HUB-03 question

Lynxmotion Servo Erector Set
1

I’m not sure where to post this, but I’ll try here.

I am using several HUB-03 and I am having problems with the hex set screw. It seems to use a 1/16" hex, but when I try to tighten it, it slips. I have tried wrenches from several sets, but I still get the same problem. They all seem to be a loose fit. I have not stripped the screw or the wrench. I can’t get them tight enough to do that. Are these not 1/16"? The wrench size is not listed in the online catalog. My guess is a 5/64" would do it. Correct? If so, I’ll have to dig one up.

Thanks for any help.
Bob

2

The set screw for it is a 6-32. It is a 1/16" (0.0625") hex, but some drivers are actually .060" and they will slip.

3

Jim, do you mean to imply that some allen wrenches marked as 1/16 are actually .060???

4

um, yep…

5

That is scary.

Thanks for the warning.

6

Since your wrenches were to small, hopefully you did not round off the hex socket.

7

Not likely. The set screws are made from an alloy and are high quality. But the quality of hex drivers on the other hand varies widely, as does the cost. This is one place where you don’t want to skimp.

8

Jim,
Since the hex drivers I used came from several sets, I don’t know where to go to get a “real” 1/16". I guess I could take a micrometer to the stores with me!
Could you offer them as a product? I would gladly purchase a few.
Thanks!
Bob

9

In a pinch, if you can live with the head a screw protruding from the edge of the hub, you could replace the set screw with a #6-32 socket head cap screw of sufficient length to torque down on the shaft. Most screws will not be nearly as tough as the material set screws are made from, nor have the correct tip profile at the shaft end. Whether you would need to occasionally re-torque the screws or not will depend on how much instantaneous torque you are applying to the shaft/hub joint. If you always have nice up and down power ramps it might never be an issue. If you slam power on and dynamic brake a lot, well, either keep an allen key handy or maybe you should stay with finding a set screw + allen key combination that work well. :wink:

10

No, it’s fine. Tough critter as Jim mentioned. The wrench looks fine, too. No obvious wear. Just can’t get them to tighten much before it slips. If I angle the wrench a bit, it helps. But then somtimes it is tough to loosen it if I have to take a hub off.
Bob

11

No, it’s fine. Tough critter as Jim mentioned. The wrench looks fine, too. No obvious wear. Just can’t get them to tighten much before it slips. If I angle the wrench a bit, it helps. But then somtimes it is tough to loosen it if I have to take a hub off. I’ll have to find a better wrench by taking the set screw with me to the stores.
Bob