Home Made Gears

[john9]

Hi, I haven't posted for a while since I finished the Bolton #12 I decided to
go back to the first engine I started to build and never finished, an Elmer's Geared (Hypocycloidal) Steam Engine, it was never finished because of the internal gear that is required, I ordered one from Boston gears USA(big dollars)but they sent the wrong one, external instead of internal so I moved on, now I want to show my setup for cutting internal gears also some bevel gears for the Bolton#12,
I made the internal gear with a single point cutter mounted in a shaper, to get the correct profile cutter I cut two teeth from an involute circular cutter and ground it down to one tooth with a square stub to mount in the end of a rod mounted in the shaper, the involute cutter cost $15 and you can get about 6 single tooth cutters out of it, it worked out well, some photos of my gear cutting,
John.

 

[JimDawson]

Very Nice!

 

[gr8legs]

Lovely!

 

[turnitupper]

Credit where credit's due. I think that idea of chopping the involute cutter up is bloody brilliant!
John.

 

[brino]

Nicely done!
-brino

 

[FOMOGO]

Great job. So basically using that single tooth as a broach. How many passes were required to produce each V to full depth? Mike

 

[Silverbullet]

Thinking outside the box, way to go . Where there's a will there's a way. Nice set up for the shaper , old time gear cutting . Oh to hear the old overhead gears clanking and grinding when put under a load. Man am I old ,remembering working with mills ran by big old flat belts slapping , a rewarding time now I think of it , but oh my god the work was exhausting .

 

[ogberi]

Is there a difference in tooth shape between internal and external gears? How does the number of teeth and cutter number correlate on internal gears? Great idea, though! Never thought to chop up a gear cutter to make single point cutters. +1 for thinking outside the box! Or is it thinking inside the gear?

 

[Tony Wells]

The difference is essentially the Addendum allowance between the internal and external gears. In simpler terms, the pitch circle difference or clearance between running gears. If you are making a mated set, no problem, you're cutting to fit. If you are trying to make spec gears, then you need some rather odd instruments to measure the tooth thickness at the proper depth.

 

[ogberi]

That is about what I thought. I need to break out some thin plywood and the scroll saw and make a solid model to wrap my head around it properly. I imagined a rack curved into a circle with the teeth on the inside.