VintageTechnologies wrote:I have an adapter made of pot metal that had swollen over the years. I removed the locking pin and then wrapped some 100 grit sandpaper around the adapter end and twisted around until I had removed enough metal to fit. Of course you will lose the gold plating on the end, but what other choice do you have?
^^This.
I would add that you really need to purchase an inexpensive means to accurately measure the neck of your adapter -- I prefer calipers, and you can pick up a set very cheaply. Once you have them, you'll be surprised how much you use them on other projects moving forward.
By not actually knowing where the greatest deviation of diameter is from the proper size, you will likely just cause unnecessary damage to the part. Also, by accurately measuring, you stand a much better chance of creating a perfectly round mate for the horn opening. Deviation from round will only compound issues related to the proper fit of your accessory.
I've used "00" (medium) Emory cloth (about a 6-inch by 2-inch strip) to reduce the outer diameter of a couple of my adapters (A "Jewel", and "Oro-Tone"). I don't use coarse, because I prefer to just put a little more time into this process, instead of the necessity of removing any deep scratches later. The nice thing about emery cloth is that it is very flexible, and doesn't quickly disintegrate while using. The "00" grit won't leave horrible deep surface scratches in the metal, but will nevertheless leave some scratches. If you want a better finish for the surface afterward, use a fine sandpaper as necessary.
Measure the diameter of your Diamond Disc Reproducer horn-end with your calipers to understand what the diameter of your adapter should actually be.
Check the diameter of your adapter, measuring all around and noting where the diameter is large in places. You can mark the "high spots" with a pencil, so you have a visual reference.
I would be very careful if/when removing the orientation pin from a pot metal casting, the casting can easily break, or chip. You may need to firmly grip it with a pair of locking pliers, and carefully twist it back and forth, to slowly get it to come free from the casting.
NOTE: I wouldn't use much force to break it free, if it doesn't come out easily, leave it in place and try to work around it. You don't want to break your adapter, you just want to repair it. DO NOT use penetrating oil on the pot metal! It can exacerbate the decay of the metal, and the porosity of the material will negate the removal of the smelly crap!
Remember, if you damage the hole that the pin comes out of, it may not fit as tightly as it should when you reinstall it back into the adapter.
I might prefer to carefully remove any excess material from around the pin with a fine jewelers file, after using the emery cloth around the rest of the part's diameter.
After removing a little material, measure your progress. When you think you've removed enough material that the adapter will fit the horn opening, check the fit in the horn opening. You should do this frequently when you're close to a good fit, so that you can get a feel for your progress.
When you are able to finally insert the adapter into the horn throat, you should be able to identify where contact is being made on the adapter's mating end. The surface of the contact areas will be shinier that the rest of the metal. If you can't visually identify these places, you can apply some black marker on the adapter end, and note were it gets rubbed off from contact. This will show you where the remaining high spots are located, then you can focus on treating those places, as opposed to other areas were it may no longer be necessary.
Remember: you want the end to be as round as possible, and to not end up having a lot of slop when mounted to the horn. It should ultimately be an air-tight "slip-fit" connection.
I hope I've explained myself sufficiently, and good luck!
Best,
Fran