C-clamp observation....

Re: C-clamp observation....

Lee Schierer in McKean, PA

I've never seen this happen. I would remove the lube.

Lee

Re: C-clamp observation....

Stuart Johnson

The dry lube is probably the cause. When you clamp down the clamps are under pressure. When you release the clamp there is an ability to release some of the pressure. Or, the clamps are just messing with you.

Re: C-clamp observation....

William Duffield

The cabinet shop where I used to work had one hand screw that did that. Although there were theories, we never really isolated the problem. We marked it so we were forewarned not to trust it in critical operations. We never lubricated any of the hand screws.

I have one in my shop that also acts wonky, but I think that one is due to a failed pin between one of the handles and the all-thread. Whenever I get around to it, I should be able to easily fix that one.

Re: C-clamp observation....

Bruce, a MN Galoot

Don’t know about clamps, but I once asked a machinist I worked with whether the screws he lubricated wouldn’t unscrew under pressure. He said no and that there are separate torque recommendations for dry and lubricated screws and bolts.

The screw didn't back off...

Clint Searl

...The C got bigger.

Its the lube...

John in NM

I've seen that happen with screws now and then. The shallower the thread angle, the less it will be a problem, but its rare to see on dry threads.

Re: Its the lube...Don't know what got into me

Barry Irby

Must have been some sort of maintenance fit...

This clamp is a heavy duty Jorgenson with Acme (Meep Meep) or square threads. Not sure why I lubed it.

They do need it now and then...

John in NM

I just lubed one of my Wetzlers that I use a lot - tiny bit of 3 in 1 on the threads and the screw works a lot smoother. Eventually the threads rust a bit and start sticking.

A response to the clamp post above this morning reminded me where I have most often seen threads slipping - on one of the Jorgensen wood hand screw clamps I bought when I first started woodworking seriously. Between this thread and another on a gunsmithing forum, I think I can fix it. A bit of powdered chalk might just take care of the problem.

For yours, maybe rinse with some paint thinner or even alcohol or water to try to get the bulk of the dry lube out. Probably some will stay behind and you then will have a nicely working clamp. If it needs a little lube a drop of 3 in 1 will do the trick.

Re: C-clamp observation....

TomD

Yes, you want to lube machinery screws, but in most cases they can be really torqued down because the underlying materials are barely compressible at the loads involved. The threads need lubrication to be brought to maximum torque, and they have good surface contact, and are tight tolerances. With C clamps, there are some very loose threads, you have disparate materials, like chrome on iron. For whatever any of that means.

Build quality makes a big difference on C clamps. I had some nice Record clamps, they had machinery like fit, but the metal in the screw would rust in any environment north of Death Valley. I would lube those screws, and they gave no trouble. Perhaps because the fits were good, and the surfaces had had some texturing from light rust.