class of thread fit on studs and all-thread

I need threaded suds 4-3/8" long for a job I'm doing. I was using all thread but I need a snug fit on the nut I'm using. The local fastener place tells me that all-thread is made to a "commercial nut fit" not any class of thread. I can't find any reference to a "commercial nut fit" in the machinist's handbook.

I can find B7 studs at Mcmaster, but they are $2 each. I don't need any high strength material, just a nice thread fit. I would like to get a class 2A thread on a plated steel rod.

Any suggestions?

This is a height adjustment screw on a small machine. I machine a nut from 1018 steel and slot it, then pinch the slot closed to get rid of as much slop as I can, but all thread is not uniform and I get tight and loose spots.

Thank You, Randy

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Randy
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Just a WAG, but could you machine a recess on one side of the nut and adhesively attach a thick rubber washer in it with a center hole sized appropriatly to give you enough friction?

Sort of like a weak elastic stop nut?

Jeff

Reply to
Jeff Wisnia

Hi, Randy. Have you tried running a split die over the threads? Squeeze the die down to where it takes a little off all the threads. Is your problem caused by plating on the rod? Have you tried non-plated rods?

Paul

Randy wrote:

Reply to
co_farmer

Heh!

"Commercial nut fit?"

I'm sure you'll find that all-thread has a class 2 thread. That's not what you need-----interference threads are a class 5, and you're not likely to find them anywhere.

If your application is one whereby you adjust, and want the setting to remain, if you have a surface against which you can tighten a nut, simply double nutting will prove very effective. It's not even all that inconvenient to further adjust. You also might consider either locking nuts, which eliminate slop, or nylocks. All depends on what you're trying to accomplish.

Harold

Reply to
Harold and Susan Vordos

You could lap the screw and nut together to even it out.

Don Young

Reply to
Don Young

aviation nuts and bolts differ from the hardware grade in their fit. I think you'll find that aircraft nuts and bolts are class 4 fits. usually unf, with unc in smaller sizes

Stealth Pilot Australia

Reply to
Stealth Pilot

All I've ever seen spec'd was classes 1,2,& 3. That's in 20+ years around planes.

Now you got me curious....

Cheers Trevor Jones

Reply to
Trevor Jones

The guy at Associated Fastener (AF) tells me a commercial nut fit is one where a nut will spin freely down the treads, no other specs are held except you can put a nut on it. McMaster specs the B7 rod at a class 2A fit, and the Stainless rod at class 1A. The rest have no spec listed.

The rod has a knob on top and nylon washers with a nylok nut under the top plate to hold friction on the adjustment. I don't need double lock nut or anything like that as this has to be adjustable by hand with the knob.

I don't think it's the plating on the all thread, it's that the all thread is out of round slightly, or the thread pitch varies, that is why I get tight and loose spots as I turn the adjustment up and down. If AF can't get me studs with at least a class 1A fit I'll have to go with McMaster. The B7 rod comes plain, I'd need to have it black oxide like I do the nut I guess, how well does B/O wear on B/O.

My next lot will be 150 peices, think McM will discount that quantity?

Thank You, Randy

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Randy

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