Saturday, August 27, 2022

Blackening Zinc Plate

The 5" screws are zinc plated.  There are products specifically made for blackening zinc plated steel.  It is not commonly stocked as near as I can tell.  Instead of oxidizing the zinc, it  molybdates it.  This is curious because zinc molybdate is white not black.

I used one of the DIY black finishes a few years ago for an American Arms PK-22, a licensed copy of the PPK which uses a zinc frame and receiver.  It came out okay, but I wonder if this product might have been a better choice.

The combination of thumb nut and 5" screw should work.

It is a tight enough fit at the head that I doubt it will move on the screw either direction.  I may put a lock washer between head and thumb nut and a lock washer and nut on the other side as well to get it very screw.  Another extreme solution is the drill a hole in the other end and use a set screw to lock it very solidly to the screw.

Turning it into the mirror holder, the thumb nut turned on the screw, so next step is lock washer.  I have an application test.

I thought that I ordered 5/8" diameter thumb nuts but these are 1", a bit too big.  No, I ordered 1". I was clearly no thinking so I ordered some with 5/8" diameter.

The more I think about it, once I get the right thumb nuts the more I think I will do some small set screws to hold these in place.  Setting them up in the mill to drill the holes and tap is easy. 

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