Restoring platen knob Royal KHM 1937 typewriter

I have bought a Royal KHM (1937)  typewriter. The person who sent me this beautiful machine made a mistake by packing it unsafe.
So it was damaged. The right black platen-knob was broken.
Now I can't find a new one so I want to glue the broken pieces, to then make a mold and recast it. Yet first I have to loosen the remaining piece
from the bolt. Yet that is difficult as the bolt does not give while trying to turn it loose.
Does anyone here have a method how to loosen this without damaging the rest of the knob?

In the picture you see the black broken knob that is fitted on a bold that can be fastened (see the two little screw holes on the neck) on the platen of the typewriter.
At the other side is a metal flat disc (see the yellow arrow).
The Bolt has just above the screw holes (see the red arrow) a thin seam that suggests as if it exists out of multiple parts that can be loosened from each other.
How else could someone in the factory have fitted the black knob onto the bolt? I Have tried to loosen the parts but it is so stuck I just don't know.

Does anyone here have any experience with this problem? Please answer if you have a solution. Thank you.

I have no knowledge about this... However, r ransom has some information on typewriter repair in this thread.

I claim no expert knowledge. (But I love old typewriters!)

Looking at the photo, the left shell seems far too thin to have been threaded. I would guess that they were two tight-fit pieces put together, held in a jig, and drilled and tapped to produce the screw bolt holes visible.

Disclaimer: This opinion is from the Internet, and is likely worth less than what you paid for it.

The answer is that it can NOT be unscrewed.  That is a knurled surface and it is actually supposed to hang onto the surface both ways.  The knob was molded in place on the steel part.

If I were going ro repair it there are 3 options I would say.  1.  Glue the pieces back together if you have all of them.  Likely not the case as this looks like bakelite or a bakelite relative so some of it likely powdered.  Since this older plastic is hard to glue successfully usually unless it is just a couple big pieces I would not got this route.  2.  Is making the broken piece.  To help anchor the new piece I would put a screw into the the old plastic each way to help anchor it.  Those screws need to be put in with extreme care as this plastic is brittle and will split if it isn't done with care.  I would create a 2 part or 3 part mold on the undamaged area and then rotate it to the new area and then using a black epoxy I would cast the new section in place against the old.   With a little care you might be able to use clay for this so you didn't need expensive molding materials. 3.  is completely rebuild the piece.  Which is what it sounds like what you are choosing to do.   The fact that you are building a bigger piece means you will likely need better mold materials  Certainly doable.  and if you can make it in a fiber reinforced epoxy it will be durable.   Will likely end up wanting some expense mold making compounds so not cheap but with care you can probably match it well enough it would take a real professional to see it had been replaced.

Another option if you have access to a metal lathe is simply build the whole part out of metal.  Probably the easiest answer if functionality is the goal.

That said because old typewriters are cheap if you can find them probably the cheapest answer is just to buy a replacement for the whole machine.

I thought the same, there is no movement and the knob is cast already on the metal, the bakelite is not instald on
the metal later.
I just was not sure. The bolt has a messing or kopper core, probably the iron was once in parts, hence the seam, then it got this copper core.
So it seams unscrewable but it’s not, I think I wil use epoxy to glue everything. Then make a mold, clean the metal from Bakelite and will cast the new knob on to the
metal.

Thanks everyone!!!

Hey Henry,

Have you made progress?

Helpful to know where in the world you are so suggestions have a chance to be tailored to local situations.

I have rebuilt, restored, recast, and turned knobs on clamped-down hand drill, drill press, wood and metal lathes. Without spinning the glued together part it will be difficult to get it round. Once it is as good as you want it shape-wise, then maybe you can just paint it and reinstall forgetting the recasting steps.

I have used super glues, type 3 wood glue, plastic repairing epoxy, "ordinary" epoxy, J.B. Weld, and weird mixtures

To give more suggestions than just general ideas we need to know more about; how complete the part will be once all the pieces are glued together, the toolkit you have available, the results you want, what glues are available...


Cheers
Dan