Days Since Z-Zero Death Plunge: 0

Had several days of perfect cutting with multiple files, until today.

The subzero plunge returned today and of course on a piece that was painted and covered in vinyl to make a sign. It couldn’t have been on the unpainted plywood cutouts, it had to wait for the right moment to make it really count. :face_with_symbols_over_mouth:

I know there is an FAQ somewhere that makes it clear it was my fault, but unless there was static or an EMP, I’m still not convinced. Offsets were cleared, all zeros set and the first tool of the job was measured by BitSetter- I always let the machine measure the tool even between runs, just in case.

No support or troubleshooting expected, just bemoaning another encounter with this unwelcome feature.

For folks who are reading this and wondering where the mentioned FAQ is, see:

Possible causes:

  • disconnect in how origin is set in file and relative to stock — be consistent
  • changing a tool without using the interface — always use the interface
  • lost steps due to mechanical interference — watch out for hoses, cords, &c.
  • lost steps due to inadequate lubrication — lubricate when necessary, see:
  • tool coming loose in collet — install tools consistently so that their positioning can be verified and use a pair of good quality wrenches and a firm squeeze to tighten (the button should only be used to hand-tighten so that things will stay in place)
  • intermittent electrical connection — check all wiring and connectors, usually a loose connection will be revealed by the connector being warm due to resistance — there’s also usually an odd noise when steps are lost
  • setting retract height so high that the machine maxes out at the top of travel and loses steps — make sure that it is possible for the machine to lift to retract height safely
  • positioning the BitZero for a corner probe and then probing for Z only — position the unit so as to match the probing being done

or a software bug or some other gremlin — please let us know about any such at and we will do our best to look into it with you.

Tourist info:

1/2” stock, positioned on 1/4” MDF waste board tape/glued to Shapeoko waste board
CC configuration: Z Zero at top of stock and retract of 0.5”
CM Fitted 1/8” probe, measured with BitSetter, X/Y/Z zero set manually at center (clear all offsets, set all zero), visually verified by location and CM values.

I don’t remember if I loaded the file to cut before setting zeros or after - I don’t recall it ever mattered which order those are done.

Started job, secured requested end mill (1/16” 2-flute downcut), measured by BitSetter.

After the plunge event, shutdown and reinitializing I checked zero settings.
X & Y remained perfectly aligned at the expected zero location.
Z zero was now ~1” lower than where I had set it. It was somehow set below the stock, temp waste board and into the Shapeoko waste board.

As someone else who has had this problem and read the FAQ I have a question about how Bitsetter actually works behind the scenes. Does it simply update on offset measurement when it runs? Or does it completely overwrite the zero? In the document it says:

Here’s what users are doing to crash their Z-axis.

  1. Start the machine and hit “Initialialize
  2. Go to the Jog screen.
  3. Realize that they want a different tool in the router and change cutters.
  4. Set program zero
  5. Run a program
  6. Crash

The error above is in step 3. If you change tools unprompted, something bad is likely to happen.

Since the machine will ask you to load a tool at the start of a new job, shouldn’t that reset where the zero is? It already has Z zero set before and now has remeasured the tool. Does it crash because the zero was set with an unknown length of tool sticking out from the spindle?

Your question may be more general, but for my experience, the length of the probe used to set zero was measured by BitSetter, as was the first tool for my job, so both tool lengths would have been ‘known’ to the machine.

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