Wooden gears.

[Twest3259]

Have any teams in the past used wooden gears? and What where the advantages disadvantages? How did you fabricate these gears? Would wooden gears be reasonable for a 2x2x5 robot designed to sumo?

[orangemoore]

This is a website that has a gear template maker it is not free. It also has a lot of stuff on how he makes the gears

http://woodgears.ca/gear_cutting/template.html

[EricH]

Originally Posted by Twest3259

Have any teams in the past used wooden gears? and What where the advantages disadvantages? How did you fabricate these gears? Would wooden gears be reasonable for a 2x2x5 robot designed to sumo?

I can't think of anybody using wooden gears in FRC.

And I can think of some reasons why.

• Wood won't necessarily slide against wood as well as metal does. Wood also doesn't take grease as well to make it slide better.
• Wood splinters. Ouch.
• Metal tends to have more strength for this sort of application.
• You just about have to make your own. Wood may be a bit easier to cut than metal...but you still have to do the cutting.

This is not to say that you couldn't use wooden gears, particularly for something that smallish. A wide face width and some very good sanding would help, as would using a spoke-and-cage type of setup, where one gear is a circle with a bunch of dowels sticking out of the flat side and the other has a bunch of dowels sticking out of the curved side.

As a more practical alternative, I would suggest plastic gears, which you could probably find at your local hobby shop (though those would be servo replacement gears most likely).

[Bertman]

I would think it would depend on the application, the wood species and the load. Wooden gears have been used for centuries in everything from clocks to windmills. As for lubrication, tallow and parafin can work wonders. Do your homework.

[Twest3259]

Thanks Y'all, And I shall go do the homework now.

[rsisk]

Not the greatest picture in the world, but these gears were used on a robot at the Alamo regional in 2011. They were quite awesome looking and worked fine.

[Seth Mallory]

The best reason for wood gears are because you want to use them. If you do a good job I and many others would like to see them. Wood is a great and modern materiel. I work on transit busses and they have wood floors. It does not crack like metal floors did.

[Ian Curtis]

Gearotic Motion is in my opinion hands down the best hobbyist tool for generating gear toolpaths, but perhaps a bit pricy for a student ($120). Gearotic Motion can generate some really crazy stuff, particularly if you are into clockworks, and it is written by the guy who wrote Mach3, so you know its good stuff.


Perhaps the easiest way is to just download a drawing of a gear from SDP-SI and and export it to whatever format you need to cut. I would love to see someone make use of wooden gears, something I'd love to do next season.

When you say 2x2x5, is that in inches? mm? ft? meters? What kind of motors are you using?

I've never seen wooden gears spinning crazy fast (like the pinion on the output shaft), but just because it isn't common doesn't mean it won't work.


Interesting historical sidenote, some of the first mass produced good were clocks (with wooden gears) for middle class Americans in the 1840s or so, long before metalworking tools were common!

[dtengineering]

Our team had fun with wood... arms, chassis, even pulleys and bearing blocks...

http://www.chiefdelphi.com/media/photos/22924

But never tried gears. I'd be tempted to use some nice void-free plywood, like baltic birch, rather than "real" wood, just to eliminate cracking on the grain lines.

The pulley in the photo above looked great, but broke during qualifying at GTR so we replaced it with a plywood one that lasted forever.

Jason

P.S. Ironically, our modified auto mode while we were fixing the pulley found us an invite into the elimination rounds... it was about the only time we did better due to something breaking.

[ToddF]

If you want a free solution for generating gcode for making gears, you can use Inkscape with the gcodetools extension.

[fb39ca4]

Not gears, but last year our team used laser cut wooden sprockets in our belt drive. They were made up of 4 5mm sheets of plywood cut to the shape and bolted and glued together. The durability of wood wasn't an issue, it was the acrylic we used on the sides to keep the belt from sliding off that kept on breaking.

[Kusha]

We use wooden gears for our BEST competition. We have a CNC that can only cut wood. We design them in Mastercam. If you want to make wooden gears, we've found that laminating them with Masonite stops the gears from chipping, wooden gears have a high tendency to chip.

[gabox2102]

In 2012 our team designed gears that we cut with our laser cutter. They were acrylic an plywood stacks of .25 thick material. We did this for our custom gearboxes for the shooter. We even ended up creating a cad model that would automatically generate gears by just inputting a size and a ratio. This made it really easy to try different speed and torques without having to use pulleys as we have issues with polycord. This year we also used all inhouse laser cut acrylic timing pulleys for our gearboxes and we have not had any problems with it. I can post pics if you guys want

[Ian Curtis]

Originally Posted by Kusha

We use wooden gears for our BEST competition. We have a CNC that can only cut wood. We design them in Mastercam. If you want to make wooden gears, we've found that laminating them with Masonite stops the gears from chipping, wooden gears have a high tendency to chip.

What size bit did you gut them out with? The one thing I am worried about routing them is that the radius of the cutter might do funny things in between the teeth. Did you do anything special to combat that, or was your bit so small relative to the tooth profile it didn't matter?

[AdamHeard]

We have routered a ridiculous amount of baltic birch ply this year on our routers.

I'm surprised we haven't cut any gears yet, we certainly will cut some comically oversized ones at some point though!