Victorian Whitworth nuts.

[Neil WyattModerator @neilwyatt]

> I wonder if in Planet of the Apes all the monkey engineers put the big nut over the little nut?

Nothing comes loose on The Planet of the Apes – they get gorillas to torque everything up tight.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Michael Gilligan on 08/06/2014 23:08:52:

As to whether "flat face down" acts as a locking mechanism; or [contrarywise] stops you doing it up tight in the first place; I think I'll sleep on that one !

.

O.K. I've slept on it, and been for a walk in the sunshine

Here's what I think is the answer:

If it's a proper engineering job and, for example, we're using the nuts on studs to fix a casting, then Ian's way is correct.

BUT if it's "agricultural" work [bits of black steel strip, roofing materials, etc.] and the nuts can be held with a spanner whilst the screw is tightened with a big screwdriver, then using the nut flat-side-down makes sense.

… Discuss …

MichaelG.

 

Edited By Michael Gilligan on 09/06/2014 10:05:30

[Michael HornerParticipant @michaelhorner54327]

Posted by Ian S C on 08/06/2014 11:43:30:

I think you will find that the size of some nuts on some old machinery was made to fit the space by individual makers. The thing I have with nuts of this vintage is the square ones, people put them on up side down ie., flat side down, chamfer up, where as it should be the other way. Ian S C

Hi Ian

Is this something to do with the technology of the time. I.e. the side we are calling flat, wasn't. The side that was chamfered has been machined and so that was the side to use.

All modern referance to square nuts I found shows the chamfer to the top.

Cheers Michael.

[Ian S CParticipant @iansc]

If your thinking of lock nuts (Din 7967 Counter Nut), and which way round they go, the use of Palnuts for locking cylinder base nuts, and engine through bolts on aircraft engines should answer that one. These nuts are made of thin spring steel, one place you often find them doing service as nuts is on volume controls, switches etc on radios and other electronic gear, holding them to their panel, but in aviation they are screwed down on the full nut. Sorry a bit OT.

Ian S C

The lock nut question has been asked in just about every place it could be.

Edited By Ian S C on 09/06/2014 13:43:18

[Gordon WParticipant @gordonw]

Just had a walk round my collection of old junk. All the square nuts with any chamfer has the flat side in contact with the part ie. chamfer up. No washers . But who knows how many times they've been on and off? BTW modern square nuts on spout bolts and roofing bolts are just stamped out and have no chamfer. Usually the nut is inside the rounded part and the nut is trapped while the screw is turned.

[Nigel McBurney 1Participant @nigelmcburney1]

I have been restoring i/c stationary engines for 40 odd years, plus pumps and grain processing mills, all the stationary engines some now over 115 years old have machined hex nuts usually large size whit, , Ruston Hornsby used bsf on big end bolts by 1923 nuts were castle with split pins. Bamford made many types of cast iron framed roller mills for proccesing animal feed, frame bolts were coach head with square nuts fitted flat of nut against the casting,iteresting fact was the hole for the bolt head was cast square so that the bolt could not rotate when tightening the nut,time saving by only needing one spanner,the engineering bits of the mills had normal whit big nuts . Wooden trolleys and bearers for the engines had square nuts,flat against the timbers ,some had round washers or occasionally square ones. Lock nuts were all large nut then small nut,plus on big ends a split pin. American imported engines were similar though Amanco engines had two normal sized nuts for lock nuts, typical American logical production engineering,why have two part numbers ,its cheaper to make twice as many nuts of one size rather than produce two sizes and the assembler cannot get them the wrong way round,and by the way the US also used a larger size nut. Why the larger nut,well in those days spanners were generally carbon steel without any chrome vanadium alloy ,so the spanners needed to be larger,due to the lower strength of the steel . the war and the availabilty of better spanners and the large whit nut could not be used in restricted places in modern designs.

I think the era of machine and engine building in the first half of the 1800s was where square nuts were used as an engineering function rather than a more agricultural function,as square nuts were easy to make ,there was no drawn bright hex bar in those days and gradually replaced the wedge and cotter, the raised side of the nut fitted onto a cast surface may have been used as a self aligning feature ,proving it would be difficult as most surviving pieces of machinery have probably been stripped or rebuilt many times.

The arguments about lock nuts will go on for ever , but the facts are a lot of good engineering books from the 1880s onwards show thick nut on first, the threads were usually coarse pitch Whit and the bolts of relatively low tensile strength steel and it worked ,on thousands of machines ,if any further safety was required they put a split pin through the bolt just in case, Modern theory on locknuts relies on very high strength steels not available to the Victorians

[clogsParticipant @clogs]

HI guy's…..would like to add my 2 pennyworth..if I can…

1. I have just recently pulled my 1925 Citroen to bits and can 99.9% say that the road spring/axles have never been out of it and the thinner nut were on the outside….!!!!

