.

4

i forgot totally about ramping, i will do some experiment on estlcam and rummage around to find useful gcodes for that ;).