These are plastic which is neither here nor there, but the plastic under the 5mm hex screw that holds them to the rings doen't extend all the way down to the ring below them. This means that they're very easy to break. My SV102ED came with one that was cracked already and it broke when I moved it. I could have sent Stellarvue $9 plus shipping and buy a new one with the same problems or build a new one.
The original bracket with the center broken out of it held above the new one
The new bracket in position
The RDF mounted
The new bracket was made from a piece of scrap 3/4" aluminum that was first cleaned up on the mill so that the edges were parallel. A cutter 'darned close' to 1" was used for this and, as the 'slot' in the bottom that leaves 'wings' to keep the bracket sort of square on the rings is 'darned close' to 1" wide the same cutter was used to hog out the slot. The slot is actually just a hair narrower than the one on the original so it fits the rings a bit better.
The dovetail is about 1/2" across and after eyeballing it next to a 75 degree cutter it seems to have that angle. So the new piece was scribed with calipers and the dovetail cut to a depth of .080". Then the centre was found and a hole drilled through with a #7 drill bit then countersunk with a suitable cutter that was selected to fit the hole in the original plastic part.
I can guarantee that the centre won't punch out of this one.
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