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Wooden Gear Clock #3: Cutting the Wooden Gears Part 1

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Blog entry by avgjay posted 03-06-2012 05:31 PM 4670 reads 0 times favorited 3 comments Add to Favorites Watch
« Part 2: Making Plywood - Wooden Gear clocks Part 3 of Wooden Gear Clock series no next part

Hello again!

First off let me apologize for the absence of posts lately. I have had a severe case of Lifus Interuptus and with one thing leading to a BaZillion others I have been unable to sit down and put thoughts to screen, even now my Newfoundland is trying to see how much drool can fit in a keyboard. So sorry and hopefully the posts will be a little more regular for a while.

Sssoooo… let us begin with the fun part of this project. Cutting the gears out.

I am splitting this topic up into several posts. Building six clocks, I tried out a couple of ways to cut the gears looking for the most accurate and efficient way available to me. I perfectly understand that either a CNC or laser could cut all of the parts for this project in an alarmingly short time with superb accuracy. Since I have access to neither of these VERY pricey tools, nor the desire to use them, I went with more traditional options.

The first option and the subject of this post will be using a scrollsaw. I figured that since the pattern came out of a scrollsaw magazine and all, this would be a good method to start. Now I do not actually own a scroll saw, but my father does and he graciously allows me to borrow his tools… often. Thanks Pop!

Hopefully you have all of your plywood laid out in front of you, separated by thickness. If you are using a pattern from a magazine, like I am, you need to make copies, lots of copies. Make more copies than you think you need. It is always better to have more copies than you need than to have one too few, and then late one night as you are plugging right along, in the groove, and just whipping through these gears when suddenly you realize you have forgotten that last pinion or gear and now you have no more patterns. You come to a screeching halt causing all of that precious mojo you have been building up to go right out the window along with several incoherent sentences worth of swear words.

Okay so you have your copies and your plywood. I recommend cutting out the patterns and sorting them by thickness and wood type as the pattern calls for several thicknesses of plywood but also several thicknesses of hardwood, the dials, runners for the weight line, caps, and the pallet, so separation is important. Once done sorting arrange the patterns on your stock trying to fit little parts inside the gears and leaving room around the outside to make cutting easier, Try to put the gears fairly close together to minimize waste. Because you are cutting gears that have lots of teeth and holes there is a fair amount of waste involved and minimizing this as much as possible is always a good thing.

With a rough layout of the patterns, grab your spray adhesive and with all of the surfaces clean and free of debris, spray both the wood and your pattern. You do not want the patterns moving on you. Quick Tip – a little mineral spirits and the adhesive will dissolve leaving your parts free of paper when all is done. After giving things a few moments to allow the adhesive to tack up, carefully place your patterns lightly on your stock. I recommend doing this for all of your pieces now instead of having to go back after some of the parts are cut. It makes it a lot easier to keep track of which parts are done and which have yet to be cut.
After the patterns have been laid on the stock press down firmly from the center of each pattern smoothing outward to remove and wrinkles or air pockets, either of which will distort the patterns making fitting the clock together and getting it working all that much more difficult.

Patterned wood in hand, head to either your drill press if you have one or grab your favorite drill, electron powered or meat powered, and drill a pilot hole for your saw blade in each of the blank spaces of the gears.

I also highly recommend that while the patterns are still fairly large go ahead and drill out hour, minute, and second holes in each of the gears. It is easier with them in this state than when everything is cut out. Just trust me on this one.

Saw blade picked out, I used a #5 crown tooth for the tricky bits and #9 reverse tooth for the teeth themselves. Patterns affixed, and pilot holes drilled it is now time to find a comfortable position in front of your scrollsaw and start cutting some wood. If you don’t have a scrollsaw you can use a fret saw, coping saw, or even a dremel I’ve heard. They all cut pretty much the same way. If you have a 1” belt sander, it might be easier for you to leave the lines and come back later and sand to them. I don’t have such a tool so I went straight for the money cut.

Now you will probably break many blades, especially in the thicker material, but the best advice I can offer here is to go slow. Take your time, DO NOT RUSH, the more accurate your cuts the less fitting you will have to do come assembly time. I found that cutting the outside teeth first and then the interior pieces allowed me to work with a little more precision. I don’t know if it was the saw I was using but even with shimming the insert flush all of the interior cuts would interfere with the smooth curves I was trying for on the teeth. A word of caution: even though the gullets are not friction surfaces they still matter. I had one gear that for some unknown reason my gullets were too shallow and I ended up filing all of them by hand to get everything to mesh, I had already glued pieces together and could not put it back on the saw.

Although some may see this as tedious, I found that plugging in an audiobook or music and just tuning out the rest of the world to focus on the very precise cuts to be very relaxing and even a little therapeutic. With a little patients and a lot of attention to detail you will soon see a clock take shape, careful with contact surfaces they are IMPORTANT.

After completing my first set of gears this way, with perfect hindsight and the experience of the other methods, this was not my favorite method. Granted I do not do tons of scrolling and my technique could definitely use some work, I found that even paying close attention to my lines I still ended up with a lot of variation in my teeth up to a 1/32” sometimes and I then had to file until everything fit. But that said it was a lot of fun and had that free hand feeling that is hard to get with power tools.

Next time… the bandsaw!



3 comments so far

View Ken90712's profile

Ken90712

15161 posts in 1912 days


#1 posted 03-06-2012 10:55 PM

Very interesting, Look fwd to more of this blog!!!!!!!

-- Ken, "Everyday above ground is a good day!"

View Philip's profile

Philip

1148 posts in 1262 days


#2 posted 03-07-2012 05:49 AM

This is great! I am fascinated by clock movements and will definitely try this some time.

-- I never finish anyth

View Michael1's profile

Michael1

403 posts in 1383 days


#3 posted 03-10-2012 02:50 AM

Another great post and very informative. keep them coming!! I am looking forward to trying a clock build myself. Thanks for posting this

-- Michael Mills, North Carolina, http://www.scicaskets.com

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