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Good wood for wood geared clock?

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Forum topic by LiveEdge posted 08-11-2016 10:05 PM 492 views 0 times favorited 12 replies Add to Favorites Watch
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LiveEdge

486 posts in 1081 days


08-11-2016 10:05 PM

I am not a scrollsaw expert, but I probably put in 20 hours on my Star Wars AT-AT (see projects). Anyway, I’ve been smitten by wooden gear clocks and would like to try one. I don’t want to do it in plywood though (boring!). I’m thinking of using 2-3 different woods but was looking for opinions of good options. To me, the optimal characteristics would be:

Stable
Interesting
Soft (because I figure the scrollwork would be easier)

Thoughts?

I think one may be Quaking Aspen. I have some already, it’s very soft, and would make a nice color contrast to something darker.


12 replies so far

View johnstoneb's profile

johnstoneb

2143 posts in 1634 days


#1 posted 08-11-2016 10:34 PM

Baltic birch plywood for the gears. The torque on some of the gears is tremendous and you need the strength and stability the plywood provides. You risk stripping the teeth off the gears is you use solid wood and humidity cause extreme swings in accuracy even using plywood. You could try laminating some solid wood and that three plys would probably give you enough strength. You could try it with two plys might work. You need hardwood for the face and back supports as they also serve as bearing surfaces. Some clocks do have a brass insert for the shafts to run on but not all. I never had any trouble cutting with a scroll saw. You’re talking 1/4” to 1/2” max.
You can get quite a bit of contrast using hardwoods for frame and brackets and plywood for gears.

-- Bruce, Boise, ID

View bobasaurus's profile

bobasaurus

2658 posts in 2645 days


#2 posted 08-11-2016 10:37 PM

You can glue up your own fancy plywood for the gears. Check out Charles’ clock:

http://lumberjocks.com/projects/16697

-- Allen, Colorado

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LiveEdge

486 posts in 1081 days


#3 posted 08-11-2016 11:06 PM

Hmmm, I didn’t think about losing teeth due to the grain pattern. I did some more exploring around the internet and found someone who was making hardwood gears using pie shaped segments glued into a circle. Seems like quite a bit of extra work, but might be worth it for some of the select gears to provide contrast.

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Rick M

7910 posts in 1841 days


#4 posted 08-12-2016 06:01 AM



Baltic birch plywood for the gears. The torque on some of the gears is tremendous
- johnstoneb

If there is enough shear to break solid wood then commercial plywood is the last thing you want to use as it is weak in shear along the plys. That’s why turners don’t use it for faceplates or it will delaminate. And why OSB is recommended as better for sheathing than ply. And why OSB is used in engineered wood i-beams instead of plywood. Tremendous torque in a plywood gear would delaminate the plies. I’m not saying plywood wouldn’t work or isn’t ideal but stability, not strength, would be the reason for choosing it. I like the idea of segmented rings for gears, or a homemade plywood.

-- http://thewoodknack.blogspot.com/

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jdh122

879 posts in 2279 days


#5 posted 08-12-2016 11:17 AM

I have no experience making anything like this, but if I were you I’d try experimenting with elm. It is relatively soft, and the interlocking in the grain might make the teeth less likely to split off. Its grain structure explains why it was the preferred wood for the hubs of wooden wheels.

-- Jeremy, in the Acadian forests

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LiveEdge

486 posts in 1081 days


#6 posted 08-12-2016 02:53 PM

Thanks. I’m not even sure I’ve seen elm in my hardwood store here in town. An interesting choice though, for sure!

Although I tend to jump into projects with both feet, I think in this case I may start with the simplest clock I can find and then work from there. I may do a combination of ply gears and solid wood ones. I wonder if I could determine which gears are under the most stress (or are they all equally stressed)?

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LiveEdge

486 posts in 1081 days


#7 posted 08-12-2016 04:14 PM

One thought I had about the solid wood and warping would be if you could minimize that by quickly sealing both sides of a finished gear with polyurethane? I don’t live in a climate with high variation in humidity anyway, but I thought you might get even less movement with sealing.

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Rick M

7910 posts in 1841 days


#8 posted 08-12-2016 04:41 PM

Or use quartersawn.

-- http://thewoodknack.blogspot.com/

View oldnovice's profile

oldnovice

5723 posts in 2829 days


#9 posted 08-12-2016 05:25 PM

How about Paperstone?
Mainly used for countertops, it is paper in a binder that cuts easy, with carbide, similar to hard plastic, has no mineral content like Corian or similar products, is available in different colors, and thicknesses.
You can get samples and buy cutoffs for reasonable prices from the link above.
I have used it for some projects that I have yet to post.

-- "I never met a board I didn't like!"

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Redoak49

1944 posts in 1450 days


#10 posted 08-12-2016 08:01 PM

For a first clock and learning to cut gears, I would just use Baltic Birch. If it goes well and you enjoy it, then try other woods.

I have cut some gears out of Baltic Birch and it take a lot of patience and skill to do it well. I am just a beginner.and made a few that work well. I know that I need practice to develop the skill.

View LiveEdge's profile

LiveEdge

486 posts in 1081 days


#11 posted 08-12-2016 08:13 PM



For a first clock and learning to cut gears, I would just use Baltic Birch. If it goes well and you enjoy it, then try other woods.

I have cut some gears out of Baltic Birch and it take a lot of patience and skill to do it well. I am just a beginner.and made a few that work well. I know that I need practice to develop the skill.

- Redoak49

Don’t you know that’s the exact advice I don’t want to hear! ;)

View Steve Peterson's profile

Steve Peterson

324 posts in 2543 days


#12 posted 08-12-2016 08:41 PM

I agree with redoak, even though you don’t want to hear it. Making a wood gear clock is hard enough. Why complicate your first clock by adding another variable.

I have seen old wood gear clocks with solid wood gears about 4” in diameter or less. If you go any bigger, the teeth may not mesh properly after expansion/contraction due to humidity.

If your design has larger gears and you don’t want plywood, then you will need to build up a segmented gear. A wheel with 8 or more “pizza” slices is likely to either crack or warp. Each piece wants to expand in width but not length. Spiral shaped spokes might allow the stress to be relieved without warping. It would take some experimenting.

I suggest to just use plywood for your first clock. Woodline sells a clock kit and also sells different species of wood on the outer layers. It is a bit pricey though at around $30 for 6 pieces of 8” by 8” plywood. Another option is to laminate nice looking veneer on the outside of Baltic birch.

-- Steve

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