View Full Version : Which involute gear cutters?

01-01-2011, 12:07 AM
I have a question for some gear experts, I have a need to make quite a few gears, what would be a good PA for a wide variety of uses? I realize that it would depend on the application, here are a few examples of some uses I have in mind.

Gear reduction for a hand held model airplane engine starter
Gear reduction for on board model airplane engine starting system
Other small gears for R/C vehicle use.(some RPM 10,000+)
I would also like to build a couple of small gear pumps for a couple gizmos I'm building.

What are your thoughts?
Thanks in advance

01-01-2011, 02:42 AM
20 degree pressure angles were adopted because on smaller sizes (that is, small numbers of teeth-I think 14 is the magic number) the 'old' 14 1/2 degrees pressure angle required the teeth to be under cut, weakening them.
If you are doing small stuff (model aeroplanes etc) have a look on eBay under 'gear cutter' - they have usually have small tooth gear cutters as a set for metric gears (sized by module).


01-01-2011, 09:37 PM
I would go with a 24 dp are a 32 dp. Pa is up to you but I prefer 14 1/2 degrees.

01-02-2011, 07:41 PM
Thanks for the replies, I think I settled on something.

I'm ordering a metric set of gear cutters, module 1, 14.5 degree PA.

There are a few reasons I am going with these, 1) module 1 is as close to 24 DP as I can get in metric, 2) I have determined that this is what the change gears on my lathe are, and 3) I can get a full set of import cutters without spending 3 fortunes.

Thanks again for the input.

01-02-2011, 07:43 PM
Loads of module cutters on ebay.de

01-02-2011, 07:59 PM
I had to make the same decision when outfiting my Lorch for change gears. I made the same choice - 14.5pa and mod 1.

Living where I do, in retrospect I might have gone for 24DP, purely because so many Myford change gears are available. Mod 1 gears are thin on the ground, and there will come a time when you'd be pleased to pick up a few without making them.

My decision was actually made when I came across a bunch of 1 mod gears with a 15mm ID and a 1/8" keyway. Later I came across another hoard, with a 20mm ID and two keyways. Simple matter to make some adaptors.

It's a good choice, both strong enough to transmit plenty power, and small enough teeth to be fairly easy to cut.

I'm sure you'll find a few import machines use them, but I haven't found many yet.

Good luck.