the dreaded internal gear....
Posted: Wed Jan 21, 2015 1:20 am
howdy do all. i have obviously made the plunge into the land of gears...oh boy i have some projects lined up! (reminds me...i actually oughta fire up this license and get the 3d printer going too. currently this is the first forum board ive paid to join. funny.)
question of interest... i see a few posts that delve into the maths but not much on the actual practical side of things. ::)
how to CUT an internal gear???
i know theres really only two ways...
broach.
shape, using either a full or partial gear cutter.
(and basically they are both the same anyway, just the diameter of the cutter differs, and the number of strokes/DOC).
i guess theres the option of a tiny endmill but in my mod it would really be tiny...microscopic almost...
sourcing it out costs money i dont have. no laser wire water or similar cutting.. plus i need precision, and width.
has anyone actually tackled the process?
i sorta need small internal gears. :-X about the size of whats in a bicycle hub.
possibly in production, so its worth spending some time making a broach.
would i be correct in thinking that i could do this;
take fairly long blank of tool steel.
turn to required OD, and taper to base circle of gear.
cut the blank as an external gear with matching proportions to requisite internal gear.
if i was smart i would have cut a fairly steep square sided thread down the blank on the first setting, but now i would do it if i hadn't.
carefully grind relief on all the teeth so formed.
i forgot to harden the steel didnt i?
now...with luck it wont deform. but that isnt going to happen ::)
it would need finish grinding...
simplest way is to "thread" a grinding wheel so it resembles a hob and run the cutter on centres.
get the 60 ton press and away i go...
sounds like a lot of work to make a gear...but the end result would be worth it... especially as i might have reason to pop out 50 or so, more in the future.
any thoughts?
any tips?
any real life experience in cutting TRUE INVOLUTE internal gears? not clocks, cycloids, timber or anything. real ones. for gearboxes and high rpm. :-\ i also cant sit around twiddling my thumbs for hours waiting for each one...
fussy, arent i? :P
cheers :)
question of interest... i see a few posts that delve into the maths but not much on the actual practical side of things. ::)
how to CUT an internal gear???
i know theres really only two ways...
broach.
shape, using either a full or partial gear cutter.
(and basically they are both the same anyway, just the diameter of the cutter differs, and the number of strokes/DOC).
i guess theres the option of a tiny endmill but in my mod it would really be tiny...microscopic almost...
sourcing it out costs money i dont have. no laser wire water or similar cutting.. plus i need precision, and width.
has anyone actually tackled the process?
i sorta need small internal gears. :-X about the size of whats in a bicycle hub.
possibly in production, so its worth spending some time making a broach.
would i be correct in thinking that i could do this;
take fairly long blank of tool steel.
turn to required OD, and taper to base circle of gear.
cut the blank as an external gear with matching proportions to requisite internal gear.
if i was smart i would have cut a fairly steep square sided thread down the blank on the first setting, but now i would do it if i hadn't.
carefully grind relief on all the teeth so formed.
i forgot to harden the steel didnt i?
now...with luck it wont deform. but that isnt going to happen ::)
it would need finish grinding...
simplest way is to "thread" a grinding wheel so it resembles a hob and run the cutter on centres.
get the 60 ton press and away i go...
sounds like a lot of work to make a gear...but the end result would be worth it... especially as i might have reason to pop out 50 or so, more in the future.
any thoughts?
any tips?
any real life experience in cutting TRUE INVOLUTE internal gears? not clocks, cycloids, timber or anything. real ones. for gearboxes and high rpm. :-\ i also cant sit around twiddling my thumbs for hours waiting for each one...
fussy, arent i? :P
cheers :)