Question on how to make a part - ( very small splines )

DHarris

DHarris

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Ok, the part in the photo is a Servo Horn for "giant scale" rc aircraft (80" wing span and up). I need to make some "unique" configurations to fit into planes that the stock ones (or even after market ones) just won't fit. So, here's the question: as close as I can measure, the id of the spline hole is ~ .215". I can't measure the depth of the spline for major diameter. There are 25 splines in that little bugger. (edit: material is aluminum)

So, how do I make splines that small? ( I have a Sherline lathe & mill available).

thanks for reading and any / all suggestions.servo horn.jpg
 
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Material is aluminum or steel?

-frank
 
Hi Frank, It's aluminum - I've edited the post to include that data now - -
 
Cool, thanks.

Couple thoughts come to mind right off the bat:

One is broaching on the lathe using a smallish HSS cutter much like doing had wheel graduations, except this would be in an inside diameter instead of a handwheel's OD. 3/16 cutter maybe get in there but still be rigid enough to push in as a broach.

Second thought is if it's aluminum, could you make a male version with splines and broach it in one shot? Not much material to move, really. Got a shaft to try one with?

Looking forward to seeing some of the other suggestions as they come in.

-frank
 
Hi Frank,
Would love to have a steel shaft to use as a broach, unfortunately, the mating part is typically a small brass gear on the Servo output shaft. maybe someone will be able to tell me how to make a steel "broach" to push thru the aluminum! (I just can't think of any way to cut "teeth" that fine!
Dave
 
I would imagine the easiest way would be a splined rotary broach. It's going to be expensive - you need to drive head and then you'll probably need a custom broach. It would work fine but its going to cost you.

 
Thanks everyone;

Mikey, yea - knew it would not be cheap to buy something, just hoping there was a "hobby" way to do it!

kd4gij, Yes, I've had friends tig up parts for me in the past, just galls me to have to destroy a perfectly good part to create another.

will keep digging to see what I can come up with!

Dave
 
If you have a hobby shop near you. They might have a hub. Another thought look for the local flying clubs.
 
Call Westco broach in El Monte Ca and ask Tony . If anyone knows he will .All he does it internal blind broaching and he makes his own tools.
Jimsehr
 
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