It's Crafty: How To Make Wooden Gears

I'm a wanna-be-maker ... a person who creates things out of old and new, using old-fashioned materials and new fangled things to create mish-mashed, funny-looking, really cool whatcha-ma-call-its.

An example?  The North Skirt how-to http://steampunkworkshop.com/north-skirt and YouTube video http://www.youtube.com/watch?v=4jSASY-DCIo.

I'm trying to learn by doing, which involves getting into trouble, making mistakes, and hopefully fixing and learning from them.

I spent three days at Christmas in a basement workshop trying to make wooden gears.  I learned just a little about using some power tools: the drill press, the band saw, the scroll saw, the belt sander and the drum sander.

I made a few mistakes, but on the fourth attempt, I had a level of success.  Here's how I did it, a few things I learned, and what I might do differently next time. 

How To Make Wooden Gears

1.  Decide on the type of gear that you will make, and think about the size.

This is a discussion on spur gears.  There are several other types of gears, but I wanted to go for the simplest type first.

Spur gears are the ones you most usually think of when you think about gears.

I was not too particular, except that I wanted a few different sizes to make it more interesting.  I am planning on using the gears on a box that is about 9-inches square, so I didn't want to make them too big.

If you are planning on using the gears to make something move, that will drive the size of your gears.

2. Pick Your Materials

I began with an old breadbox and two discs.  I eventually decided to use the base of the breadbox to make the gears.  This meant that I was using maple that was three-quarter inches thick.

3. Design Your Gears

That's a loaded three words right there.  The design of your gears will be determined by your planned use, but I'll go with my requirements for now, which was that I really just wanted two gears that were of different sizes and that would interact with each other.

It would take a chapter to describe gear design in any real way, so I will just list a few facts that I found out about gear design through trial and error, a bit of reading and internet searching.

a. In order for two gears to mesh, the number of teeth per unit of circumference must be the same.

E.g. if we have two disks of different sizes that we will use to cut gears, and we want to have one gear tooth per inch, the circumference of any one of those gears will be in whole inches.

b. The shape and size of the teeth on each of the meshing gears matters.  For now, I'll say that they should be the same, though that is not entirely true.

c. You can skip a lot of the hard work and print up some design templates with this gear template generator: http://woodgears.ca/gear_cutting/template.html.  Try varying the tooth spacing and contact angle, and print up several templates, each with different numbers of teeth.

4. Transfer Template to Wood

I'd cut my discs out before deciding to make the templates, but you can skip that step and just apply the templates directly to the wood.  Be sure to leave enough space between templates for the saw.  (I used a band saw for this, and it was a great help.)

Cut the template outlines, and stick onto the wood with rubber cement.  The rubber cement will let you take the template off after cutting without too much residue. 

Outline the template paper by marking the wood with a black marker.  I like permanent markers.  It will help you when cutting.

5. Rough Cut the Disks

Rough-cut the disks so that each templated gear piece can be fashioned separately.  My gear pieces were already cut, so I didn't need this step.

6. Cut the Gears

Cut along the outside of the template.  A line which seems very thin when drawn on paper, will seem so thick when you are cutting with the band saw.  Pick the outside or inside edge, then stick with it for all the gears.  Since I'd marked the wood, I planned on removing any wood that had the black marker applied to it.

7. Finish the Gears

I "finished" the gears using a drum sander.  This is an important step as the smoother the edges of the teeth are, the better they will slide. 

8. Mount the Gears

I put the gears onto a piece of the maple wood from the bread slicer to demo.  They work well enough for a first try.  They would work better if I finished them more, but I'm tired, so they're done.

What I Learned and A Few Things I would do Differently Next Time

You can save a lot of work by doing a bit of planning.  It helps if you know what you are making before you make it.  That didn't happen here, which is why it took three days of doing!  A note about this is that I don't mind having spent three days at it, because that is my way to learn. 

The Internet is an amazing resource.  A search on "How to Make Wooden Gears" would have been a really good thing to do BEFORE starting.

I would use thinner wood and design in more, smaller teeth.  I think the gears would be less likely to bind when turning.

It's huge fun to make your own gears, and what a sense of accomplishment you get out of those clumsy pieces, even if they do bind up a bit!

If you really want to get the whole story, view the video.  It's eight minutes long, but for three days cut into a video, it's pretty short.  https://www.youtube.com/watch?v=whlvtqfVo-Q

More photos from this effort are posted at http://handmadepenguin.com/blog/?p=2169