UNC Nuts - Large!

For a work project I need some 2" 4½ tpi UNC nuts, preferably plain steel as they need modifying by welding on extra bits. So far I've miserably failed to find a UK supplier of said nuts. Does anyone know of a UK supplier, I need about a dozen?

Alternatively I'll have to make the darn things. In principle screwcutting a 4½ tpi thread isn't an issue. It's a standard setting on my lathe QC gearbox and the Ainjest unit can cope with half threads. The problem is finding a 4½ tpi threading insert. They do seem to exist, but not at the suppliers I use, like Cutwel. Instead I could use a 6mm insert, or a home fudged HSS tool, and finish the thread off with a tap. This may be preferable, as the mating part is on a large rock crusher 6000 miles away with no access except during the 6 monthly shutdown. So the nuts need to fit first time. A new tap is around £170, so three times that for a complete set. However I only really need one tap, ideally taper. There are taper and second taps on Ebay for £22 to £45. I may just buy the £22 second tap anyway, as it's relatively close by from a seller I've used before, so I can collect. Any other ideas on making the nuts?

As an aside the rock crusher is driven by a 17MW induction motor, complete with variable frequency drive - yer not going to find that VFD on Ebay!

Andrew

2" UNC nuts and a 17MW motor on a model engine. WOW

That is one big mother (excuse my language) of a model. I can only imagine the size of the real thing. (LOL)

Paul.

You could try Willams Fasteners of Sheffield. They certainly used to do big stuff at their previous premises.

If not, they would probably make to order, though I dread to think the cost.

Try your local Caterpillar earthmoving equipment dealer?

Or machine them up oversize and dispense with the expensive taps. A thread that size you can make oversize by a fair bit and still have 75 per cent thread engagement. HSS threading tool bit should not be a problem to grind up. It was done that way for several hundred years before inserts became de rigueur.

I did wonder about contacting a local steel erector, s that's the sort of size that might be used to bolt single post columns into their concrete plinths. I suspect though, that they would be metric for terms of cost.

A lot of UNC studding is used in oil / chemical industries to secure flanges on pipes and vessels. If you can find a fastener supplier to those industries you might get lucky.

You could quite quickly spend a lot of your valuable time chasing, which might make the price of taps seem not so bad by comparison.

UNC are truncated 60* metric threads :- https://en.wikipedia.org/wiki/Unified_Thread_Standard So to grind up your own tool should not be too difficult. I have tried to tap out a 1 1//4" Whit turned turned thread and found that because the tap starts off with the full width thread but only .01" deep it did not want to align itself into the existing thread but started to cut an extra one. I think the leading cutting edges needed to be narrowed and tapered so the cutting edges align into the old thread.

Frank

Norbar list a 2" UNC nut as a spare part

**LINK**

no price indicated though.

These people sell them, just over £4 each

Surely all you need is a 2" x 4 1/2 screw?

You can then experiment with inserts/home ground tools until you get the result you need.

You could also use a tap of smaller diameter as a form tool.

Neil

Last option won't work Neil as 4.5 tpi is only used on 2 and 2.25" threads

I just tried CP Fastenings of Portsmouth for you, but they only have nuts up to 1 1/2" UNC in stock.

George

Andrew,

https://www.shop-apt.co.uk/unified-un-internal-threading-inserts/27nr-45-un-t300-internal-threading-insert-general-use.html

Hope you have a holder for those 27mm inserts Andrew or thats another £150 on top

If that company I linked to have sufficient stock then off the shelf nuts must be the most economic way especially at just £4 a pop. by the time you have bought hex bar, cutter, holder and labour its a no brainer.

Thanks one and all for the information.

George: Thanks for calling on my behalf, most places seemed to stop at 3/4" or 1", so 1-1/2" is pretty good.

Neil: I did think of using a bolt as a 'gauge' but if I can't buy a nut where the **** am I going to buy a bolt?

KWIL: Thanks for the insert link, not a bad price either.

JasonB: Thanks very much for the link - no idea why I couldn't find that despite spending a couple of hours yesterday evening searching. They do seem remarkably cheap. Before we established the thread type I was looking at M42 nuts, more easily available but about £15-18 each.

Anyway, the client has altered the goalposts yet again, but has given us the go ahead to buy, so I've ordered some nuts from the link kindly provided by JasonB. At least an internal threading toolholder would have been cheaper from Cutwel than from APT.

While it would have been an interesting exercise to screwcut the threads, I'm operating in real world where time and (the client's) money are paramount. So JasonB is quite right, it's a no brainer to buy the nuts and modify them rather than screwcut from scratch. I doubt I could buy the material for £4. We're up against very short timescales. If we miss the short 6 monthly shutdown we're in deep doodah.

Andrew

Keep us posted of your propgress Andrew and I'll keep a look out for your nuts on Sky, Something like Yukon Gold sounds like a likely program.

J

PS 2-4.5 UNC got the google result

Another supplier **LINK** Niko.

Woohoo, the nuts arrived today. I was hopeful about size as the delivery driver wasn't exactly skipping up the drive. At first glance they look like the right size. I'm collecting the £22 secondhand tap bought on Ebay at the weekend, so that will give the definitive answer to the are they the right size question. The nuts are a bit rough, but what do you expect for £4 each, and they're going to be machined. welded and hacked about anyway:

Andrew

Bit late now you have the nuts but I used to work next door to a nut/bolt maker.

Stanley Horne & Son

Bentley Mill Close

Walsall

West Midlands

I picked up a 2" UNC tap, bought secondhand on Ebay, over the weekend. Even better the nuts fit.

Just need a suitable tap wrench now, although I'm not sure there'd be room in the workshop to swing it.

Andrew