How to attach plastic fan (worn)

Jun 08, 2017 22 Replies

This from a B&D circular saw approx 18 years old so part not available. The plastic fan is worn and loose on shaft, I am assuming it was just a tight fit, how best to re-attach the fan, assuming the saw lasts another



18 years it will outlast me so a bodge will be ok. I am also replacing a worn bearing which I think I have sourced on ebay.

formatting link


Not much help, but I had a B&D router that this happened to, too. Couldn't find a way of sorting it as the type of plastic used doesn't glue well. And without the fan the motor soon burnt out.

Probably polythene and not keen on being glued. Epoxy + a fillet at each side?

A fillet being a ......Bush, washer?

Locktite 660 but not sure if it will handle temperature, or sleeve it with thin sleeve.

I think a few small notches cut in the polythene into which the epoxy can lock. and the fillet made from the epoxy. if when setting it forms a blob on one side, trim this for symmetry to balance once hardened.

Notches sound good to me.

A fillet is a triangular section of infilling. Google for fillet weld.

Probably below 100C so Loctite should be OK. Sleeve is good, but if he had a lathe I don't think the OP would be asking here.

Thanks for all the suggestions. I dont have a lathe but if I can find a slightly too tight sleeve I can attempt to increase the internal diameter slightly using a drill (as a crude lathe) and some sandpaper. I can take my time as I have another circular saw to get by with.

Epoxy's no use on a hot spinning motor.

NT

Such plastics are joied by melting them together.

NT

If the interference fit has failed, any gunge is going to have to be at least as strong as that where it adheres. And with some plastics, this is impossible.

So why do rotor windings get epoxied into place to stop them flapping about and snapping?

There are glues for "low surface energy" plastics, e.g. 3M DP8005 but they're not cheap ...

The kind of epoxies diyers use with the methods diyers use produce a glue that turns to a putty-like consistency at 60-80C. That is not a good option at all for a hot motor shaft driving a fan under heavy load with heavy vibration.

No-one has mentioned the option of cutting a new flan from tinplate. Go as light as possible as it will be impractical to balance it properly.

NT

Fair point and gives me another option.

Yes. But if it's stripped its splines or whatever, not going to be easy to do. And given the extremely high RPM, balance could be a problem too.

It's either side of the fan, in a nice blast of fresh air.

If it comes off the shaft, would that be a phantom flan flinger? :-)

Usually it's heated air, and the spindle gets pretty hot too. But whatever, it's your machine, be as daft as you like.

NT

that isn't what I saw. Maybe you saw a different pic. Anyway why would that be hard?

Equally possible whatever fixing is used. How silly.

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required