how to cut R/C servo spline grooves into a hole in metal ?

I'm looking for ideas on how to cut R/C servo spline grooves into a hole in aluminum.OR even on how to build a tool to do this for small production runs, say 5 to 10 at a time or so - by hand is
fine. Maybe some kind of lever operated punch ?
OR - maybe if there is a way to just press the spline grooves onto a shaft of steel and then harden it I can fabricate a punch that way.
I just got a Sherline mill machine with a few of the basic accessories, if that helps.
Any ideas are welcome ! Thanks ! JCD
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I would drill the hole in your gear the size od. of the largest dia of your shaft you need to press it on... Then I would rub some never seaze on the PTO shaft... Then I would mix some J-B weld up and press on the gear and squese in the J-B weld around the splines... After it drys you can press the gear off and you will have what you want....
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You are aware that you can buy aluminum servo output arms. There may even be titanium ones if you search around and have lots of money,
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Yes I am aware of that. Probably will turn out to be the more time and cost effective solution, and I can just modify the arms if needed for my project. Thanks !
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    Is this a through hole, or a blind hole? The suggestions below are assuming a through hole. For a blind hole, you will probably want something like a wobble broach -- and I have no idea how you would find one in the right size. You might have to make one. Look them up on the web.

    Hmm ... I would suggest finding out what gear that duplicates, and buy some gear wire of the proper size. Turn a series of steps into it like a broach, then harden it (it is probably annealed so it can be machined to fit into hubs of larger gears), and you have a broach for the purpose,
    Have you ever seen a broach? There are two fairly common styles -- the ones used with bushings to cut keys in hubs, and square or hex ones for making appropriate sized and shaped holes in workpieces. Look them up on the Dumont web page (just search on "Dumont broach" (without the quotes) to see what they look like.
All need a press. I don't know the size of your needed spline, but I suspect that the little 1/2 ton presses would do for that. For some things, the three ton which I have is marginal.

    It sounds a bit minimal for this task. A sherline lathe could be used in cutting the steps and clearances in the gear wire to make the punch -- or any other small lathe.
    Good Luck,         DoN.
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Servo output splines are only about 3/16" some much smaller. A few slightly larger. In the old days most servos had square output shafts. I still have a few.The introduction of splines was a real breakthru. Most servos come with about 5 different output arms/wheels. Computerized radios have sorta negated the need for some of these. Mostly hey have always been molded nylon but you can get metal ones anodized in pretty colors for showing off your wallet.
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Thanks to everyone, including DoN above. I didn't know what a broach was until tonight. But I will by tomorrow sometime! Thanks again - JCD
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I would suppose that there are many folks here that make holes in metal parts frequently, that don't know what type of hole you're referring to, and I'm one of 'em.
As far as internal splines go, they're one of the more difficult types of holes to make, depending on hole depth/metal thickness, accuracy and load characteristics. A relatively easy way to make a hole with serrations (not exactly splines)is to drill small holes in a circle. Changing the circle size and drill size will obtain different results, maybe a certain combination will work for your parts. Your application isn't extremely critical, and I assume the reason that the shaft is splined is to permit installation of an accessory at various positions. I have no idea if another fastener (shaft nut) is utilized to keep the parts (you're wanting to make) in place.
A followup reply suggests that the hole is about 3/16". If you would care to be more descriptive, you might get more help.
When I first saw the question, I though that the servo shaft could have many really fine splines. If there were only 6 splines (for example), I might try pushing a Torx (Tor-X) driver thru a hole in aluminum. This method would involve distorting/displacing the hole in the aluminum part (instead of trying to punch a precisely splined hole). You'd need to experiment with various sized holes in small increments, as a slightly different sized hole might produce better results. Polishing and/or slightly tapering the driver splines and using a heavy duty lubricant may improve the results.
The method you use to push it thru will depend upon what tools/equipment you have, or might be inclined to get. A small mechanical (Panapress) press would very likely improve your chances of being able to attain repeatable results.
If it turns out that you determine that matching the splines of the shaft isn't going to be cost effective for you to do, then you might pursue other ways to accomplish your task. Maybe you could locate small splined hubs that fit the shaft (in brass, maybe), that you could then solder extensions to. Modifying available servo arms/cranks? might be easier, depending upon the method used. I've used the "magical, miraclulous" aluminum repair rod for fabricating and repairing many small aluminum parts. If you're comfortable using a propane torch, it might be an option for you. Don't have great expectations of great looking results. If you aren't experienced in using a torch, experiment with a lot of small scrap aluminum pieces, as it's fairly easy to completely melt/liquify small parts.
WB ............
pogo wrote:

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