Gear timbers

[Rubber.Piggy]

Hello all,

I've working on my first wooden clock work. I'm using the gear train design in the 3 part series in AWR a year or two ago.

I would like to do it without laminating or using plywood and mdf and was planning on using straight grained, quarter sawn hardwoods. I won't be making single piece gears, but gluing wedges together so the grain runs out from the centre all the way around. Does anyone have any timbers they have found particularly good for this?

Thanks
RP

[WhatsWood?]

I would try the timber the AWR article used for the gears, jsut use as wedges rather than as the external edges to the ply wheels (from memory).

Good luck
Matt

[Hobbyhorse]

I used self made plywood using European Oak and epoxy glue for the first clock I made and on the second have used a New Zealand native timber called Tawa glued up with radiused segments also glued with epoxy. I managed to leave one I had glued in front of the window and when the sun landed on it, it fell apart through the movement which I was somewhat surprised at. I remade the broken joints and glued it all back together and it has remained sound to date. Tawa is straight grained and reasonably hard....it was used a lot in flooring.
I am not familiar with your Australian hardwoods but I am sure there are several that would do the job well,
Good luck with the project.

Rhys:)

[Rubber.Piggy]

I used self made plywood using European Oak and epoxy glue for the first clock I made and on the second have used a New Zealand native timber called Tawa glued up with radiused segments also glued with epoxy. I managed to leave one I had glued in front of the window and when the sun landed on it, it fell apart through the movement which I was somewhat surprised at. I remade the broken joints and glued it all back together and it has remained sound to date. Tawa is straight grained and reasonably hard....it was used a lot in flooring.
I am not familiar with your Australian hardwoods but I am sure there are several that would do the job well,
Good luck with the project.

Rhys:)

I've wondered about self made plywood, mainly if it's really worth the trouble. How thick did you make the sheets? How stable are the clocks throughout the year?

Your epoxy story made me smile. I only use it for filling, I don't trust it for joining and laminating. Always a pva based glue for me.

[Hobbyhorse]

RP, there are photos of the clock I built on this forum under.."my wooden clock movement"..
The front and rear panels are 12mm and made up in three ply whereas the gear wheels are 12mm and made up of 5 ply. I have a drum sander and after rough cutting the laminations on a large throat bandsaw I trued them up on the drum sander to the required sizes, spread the epoxy and then clamped them between two pieces of 16mm MDF. The clock has been running for something over a year and there has been no distortion or delaminatimg.
I have used epoxy for laminations on my yacht for many years and had no problems both in flat or heavily curved sections. I have found PVA to be a problem in that it introduces a water based material from which the water has to evaporate after it has soaked into the surface on first application. I have had trouble with stability of the lamination shape as it dries out.

Rhys.

[Pomare]

I use African Rosewood for the gears in my clocks. It is stable, machines well and glues well.
I make the blanks using 30 deg segments. Use alphatic PVA and glue the blanks together on a piece of plate glass - PVA doesn't stick to it and it ensures they are flat.
Blanks are then faced in the lathe to thickness before mounting about six together on a mandrel to machine the outside dia tru and cut the teeth.