M4: arm ordering

Is there a reason why we could not have the lowest arm be one of the top arms? Now that I am 100% sure I have the arms on in the right order I still see that the lower left arm interferes a little with the dust hood (3d printed part) when Z is all the way down. I was wondering, why not have the order such that one of the top arms is lowest instead?

We can pretty easily change the order of the arms in software so it’s not a requirement that it be that way, but I picked that order to try to balance the forces. Having the upper arms be the top ones helps to counteract gravity which is trying to tip the sled over in the other direction.

Again, not 100% sure that it’s the right answer, but that’s why I chose that order.

ok, sounds good. I guess in nominal operations, you would not really be running the thing with Z all the way down hardly ever so it probably is not a big deal either way. I was only wondering if this might also be part of my calibration issues. Probably not is my guess though. I’ll watch it during my next run through and see if the belt rubs on that part during the calibration.

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It’s certainly not ideal. We might want to tweak the design of the dust collector at least.

the top is round, wouldn’t any arm that’s at the top have the same problem?

David Lang

The lower left and right arms are the problems (for the dust shroud anyway), but only during calibration as you would raise Z at least a little with a bit unless plunging very deep (which I probably won’t do, I’m intending on mostly cutting 1/2 or 3/4 stock for the most part).


ahh, sorry, I missed that it was the dust cover for the vaccum that you are

David Lang