Thread type and source for Ibach or similar piano boss?

[Withindale]

I am looking for a brass boss for an Ibach similar to, or a bit larger than, this one, 45 mm diameter.

It would be very helpful to know the thread type that Ibach would have used in 1905. The external diameter of the threaded bolt coming up through the soundboard is about 7.85 mm.

Would anyone be able to suggest a source for a boss here or in Germany?

In case Ibach still have some spares, I contected Rolf Ibach a few months ago and will send a reminder.

Thank you.

[Colin Nicholson]

Some of this info may be useful.....
If I need any kind of special 'metal piano bit' i.e. screw, hinge repair, grub screw, lyre butterfly screw, pedal hinge pins, pressure bar screw etc etc.... I contact a local friend of mine who is a retired mechanical engineer/ steam engine & locomotion builder, and who specialises in restorations, pressurised tanks (for steam engines).... and brass ornamentation screws etc however,.... the name of a piano doesn't come into the equation - he just asks what 'job' it does, and sometimes out of interest, he likes to see where it attaches to, just out of interest. Just recently, I needed a pressure bar screw for an upright (one broke off) - so I just handed him another screw, and he made it!

If there is anything missing (in your case the brass boss)- he either pops around to my workshop, does some 'measuring up' .... and often is the case, the original thread/pitch types don't come anywhere near - even with his vast selection of imperial tap & dye sets.

So this is what he does:-

1. Measures the overall length/ diameter of the external screw with calipers.
2. Wraps one EXACT layer of strong masking tape around the thread (no overlapping)
3. Pencil rubbing of the thread thickness, pitch, angle and length of thread.
4. Carefully unwinds masking tape, and stores on some white paper.
5. Makes a small technical drawing of the screw thread & various info.
6. In his workshop, compares this with other similar tap & dye sets.
7. Manufactures the part on a lathe (using another identical part if available)
8. Re-taps threads to fit.

Takes far too long to try and find an original part from another piano, unless a project piano - and in no rush.

My friendly engineer has a beer or 2 with me.... but he never tells me or shows me how he did the job, nor does he share info such as thread sizes/ designs etc.... he just does the job, and I'm happy..

Colin

[Withindale]

Thank you, Colin, that's very helpful. Would you put me in contact with your friend if I don't get any joy from Germany?

If I can find a (reasonably) matching boss we can look at re-tapping or an insert. Otherwise start from scratch.

Thanks again.

[Colin Nicholson]

see PM

[Withindale]

Thank you, Colin.