Author Topic: Plywood for clock gears  (Read 11615 times)

Offline jrbeall

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Plywood for clock gears
« on: April 08, 2007, 05:42:38 AM »
I recently had a question about making plywood for clocks so I thought it might be well to put my answer here for those who are just beginning and have not done this before.  

Solid wood gears will expand and contract with humidity and are not really suitable unless you have a great deal of slop built in.  I make my own plywood but with commercial veneer.  It would not be possible to cut it thin enough in the shop.  Veneer is cheap and available in endless varieties.  I use epoxy and a vacuum press to laminate it and 5 ply is about as thin as I use.  It makes a wonderful material, completely free from voids and very stiff and strong.  For pinions I normally use 7-9 plys and they can be made very small because of the strength of the plywood.  Don't use water base glue for this purpose, you will end up with wheels that look like potato chips.

Offline millerdlca

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plywood
« Reply #1 on: April 08, 2007, 03:03:43 PM »
Do you use ordinary veneer thicknesses?  Pictures I've seen look like the veneers are thicker than the usual 0.025" that is available around here (although it's difficult to tell the scale of gears in various close-ups).  

I made some up about 20 years ago using ordinary veneers and it took about 10 layers to get a 1/4" thick blank.  There is a little cupping visible when you hold a straightedge against it but it's not bad for that length of time sitting unfinished in a box in the basement.

Dennis

Offline jrbeall

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Plywood for clock gears
« Reply #2 on: April 09, 2007, 04:04:13 AM »
I use ordinary thin veneer and my wheels run about 1/8 thick and the pinions 3/16.  I have always tried to make my wood works as delicate as I could.  Just my preference.  For thicker material I normally just glue up two or more thicknesses of the thinner plywood.  I have a Performax sander with a digital readout and it allows me to get my plywood very flat and accurate.

Offline jss

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Plywood for clock gears
« Reply #3 on: April 10, 2007, 02:41:45 PM »
Build your press information

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Mckenzie

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Plywood veneer
« Reply #4 on: April 11, 2007, 08:55:57 PM »
After shopping around today, I found that most of the locally available veneer is "paper backed".  Is this appropriate for multiple layers?  Any ideas on what type of epoxy to use?  System Three offers T-88 (which is said to be structural and non brittle) and General Purpose Epoxy . . . will it make any difference in the end product?

Offline jrbeall

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Plywood for clock gears
« Reply #5 on: April 12, 2007, 04:06:59 AM »
You would not want to use paper backed veneer.  It might work but it would be putting layers of softer material in your plywood.  If you look on line, you will find lots of veneer.  I use West system epoxy but I imagine system 3 would be fine as well.  Try to find veneer that is as wide as possible because you will lay each layer at 90 degrees to the last and the width of the material determines how big you can make your plywood.