Wooden gear construction

[gamefreak]

Me and my insanity just got electrocuted by some interesting ideas. But since my insanity sparked it im clueless as to how to do it, so now im here...

Now many of you are familiar with gears and the technical aspects of them, I however, am not. So I want to make a project that uses those good old fashioned wooden gears. The kind with the dowelesque rods sticking out to form the teeth, but after suffering from a headache for the better half off the day and messing up on a physics problem 10 times making the same mistake every single time(I caught the mistake because it was an impossibility) I just cant seem to wrap my mind around how they work.

So my plan is to make my own gears out of wood using pegs as the teeth(I find real teeth would be more difficult), i know that i cant just throw them together because otherwise they wouldn't "mesh" and the thing would lock. How do I ensure the proper construction of the gears? Do i only have to ensure the pitch is correct?

This is what i am talking about:

[ang5t]

Now I've never messed with wooden peg gears before, but I would think that it should probably work the same way. 1st off, find out the diameter of yout 1st gear in inches, then count the teeth. Divide the teeth by the diameter. Make sure these #'s match up and it should work. In theory anyway.http://www.societyofrobots.com/mechanics_gears.shtml The only thing you'll be missing is the pressure angle, as your dowels probably won't have one. Hope this helps.

[gamefreak]

Yes, thank you, but how do I make the teeth spaced correctly? What angle apart does each tooth have to be from the last one? How do i determine the length of the pegs?

[izua]

oen word. CAD.
(which is actually an acronym for three others XD)

[gamefreak]

Umm? that isnt helpful. hmm, lets put nonsense into CAD and get magical results, right......
CAD is only useful if you are modeling what you already have worked out. So how do I determine the length of the pegs so that they do not jam? I figured out the pitch due to ang5t but now im confused about how long the pegs can be.

[jka]

Yes, thank you, but how do I make the teeth spaced correctly? What angle apart does each tooth have to be from the last one? How do i determine the length of the pegs?

Take a look at http://woodgears.ca/gear_cutting/template.html

[gamefreak]

I dont want those kind of gears, as stated in my first post, I want the old fashioned wooden peg gears. The circular disk with pegs coming out perpendicular to the flat surface of the disk.

[gamefreak]

Heres a thought, what if I wanted to make wooden chains to go with the gears? Since the gears are simply pegs then it should work fine as a sprocket, correct? So how would I design a chain?

[Trumpkin]

http://science.howstuffworks.com/gear1.htm Not sure if this will help you or not. 

[gamefreak]

yea I looked at that, but it didnt really answer many of my questions, I think I have the gears themselves understood, but im curios as to how to build a chain for them, I figure that the teeth should act just fine as a sprocket.

[Admin]

The thickness of each tooth also needs to be accounted for - it depends on the forces you expect/calculate. If the forces are too high, the teeth will bend/break.

CAD is only useful if you are modeling what you already have worked out. So how do I determine the length of the pegs so that they do not jam?

I find CAD sometimes helps me visualize the problem much better, helping me work it out. My CAD also lets me animate motions, so it'll be useful to see if anything jams. You could also print your design out on paper, pin it to cardboard, then rotate the gears by hand to see if it works.

[gamefreak]

I Have inventor for that, I can do more than animate, I can simulate(thats right, I said it).


I can understand visualizing the problem, but useless posts advertising a product annoy people when it does nothing to help the problem.

My thinking for gear teeth is 1/8 to 1/4" thick dowels, but im wondering how well that can put up with high DC motor RPM. I was planning on taking a plain 6 volt motor from radioshack and then lowering its RPM with some wooden gears. My thought is that things that dont involve torque I should be fine, but to raise/lower an arm the teeth would take a beating and eventually shatter.

[Admin]

but to raise/lower an arm the teeth would take a beating and eventually shatter.

There is actually a way to calculate this to ensure it doesn't happen. It's kind of a long story, but google around for 'bending beam stress analysis', 'fatigue analysis', and 'creep analysis'.

[ahdlm]

Peg gears are so fun to work with!

I've been trying to make a rather complicated machine using wood construction, so peg gears became an integeral part.
in trying to figure them out, I managed to make something rather fun.

http://cellulosicarmsfoundry.blogspot.com/

scroll down to see pictures of my rubber band gatling gun.  hand cranked using a simple "bevel" peg gear.

I had tried to size the set for 1/2" pegs, but it turned out I needed more clearance and had to try to sand the pegs down once they were attached to the base.

If you'd like to see more on peg gears than you ever thought you could find, check out this site:

http://www.leonardodigitale.com/login.php

it has the collected sketch books of DaVinci.  there are lots of examples of peg gears in the Codex Madrid as well in the Codex Atlanticus.