Instrument glass replacement

There are often percentage of rpm and many other instruments on eBay, mostly unserviceable or condition unknown. eBay user chrisw8511 has various types up for auction and buy it now at the moment.

I know nothing of old instruments, but I do tinker with old watches. Bezels are usually either snap-on (often v. tight!) or screw on. Given that this instrument supposedly contained a vacuum of some sort (cf. Dry Crank) I wonder if it was assembled from the back, i.e. glass was dropped in first and sealed into the case, then the mechanism, then the back with some sort of spigot to draw out air and/or replace with an inert gas like Nitrogen?

Is the glass flush with the bezel or proud? If the glass is proud, they were usually (in watches, at least) mounted by heating the bezel ring to make it expand and then dropping the glass into its seat. When the bezel cooled, it gripped the edge of the glass very firmly – no need for glue or other adhesive. As ian_ said, a photograph or two would probably help.

Good luck – just try not to do anything irreversible!

Jeff

Thanks, that may be the case in respect of instruments to be used in flyers, however mine is static/just for show!! Perhaps an oil filter strap and brute force???

Hi Bravo24
I thought that the percentage of rpm instruments were sealed with a vacuum inside. Therfore if the glass is cracked or broken, it was considered unservicable.
So I dont think that you can just swap the glass over?

Can’t help with the repair but would love to see a photo of the panel. Sounds interesting.