Quick release or butress thread ?

I have an application where it would be convenient to remove a tightened nut with say 1/2 turn rather than have it wind it off all the way.

I have had lots of good screw screw cutting experiences in my model engineering years and I keep thinking of quick release threads but have no experience with these apart from seeing them on a large bore gun.

My application would be around 3/8", is this too small to be practical?

Peter

Loctite the nut onto the thread and use a wrench with a tube on the handle to undo. The stud will shear of well within a half a turn.

regards Martin

)

How about something like this?

**LINK**

Mike

Depends on the application, does it need to be threaded.
Cam lock or similar if its for the same part, work well.

I don't see any reason why an interrupted thread wouldn't be practical at 3/8" diameter. They're easy enough to make in simple form, but remember that removing large slices of thread weakens the joint. Used on artillery because the breach swings on a hinge. The interrupted part allows more clearance, allowing a more compact construction. For obvious reasons considerable care is taken in design and manufacture to make the breach strong enough; an artillery interrupted screw isn't easy to make because the male and female are made to close tolerances out of tough steel.

Apart from artillery, I don't recall seeing an interrupted screw on an ordinary object. The more usual alternative is either a bayonet fitting or a multi-start thread. A 2 start thread unscrew twice as fast as a single etc.

Dave

Have a look for quick release nut. They are sometimes used on fixtures. I think Berger do them, there may be others, may give you an idea as to how to do it.

One difficulty with an interrupted thread as on naval guns is that it only works in one position. If the nut ever has to be tightened 1/4 turn more or less it will disengage (in practice even 1/8 of a turn would probably weaken it too far).

Brian

Thanke everyone, pleased I asked, lots of useful info on nuts I've heard about!

The angled/quick release nut sounds an interesting solution which I intend buying or making.

Peter

I believe there was an American(?) design of woodworking vice that used an interrupted screw as a quick-release mechanism.

If you run an endmill through gently at an angle rather than a drill it won't wander.

N.