Plunge Rate Doesn't Match Gcode

Gcode file is to big but here I attached a snippet. Essentially the machine is plunging at a FAR slower rate than the F360 command on each line suggests.


I am doing Trochoidal Milling, and my first thought is that the volume of commands is slowing everything down. There are a lot. Am I correct here? I run my machine off of an old laptop and I’m sure the processing power is garbage.

That gcode does not look familiar how did you make it?

Does my crown gcode work perfectly?

Sorry Ryan,


Should have included more info. My MPCNC has been working perfectly for a few months now. I’ve been doing really detailed wooden reliefs and I am blown away by the accuracy and detail you can put into a wooden relief with a .5mm diamater tapered bit.


I dove into aluminum lately which is when I first saw this issue. My test cuts into aluminum have actually been half successful. I’ve done a few pockets now with 2% Troch stepover, 7.5mm DOC, and 18mm/s feed rate with a 1/8" single flute carbide end mill. I’m getting these nice fat chips that clump together in balls (makes me smile just thinking about it). My problem is that the plunge rate is incredibly slow. I try to up it in the ESTLCAM settings and it just doesn’t speed up. I’ve modified other settings for the tool and confirmed they have an impact, so I know I am definitely applying the changes to the path. I also verify the commands in the GCODE.


Another thing to note is that the plunge is slow the whole way down, it doesn’t plunge quickly through the air then slow down when it hits the aluminum. Also it plunges to the correct depth and finished the pocket as ordered. Its just slowing down the rate and I have no idea why. I am still partial to my first explanation, but maybe thats because I’m used to running <3mb programs but as soon as I got trochoidal milling involved they are 5-10x that size and my command prompt in repetier is a lot busier than I am used to seeing.

Those moves are very small. A large number of small moves can have this problem. Running from SD is the best remedy I know of.

Trochodial will slow everything down. It helical spirals into plunges.

I was playing on Saturday a bit with it around.

I had the back-plate of the printer.

Normal milling with 1 mm steps 10 mm deep was 970 lines of code

The same plate witch trochoidal milling in 2 x 5mm steps went to 470000 lines of code

Then another try with the full 10mm and the oscillator switched off was something around 340000 lines if I recall well.

All done with CNC.js over a Raspberry, (don’t remember if it was the Pi2 or Pi3). I doubt that connecting to the Pc makes a difference in speed.

I looked at my g-code and it looks similar to the one posted.

I might be wrong on this but I doubt that any speed adjustments in the g-code would do any difference. Those moves are so tiny that they moving constantly within acceleration deceleration ramps. So my guess is to try adjustments there, but that will most probably result in odd behaviour for normal operation.