Wooden Gears

So far, no one has mentioned MDF. It has no grain, but the dust is reputed to be pretty nasty.

Or it totally out of court mas not being real wood, instead of ,as I understand it, resin bonded wood dust?

Howard

Epoxy is probably millenial-speak for glue

pgk

A "respectful" virtual elbow bump to you for being in touch with youth!

The dictionary says "synthetic" resin but does that preclude epoxy resin from occurring in nature?

I am reminded that petrified resin becomes amber which is not unlike a blob of cured Araldite.

Whatever wood you decide on, you need to understand that wood is strong along the grain, but weak across it. That is why plywood is mentioned above. In practice, making your own from layers of veneer might be best.

And then you need to work out how to cut the teeth without destroying the outermost edges. Once you are sure that the laminations are properly stuck together and waterproof, it would help to add an extra sacrificial layer both sides using a water soluble glue, cut the teeth ignoring the fact that bits flake off, then soak off the outsides.

Good luck

Tim

Edited By Tim Stevens on 22/08/2020 15:31:17

Though given the ease at which wood can be cut with a router and a lot of schools have small CNC routers then with a small dia cutter the gear could be cut flat with the tool following the path of the teeth rather than using a cutter at right angles to the gear. With an up/down shear cutter you won't even risk any tearout, also known as compression spiral cutters.

Edited By JasonB on 22/08/2020 16:12:43

An alternative gear-tooth cutting method, if you can access the kit, would be to draw out the gears in a CAD program and get them laser cut. This method uses a hot beam of light across the gear, so there should be no tendency to tear at the grain.

I think there are adverts in MEW for this sort of service.

Cheers, Tim

If MDF is a possibility then you might also consider Valchromat, which is a similar product but using a melamine resin rather than formaldehyde. It machines very well, better tha MDF, and is much safer.

MDF can be sealed and strengthened by "varnishing" with PVA slightly diluted, or possibly better is a Ronseal product for treating wet rot, which is a resin dissolved in a volatile solvent. This soaks readily into the material without making it swell, then dries sticking all the fibres together making it much more resistant. Either would probably be suitable for Valchromat as well.

In boatbuilding plywood (and other woods) are treated with a liquid epoxy resin which soaks in and seals it, also making it much stronger. Look up "West System Epoxy".

Edited By John Haine on 22/08/2020 18:13:44

My personal objection to this would be an aesthetic one, because the cut surfaces are scorched black.

George B.

Edited By Georgineer on 23/08/2020 11:54:05

Resurrecting Mick’s thread, because I think this may be of general interest:

**LINK**

https://www.hodinkee.com/search?q=wooden+wheels

MichaelG.

That is a beautiful thing Michael. As for my son's venture, I think that he has settled on maple to make the gears. Now all he needs is the means to cut them as in Michael G's link.

Mick

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I remember sometime in the late 60s our village blacksmith recall that many years previously he had repaired the watermill gear with inserts made from Holly. The individual teeth were trimmed to fit the rim . I guess the logic was that the frame of the big gear was made of timber with a bit of resilliance but the teeth were hard wearing and easy to replace. Other than that it sounds like this lad is going to build a nice little bonfire.

.

What he has made seems to be ‘a nice little earner’ : **LINK**

https://www.clockwright.com

MichaelG.

When we were kids did we not scorch the ends of our arrows black to make them harder ?

regards

Hardwood lapping sticks are available up to 25 x 6mm section which may not be big enough. They are laminated and very hard and strong.

www.moleroda.com