Quick release or butress thread ?

[Peter BellParticipant @peterbell11509]

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

[Peter BellParticipant @peterbell11509]

[Martin KyteParticipant @martinkyte99762]

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

)

[Mike PooleParticipant @mikepoole82104]

How about something like this?

**LINK**

Mike

[Brian GParticipant @briang]

This might be an idea?

Brian

[JonParticipant @jon]

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

[SillyOldDufferModerator @sillyoldduffer]

Posted by Peter Bell on 01/08/2018 13:45:29:

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

Peter

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

[HOWARDTParticipant @howardt]

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.

[Brian GParticipant @briang]

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

[Peter BellParticipant @peterbell11509]

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

[David TParticipant @davidt96864]

Posted by SillyOldDuffer on 01/08/2018 16:57:27:

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

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

[Neil WyattModerator @neilwyatt]

Posted by Peter Bell on 01/08/2018 17:48:50:

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

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

N.

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