z-axis problem

drew dxf drawing in LibreCAD with all dim in MM.
Loaded dxf dwg into EstlCam which was setup for all MM and for Z axis to reference top of material.
material is Styrofoam that is 18.10mm thick so I put two layers since I programmed for 3/4" material which is 19.05mm thick. So I expected cut through from the top sheet into the 2nd sheet.

I had 39.5mm of bit exposed from the tip of the bit to the edge of the collett.
I started the program and it drilled a couple of holes that I “think” were too deep.
Then it moved to cutting a large oval hole. When cutting the hole I had to hit the E-Stop.
The hole was cut a little bit at a time until it tried to go deeper and it drove the collet approximately an 1/8"into the Styrofoam. It should have stopped more than 20mm before it got to that point.

Anyone have any clues where to look? It appears that x and y are right on in there movements.
And I haven’t made any hardware mods from what I purchased with MPCNC.

You’re either moving the Z too fast, so it’s skipping steps, it’s harder to go up than down, so it will skip on up movements. Or you need to put some grease on the threaded rod.

Thanks for the response Barry.
I’m totally new at this and should have posted my question in the MPCNC section instead of this one but since I didn’t I’m going to ask my followup here.

Since I don’t have a clue, where can I slow down the speed of the z-axis without impacting the speed of the x,y axis which appear to be working fine?

Thanks for taking the time with me. And after this I’ll get over where I’m suppose to be. Promise. You just have to watch out for us 72 year old fogeys trying new stuff.

Depends, which software are you using?

Repetier.It was in the tool menu. I stubbled across it.I still have problems though even after I slowed it down to 2mm/sec in Styrofoam. And greased a screw that is brand new with no burrs and no noticeable friction that I ran through a die before I installed.

I’m going to go ahead and move over to the section I’m suppose to be in. Thanks.

Oh, I see I’ve been moved…duh.
I found that the vertical speed on the bit was 10.6mm/sec and I changed it to 2 mm/sec which doesn’t seem fast at all for Styrofoam.
I marked my bit with a black marker at 19.05 mm (3/4") so I can sort of see what it is doing since the foam is less than 3/4" (a little over 18mm)
Started things up and it appeared the two helical holes that are drilled first did drill at 19.05( 0r as close as I could eyeball my mark).
It then moved to the hole.
It appeared to be doing fine and was what looked to be the exact middle of the last lap of cutting the hole when it sunk the bit up to the bit up to the chuck (an additional 20mm)
Code generated by Estlcam V10.013
using 1/8 end mill 1.02 vert step 2mm/sec vert speed
Repetier Host V1.6.2
everything set for mm/sec
ref to work piece surface
gcode attached
any and all help always appreciated

here’s the right file

rt_outside.zip (6.13 KB)

Your feed speeds aren’t being duplicated for each cut. The ramps board has a funky habit of just using whatever speed it used last. Adjust your estlcam settings with this guide.
https://www.v1engineering.com/estlcam-basics/
Make sure you checkbox the feed settings.

Here’s what a chunk of something I made looks like;

G02 X4.9350 Y6.7281 I0.0452 J-2.5743 F1800
G02 X6.2612 Y5.8881 I-2.3413 J-5.1633 F1800
G02 X6.7715 Y5.0713 I-1.5230 J-1.5191 F1800
G02 X7.0262 Y3.7500 I-5.1519 J-1.6782 F1800
G01 Z-2.0000 F480
G01 X3.7500 Y3.7600 F1800
G01 Y6.9938 F1800
G02 X4.9350 Y6.7281 I0.0452 J-2.5743 F1800
G02 X6.2612 Y5.8881 I-2.3413 J-5.1633 F1800
G02 X6.7715 Y5.0713 I-1.5230 J-1.5191 F1800
G02 X7.0262 Y3.7500 I-5.1519 J-1.6782 F1800
G01 Z-3.0000 F480

See how it has the feed rate at the end of each line?

Here’s yours;

G02 X296.5018 Y117.0801 Z0.1613 I-0.1984 J0.0000 F120
G02 Y117.4239 Z-0.1773 I0.0992 J0.1719
G02 X296.7994 Y117.2520 Z-0.5160 I0.0992 J-0.1719
G02 X296.5018 Y117.0801 Z-0.8547 I-0.1984 J0.0000
G02 Y117.4239 Z-1.1933 I0.0992 J0.1719
G02 X296.7994 Y117.2520 Z-1.5320 I0.0992 J-0.1719
G02 X296.5018 Y117.0801 Z-1.8707 I-0.1984 J0.0000
G02 Y117.4239 Z-2.2093 I0.0992 J0.1719
G02 X296.7994 Y117.2520 Z-2.5480 I0.0992 J-0.1719
G02 X296.5018 Y117.0801 Z-2.8867 I-0.1984 J0.0000
G02 Y117.4239 Z-3.2253 I0.0992 J0.1719

Also not sure what your I and J settings are.

where are the I and J settings input at?