Washers under nuts

I do the same for all the same reasons. An ordinary stamped washer is so cheap that I would need a good reason not to use one two.

Me too, seems the right thing to do

Tony

Dave

Wrong way round. The 60degrees thread is the weakest and less likely to un-do. The thread is a double wedge, a small pitch and large thread angle will give a small angle wedge. Hence the use of 60degrees and 26tpi used on cycle threads. It also suggests that BA screws would be frequently undone and done up.

As for washers, generally they have been used under nuts for at least 170 years. Before then washers were difficult to make and not used. There are no washer on the Pontcycslite aqueduct. I worked with jet engines where each set of flanges were held together with 100s of flanged screws and nuts (without washers). I don't think washers were used with larger, ordinary, nuts used in the core of the engine.

As for models, this is simple. If the model is "generic", such as a Stuart 10, use washers. If it is of an actual full size engine etc, copy the full size. If it is your own design you can make the rules (but you should stick to them).

JA

The thread answer suggests that lab technicians would be cack-handed and motorcyclists very careful with spanners.

Edited By JA on 30/01/2021 13:19:15

Edited By JA on 30/01/2021 13:20:05

I remember one of the F1 team engineers, may have been team McLaren? He said he didn't use washers on the cars because he didn't see why they should get a free ride around the race track. In other words washers are not an essential component.

IanJ

I suspect that washers every where came from working on costs plus jobs for the MOD in the cold war where if you added washers everywhere on thousands of bits of kit and got cost plus profit it would add up.

Reason for this is everyone iIhave met that worked for GEC, Marconi, BAC etc wants washers every where, and when asked why because there supervisor or manager insisted, never have got a good explanation.

Commercial people I have worked with only wanted them if to cover slots or protect paint etc.

Steve

What do you expect with a freezing workshop and bitterly cold high winds and rain from the east.

JA

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br

I should not really reply to this.

There is nothing at all wrong with your question and after some consideration I tried to give a sensible reply to it and Dave's comments. I DO NOT consider it a beginner's question at all. Everyone is still learning, I hope.

My comment on the weather was due to the sort of trivial replies that had been posted.

JA

I thought that this was an excellent question to ask. I've always thought that a washer should be used but note from some of the replies that this may not be the case.

My 'go to' book is a text book for draughtsmen dated 1880 and shows various engineering items and assemblies with instructions as to how they should be drawn.

It shows washers being used in some assemblies but not in others, so no answer there then. I would still tend to use washers unless there was a specific reason not to.

Brian

I suggest that the reasons for differing angles on early thread systems were not recorded when they were 'invented'. Very likely the earliest threads in use were made by craftsmen working by eye, and very often in wood rather than metal. As soon as there was a need for lots of threaded parts, and interchangeability was the aim, attempts would have been made to set 'standards' for each workshop. When it became obvious that general standards would be an even better idea, the threads were standardised on what was in use most generally at the time - and using the dimensions system of the area, or the trade, involved. So, steam engines made in Newcastle on Tyne used inches and sixteenths for bolts and threads, and then Whitworth came along and copied the flank angles they used for his thread standards - generally around 55 degrees. Engineers in France would be likely to use the metric system as soon as it was created (just in time, really), Germany used Whitworth or Metric depending on designer whims, or availability of tooling, or whatever. Later when electrical work was done the standard preferred for small stuff for switches and domestic fittings was BA, set out by the British Association at the request of electrical engineers, not according to previous good practice but on theoretical principles of proportion. Specialist trades like clock and watch making, and sewing machines, also developed their own thread systems, to meet their own specialised needs.

And every trade seems to have had odd special sizes - such as the 9/32" x 26tpi BSF thread just used for bicycle pedal cotters, and the German 68mm and 82mm threads for Honey Pots only.

Spanner sizes are a further area for confusion, irritation, or enthusiasm.

Cheers, Tim

I was forgetting - long ago I was talking about washers with engineers at Land Rover. Their explanation for 'shakeproof' washers (the ones with radial blades twisted like micro-propellors) - was 'Oh, those. They are designed so that the rain water gets into the threads and locks everything together properly.'

Cheers, Tim

Mick B1 - A question I have wanted to ask for some time. Thanks for raising it.

From the answers given, I think I will base my use of washers as follows:

1. Under the part that rotates
2. To protect a surface
3. If I want to spread the load I will use a large washer not a standard size one
4. It looks right
5. I won't beat myself up if I don't fit one

I saw a chalk drawing on the wall of a factory some years ago that showed a machine screw with legs chasing a nut also with legs and the caption was "not without a washer"

Simply put, no not always.

Most nuts on cars or steam engine don't use washers.

I remember a piece in ME claiming washers were never used on prototype steam engines, ironically the one pictured on the cover had washers...

To protect paint nuts can be fitted bevel edge down.

Neil

Stuarts never specified washers!

They are very rarely used on prototype steam engines and where do you see them on cars - only where there is a specific need for them.

Random washers for appearance’s sake on engineering models are like brass belaying pins on model sailing ships (ugh!!)

Rant over!

Neil

Because they are electronic engineers not mechanical engineers

Neil

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Answer to the original question is YES, as they don't do a lot when fitted above the nut

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Just had a look at my Stuart 7 that I finished quite a few years ago. There are no washers.

(There should be a "smiley" of a head being hit with a hammer)

JA