"Hobbing" involute gears

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Fluffy

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Lismore, NSW. Australia.
G'Day All,
I have a need for a 0.6 module (42 DP approx.) involute gear cutter of my next model. Before purchasing a milling cutter, I thought that I would try to cut a trail gear with a home made "hob like" cutter. I stumbled on an article from Metallmodellbau. Although in German, the excellent photos & drawings were enough to communicate the basics. As I had some annealed tool steel so there was nothing to loose in having a go. An arbor was turned to suit a Ø16 ER collet & the hob blank was bored to suit.
The arbor & blank were set between centres & the blank turned to calculated sizes. The primary & secondary clearances then milled & the cutting edges honed. Before any heat treatment was considered I thought that I would attempt to cut some aluminium gears. The cutter appeared to cut quite well in the annealed state, but will be heat treated.
The cutter is Ø28 OD, Ø16mm bore, 21 mm in length, the teeth to suit the transverse pitch of 1.88mm. The gears are 19.2 mm tip diameter with 30 teeth.
I am pleased with the result & I am now going to try the some larger modules.
For the members that have used this method, have you had any problems?
Regards to All,
Don.

DSCF3869.jpg
 
Have recently used a one piece hobb to cut some mod1 gears. Worked out great, made the hobb out of silver steel (drill rod), the gears were brass.

Paul.
 
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