Pivot Studs (#115-73) have machine threads, but servos don't

[marked23]

I just put on my first servo support. I'm not thrilled about the pivot studs.

The studs have machine threads. The servo output gear is "tapped" for sheet metal screws. Am I supposed to cross-thread these things together?

If so, what is a good technique to make sure they go in straight?

-Mark

[capebob]

The studs have machine threads. The servo output gear is "tapped" for sheet metal screws. Am I supposed to cross-thread these things together?

If so, what is a good technique to make sure they go in straight?

-Mark

Mark, Yes to cross-threading and I use the appropriate size nut driver. It's not as hard as it looks.

Bob

[bighands3d]

The work on the JR 3811 metal ouput gears, and some of the older futaba metal output gears..

Yes a nut driver works best for installing them don't overthighten and use the correct ones they are two sets included in you kit. One set with larger threads and one with smaller threads.. I don't remember which is which.. though..

[DavidH]

Mark,
As others mentioned, the studs will screw right into plastic gear servos.
The studs were designed for the metal output shaft servos.
JR = 3mm screw in metal output shaft
Futaba = 2.5 mm screw in metal output shaft.

The 2.5 Futaba will work in the Futaba plastic out shaft servos. I have even used the JR 3mm studs by running a 3mm tap into output shaft before installing them on Futaba servo.

David

[whirlyspud]

They really should make another stud for the futaba's with a plastic spline. The current method is just cheesy. .

David's deal above with a tap and the 3mm studs is probably the best way to go if you have plastic splined servos like a 9252.

Mike

[bigrcr]

Actually the JR servos with plastic output gears when new have no threads in the output gear/shaft. You create them when you screw the screw into it, whether it be a self tapping screw or a machine threaded one. Don't know about Futaba plastic output shafts being threaded, but I bet not. The usage of either method into a plastic output gear/shaft isn't cheesy at all, just do not put a self tapper into a metal threaded output gear that was intended for a machined screw. :arggg:

[whirlyspud]

I do not agree.

Using a 2.5 machined thread screw in a hole that already had self taper is CHEESY. Cheesy Cheesy Cheesy.

"Don't know about Futaba plastic output shafts being threaded, but I bet not."

I'll take your bet. Have you ever seen a 9252, or any other futaba plastic splined servo for that matter that came out of the box without a small round servo arm already attached? With a self tapping screw I might add.

Now for a metal splined servo, the setup ma has works great. They should make up a new stud for those of us with 9252's or other futaba servo's with plastic splines. They should make a stud to match the thread used on the screw provided with the servo.

All of this aside, the thread form of a standard machine screw, be it metric or standard is not the best for use in plastic. This may be the reason Futaba did not use them there in the first place.

Maybe Cheezy is a little harsh, but you have to admit, it could be better.

Mike

[Rob Stump]

Well, I can vouch for Futaba and I think John has probably seen a 9252 at least once in his lifetime :wink:. The output gears all start out blank and are tapped by the first screw that goes in. If its the cross-threading you're worried about or if you're really wanting it to be perfect you can order a virgin gear set and freshly tap it with your pivot stud but I assure you it is not necessary.

The pivot stud when used with the brace is there to hold the wheel down and balance the servo shaft under a load. It could be threadless and still serve the same basic purpose because of it's design.

Futaba uses the screws just to keep the wheel from coming off due to vibration or torque when loaded. The pivot stud and servo saver assembly primarily serve an entirely different purpose.

Regards,

[whirlyspud]

The facts remain. A standard machine screw is not the best thing to use in plastic. As for the 9252, he was implying that the futaba splines did not already have threads. I refuted that. Nothing personal. It's not even the main issue. I've seen a few Furies with the servos stripped out with this setup. Granted, the people working on them may have been ham fisted, but the fact remains, the screw is not the right one for the job. Why is it so hard for you guys to admit this? Someone should either design the right screw, or just recommend the use of a metal splined servo from the start. It's pretty simple.


" The pivot stud when used with the brace is there to hold the wheel down and balance the servo shaft under a load. It could be threadless and still serve the same basic purpose because of it's design. "

If they had intended it to be used as you say it was designed, then they would have made the studs with a shoulder that could not be pushed up thru the bearing in the support.

Mike

[Rob Stump]

Thanks for all the credit....

Good luck.

[whirlyspud]

Sorry about the credit comment. It did not come across very nice.

Mike