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Show"N"Tell ( What you have made with your CNC machine.) / Re: Another Turner's Cube.
« on: May 12, 2019, 11:57:23 AM »
Crazy ain't it!!! Hopefully we can come back in another 11 and say the same thing.
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where have you been hidingYeah, I've been MIA for a bit. Been kinda super busy lately. Quit a job of 14 years, started building a new house, and shop, been busy in my current shop, started a new job, the list goes on. Maybe it will slow down a bit come winter. New shop is not a monster by any means, but it should hold enough equipment into the foreseeable future. At least I can fit a machine thru the door on this shop.
My backlash for 1" moves of 40" moves is within 0.0002" repeatabilityNot exactly sure what you mean, but I think you mean 1" moves, repeated 40 times. Repeatability and backlash are two separate things. Think of repeatability as positional accuracy over a number of cycles. Backlash is the free play, or gap, between drive components when there is a change in direction. There can be a massive amount of backlash, and you can still have superb repeatability.
whether it's a 1" diameter circle or a 8" circle... they are all out of round by 0.030"Davek0974's advise is great, and you should do that, however, you state that the deviated amount is the same, regardless of circle diameter. If the motors steps per unit were off, the deviation would not be consistent on different sized circles. Sounds like backlash now. That does not mean that your steps per unit are correct, and you should still check it. As Dave stated, use as long of a distance as possible. If you have a set of 6" calipers, use those. If you have 12", use those instead. Remember, move enough distance to take the lash out, and then measure in that same direction.
one circle seemed to start and stop a lot, while others were a continuous motion/soundMost likely, the machine is doing exactly as the code is telling it to. There is nothing indicating a problem with the machine by this. The start/stop is segmented code (less than desirable in my opinion) being executed (G1), and the other pass is using circular interpolation (G2,G3). You can take a look at the code to verify. The reason behind the code being generated as segments, can be vast. There might be a setting in your CAM program that can have an impact on this.
should my dual motor Y axis acceleration setting be.....When your trying to remedy a problem such as this, I would turn the accel down, to eliminate it from the equation. Turning it up may just introduce a new problem into the mix and make confusion/aggravation shoot through the roof. You can always tweak the accel later on, when the problem is fixed.