Since I'm clueless in machining matters, I'm stuck again with mismatched parts and looking for assistance.
I have purchased an El-Nikkor 150, which is threaded on the back -- 39mm, I'm told. Looking at KBX Photgraphix for a disc to mount it in, to hold it to the cone of my D2 (I have one for my 135 Componon, held by retaining ring, but much smaller than the Nikkor back), I had a choice of an out-of stock used disk with the 39mm threaded flange already included or an in-stock plain disk with a 39mm hole. Knowing that the former could be years away, I bought the latter, albeit at an ouch-price with the shipping, and gladly took the offer of a flange at a great price from a member here.
The problem is, the hole in the disk is just slightly too small to accommodate the threaded part of the flange. The screw holes in the flange are for countersunk heads, but of course that side is on the side opposite the threaded part. Therefore, I need to either
1. pay a machinist to widen the hole and tap or drill the three, #3-56 screw holes into the board to attach the flange (though I am concerned that widening the hole would get it very close to where the 3 flange screw holes would be. The disk is 1.5mm thick. KBX says it's plenty thick enough to thread); or
2. reverse the flange, putting the countersunk side against the disk, and use flat head screws. Then the question of clearance from the top of the heads to the back of the screwed in lens may be an issue; or
3. find a retaining ring for the back of the Nikkor. I have no idea what the thread is.
Given what I've already spent, I will great grateful for learned advice.
I hope the photos help.
Lens1 and Lens 2 show the the non-countersink side of the flange. Lens3 shows the potential head-clearance issue. The distance with the lens fully screwed in appears to be about 1/16".
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