Why is there a small gap between surface and endmill after probing?

Good day, everyone. I have just gotten the onefinity probe and I noticed that after probing, if I were to get the mill to go to z0, it will still have a small gap between the surface center and mill. Is that by design? I’ve been doing the paper zeroing until this point.


With CNC machines have a zero offset so that way they can move from zero to the start point of its cut without cutting a straight line across the top of the machining piece. Some machines you can setup the offset. I’m still waiting on my machine so I do not know if you can setup the offset but with my milling machine I usually set the zero offset to .75 so I have plenty of clearance across the top of the material for my bit to clear.

I see. Now in fusion 360, I usually set the starting point as a stock corner. That stock corner, height wise, perfectly aligns to the surface of the panel model I’m trying to mill. Does that mean that mean I’m going to be losing that 1mm offset? Do I have to compensate for that 1mm by getting cad software to mill 1mm deeper?

No you do not have to compensate If you are using a probe and your probe dimensions are correct on the probing script setup plus if your working surface is perfectly level. A clef note** If you ever get into engraving letters using V-Bits save yourself a ton of wasted material and surface your working surface first. If not cutting a little deeper by mm’s is not a bad thing in my opinion.

A few things I would look at from your video.

First - I’d make sure you have the correct value for the thickness of the probe in the controller, the default is 15.4mm but mine measured 15.45mm:

Second - your spoilboard looks like it can use a surfacing to make sure it’s flat and parallel to the rails, since the probe is about 2x2 inches square it’s taking an average height - in fact likely finding the high spot in that 2x2 area which is throwing you off a bit,

Finally - make sure your stock is flat - similar to above the probe is finding the average high spot - if you were to move the x and y around in that area with z at your work offset 0 value - you may find a spot where it touches the stock (after completing the first step and verifying the thickness of the probe)

Hope this helps.


Start your probing cycle closer to the touch-plate as you maybe introducing errors by starting so far away from it.

Miles - you should not have a gap after probing. Aside from the suggestions already noted, it do have some debris on the material, I would ensure the probe is completely flat against the material.


You may need to fine tune your probe

I figured I might have, but this is a repeatable occurrence no matter the distance.

Yep, I’ve explicitly gone over the dimensions with a caliper to verify my particular probe matches the values. Everything was adjusted accordingly.

The weird thing is that the probe is nice and flat against the aluminum stock so it shouldn’t be doing this at all. I can run the probing repeatedly on the same spot in case of errors and it would always result in the same gap. Gent above had mentioned that this is normal behavior for probing?