# RT Rehab



## francist (Dec 1, 2019)

Got the little rotary table tuned up enough to actually do something. This is the one I bought a few weeks ago and right out of the gate I knew I was going to have to put some time into it.




I had intended to put together a more thorough play-by-play of what I did but it was starting to feel like a bit of a reach and wasn’t really that captivating. Most of it was just deburring and getting better fits on the parts, so this abridged version will have to suffice.

I stripped off all the ugly paint, cleaned up the dials, inked in the graduations so I could see them, and massaged as much lash as I could out of the worm assembly.




The casting itself was not too bad but I did clean up three of the edge faces on the shaper to get better fit for the dials as well as more consistent reference edges.




Probably the most fun was making new furniture for clamping the table and indicating the degree markings.







Nothing I did miraculously changed it into a super-smooth, ultra-precision tool, but it did make it a lot more pleasing to use. And in the process you always learn a whole bunch about how the thing works or is supposed to work, so there’s value just for that.




Thanks for looking!

-frank


----------



## DavidR8 (Aug 9, 2020)

Thanks for the write up Frank. 
What size is the table?


Sent from my iPhone using Tapatalk


----------



## francist (Aug 9, 2020)

DavidR8 said:


> What size is the table?


It’s a whopping 3-1/8” in diameter!


----------



## WCraig (Aug 9, 2020)

Very nice work!



francist said:


> ... cleaned up the dials, inked in the graduations so I could see them, and massaged as much lash as I could out of the worm assembly.


Could you expand a bit on the above?  What did you do with the graduation marking?  How did you remove backlash?

Craig


----------



## francist (Aug 9, 2020)

@WCraig 
The graduation markings were just so faint that they were difficult to see. For one thing they weren’t of even depth — some were shallower than others ( not sure if these are etched in, perhaps, or stamped, don’t know) and they didn’t stand out well. So I re-blacked them using some black enamel. I used to do this a lot when I worked with a silversmith making things like painted key tags and a signs — you place the enamel paint in the recesses and while it’s still wet carefully wipe the excess from the non-relieved areas. I use small slips of newsprint moistened with solvent (old telephone book pages were great when they made telephone books because they won’t scratch a polished surface) over a hard rubber block to remove the excess but not the paint in the recesses. Lacquer works better than enamel (fewer solids) but either can be done.

For the backlash, much of that was a result of the method of restraining the worm. There is an eccentric pin that loosely engages the tail end of the worm shaft so the mesh of the worm and table may be brought closer or further apart. With that brought closer into proximity much was gained. I also added a shim washer to the nut-end of the worm shaft where it passes through the knob to smooth things out there. Thirdly, the dog pin that engages into a groove around the worm shaft was really poorly fit, so a totally new one of those aided in tightening up the motion further. There’s quite a few things going on in one of those rather simple mechanisms, and a bit of slack here, a bit more there really starts to add up. Going through the entire thing from the ground up was really useful.

-frank


----------

