
Templates for Cutting Gears from Wood - rmbryan
https://woodgears.ca/gear_cutting/index.html
======
MatthiasWandel
Matthias Wandel here.

Funny how my old stuff shows up on hacker news from time to time, though it
was less than a year ago that I ported it to javascript, used to be flash,
cause when I created it more than ten years ago, javascript canvas wasn't
mature enough yet.

~~~
jld
Hi Matthias!

Big fan of your videos. I hope your tendinitis improves and you can make it
back into the shop soon to make more power tools out of old furniture other
people have thrown out.

Cheers!

------
bityard
Matthias is one of my personal heros, I've been reading/watching his stuff for
years. His videos are mostly what got me into woodworking and made me see it
as more than just a way to build furniture. I built a bandsaw, out of wood,
based on his plans: [http://blog.bityard.net/articles/2019/January/i-built-a-
band...](http://blog.bityard.net/articles/2019/January/i-built-a-bandsaw.html)

~~~
Jedd
Fantastic read, thank you. Hopefully you're not put off metric for life -- so
much as put off low-quality tools. I'm a bit envious that you have a
thicknesser at less than a year 'into woodwork'. Presumably one of the
benefits of living in North America. (In AU decent workshop tools are
hideously expensive, with limited ranges available domestically.)

------
fimdomeio
If you want to go further down the rabbit hole check is youtube channel.
[https://www.youtube.com/user/Matthiaswandel](https://www.youtube.com/user/Matthiaswandel)

------
dougk16
Sort of related tool I made a year or two ago:
[http://dougkoellmer.com/front_rack](http://dougkoellmer.com/front_rack)

I used this tool to make a PVC front rack for my bike:
[http://dougkoellmer.com/front_rack/attached_side.jpg](http://dougkoellmer.com/front_rack/attached_side.jpg)

I tried to do all the calculations by hand, but eventually realized I needed
to make a little custom CAD program like this to help me. I tried more
general-purpose CAD programs but couldn't figure out how to set up the
constraints I needed.

Anyway I think there's a lot of usefulness in purpose-built online tools like
this for generating templates and plans. Such programs are pretty easy to whip
up too using the Canvas API and a basic geometric primitives library.

~~~
cr0sh
Do you know about OpenSCAD and OpenJSCAD?

[https://www.openscad.org/](https://www.openscad.org/)

[https://openjscad.org/](https://openjscad.org/)

They are both basically "CAD/CAM for programmers" \- and allow for parametric
models to be designed. In fact, there are more than a few models like that on
Thingiverse, so if you needed to resize something to fit your needs, you can
(plus tons of gear and other similar custom power-transmission systems).

Of course, that's all for design and modeling - it wouldn't help for other
problems, where some form of calculation and checking of a "model" (in the
sense of a simulation or idea - not necessarily a complete physical object
rendering) is needed.

You see a ton of these kinds of tools in the electronics and hobbyist realms;
quick calculators to tell you how much resistance to use for various LED
configurations, or 555 timer customizers for common circuits - things like
that. I know of one out there which gives you torque/power curves for a
variety of different RC hobby electric motors. There are of course several for
physics simulation and testing, too...

~~~
avmich
> it wouldn't help for other problems

I once had a problem with OpenSCAD when I needed to sort - within model -
objects of different kinds. The example sorting algorithm (a quicksort) is
shown in the documentation, but it was working only with a particular kind of
objects.

Long story short, OpenSCAD turned out to be powerful enough to have a Lisp
written in it. Lisp manipulated strings and allowed factoring out the sorting
algorithm and applying it with different comparison algorithms, supplied as
parameters. Given Lisp, I think it's possible that a lot of things can be done
in an OpenSCAD script.

------
jbj
do a youtube search for "wintergatan" and you will find an artist making very
nice use of wooden gears

~~~
gitgud
He says in one of his videos that he uses Mathias's Gear program (the one
linked) too

------
projektfu
I was thinking that this would only be good for light duty as at least some of
the teeth would be along the grain and liable to break off. Then I went to the
homepage and, indeed, there are pictures of gears with the teeth glued in so
that they have a different grain from the underlying gear.

~~~
crgwbr
A better option would be to use aircraft or marine grade plywood—somethings
that’s guaranteed not to have voids. It’ll be a lot stronger than making the
teeth individually and attaching them to a round core.

~~~
bacon_waffle
The strength of wood is quite directional; since the plys in plywood are not
in the same orientation, it's almost by definition less strong than a solid
piece of the same type of properly oriented wood.

~~~
theothermkn
A lot of people believe this, but it is incorrect. In plywood, the glue
transfers the load across the faces of each ply from strand to neighboring
strand through the adjacent plies. This can result in a stronger bond between
neighboring strands than if no cross-plies were present. This amounts to more
than just splitting resistance.

As a parallel case, consider multi-ply composite construction, where sheets of
fabric, sometimes of sheets with a single fiber orientation, are laid at
angles to each other to spread the loads in exactly this way. They both better
approximate an isotropic material, and are stronger than an equivalent
thickness of singly-oriented plies all in the same orientation.

~~~
bacon_waffle
Sorry, I think you're misunderstanding my argument. I agree that wood
reinforced glue is stronger than wood, but it's not really speaking to
improving a wooden gear as above.

Gears are subject to predictable stresses, and so being able to orient a
material to best handle those stresses will make a stronger gear. Plywood,
like anything else, is a compromise that, as you say, has a more isotropic
character. Obviously, there is a wide range of strength in wood, and so
plywood. I think it's reasonable to say that one could construct a stronger
gear using teeth from readily available solid wood, then readily available
plywood. Good luck finding hickory plywood :).

To your first sentence though, if you take the same size and quality solid
board and piece of plywood at your local hardware store (making a reasonable
attempt at an apples-to-apples comparison), the board will be almost certainly
be stiffer and stronger with the grain, than the plywood will:
[https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_...](https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr190/chapter_12.pdf)

------
tiborsaas
A friend of mine made a similar tool with vector asset export options:

[https://geargenerator.com/](https://geargenerator.com/)

~~~
dawnerd
Should let him know his site breaks the back button

The visualization there is pretty cool though!

------
munk-a
I am impressed and amused that this tool supports zero spoke gears.

~~~
avmich
I'm impressed with negative gears :) . No other numbers though?

------
tgb
What makes these specifically for wood and not, say, metal?

~~~
6nf
I think usually metal gears are not cut by laser cutter or CNC router, but
instead slotted using a milling cutter one tooth at a time and then the blank
is rotated to the next position to cut the next tooth.

But of course if your metal gears are large enough to cut from the flat side
then this template will work fine.

~~~
bacon_waffle
There are many ways to make gears, hobbing is one of the commonly used
processes for cutting them from a blank. There is a cutter that looks
something like a milling cutter, but it is turned in sync with the gear blank:
[https://en.wikipedia.org/wiki/Hobbing](https://en.wikipedia.org/wiki/Hobbing)

------
DubiousPusher
Very cool but cutting with a band saw seems very subject to creating
irregularities in the gears.

~~~
yreg
Probably intended to be cut with a laser or a CNC.