2. from memory can't remember the correct name but when we built wind-turbines we relied on this to keep nut's tight…..no not lock-tite….well not all the time ….hahaha…

the idea is that the length of the stud (thats the distance between tightening faces) should be no less than 5 times the diameter of the stud——so torquing to the engineering standard for the given stud size creates enough stretch in the stud to keep the nut from loosening….

cheers Frank in France

[Neil WyattModerator @neilwyatt]

Back to the original topic, here's a couple of excerpts from an etching of an engine I'm modelling. As far as I can see the etching is very accurately to scale – but look how thin the screw threads appear compared to the size of the nuts:

It may be exaggeration, but I don't think 'one size smaller' BA nuts will be right for this engine.

Neil

[Howard LewisParticipant @howardlewis46836]

FWIW

The only nuts used in the Levant engine, (just four from memory) in Cornwall are square nuts (probably made, with the bolts, by a local blacksmith; so unlikely to be a standard thread!)

The thick nut is there to provide the clamping load. The thinner lock nut is there to provide frictional load on the threads to prevent the clamping nut from loosening.

If the thin nut is fitted and tightened first, there has to be a risk of stripping the thread, because it will have less than 1D engagement.

My practice has always been to use locknuts on the outer side of the clamp nuts.

In contrast, the drawing instruction books, by A C Parkinson, used when we were at Technical College, showed the thin nut fitted first. The text advised tightening the locknut "with ordinary force", followed by "tightening the full nut upon it" and then slackening the locknut against the full nut.

This was bound to decrease the clamping force slightly, which in the longer term could result in movement, leakage from, or failure of, the joint. This advice predated the widespread of torque spanners.

Torque tightening produced, within the variations of the coefficient of friction between the male and female fasteners, a fairly consistent clamp load, and sufficient friction to prevent relative movement.

For a really secure fastening, use a mechanical locking method, castellated nut and split pin, tab washer, lockplate, or cross drilled nut/bolt head and wire locking. These methods were used, in preference to spring washers to ensure security of the hardware for Big End and Main Bearing caps in engines, or parts in transmissions.

The practice on Rolls Royce con rod bolts used to be to measure the length when slack and then to tighten the nut to produce a given extension. Since the characteristics of the bolt material were known, the clamp load would have been calculated, and so produced fairly consistently. This must have resulted in a secure fastening, since I can not recall any instance of a bolt coming loose.

For several years, now, Yield Tightening has been used to produce the required clamp load between parts, and to maximise the efficiency of the fasteners. This produces sufficient friction between the threads to prevent slackening.

For many years, now, Industry has used anaerobic sealants to ensure security of screwed joint systems.

Howard

[Michael GilliganParticipant @michaelgilligan61133]

Stretching the topic [and the bolt] a little further …

these Load Indicating Washers are worth a look.

MichaelG.

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Howard Lewis on 15/10/2014 08:37:43:

For a really secure fastening, use a mechanical locking method, castellated nut and split pin, tab washer, lockplate, or cross drilled nut/bolt head and wire locking. These methods were used, in preference to spring washers to ensure security of the hardware for Big End and Main Bearing caps in engines, or parts in transmissions.

The problem with castle nuts is that heavy handed mechanics would often do them up tight and then force them round to the next available split pin position, possibly stretching the bolt.

When I my restored vintage car engines I used to make a set of big end bolts with one or two extra which I would tighten in stages with a torque wrench until there was just measurable permanent stretch. I would then tighten to 20% lower torque. If using castle nuts tighten to the correct torque and if necessary remove the nut and take a light skim off so that the holes would line up at the right torque.

Russell.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Russell Eberhardt on 15/10/2014 11:19:15:

The problem with castle nuts is that heavy handed mechanics would often do them up tight and then force them round to the next available split pin position, possibly stretching the bolt.

When I my restored vintage car engines I used to make a set of big end bolts with one or two extra which I would tighten in stages with a torque wrench until there was just measurable permanent stretch. I would then tighten to 20% lower torque. If using castle nuts tighten to the correct torque and if necessary remove the nut and take a light skim off so that the holes would line up at the right torque.

.

I was interested to see Guy Martin working on the fitted bolts on the Spitfire … After torquing them correctly, the bolt was drilled in-situ [via the castellation slot in the nut] for its split-pin.

… Tricky job !!

MichaelG.

[Ian S CParticipant @iansc]

In my book on blacksmithing, it shows the bolts with the nuts on with the chamfer against the material being bolted. When the smith made the nuts he took a bar long enough to make the nuts he wanted, right width and thickness, he would punch the holes, or perhaps drill them, then tap them and then cut them off on the anvil, the cut off tending to push the top edge down, and the corners maybe got a whack with a hammer, no worry about sharp corners, no H&S blokes about 150 to 200 years ago. In later years, bigger production the nuts would be punched and cut by machine. Ian S C

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