The source of confusion, I think, Jason is this page, where the clearance diameter of D is given as 14mm and then qualified, in brackets, with the words "9/16" UNF stud" .

As I said I think it is 14mm x 1.5 on th etop of a 9/16" shank to match 9/16" hole in post. If not it's 14mm all the way to the bottom shoulder and a looser fit in the hole

Me too.

If the available stud screws into the lathe, fits inside the tool post and projects from the top, then use a nut that fits the stud with a couple of washers to spread the load.

The post won't be centred on the stud which isn't ideal.

But you can now use the lathe to make a stepped washer that fits inside the bore of the post and you're done. M8 stud inside a 14mm bore – think that's what you have – gives plenty of space for this.

That's a couple of minutes work, but could be better; I would make a complete new nut with a permanently attached handle so the post can be loosened without the use of a spanner. Like this:

That's how the Myford size Dickson toolpost is fitted to my WM250

Margaret, right, now I understand your confusion.
Where did the middle screenshot of the three in your second to last post come from?
It's misleading in its presentation.

Out of curiosity, where did you source your toolpost, we know the stud came from LMS?

I believe the 111 toolpost and the stud details you have circled, in column D, is likely to lead to a misunderstanding
That toolpost will take either a M14x1.5mm stud with the appropriate nut, **OR** a slightly larger diameter 9/16" UNF one.
The nuts are not interchangeable between studs.

The model 100 in row A above may **ONLY** take a 14mm stud as it likely has a smaller hole, so 9/16" won't fit.

Bill

Edited By peak4 on 24/09/2023 16:30:47

OK, I think I've got there folk (maybe )

For whatever reason related to Margaret's lathe, the studs supplied by Ketan don't fit.
She needed a stud where one end is internally threaded M8 and was able to obtain one from LMS
https://littlemachineshop.com/products/product_view.php?ProductID=3712&category=521186833

This has an external 9/16" UNF thread, and needs the appropriate nut.

The ArcEuro web site and paper catalogue differ slightly in their presentation, but the column which specifies the stud size/hole diameter is labelled as øD where the ø refers to the hole diameter's nominal size.

On the web site, The 101 toolpost says øD 14mm (M14x1.5mm Stud)

But for the 111 toolpost says øD 14mm (9/16" UNF Stud)

i.e. same hole diameter, but just mentions a different stud; likely either will fit.

Ketan supplies a stud suitable for an SC4 lathe, but that has an M12 lower thread and an M14x1.5mm top thread
https://www.arceurotrade.co.uk/Catalogue/Machines-Accessories/Lathe-Accessories/Tool-Posts/Model-100111-Tool-Post-Stud-and-Nut-for-SC4-Lathe

I'm guessing this was the source for the nut which doesn't fit Margaret's LMS stud from the US.

It looks like the ArcEuro stud wouldn't fit Margaret's lathe, hence ordering a suitable one, (threaded M8 internally), from abroad, which unfortunately didn't come complete with a suitable nut, though for a US buyer, they are readily available.

The end result is that Margaret just needs a 9/16" UNF nut and washer, which should be easily available.
9/16" UNF flange nuts seem hard to find in the UK, and I've tried quite hard; up to 1/2" do seem to be around.

The only possibility I did find for an off-the-shelf flange nut was a wheel nut for some very specific American cars, such as a Dodge RAM; most UK 9/16" UNF wheel/lug nuts have tapered or spherical seats, rather than a plain flange washer, so would be unsuitable.

Bill

If I was in the same situation you are Margaret, that stud would have been a simple to replace lathe project. I'd do it between centers just to keep everything a bit more concentric. Obviously metric is now the much more prevalent standard in the UK. And whatever the female threads that have been tapped through the top slide for the bottom of the stud you'd of course have to match those. At the top you can cut whatever thread pitch and size is the most standard and available where ever anyone is as long as your lathe is capable of cutting threads in either the metric or imperial pitch you want to use.

