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MG Midget and Sprite Technical - Sheet steel gauges

I seem to recall that most Spridget bodywork is 16 or 18 gauge. But what does that work out as a measured thickness.
i.e. what fraction of an inch or millimetre do the standard gauge sizes convert to?
Guy Weller

http://www.8886.co.uk/ref/standard_wire_gauge.htm
David Billington

Guy. I am doing some renovation work on the GMC at the moment and that IS 16 SWG, I'm sure the midget and Sprite are closer to 20 SWG and more modern cars now 22 SWG.

Mark.


Mark Boldry

Gauge measurements are the number of sheets it would take to make an inch. So 16 gauge is 1/16 inch thickness 18 ga is 1/18 in thick and so on. The higher the gauge the thinner the metal. C
C. J. Charvet

Thanks, That will do it.
I was familiar with using 8 gauge wire for forestry fencing, or 10 / 12 gauge for HT fence strain wires.
I know that the higher the number, the thinner the wire.

And Mark, you are right. I have just mic'd an offcut taken from the outer footwell wall of my sprite. It measured at 0.036 which, using the link that David supplied, that works out at is 20 gauge (Imperial SWG) or 19 gauge (AWG). I guess some panels might be thicker, but that is a good general start. I have been given a large sheet of 18 gauge, I guess that will do for much of what I want.

But, CJ, I cannot see how the figures in these tables relate to your definition though. ?? Perhaps there are other units in use as well as SWG and AWG.
Guy Weller

In the table, is diameter maybe including the insulating sheath where the gauge is only the metal?
C. J. Charvet

C,

Have never heard of what you describe befeore. It only works for 16g approximately, but none of the other gauges, whether you use AWG or SWG - where did you find it?

Richard
Richard Wale

IIRC the inner sill panels on a sprite are 2mm (14swg), the outer sills are something like 1.2mm (20 swg) for OE sill panels or slightly thicker. The pattern parts with the insert at the top front of the sill were some what thinner.

CJ,

Your explanation works for 16swg which miraculously is about 1/16" (0.065") and 1.6mm but doesn't hold water for other values, doesn't work for AWG either given details here http://www.simetric.co.uk/siwire.htm . I have seen info on the basis before but can't recall it at the moment, something to do with the number of plates of a given thickness to make a pound. That doesn't explain the difference in SWG and AWG either. In the UK now, while we may ask for an given SWG thickness, the material is metric and I suspect most of the world, excepting the US, does the same. IIRC the thickness numbers are largely related to the reduction in thickness achievable during each rolling stage, a maximum reduction being possible before annealing of the sheet.
David Billington

Everyone is talking about wire gauge. We are talking about sheet metal right? See first post:) I don't know wire. But I'm sure on the sheet metal. If any gauge of sheet metal is welded correctly it will hold water.
C. J. Charvet

Even the actual measurment of most 16 ga sheet steel is going to be off from my example. I think the wire gauge must be different because it has to be more consistant for its purpose. But that is where the measurement was derived. Then I could be be crazy.
C. J. Charvet

CJ,
From that same web site link that David has been posting to, sheet metal and wire both use the same gauge thicknesses.

I know I posed the question in the first place, but I have an idea that the gauge related to the length of wire that could be produced from a standard weight. Possibly the number of feet or yards that could be drawn from a lb of steel?
These "gauge" measurements are very archaic, derived when the steel industry in the UK was in its infancy. They will also have an historical and social significance relating to how many pence the steel men could earn in a day.

What I really wanted was the gauge and therefore the thickness, and modern equivalent metric thickness, for most of the general construction.

And the answer is 16, or 0.036" or 1.2mm

I know that some sections (e.g sills) are thicker, and I have in the past chosen to use thicker steel e.g when replacing a battery shelf
Guy Weller

Guy,

In the UK sheet was SWG, now metric. Here are the equivalents for SWG, with thicknesses in inches and millemetres:

10swg 0.128" 3.25mm
12swg 0.104" 2.64mm
14swg 0.080" 2.03mm
16swg 0.064" 1.63mm
18swg 0.048" 1.22mm
20swg 0.036" 0.91mm
22swg 0.028" 0.71mm

Today's metric sizes are usually 3.0mm, 2.5mm, 2.0mm, 1.5mm, 1.2mm, 1.0mm and 0.8mm, but it is possible to get 0.9mm sometimes (the old 20swg).

Richard


Richard Wale

Thanks Richard
Guy Weller

Maybe the way it was explained to me was just over simplified. Glad you got what you needed. Cheers
C. J. Charvet

Gauge is really no good way to measure thickness since the thickness of a specific gauge will be different depending on what gauge is used. There are a plethoria of different gauges for different materials and even multiple gauges for the same material and application area.

Check out http://w3.uwyo.edu/~metal/gage.html for a nice piece of information regarding this. It will make anyone in their right mind want to go metric ;-)

For a conversion table for sheet metal SWG: http://www.simetric.co.uk/sigauge.htm where you will also find more conversion tables for other stuff aswell.

//Erik
E Lindgren

Erik,

Thanks for the links. I am aware of the different gauges but the one commonly used in the UK is SWG so when I quote a thickness I will specify it as SWG or mm or inch thickness as appropriate. I does get annoying sometimes when people just quote ga or similarly temperature without mentioning F or C, normally US posters quote F without giving the units in my experience, one can normally tell from the context.
David Billington

This thread was discussed between 26/04/2008 and 06/05/2008

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