Wire Gauge to Millimeters on old plans

A caution to anyone translating old plan into metric sizes, especially boilers.

I looked up 18 gauge on the web when looking at an old boiler plan as I thought i may have a tube the right size. I was surprised when 18 gauge came up as 1.0mm as my recollection was that it is slightly thicker than that.

I had foolishly searched for 18g to mm, searching for SWG to millimeters gave me the correct figure or 1.2mm.

The reason is that there are various different wire gauge systems (also used for plate and tube) and 18 AWG (American Wire Gauge) is about 1mm.

Old British plans universally use SWG which is rather thicker for any given number. So be warned, check you are using SWG sizes if converting an old British plan or you may end up with a dangerous boiler that is significantly under strength and won't get passed by a boiler inspector.

Neil

P.S. For beginners - the reason wire gauges get smaller as the number increases is that the originated as the number of times a wire was pulled through a die to make it thinner. 18 gauge wire originally meant it had been pulled through 18 dies, so you can see how the use of different sets of dies led to different numberings (such as Birmingham Wire Gauge). SWG was introduced in the UK and AWG in North America to bring some standardisation, but sadly the opportunity to make both sides of the Atlantic the same was missed.

Came across this when helping my wife sort out some old knitting patterns and needles given to her by a friend. There's a really useful website at

https://www.convert-me.com/en/convert/wire_gauge/needleUK.html?u=needleUK&v=18 Just type in the SWG, and you get mm to three places of decimals.

That seems complicated - can someone teach me how to get these web addresses to appear as "Link"?

Edited By Mike on 02/09/2017 10:59:04

 

Edited By Brian Ess on 02/09/2017 13:48:01

As luck would have it [*] ... I found this very useful tabulation a few days ago: **LINK**

http://www.cadceptual.co.uk/images/uploaded/guides/awg-swg-tables-download-original.pdf

MichaelG.

.

[*] relating to an ebay purchase of some NiChrome wire from a Seller who was apparently not aware of the difference.

Thanks Brian - easy when you know how!

Thanks to Lambton who has sent me a scan of a table comparing different wire gauges from one of our old Model Engineer Handbooks.

I have created an article where you can download the PDF.

If anyone would be interested in converting this into a spreadsheet with metric equivalents, please get in touch as we could use it as a pull-out in MEW.

Neil

Edited By Neil Wyatt on 02/09/2017 19:22:51

Everyone appreciates the need for standards.

That is why there is so many of them.

I have started work on your 'request' Neil and sent you a pm

Make sure you convert to millimetres, not millimeters.

Andrew

I'm multiplying inches by 25.4 Andrew 😀

Out of interest a Google search  "convert inches to millimetres" gets the same results whichever of the two spellings I use.

Edited By Nige on 03/09/2017 12:08:57

Hello Nige,

I've only recently seen your PMs and sent you a reply.

l'm afraid someone else got in touch by email yesterday...

Sorry to have put you out, especially as the PMs suggest a lot of work done...

Neil

No worries Neil, see my latest pm mate

Nige