Servo spline geometry help

[nesikachad]

I've machined my own servo arms and I need the geometry for the splined output shaft on the servos. I am using Hi tech's but would like info for all three of the big brands. (JR, Hi tech, and Futaba)

If anyone has a print or information that would be helpful I'd be very grateful.

Thanks.

C

This is also posted up in the transmitter/receiver/servo forum.

[Vern Smith]

I will be interested to see how you do in this pursuit. I went on a similar quest but from a different angle. I sent an output shaft (JR) to a broach grinder hoping it was a standard which I was damn near sure it was not. As feared, they came back with an $1,150 quote to grind me a custom broach. Maybe they will do a bunch for the same price?

If you have the right grinding equipment you could do your own. From my experience with JR servos, they do not do a real good job with consistent tolerances on their splines. It didn't matter with the plastic servo arms but does with metal arms. That's why most of the after market metal arm manufacturers are cutting them a little over sized and including a clamp screw. Now that JR is making so much torque that plastic strips out they will have to tighten up the tolerances on the splines. It will probably be wise to wait for them to do that before investing in a broach.

I don't have any experience with Futaba and HiTech. They could be better although the after market guys use the clamp screw for them as well and I assume it's for a reason.

Good luck

Vern
whiteroseeng.com

[nesikachad]

I'll just machine my own then. I guess just get it as close as I can. I concur that the spline geometry is not consistent from one servo to the next.

Fun stuff.

Thanks.

C

[Vern Smith]

If you decide to make (machine?) your own broaches I would be interested in buying a set from you.

Vern

[nesikachad]

I'll be in touch Vern.

"Broach" really isn't the correct term for what I'm doing. Calling it a swaging tool is probably more appropriate. I'm "squishing" the material more than actually cutting it. The holes are blind so chip evacuation is going to be an issue.

My plan is to just "ca chunk" the splines in the 7075 aluminum using the spindle and a G1 move in Z with no RPM.

We'll see how she goes.

I'll be in touch.

C

[Vern Smith]

That was my plan as well, sorry about the misnomer, swagging or squishing is probably a better term. I planned on using 6061. 7075-you must be anticipating some big loads? It probably won't displace or deform as easily as 6061 would.

Vern

[nesikachad]

I'm counting that it won't which is why I'm going to use either Pre heat 4140 or D2 for my tooling.

I chose 7075 cause it just machines so so so very sexy nice. It's a selling point too I guess as I do have a few locals interested in them as well.

Cheers.

[btomlinson]

I think you want a rotary broach to do the ID splines.

[Vern Smith]

OK, can we trade you some tailwheels and sniper rifles for a couple Mr. nesikachad appears to have the equipment to make his own but I don't so I would like to hear more.

Vern

[btomlinson]

Here is a video, Its very cool. One of those things you say it wouldnt work, watch it and still dont believe it. . . lol
http://www.slatertools.com/video.htm

[Vern Smith]

That is amazing and made in America too. It looks like somebody still has to make a male or female form to put into the rotary tool. For limited production shoving a broach into the hole would probably be the best way to do it unless you happened to have one of the slatter tools laying around.

Thanks for the information.

[btomlinson]

I've kicked this around myself. I would think you could make a broach and have angled clearance in the center. Almost like a endmill but much more (.003/.005) to help with the chips. The chips are going to be the kicker

[Vern Smith]

Maybe you could peck it to help with the chip evacuation? wouldn't do much for cycle time though. Who cares, it's our hobby! A hole in the center of the broach (axial) would give the chips somewhere to go for a while.

[Spdstr280Z]

	Quote: Originally Posted by btomlinson
	Here is a video, Its very cool. One of those things you say it wouldnt work, watch it and still dont believe it. . . lol http://www.slatertools.com/video.htm

I was still thinking it was impossible until about halfway through when I caught that the tool isn't driven, it rotates with the work piece. So, it is a press action just like they were stationary, but it uses the rotation and the 1 degree angle to assist the work with a rocking drive action.

Fascinating stuff !

Jason

[btomlinson]

	Quote: Originally Posted by Spdstr280Z
	I was still thinking it was impossible until about halfway through when I caught that the tool isn't driven, it rotates with the work piece. So, it is a press action just like they were stationary, but it uses the rotation and the 1 degree angle to assist the work with a rocking drive action. Fascinating stuff ! Jason

Yep,It wobbles its way through