Hmm, I just finished writing a long thread about my journey to get an XYZ zeroing block made for the Shopbot at my makerspace. That has me wondering if such an approach could be a way to speed up and improve calibration so your situation is less likely to happen and easier to recover from.
What if metal four blocks of known dimensions were placed in the corners of the work area and a similar calibration for XYZ was done for each? And then distances could be calculated or interpolated accurately between them? Would that give us a way to get consistent measurements and calibration data so less user input and manual measuring was required? [Edit: hmm since we can both measure and also calculate, would this allow us to, using differences, detect sag areas and auto adjust for chain slack etc?]
Just whiteboarding on-the-fly here but lets say I put a 2"x2" square (stepped for the work piece), 1" thick machined aluminum block (like in my post linked above) in each corner of the frame and squared to the edges of the wasteboard/workpiece… I can do a standard Z depth test to Z at top of work piece, and I can get X and Y by bump testing like in the Ron Olson video in my post. And then with that data triangulate the underlying corner of the work piece or wasteboard. Repeat in each corner and also bump measure between the two inside edges of each block pair, giving me the length between corners
Hmm I think we might only need 1 block or 1 pair of blocks. Having 1 pair allows you to do multiple measures between left and right without moving the block from one corner to the other. Then move the pair to the lower corners and repeat.
Would that give us enough calibration data to at least complete the basic calibration that is done by hand today? I realize more datapoints like in holey calibration should yield even more accuracy, but I think this would get us to a more stable starting baseline than todays manual method, would it not?
It seems it would scale to different workspace configurations as well, as I know not everyone made full 4x8 frames.
Taking it a step further, if you had two pairs of blocks and were working with a square work piece you could potentially calibrate to each work piece before starting, if there is any value in that? I’m just thinking scaling down to the smaller workpiece within the larger frame if that yields any advantage, as long as it is reasonably quick and automated. Or even automatically confirming calibration after a bit change.
Or, taking it to an extreme, and again assuming it was reasonably quick and automated, recalibrating between each depth of cut change - which would also allow throwing a warning or error if something was different from the previous calibration run on the job, to give the opportunity to fix skipped sprockets etc when detected.
@bar am I out to lunch here or do you think this is something that could be a benefit?
-Jeff