kb58 wrote: ↑Fri Dec 01, 2023 1:23 pm
I mean that if the router is repeatedly power-cycled, and if each time the servos shift position slightly, it means that over time, those slight offsets (if in different directions) could add up and become a problem. It's just a theory and is untested.
Anytime you power cycle the machine you HAVE to re-home it, however it is you do that, manually, automatically or auto-squaring. So I'm confused as to how you are even using the machine without re-homing it and/or worried it's out of square. It shouldn't matter if a stepper or servo jumps a few thou to a detent at power up. You're gonna home it and square it BEFORE you use it, no?
Again, my Clearpath power up disabled and I can grab any axis any manually drag it BEFORE I press the cycle start button to have Acorn home the machine to my home switches.
As Gary stated, there's no substitute for a rigid machine.
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We're in complete agreement. My point is that even if we have a completely rigid machine, the servos jumping at power up is a problem. If it doesn't skew the gantry, they'll be consuming excess power trying to drive to their skewed position. If the gantry is homed via hitting one home switch and calling it good, that's not good enough because they're still trying to drive to different positions due to the power-up jumping.
The difference in how we're looking at this is that you're saying a stiff gantry is always square. I'm not arguing that, I'm saying that if it's homed using only one switch on one side - calling it "homed" based on the first switch it reaches - the two servos will end up fighting each other, trying to get to where differing positions at power up.
Last edited by kb58 on Mon Dec 04, 2023 5:09 pm, edited 1 time in total.
So my gantry issues appear to be solved. I stand my my theory that any gantry-style machine using two servos will have issues unless some sort alignment is done at each power up - handling each end of the gantry separately. Even an infinitely stiff gantry will eventually have problems in the form of overheated servos due to them fighting the shifted positions, which can become increasingly large over time.