Set screws on hard shaft

Tom Gardner fired this volley in news:L_ednZ6OaZmCvrLPnZ2dnUVZ snipped-for-privacy@giganews.com:

Nope... 'called "pointed tit" screws.

Lloyd

Yep, I agree.

I only have about 7/16" thread to work with.

Maybe a small point, but having the set screws opposite each other would be the worst way to use set screws, wouldn't it? If you have to use two of them, shouldn't they be 90 degrees from each other so they are both pulling the part toward the same side of shaft?

Pete Stanaitis

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Yep, but no room at 90. I figure that oposing is better than 1 screw.

Actually it is not much better. Think of having two men pulling against each other on a rope. Now tie one end of the rope and just have one man pull. The tension in the rope is the same in both cases.

Is the part long enough that you can put two set screws both at the same degree.?

Dan

No. The action of the set screw pulls the opposite side of the part against the shaft, and that is where most of the torque resistance comes from, not from the screw itself. Two screws at 90 degrees assist each other in pulling the part against the shaft. But, two opposing set screws will fight each other. The part is not pulled against the shaft anywhere, and the tiny tips of the screws are doing all the work.

Opposing sharp point set screws digging into a soft shaft might behave the way you expected, but that's not what you have.

Afterthought: As a low-tech solution, put a little valve grinding compound in the joint and use just one set screw.

I've pretty much decided to build a clamp the next time this part comes into play. It does work OK as is, I just know better.

I see. The shaft is too hard for any setscrew to get a purchase, it's only a pressure thing. I did notice that if either set screw is loosened, the part will turn on the shaft. I'll build a clamping part.

Yep! I've used that technique before.

============== Just hit my in-basket

see

Slick device! I did make a simple split locking collar that works and is easily adjusted. BUT...I will file away the Zero-Max! Thanks!