Plastic key repair

[Cerebus]

I'd like to raise a note of caution surrounding any of the processes involving solvents (so the above and the earlier suggestion of dissolving scraps in solvent).

Were I repairing this, I'd want to clamp the key with the face firmly pressed to a smooth surface. Both to try and get a good surface finish, but also to get the repair surface co-planar with the rest of the key's existing surface. I'd probably clamp a couple of slats of something rigid over the top and press the sides of the key down to a flat surface (glass or metal treated with a release compound) to do that. That would put the sides in compression. I'd be concerned about them softening from solvent fumes while any solvent based infill dries. It would be quite easy to distort the sides under those circumstances.

[Audiorepair]

Why would you not use a putty instead?

Pro's and cons's obviously, but I'd like to hear them.

[helius]

That's true. Solvents can also cause stress cracking in surrounding material.

[Cerebus]

Why would you not use a putty instead?

Pro's and cons's obviously, but I'd like to hear them.

No, I'm not saying that - just wanted to flag up the thoughts that had crossed my mind about one possible risk of a solvent based repair. Putty has a lot going for it, I'd be a bit concerned about getting good adhesion from past experience with using them.

I'm not sure that I've got a good strategy to offer. Best I can say is that if I were to do it myself I might go for a mixed strategy - A lightweight repair to the surface with a thin layer of a like material, probably solvent based in the hopes of consolidating the remains - as little as I thought I could get away with to minimise exposure of the rest of the part to solvents, then a bit of reinforcing glassfibre tissue  with some epoxy on the back of the lightweight repair for strength and durability. My biggest concern would be getting a good surface finish and to achieve that I think I'd start off by clamping the part to a suitable flat surface that the repair could be built up against, and keep it clamped until I'd laid up all the layers. My two cents for what they're worth.

[MarkF]

I have recently been thinking about a 3D printer, for things like making unavailable knobs for old gear.

I've been put off so far at the notion (inside my own head) that small parts like these would be difficult to print finely, and would need a lot of extra work to get them looking or feeling nice, if at all.

Possibly some undeserved predudice there.

To get good results on a small knob, for example, what entry level of machine are we actually talking?

Here's a sample of some small parts I've printed.
They are untouched direct from the printer.
Printed with Hatchbox White PLA at 0.28mm layer height (What I consider 'draft mode').

Particularly note the white puzzle piece.
The touch, feel and look are almost identical to the piano keys.

[Audiorepair]

Well I'm quite tempted to get into 3d printer world now.

Can you also get stock that turns out more squishy?  More rubber like?

[MarkF]

Well I'm quite tempted to get into 3d printer world now.

Can you also get stock that turns out more squishy?  More rubber like?

It's harder and I have not printed any.

[Audiorepair]

Blimey,

this IS the future, isn't it.  Took me a while.


Thanks.