The Shop > Electronics & IC Programing

DIY bluetooth DRO for my mill

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vtsteam:
And here's the X axis reader mounted to the mill's fixed stop:

vtsteam:
DTI measured scale resolution appears to be ~ 2640 lines per inch, or about .0004" (.01mm) and repeatability is excellent. No display glitches. I haven't fully calibrated it yet, but quite pleased with that.

efrench:
That's certainly better than mine which were probably from the bottom of the barrel on AliExpress  :hammer:  I'll probably try to use mine on another project.

vtsteam:
One difference in using the original displays vs using this shop built display is that I can set the calibration in software. ie. how many lines per unit length as a setting. This is likely to vary for many reasons, including even the physical setup.

If you have a consistent error per length rate then I would suspect the need for calibration, and the scales themselves may be better than they appear. Since the original scale heads do not allow calibration, you might consider a project like this one.

vtsteam:
On to the Y scale mount:

I just didn't want to drill into my carriage horizontally in my cramped space and tap blind holes into cast iron in situ. I also didn't want to remove the table. Yet I wanted to mount the scale on the carriage and mount the reading head stationary on the base. It took a lot of thought to come up with something, but it occurred to me that maybe some kind of clamping fixture would work -- maybe fabricated out of steel angle and strip.

Below in the photos is eventually what I worked out. Not the most elegant piece of work, but it does what it is supposed to do -- it's a close fit on the extended bearers, and a couple of setscrews lock it in place. I did drill dimples into the castings for the setscrews to register in.

The main body is 1-1/2" angle iron. The downward facing leg will be where the scale mounts, inside the angle. The horizontal leg above will shield it from swarf.

The angle iron isn't quite square to the mill surface. It is rotated 8 degrees from vertical, because the cast iron bearer surfaces were at that orientation, and in fact so is the mill base edge -- that's the draft angle it was given when cast. This is quite convenient since with both the scale mount and base surface at the same angle, reader head will be straightforward to mount, and I won't need an angled bracket.

Well, I'm definitely glad to get this puzzle worked out after a lot of head scratching, and trial fits. The scale will go on tomorrow.

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