need suggestion for making our own Nylock nuts

Greetings all,

I've got a part that I make that is a tension knob. Knurled brass, threaded down the axis. It needs to have *some* drag on the thread, but not lock solid. Just enough to keep it from shifting around as the tensioner bites onto it.

Currently, we're drilling a cross hole, and pounding in a slug of nylon weedwacker line. Works just fine, but is time consuming and annoying to do. Especially as we go through about 8-10 thousand of these things in a year.

So I'm looking for suggestions of other ways to defurr this particular feline.

The obvious answer is a castable of some sort. Which leads to two questions: A) *what* castable? and (B) how to do it?
My thought is to take a piece of allthread of the same thread as the nut, grind off a flat spot down to about the root of the thread on one side, then thread a bunch of the nuts on, line the holes up with the flat spot on the rod, and inject the (whatever) then go get lunch.

But that leaves you with a solid slug in the bore, and now you have to unscrew the nuts to get them off the rod. Which may or may not be possible, given the amount of crap that's now in the bore.

I'm pretty sure that's the basics of what I'm going to do, but I'm definitely looking for recommendations for something to use as the castable filling. Urethane of some sort, I'd expect. Ideally something that's not *too* toxic, and will stick to brass.
Any suggestions?

Many thanks,
Brian

How often and how much does it need to turn?

Seems like one could alter the thread pitch just a tiny bit so the threads are in a tiny bit of a bind but turns with some effort.

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If you're making 8 thousand of them, someone can suggest changes to allow a nylon ring to be installed, then staked into place.

Lots of vendors making locking nuts.

Ask the engineers at Loctite.

Larry

Counterbore the top, and stake in a short piece of nylon tubing....just like a Nylok nut.

Talk to these folks:

Long-Lok Fasteners Corporation


ND Industries - Advanced Fastening & Sealing Technologies


Threadlockers | Nylon Patches | Industrial Tool And Supply - AFT Fastener & Industrial Supply


Products - Nylok

Thanks

Thanks guys,

That's just exactly what I needed: a fresh set of eyes. I knew I was getting target lock on these things, so a fresh perspective was just the thing.
They're a sort of oddball, yet very specific to our product, size and shape, which is why we never had them made, but now that I really think about it, there's no reason why we can't. (other than money).
That said, there were (and are) some structural reasons we never staked a ring into the end. But..... Doing them this way is enough of a PITA that it may be worth it now, given how many of the bloody things we're making.

Many thanks. You have all given me much to ponder.

Regards,
Brian

Another option would be to offset drill a blind hole along the thread axis so that it breaks into the thread and still use your trimmer string. This hole wouldn't need a press fit for the trimmer line as once the threads bite into the line it can't fall out. Hole just needs to not have a lot of slop in it.

8 to 10 thousand a year special nuts, IMO is a specialist sub contract job, .........as has been said there are firms who only do that sort of work, which cost wise I will wager - you will find surprisingly reasonable if not downright cheap.

Last time I needed "draggy nut things" I squeezed them to make them a fraction oval. Worked fine for the 20 or so needed. On production basis some sort of die in a cheepy chinee arbor press should do fine.

By classic management accounting 10,000 or so is magic number where a product maker really has to start justifying why they do a commodity or semi-commodity job in house.

From pure business point of view the objective is to get the most bang for your buck. Things like this you have to be careful not to spend more whilst (theoretically) saving money!

8,000 to 10,000 is only around 200 a week. A days work a week perhaps doing it your way. So if you have to pay the guy (or gal) doing the job for that day anyway and have nothing more useful for them to do it doesn't matter how cheap the specialist sub-contractor is it still costs more.

Time was that sort of "Stand up, hear thunder, see lighting. Any two and your are qualified" job would have been classic homeworker fodder. For small firms get the guys to take a box home occasionally for the missus to do in between cooking, cleaning and watching the kids. For bigger firms farm out to an agency that arranged such things. Heck back when I was still short enough to walk under the table one of my aunts used to paint team colours on Subbuteo on that basis. Box of blank figures appeared once a week to be swopped for the painted ones and a cash contribution to the housekeeping. Organiser represented several companies and had choice of jobs.

Or get some decent kids in over the summer holidays to do a years supply. Schools are supposed to be keen on work experience these days. I guess a goodly proportion of us here had their own timecards for holiday jobs where Dad worked.

Clive

A search for 'stiffnut' images should throw up some ideas for bendy/squishy bits without plastic inserts, but less brutal than deforming the whole nut.

George

Could you put a circlip groove inside and push in a wire c clip, or add a slot on the outside to have a c clip reach through to have drag on the thread?

One industrial name for these is 'prevailing torque nuts'

If you search on that term, you'll find engineering and application info on the various approaches, tradeoffs, cycle limits, etc.

Fwiw, there are AN prevailing torque nuts. They're often called jet nuts, and are very low profile.

Nylok nuts are made in the millions, meaning the inserts should be available from the guys that make insert nuts or their supplier. Install them the same way.

HI Gang,

Thanks for the extra thoughts.
In terms of time/hours/people, I've got plenty of other things the guys can be doing, other than pounding inserts into holes. So if it is semi-affordable to have them made up by people with better kit for it than we have, that's the answer. Because they still cost time on our swiss to make up in the first place, nevermind inserting the slugs.
We're getting mildly bogged down in final assembly. If I can take one of the guys who's currently fussing around with these things, and clear that out of his plate so he's got more time for final assembly, I'm a very happy camper.

I do like the idea of the eccentric hole along the thread, with the line slid into it. Our machine can do that (reasonably) easily, so if it turns out that jobbing them out isn't cost effective, that may well be what I do. Still inserting slugs, but much more easily (and quickly.)

Thanks,
Brian

This is only my opinion, so it's worth what you paid.

Listen to Camscan, ......he's had more experience making such parts then most of us have had hot dinners.

camscan said:

You are making nuts on a Swiss? That really is a new one for me. You need to speak to a screw machine shop that is making nuts and bolts all day. I have given you the method we used,they may well have a different and better idea. I bet it won't involve Swiss type machines

Click to expand...

Neighbors swiss shop was making brass threaded inserts, with a 3/8-16 internal thread...was single pointing
them, had it down to (5) very noisy passes...but still the cycle time was too long to compete....duh.

I think there may be Loctite as L Vanice suggested...
Could a notch like a saw cut x .200” be put to the end of the shaft, and then with a taper tap threading the part, then be assembled tight enough to have interference at the end of thread.

here's another method - a simple saw cut which is closed up, ....AKA Simmonds Nut, like this Simmonds | Precision Engineered Nut Technology | Products | DAH Turret Nut

You can have 1 cut or 2

Not sure if this will work for you or not but I have seen it done and done it myself and it is very fast. Put the nut down on a hard surface ( I have used a block of lead as a "soft" anvil) and hit across the top with a cold chisel. It upsets just enough of the top thread in two places to make the nut grabby. Takes about five seconds per nut.