9/16 nut help!

It strikes me that Margaret is largely blameless in all of this, and the info given out by ARC is partly responsible for her confusion.

I've got a Model 000 toolpost from ARC, which came, as the ARC website suggests, with an M10x1.5mm stud. The page in that link meant to me that the stud supplied was threaded M10x1.5 at both ends, as indeed it is. As expected, it also came with a matching M10x1.5 flange nut for the top end. It fits my lathe fine with no adaptations needed.

Based on this experience of ARC's website's descriptions, if I were buying a Model 100 toolpost I would expect it to come with an M14x1.5mm (both ends) stud and matching nut. Perhaps owners of that toolpost could clarify that this is the case.

Finally, if I were buying a Model 111 toolpost, as Margaret apparently did, I would expect it to come with a 9/16" UNF (both ends) stud, as the link I posted earlier suggests. It seems, however that it too comes with an M14x1.5mm stud and nut, or at least something that is not 9/16" UNF. Perhaps an owner out there could again clarify this.

With the limited thread and diameter measuring capabilities Margaret has, she seems to have gone about things pretty logically. She knew firstly that she needed a stud with an M8 female end to thread on to her lathe's existing old toolpost stud. She then deduced, from Arc's description and the roughly 14mm diameter stud they supplied to her with the Model 111 toolpost, that the nut that came with ARC's toolpost would fit the stud she needed to buy (for its female 8mm thread on one end) from the LMS.

But it didn't, because the stud and the nut that are supplied with ARC's Model 111 toolpost are presumably M14 x 1.5, not 9/16" UNF, as stated, or at least strongly suggested (if my buying experience with the Model 000 is anything to go by) on ARC's site.

Have I got this right, everyone?

And is this a fair representation of how you got to where you are now, Margaret?

I should add that in one thing you are slightly to blame, Margaret: you have visibly marred the unthreaded surface of the LMS stud, presumably by tightening it into the hole with grips? Is this how you went about tightening down the LMS stud?

If so, when you buy your 9/16" UNF nut, buy at least two: you can then lock them together at the top of the stud and turn the top one to tighten the stud down and the bottom one to loosen it.

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

Thanks all for the information and research conducted on my behalf - I appreciate it very much.

Bill - yes unfortunately I did marr the surface of the LMS stud with grips because it got stuck halfway down the lathe stud, and without a suitable nut to wind on to assist, I had to turn it with grips - even with a strong duct tape layer between them the only way it would turn fully down was to grip it tightly. It seems the suspect Far Eastern thread on the original stud was distorted by the original toolpost.

John Attle - how kind of you to do that for me,  thank you - but alas it’s a 9/16-18 nut I need to fit the LMS stud. The LMS stud works perfectly to mount the 111 but the locking nut supplied with the 111 is different to that from the US. I am sorry to have wasted your time - but thank you very much for being so kind.

I’ll purchase the relevant nuts all and report back - hopefully with some good news.

M

Edited By Margaret Trelawny on 24/09/2023 22:42:16

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

On the bright side, this is all a fantastic learning opportunity!

In addition to US, British, and Metric thread systems, they all support different classes of fit. Ordinary threads are made to fit loosely - cheap to make, quick fitting, but not full-strength. Closer fits are used when strength and vibration resistance are important - more expensive, slow fitting, and easily cross-threaded. This is in addition to damaged or poorly made threads or other difficulties.

Thread-locker is another possibility: it's a type of glue used to stop vibration unwinding threads. Comes in mild and medium strength forms, not too difficult. However, the strong variant may require heat to undo it. Thread-locker, gummed up oil, dirt, and rust all make nuts and bolts unexpectedly difficult.

As iffy threads are quite common, it's useful to own a tap and die set, just to clean them up. Running a tap through a thread easily fixes burrs and other problems, thus avoiding lots of bother. Lidl often sell cheap metric sets plenty good enough for this. Otherwise ebay etc. Worth investing in better made taps and dies if threading is going to be a regular job.

Thread gauges also save a lot of bother. As superficially similar nuts and bolts don't fit, identifying what the thread is with a gauge saves a lot grief - guessing is painful!

Grips almost always damage the work. Useful for rough work, such as removing jambed nuts that will be replaced anyway. Normally use the correct sized spanner, buying in when necessary. Adjustable spanners aren't as good as fixed spanners, but better than grips. Ditto screw-drivers, because the wrong size or type will damage screw heads.

Don't be discouraged - you're making good progress.

Dave

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

Dear all,

thank you to each and every one of you for your offers of help and suggested solutions. Your kindness and support has overwhelmed me.

As mentioned above by Ketan, he and Ian at the wonderful arceuro have gone above and beyond to help solve the issue. Thank you both so much for your superb customer service - going the extra mile to help. I cannot thank you enough.

I take full responsibility for not checking the difference between US and European specs - had I had more experience I perhaps would have twigged there may be an issue. As Bill mentions above, it has been a valuable learning curve!

The 4-bolt plate from LMS for the saddle has fitted a treat with no issues and gives a real stiffness to the tool post mount - something lacking on the standard set up.

Again, I cannot thank you all enough for your help and offers to sort the issues. You really are a brilliant community.

Hopefully, with the purchased 9/16-18 nuts and the roller bearing solution - it will be job done. I will report back as soon as everything is installed and working with hopefully good news.

Edited By Margaret Trelawny on 25/09/2023 16:13:52

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

As well as books there are some useful tutorials on Youtube.

https://youtu.be/tkEVwpl2S4Q Titled Thread Anatomy, explains some of the terms used for threads and shows the most common thread forms.

https://youtu.be/smExyKMfiIE Titled How to Measure and Identify Bolts, explains TPI and pitch and use of a thread gauge.

There are others as well but getting a good understanding of these concepts would probably have helped you figure out where your problem with the flanged nut and the tool post was.

Martin C

You cam't beat having sets of Thread Gauges to discover what this "new" thread is, in terms of size, pitch and thread form.

Can't guarantee covering every possibility, there will always be some unusual "Specials", but Whitworth, Metric and Unified gauges will cover most of what you come across., even odd ball such UNEF, or Metric extra fine, such as 12 or 14 x 1 ( For Emco lathes in particular )

I haven't got BA, but experiment using known nuts or setscrews, as gauges.

A relatively small expenditure to provide answers to many queries.

Howard

I've got BA ! Noel.

Where from Noel?

Brian

Brian try Chronos. https://www.chronos.ltd.uk/product/ba-screw-pitch-gauge/

Hi Brian, M&W No 798 0 - 10 BA ! Ex mil Pt No 910 - 5218. May well have been bought at the midland or Ally P - Try tracy tools ? Noel.

Trevor and Noel,

Thank you for the information, I didn't know if ! they even existed.

Kind regards

Brian