A little CMM

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Posts: 54
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A little CMM

Post by Moray » Tue Sep 18, 2018 8:42 pm

A few years ago, I needed to copy some components, and doing it by hand measuring/plotting was proving to be take too much time, so a solution was needed. Commercial CMM machines were definitely out of budget, so after some thought, a plan was hatched. This machine was the result of that plan-

CMM by Moray Cuthill, on Flickr

For time purposes, I bought a generic chinese 3040 router, chucked all the supplied electronics back on eBay, and built a new control box using a KFlop and Kstep. The 200W spindle was replaced with a dummy spindle to mount a touch probe, and tests began. Just using open loop control was not resulting in good enough readings, despite much fettling to get everything running with as little play as possible, so a set of 1 micron glass scales were purchased. Once fitted, X and Y were re-configured to run closed loop, and I got results good enough for what I need.

Inside of the control box -
2016-05-06_09-45-53 by Moray Cuthill, on Flickr

Nothing that fancy on the control box. KFlop/Kstep mounted up top with a bodged together breakout board to the right made with what I had lying around at the time, so I could get the probe wired in easier. From left to right on the DIN rail, are mains fuses, mains neutral terminals, Earth terminals, E-stop relay (it's only a basic setup, so it's just a generic relay that switches the main PSU), 24VDC PSU for e-stop/control circuits (aka just he probe on this!), 24V terminals, 0V terminals, 5VDC PSU (for KFlop and scales), and finally the E-stop circuit connection point (which was simply bypassed in that photo, as I hadn't added a stop button). Then at the bottom is a just a nice basic and reliable linear power supply to power the steppers putting out around 45V.
For anybody interested, my original build thread can be found at http://www.machsupport.com/forum/index. ... 732.0.html

It's not been used for a while, but I've got some more bits I need to copy, and I'd like to do it all via KMotionCNC, as it's the final machine relying on Mach3. Which is why it's been dug out from it's corner in the workshop, and into the house, so I can write the required software in comfort.

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Re: A little CMM

Post by TomKerekes » Tue Sep 18, 2018 10:23 pm

Hi Moray,

Perfect for testing the probing :)

Thanks for sharing.

Tom Kerekes
Dynomotion, Inc.

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