Dear Margaret,

I will have 9/16th dia FULL nuts but I think that they will be BSF. I may also have a 9/16th UNF tap. I will check what I have got later this afternoon or tomorrow morning. Don't despair!

John

9/16 inch outside diameter of the thread, 18 threads per inch; UNF stands for Unified National Fine and is one of the American "UN" series industrial standards for screw-threads.

UN-series threads were fitted to a lot of motor-vehicles and military equipment in the UK at one time and the fastenings are available here; though perhaps not flanged nut. You might even be able to obtain one from a garage! It does not need be flanged though – use an ordinary full nut and a thick washer.

9/16 UNF nuts are readily available in the UK.

Tony

I'm not sure how important it is to have a flanged nut, you could turn up a thick washer and use that in place of the flange with a plain nut on top, not too expensive

Margaret, I think you're getting your threads a a bit mixed up.
The ArcEuro tool holder looks to be this one which on the spec sheet says the thread is M14x1.5mm
Yes, the 14mm diameter is about 9/16" but it's not an imperial size.

The LMS version on sale, I assume is this one; it specifies 9/16" x18 tpi, which is a UNF thread.

The actual toolposts are probably the same, it's just that the fixing post is a different thread.
Traditionally the UK used Whitworth/BSF threads on machine tools etc, whereas the USA uses Unified.
The diameters may be the same size, but the thread forms are different.

Most of the rest of the world uses Metric, which is why many of the far eastern tooling imports feature metric threads; hence the same QC toolpost marketed in the US uses a 9/16" x 18UNF thread, and our version often uses the M14 stud as it's cheaper than having BSF ones made specially for us, as almost no-one uses it any more.

Your local car spares will likely have a 9/16" x18 UNF plain nut, which you can use with a thick washer for the time being; You could even use a Nyloc nut and turn off the plastic locking ring.

Your local Landrover spares counter will almost certainly have the Nyloc ones, as they are used for leaf spring shackle bolts; N.B. make sure you specify the thread to them, as they may also stock BSF (& metric).

Longer term let me have your address and I'll knock one up, but I'm not using the workshop at the moment, as I await new specs following a cataract operation; I'm not safe using machine tools at the moment.

Bill

Hi, they are also available from Spalding Fasteners. If it was me choosing one, I'd go for the yellow one. A thick washer can easily be made from a piece of flat steel, cutting it out with a suitable size hole saw, and then drilling the hole for 9/16" clearance, and then just tidy it up with a file.

Regards Nick.

Edited By Nicholas Farr on 24/09/2023 14:07:09

.

As recently stated:

There are loads of 9/16 UNF nuts on ebay.co.uk

With or without flanges, and a few interesting ‘specials’

list them with cheapest with p&p first …and take your pick

[ some are ‘stiff-nuts’ … which may, or may not, be useful ]

.

Do you need a link to an ebay search ?

… I think this might do it:

https://www.ebay.co.uk/sch/i.html?_from=R40&_nkw=9%2F16+unf+nut&_sacat=0&_sop=15

MichaelG.

Edited By Michael Gilligan on 24/09/2023 14:23:20

I recommend buying a copy of Tubal Cain's "Model Engineer's Handbook" (Link is to Waterstones' – other suppliers available. Many 'what-nots' are explained!

Margaret has bumped into the 'which standard system' problem, and it's worth thinking about. Briefly:

• British Engineering was originally based on the Inch, and standardised on Whitworth Threads. (aka BSW). Later BSW, which is a coarse thread, was found wanting for many purposes and the system was expanding by adding a fine series (BSF). This too was found unsatisfactory for Instrument and Electrical Work, so a third system, not remotely Whitworth, was added – BA. None of these are interchangeable.
• In the USA, also based on the inch, it was immediately noticed that Whitworth threads are over complicated, so the Americans adopted a different standard – the National Thread. Their system also added finer threads later on. National and Whitworth threads are similar but not compatible.
• The rest of the world went Metric, based on the metre, and produced a third system of threads. These don't match US or British sizes.
• During WW2 considerable trouble was caused when it was found British and American fasteners were incompatible – Margaret's QCTP incompatibility problem on a grand scale, with Tanks, Guns, Aircraft, Ships and machines of all types out of action due to minor technical differences. By agreement, the US and UK both adopted the Unified System, which is mostly the US National System, based on the Canadian Industrial Inch, which was 25.4mm. Almost universal in the US, and for a short time, UNC and UNF became common in the UK.
• After WW2 it became increasingly apparent that the Metric system has many advantages. Thus almost the whole world went metric apart from the USA. The UK chose to metricate slowly, gradually abandoning BSW, BSF, BA, UNC and UNF. Extending the pain badly damaged British industry. Most British engineering was exported because the UK domestic market is quite small. Foreign customers were not impressed by the mix of Whitworth, Unified, and Metric components sold to them by the UK, whilst confused standards reduced productivity and made it difficult to modernise. Today the UK is mostly metric. New design has been metric for about 30 years and it's slowly but surely becoming difficult to source older components.

So British Model engineers setting up a workshop have choices! My view:

• If the work is restoring old British manufactured items, go Imperial.
• If the work is building models from classic plans, go Imperial. This is especially true of steam locomotives and traction engines because so many good designs are pre-metric.
• If you inherit an Imperial or US English workshop, stay with it.
• Everything else, go Metric. Metric is generally cheaper and easier to source, and the trend will continue. US industry is the last bastion of English measure, and even they are slowly but surely metricating. Inches are a disadvantage when selling equipment outside the US. In the UK importing nuts and bolts, or anything else, from the US is extra expensive – avoid!

Pays to standardise if you can. In practice, it's hard not to work with all these systems occasionally. I do experimental work, where Metric is wonderful, and almost everything I own is standard metric. Imperial repairs aren't the end of my world, except I have to recognise what's needed and do the conversions. However, Imperial is a time-waster compared with the same job in Metric, because I often have to buy or make stuff specially. Metric jobs turning up in Imperial workshops are a similar nuisance. Whatever you do, don't get Metric vs Imperial vs US substantially the wrong way round!

Dave

PS Flange Nuts are ordinary nuts with a built in washer, so you don't have to worry about losing the washer.  If a flange nut can't be found, a washer and ordinary nut work just as well.   Also, flange nuts often come with ridged bottoms designed to grip: don't use this type on a QCTP without a washer underneath, or file the ridges smooth first!

Edited By SillyOldDuffer on 24/09/2023 14:38:48

do you not have a thread gauge – cheap + resolves such problems – the combination 14mm + 9/16 should indicate something is very confused

I'll check with Ketan tomorrow but I think what is on their site is the stud is threaded M14 x 1.5 at the top and will pass through the 9/16" dia hole "D" in the toolpost. ARC have a specific post stud to screw directly into the metric thread on the SC4 topslide and as all other threads on the lathe are metric they also specify a metric thread for the top.

Michael as my post above Ketan is saying they supply a stud of 9/16" dia shank, top is reduced and theraded M14 x 1.5, bottom is reduced to 12mm and threaded M12 coarse.

As the hole in teh toolpost is 9/16 you want a nice close fitting 9/16" shud shank for repeatability.

No Porkies being told