I want to make a gear

[Tony Wells]

Well, you have to define the gear form. It doesn't quite look like an involute to me, but it's hard to tell. Best bet would be to get access to a mating gear, like on the shaft, to measure out the pitch, etc. You probably could get by grinding a tool and fly cutting that type of gear. That wouldn't classify as a precision gear. Still need some dimensions to set it up. Cutting a whole gear into segments would be the easiest, I'd think.

 

[Tony Wells]

Ed, think motorcycle engines. As in kick starters. They use a section of gear, as in the photos, and a sprag clutch in some cases to allow overrun.

 

[Tony Wells]

Shaper or mill?

 

[Tony Wells]

Pick your best sample, with a good bore to reference. Drop two gage pins or dowel pins in at the extreme ends of the sector. Measure between them, and to the bore. Do the math and you can get pretty close to a working diameter and pitch to shoot for. You can grind a single point tool similar to a threading tool and single point the teeth. I'd grind two, a rougher and finisher. A fly cutter slotted at 90 deg would spin the tool.

 

[boaterri]

Here is a link to creating a multi point cutter for gears. Just scale up the size for use in a Bridgeport.

http://www.deansphotographica.com/machining/projects/multipoint/multipoint.html

Rick

 

[Tony Wells]

Proper gear cutting is no simple things, but for that you want there, it can be simplified a great deal. Do you want the pitch diameter, or the circular pitch?

You probably should scan through these definitions:

http://en.wikipedia.org/wiki/List_of_gear_nomenclature

Granted, it is wiki, and not always to be trusted, but it can be a foundation for further exploration. You will need some numbers such as the distance between gage pins in adjacent teeth, and the same between the teeth on the extreme end of the sector. Since this meshes with a round spur gear, the tooth profile will need to be the same as the sector. Tooth thickness is another dimension to measure. There are special gages for this, but you can do without for this gear. It's hardly a precision, high speed gear. Probably get away with a lot here.

 

[cyrusb]

Since that forging will have to be built up, I would try buying a full gear that matches, and cut the segment out to be welded in. Judging by your photos you could get a few done with just one gear. I am familiar with what you are doing, and think you have an advantage, in that the gears are not precision. First I would figure what diameter that segment comes from. Count teeth and search catalogues.

 

[Tony Wells]

Bill, you sure dragged this one up from the deep. The OP has left us, and many of the posts in this thread are missing.. I can't even remember what the original question was, or what the guy was trying to build.

But that's a good resource, I have used it quite a bit. Thanks for posting it.