Ideas to best hold blanks with out turning

hi, I am attempting to make a clock wheel for the first time. I picked a wheel which is approx 1.1 inches diameter and has spokes. The spokes mean you cannot used a large washer.

The arbour is made from mild steel reduced and threaded with M$ at the end. The brass blank has a aluminium backer to prevent burs when making the teeth.

I could always use a larger washer and nyloc nut whilst making the teeth then remove it. Bit should i be using super glue to stick the blank to the alumiunium or for that matter any thing else.

As always all helpful posts welcome.

Chris

My only comment is about the aluminium backing.

As this is cut, the Al will tend (as it usually does) to stick to the cutting surface, building up a hard lump. This makes this surface a different shape, until the Al eventually drops off and the process starts again. But in the meantime it will cut the brass too, and you might not get teeth which mesh properly. It just seems an odd risk to take when removing burrs from the back of the gear is so simple.

There must be a way to do this without using Al, after all it was not discovered how to extract it until about 1850.

Cheers, Tim

PS: M$ is my favourite thread, too ...

Edited By Tim Stevens on 17/03/2020 18:32:37

Hi Tim, I'm surprised, I pictured you more as an M^ thread man.

I see our master clockmaker has returned, reinventing the (clock) wheel.....

Chris

To prevent the gear blank turning when cutting the teeth select a point between spokes and drill a hole to insert a pin, probably a small roll pin will suffice.

Emgee

Cut your spokes after cutting the teeth ( or to be pedantic the gaps between them )

The burs can be removed by rubbing the wheel flat on emery paper on a sheet of glass. If you must use a full width backing of aluminium make it not much thicker than the wheel blank and use a hard temper type. Brass would be cut dry but with the aluminium you will need to use some lubrication to reduce tip welding not to aid the cutting.

Great replies so fat, thanks everyonre

Chris

OK so Aluminium is not a good idea. So plastic or wood. If using wood what do you cut it with on the sherline. I have a scroll saw to rough it out but with plastic or aluminium I get the diameters with the same cutter? I am using carbide tipped cutters (brazed). Would they cut wood?

Chris

Why not look at John Wilding's book, it tells you all you need to know. Anyway the backing doesn't have to be the same diameter as the blank, you can make it to just under the dedendum diameter and it will still support the blank. And use a big washer on the front, you don't cross out the wheel on the same mounting as you cut the teeth. And when you quote text please could you put your additional comments below the line so we can wee what your contribution is?

.

Which one, John ? ... Wilding has published so many

Or may I presume that you meant to reference J. Malcolm Wild ?

MichaelG.

.

http://www.j-m-w.co.uk/contact.html

Edited By Michael Gilligan on 18/03/2020 10:29:31

It has been suggested to use plastic or even wood as a backer. It has also been pointed out aluminium causes the cutter to reduce in its efficiency from aluminium sticking to it.

Fair enough get that but surely plastic would melt and stick when cutting the teeth and spokes? I knowplastic is often used anyone know why it doesn't cause the sticking issues that aluminium does.

Chris

Plastics and Aluminium are different animals entirely. Plastics might behave as a glue, but Aluminium welds - a true metal-to-metal to bond. Reheating plastics often softens them, or they will burn off. It might also be possible to dissolve a plastic in a solvent that has no effect on brass. In comparison, separating Aluminium from Brass could be much more bother.

To answer the original question, bigger washer and tighter nut. I like superglue, but the old guys used Shellac. Superglue is easy to apply and forms a strong bond, but the joint is hard to break after. Some superglues I've used break quickly in boiling water, others needed prolonged boiling, or even light heating with a blowlamp. Shellac makes a weaker joint and is more fuss. It needs to be heated before application, but allows more time for work to be positioned as it hardens and the joint is easily broken with gentle heating.

I'd guess superglue is more suited to the heavier work I do - a clockmaker might prefer Shellac.

Dave

OK, here’s a novel solution - why not use a brass backing disc. Admittedly more expensive but would end your mythering about things that people just get on with and try for themselves.

I have successfully used SRBP as a backer when cutting gears.

Yes they will. I just hone them with a diamond lap to make sure they are really sharp.

regards

If you are using carbide cutters, why not use steel as the backing disc?

thanks for the helpful posts. SRBP (synthetic resin bonded paper)is advocated. Also my local plastics firm suggest from their offcuts nylon and polycarbonate.

Have made one from polycarbonate so will see how I go on.

some clockmakers use a second brass backer, but the issue to me will be keeping the home made cutter sharp so the least tough stuff i go through the better.

Like the idea of pinning the blank or shellac for the spokes. This will be kept in reserve until i can gauge their need.

Chris

+1