Am I setting up my z probing incorrectly

I ran two jobs yesterday. Each job I reset the z using the bitzero v2. For both jobs I used different bits. The challenge is

For 1” thick stock - I set it to go 0.975 and it went exactly to the bottom of the stock.

For my 0.125” thick stock, I set it to go 0.1 and it went exactly for the bottom of the stock.

So if seems I am consistently off about .025” in z probing which leads me to believe it’s the way I have my offsets, but I don’t know what to adjust.

I took this screen grab from vcarve as I realise that this is where the issue could be

Also, another question, how do others work hold large sheets of 1/8 hardboard as my blue tape and bob’s CA glue was not strong enough.

A very first step would be to probe with the BitZero v2 as you usually do, and then instead of running the cut, just jog manually to the surface of the stock. What does Z value read then ?
This way,

  • either Z is not 0.0 at the surface of the stock after probing and you will know something is wrong in the probing sequence
  • or Z is 0.0, but running a 0.925" cut from there actually results in a 1" deep cut => then you would likely need to look at your G-code (checking in e.g. that it actually drives the cutter down to -0.925" only) and your Z calibration factor ($102)

@Intohouse are you actually measuring the stock to make sure it’s exactly the dimension you think it is and not just nominal? The Home Depot page says that 1/8 inch material is actually 0.125 in, but it would not be uncommon to advertise as 1/8 and get 3 mm or thinner.


@theworkshope Yes, I checked the actual dimensions vs the nominal (but thanks for asking as it is a common school boy error)

@Julien I checked the file on NCviewer and this looks correct. I’m going to take my one inch board and do some test cuts with different $102 settings to see if that is the root cause of the issue

If you haven’t calibrated your belts, all bets are off.

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It is amazing, isn’t it…

I spent the afternoon thinking about the perfect workflow to test changing of $102. This evening after the Blackhawks game (They won finally :partying_face:), I set up my tripod and camera to record all of the testing I was going to do.

And, as most people know, when you want to record your actions, every step takes three times as long, but I wanted to make sure I could show evidence of the issue when asked for further details.

Anyway, I surfaced the new spoilboard and then began the test by cutting out my test rectangle, and wouldn’t you know it, the issue didn’t happen. It was a perfect cut. :flushed:

So on one end I am absolutely thrilled, because it appears my machine is working as it should. On the other hand, I feel like I have egg on my face :weary: and feel so bad for wasting everyone’s time.

I do have one question though…In the picture below, it is of my latest surfacing job. In the top half of the board you can see virtually zero surfacing lines, but the bottom half of the board you can, however when you rub your hand over the bottom half of the board, you really difficult to feel any of the lines. Thus the question…

  1. What would be out of alignmet that would cause this?
  2. Can I just ignore it?


Something is holding the trim router so that the endmill isn’t perfectly plumb/square to the movement of the gantry, or it’s climb/conventional cutting differences since it’s confined to one corner.

I’d leave it be for now and start using the machine, at least doing more testing — if you come up with a test cut or project where this is an issue, then you can work to resolve it.


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