Thread: Teeth design

Rosco
Cycloidal teeth are very picky about depthing or arbor spacing. More so than involute gears. You don't say how you are cutting the gears, what you are using for wood or how you finish them.
The face of the gears must be VERY smooth and uniform in shape. Unless you are using a CNC machine you should cut the gears almost to the line and then file and or sand to the center of the line. If you overcut the line, fill it back in with epoxy and recut.
You might try building up the face of the gears with CA in three or four coats and filing them down to shape. This gives a hard smooth surface but thats a lot of work.
If all else fails I can cut a set of gears for you on the CNC machine.
Regards
Joe

Thanks Joe for the offer. I have a DIY CNC.
I have since found some gears that I copied and cut on my CNC to see how they went and they are working better than my involute teeth.
I have studdied them and they look to be Involute on the gear that is rounded with a 14.5 pressure angle and cycloidal on the pinion that has the teeth at .4 size (.5 size means tooth as wide as the space between teeth). The cycloidal teeth are also rounded off.
I am going to try that for the moment, but am still very interrested to hear anyone elses ideas.

cheers
rosco

p.s. I like your idea Joe about the CA. I'm going to give that a go on the first gear ratio (64-8)

G'day Roscopeeko,

I am a little behind you on the same journey with producing wooden gears for a wooden clock, and looking at how I might come up with an effective way of cutting involute teeth without a CNC, or similar expensive approach.

Would you be so kind as to briefly outline the specific difficulties you have encountered with the 64 and 8 teeth gears.

I interpret you to say it is difficult to get an involute profile to work in wood.

appreciate your help with this.

DrB

Have a good read through the engineering section of this web site...
Gary's wooden clocks-engineering-animations
Go down the page a fair bit
I tried his gear profiles on the plans for his clock.
His gears seem to be involute with a pressure angle of 14.5 (I have heard previously that this is better than 20 degrees for wood.) that are rounded off and the pinions seem to be close to cycloidal at .4 width rounded off.
This web site talks about the downsides of Involute and the pro's of Cycloidal
The main problem with involute i that they are s'pose to touch at 3 points at all times.

Read up its a good site!

There are heaps of movies on you tube about how to cut wooden gears without a cnc. I have never done it myself.

cheers
rosco

Hi Rosco,

great stuff, much appreciated.