Rotary Table DRO Encoder (Part 3: Keyway cut, assembly, testing, and calibration)

[@MattysWorkshop]

Gday, you really did a nice job fitting the encoder to the rotary table, I have the TouchDRO unit on the Cincinnati mill and can’t fault it, great DRO, awesome job mate, Cheers

[@fna-wrightengineering]

Thanks, Matty! This project came out better than I had hoped. Haven't had occasion to use it yet, but I'm sure I will eventually. I've been super pleased with TouchDRO. I think it really can't be beat for the price and functionality. I've got one on all my machines, except the optical comparator (which may get one, as well. Haven't decided).

[@joet.4756]

Love it!

[@Steviegtr52]

I have the same rotary table. I used it a lot when making the sensitive knurling tool. Unfortunately your mod would not have worked. As i had to go clockwise & then back round anti. But must say you made a 1st class job of it. Regards. Steve.

[@fna-wrightengineering]

Much appreciated! And yeah, having it only turn in one direction can definitely be a limiting factor. But it's pretty quick and easy to take off the encoder assembly, and just swap the regular handle back on, if needed. I'm diving in to your knurling tool build videos now! Looks like a fun build. Cheers!

[@dbugman1]

how did you hook the encoder to the dro ? im actually wanting to do the same thing but for a tubing bender ?

[@melgross]

Do you have a way to override the one way bearing for those times you go past your mark? We all do that here and there. Do you seriously think they can’t count out a 90:1 gear ratio there? Remember that you’re not measuring table movement, as we do with mill and lathe DROs, but rather the movement of the worm shaft. So this DRO will not account for slop. In theory, the bearing will account for that, but there is slop there as well, as it’s not intended for this purpose.

[@fna-wrightengineering]

No, no way to override the bearing, short of removing the whole assembly, or going allllll the way around again. I admit, this is a drawback. No, I don't expect it to be a perfect 90:1 ratio. The test I filmed happened to end up that way, but I redid the test later, and repeated it several times, and came up closer to 90.04:1. I'm aware that I'm not directly measuring table movement... That would definitely have been my preferred method, but there's no room inside the table body to put an encoder. The bearing is not there to eliminate backlash, it's there to help prevent any from being introduced. Theoretically, this contraption has single-arc-second resolution... But let's be realistic. It's an import encoder, with an import one way bearing, on an import rotary table. I'm not naive enough to expect (nor do I actually need) that level of precision. I addressed a lot of of this in the first video of the series. But hey, I appreciate the input.

[@Copozeras]

Pretty cool build, except the one way bearing, if you pass your number you have to turn the handle 90times to get there again, without the one way bearing you would have to go opposit few degrees and come up to your number again.

[@fna-wrightengineering]

Yeah, that is one drawback. However, the one-way bearing is essential. There is a small amount of play in any gear system, and in this case, turning the handle backwards would introduce error in the readout due to this backlash. The bearing eliminates the possibility of causing that error, basically sacrificing ease of use for accuracy. Ideally, the encoder would be inside the body of the rotary table, driven directly by the table itself. However, there isn't room inside the casting to allow this, hence my solution.

[@Copozeras]

@@fna-wrightengineering I see now! You are rigth hmm

[@craigtate5930]

You weren't kidding about trying to get really good repeatability what sorts of projects are you planning to build in the future?

[@fna-wrightengineering]

Haha yeah, I'm mildly obsessed with repeatability. I think my next project will be turning the other B&S 738 indicator I've got, into a "3D Smeller" for the shaper. I've also got another hollow-shaft encoder, which I haven't decided on a use for, yet...