Due to the number of various thread standards used over the last 100 plus years, with a lot still in use and some obsolete or almost so today, I'd agree and it can be a bit confusing. I've also read and for various manufacturing purposes, there's over 600 thread sizes, thread forms, pitches, flank angles, root and crest shapes that are common or at least still being used today. And yes having a couple of those different metric, imperial or possibly a few others such as BA depending on exactly what your doing, those thread gauges are almost a requirement for most of us. There's also a fairly easy method of substituting almost any thread pitch standard to something else that is convenient with a online search for the dimensions. Old Model Engineering drawings would be a prime example. Something like those BA threads to metric or imperial, just look up the recommended tap drill size for whatever size and thread pitch is used on the drawing, then find a tap drill chart for the thread pitch standard you want to use for the fine / course thread pitch you have available that would be closely comparable to the drawings tap drill size and just use that. The very small sizes such as 9BA -16BA could be difficult and probably expensive to replicate with either metric of imperial. Think about it this way, any of those metric and imperial thread pitches were standardized for the expected use while still being adequate for strength. Since either still has to do the same job in whatever size and pitch they are, there sizes are quite comparable to each other. Only the diameters, TPI or threads per MM are just slightly different between the two systems. So for what almost any of us are doing, then the substitution method I mentioned will work fine. For very high strength and safety critical items, without question proper engineering data and high grade screws and/or nuts would still be the safest method. And for some such as the Model Engineering 32 and 40 TPI thread series, it's of course not quite as easy. So those might also be necessary. But again it just depends on what your doing.

For myself and in North America, our Machinery's Handbook would be pretty much the usual source for most machining standards. And it has about everything I might need, especially so for threads. I've heard but don't actually know the Zeus black book of standards that seem to be common in the UK and Europe are comparable and possibly even better for some topics. Yes most or maybe all of that information could be found online and for free with enough searching, but it's not convenient or all in one place. And if that Zeus information is anything like what I'm using, then it should greatly simplify anyone's understanding about threads and a whole lot more. Online forum posts or even videos simply can't provide the same amount of detail for obvious reasons.

Dear Margaret,

I have made an M14 x 1.5 mm flange nut for you. If it does not fit then you probably need a 9/16 UNF nut as discussed. If you PM me your address I can pop the nut in First class post tomorrow morning.

John

Hello Margaret and others,

I don't have an operational lathe at the moment otherwise I would have been in a position to make a special purpose nut for this job. What I can do though, which might be helpful to someone else willing to do so is provide the screw cutting parameters for a "mixed race" nut, based on Myford equipment.

9/16 inch equates to 14.1 mm and 18 TPI equates to a metric pitch of 1.41 mm

Gearing for Myford for that pitch will be a 25T driver coupled through 19 TPI for a gearbox lathe. Resulting pitch is 1.393 mm

For non gearbox lathes [including ML10 and Super10] the gearing is 25 x 50 as drivers, with 45 x 63 as driven gears. The pitch in this set up will be 1.4 mm almost exactly

So we finish up with an M14 sized nut threaded to 60 degree metric standards having a pitch of 1.4 mm.

I hope that is useful information

Regards Brian

Thank you to the collective for trying to help the OP to solve his problem.

I have to admit that ARC's catalogue and website were responsible for the OPs confusion. Our Ian is the process of resolving the matter with the customer.

The factory produces these toolposts for the U.S. (imperial) and the European (metric) market. European demand for this product is lower than the U.S., and the quantity we need has to fit in into whatever is being produced at the time. Normally this is fine as long as our website is updated to reflect what we have received into our stock – metric or imperial stud/nut.

ARCs failure to check the specifications received vs what was stated on the website led to the confusion. This has now been corrected.

Ketan at ARC

Nah, don't beat yourself up! Threads are foggy.

Although engineering is standards based, the history is pretty complicated, and there's still plenty of opportunity for confusion. For that reason most of us own small reference libraries!

As professional engineering books are inclined to be dry and mathematical, they aren't beginner friendly. Fortunately, books have been written for us. Sparey is excellent on lathes, though he assumes Myford and wrote in 1948. Our very own Neil Wyatt has an up-to-date book on the Minilathe. And Jason Ballamy has covered Milling. The Workshop Practice Series are good too. Faced with a new problem, I often save lots of time by buying a book.

Last but not least are the magazines. Model Engineer is a good way of picking up information on methods, tools, materials, clubs, exhibitions, and problem solving. I found Model Engineer's Workshop even better, because I'm not really a Model Maker. I do experimental, and MEW focusses better on my need to improve workshop technique. I get value from both magazines, and after 10 years in the hobby am still learning from them. The forum is excellent because it supports Question and Answer, and members with a multitude of experiences all know their stuff.

Dave