Furiously busy with the project the last couple of days. Let's start with paint-stripping on most of the black parts. They got a dose of the Citristrip and covered over with some 4-mil plastic dropcloth and left overnight. Something I found that works oddly well is to slather one larger face of the part with the stripper, and then plop it face down onto the plastic. A few hours later the stripper/paint glomp will often transfer right to the plastic with no work.
After getting the paint off, I had a good look at the mirror cell base plate. $%#!! Rough grind marks all over it and some really deep gouges (0.5mm+). I had already planned to face-mill it, but today I felt the need to do something about the edges...didn't want to scan the contour for a re-profiling on the mill, so I tried sanding with a coarse ~100 grit drum on the trusty Dremel.
The Dremel sanding operation actually was a big success. In under an hour I had all but the deepest grinder gouges out, smoothed out the curve radii and chamfered all the edges for good measure. Next picture shows the result. I still need to go back and sand off the casting roughness on the inner circle.
Here's a bunch of small parts getting their 2nd coat of stripper. Somehow there are always places that don't get enough. Getting the dissolved paint off is a messy process involving mass quantities of shop towels, gloves (the stripper destroys nitrile gloves fairly fast), plastic dropcloth that gets sticky and wraps itself around everything, and relentlessly bad language. I really need to find a local machine shop with a media blast cabinet, this would have been so much less trouble with glass bead blasting.
Today was also epoxy primer day for the legs and tube. The tube got an all-over sanding first, and then everything got about 3 coats of primer with 5-minute flash-off in between.
The filled-in holes have completely disappeared.
Even more things got done that I don't have photos for. I did some measuring and figured out that I can counterbore the holes for the spring-loaded cell adjusters to about 0.120 deep with a 3/8 end mill and use some #10 low profile SHCS to bolt it down to a plate for the face milling. So I went to the hardware store and got the screws.
I also went down to Industrial Metal Supply (the go-to place in San Diego) and picked up a couple of 1/2"x4x12 6061 plates to use for that operation, and a chunk of 3.5" round stock to make a new dec shaft interface for a flat OTA mounting plate. I need to give it more engagement length with the dec shaft, and have more diameter for a bolt ring.
It also occurred to me that I can address the issue of balance issues from immovable rotating tube rings (along the tube axis) by putting a ~16" Losmandy rail on the outer rotating rings (11.75" OD for the radius blocks) and a matching saddle on the base plate. That will let me shift the tube +/- 4" for balance and should pretty much get rid of the need to add/remove tube counterweights, though it looks like there will still have to be some.