z-Axis Issue - dropping into worktable on first pass

[cswilki (Steven Wilkinson)]

My first two CNC projects came out fine and I was able to reload the project file and replicate my work.

Now, I have a new project #3 and I am finding that when I start the project the 1/4" end mill plunges way to far in and then chewed into the washboard and aluminum rail. Redrew the project in Create and had the same issue.
Project:

1. Set stock at 0.465’ with top
2. all cuts to bottom of stock use the stock bottom.

Machine: Shapeoko 4 XL

1. I mic’d my stock - .465"
2. Initialized the machine
3. set bites tool and probed on bitsetter
4. Used BitZero to get the X, Y, Z at left corner of stock (0.465 thick)

Loaded File: Attached

1. Loaded the 1/4’ 201 end mill
2. set hieght on bitsetter
3. started job and turned on router
4. 1st cut plunged the end mill about .3’ into stock and then proceeded to cut into my aluminum rail.
   stopped machine and router - emergency

took pictures

Steven Wilkinson

Image of BitZero final results

What is the machine or I doing wrong?
Coil Winding Discs 17MAR2024.c2d (112 KB)

[Woodcrafter (John Matteson)]

If the machine is solid no loose screws/bolts or wiring.

Then another possibility is maybe the cutter got pulled out of the collet during machining.

https://community.carbide3d.com/t/why-did-the-spindle-decide-to-dive-down-into-my-bed-and-rails/67019

Just a thought

[cswilki (Steven Wilkinson)]

I’ve made 5 tries at this project. Even redrew the drawing and created tool paths.

Used a different collar, a different bit and got the same results.

I’m going to reseat the cable connectors going to the z axis and try again.

Thank you
Steven

[Woodcrafter (John Matteson)]

I’ve read some post where people have had issues with GFI outlets, shared circuits, grounding issues or sources of EMI messing with electronics.

Another thought would be to take the Bit Zero out and manually set your zero’s and see if has the same problem.

[cswilki (Steven Wilkinson)]

I’ll try that, thank you

I’ll change power to a single outlet as well

[Tom_S (Tom)]

Also being a rookie I had a similar problem. Some how I had changed the toolpath Starting depth. Make sure you are set to USE STOCK TOP.

[gmalehooah (Laurent Riendeau)]

I had the same problem I was tightening the bit enough and haven’t had it since. I really reef on it now enough that it hurts. Arthritis

[wmoy (Winston)]

Just as an extra check, can you mark the shaft of the endmill with a sharpie next time you give it a try just to make sure there’s no movement there?

And as an extra sanity check, after you load the 201 endmill and it touches off on the BitSetter, can you manually jog back to the corner of your stock and see if the position readout shows pretty close to 0 in X, Y, and Z? That would confirm there was no drift or loss of steps in the intermediate operations.

[neilferreri (Neil Ferreri Ω)]

If you jog the Z an inch, she’s it move exactly one inch?
Are you configured for Z-plus or HDZ?

[cswilki (Steven Wilkinson)]

That’s an interesting question. When I’m testing the z axis it jogs more than an inch. Like 1 3/8

[cswilki (Steven Wilkinson)]

Z-plus testing the zero now and will remeasure the z drop and raise

[WillAdams (William Adams (Carbide 3D))]

You probably have the machine configured for an HDZ when you have a Z-Plus. Reconfigure.

[cswilki (Steven Wilkinson)]

Setting after using bitzero
Then I dropped rid down on top of paper until it did not move when pulled by and it registered Z: -0.000

X & Y have always (when working properly) been 0.394”. This is the staging point after probing

On the machine setup screen for testing motion this is the movement

Z: -0.655 original position
Z:-1.639 Move Z Down
Notice the movement is less than 1”. -0.016”

I also measured physical

Machine setting

[cswilki (Steven Wilkinson)]

Created a new project to test

Straight line with tool path being 0.050 depth with #102 1/8” square bit.

Measured before and after bit length in chuck and it was before and after, 0.615” in length.

Cut in 0.465” thick material at a depth of 0.0650”, 0.0150” over.

Material at left end of cut had a zero of 0.0150”
Material at right end of cut had a zero of 0.019”

To me that says the material was at least 0.015” higher at cut point. Note: I did not surface the material.

The cut depth at left end was 0.0650” so, with a material height 0.0150” over corner zero the cut would have been 0.0500

That is accurate , in my mind