Kozo A3 Switcher Pennsylvania in 1 1/16" scale

I'm in the process of looking into the viability of building Kozo's "Pennsy" in 1 1/16" scale as my first loco. I have his book and he covers this loco in 3/4" and 1.5" scale for 3.5" and 7.5 (7.25" gauge respectively. He considers this to be an ideal first locomotive.

I have come to the idea that a 5" gauge locomotive is a more suitable scale for me, the 3/4" a little small and the 1.5" is a little too large.

I have started drawing up a boiler based around a 5" tube (both sizes of Kozo's Pennsy's have a rolled tube with a butt & strap joint at the bottom).

I looked at the Sweet Pea boiler design for a comparison and it uses a 5" I.D tube - 5" I.D x 14 S.W.G for boiler and 5" x 10 S.W.G for the firebox tube.

The commonly available tubes are 5" OUTSIDE diameter. I have watched videos with Sweet Pea boilers being constructed and they are definitely extruded tubes.

If a 5.25" tube is available this would be more suitable for many reasons.

If anyone can shed any light on this and any comments about the change of scale it would be appreciated.

Graham

Graham

M Metals list both 5 inch OD 10 swg and 5 1/4 inch OD 10 swg copper tube in their catalogue which can be downloaded from their website.

Gordon

Gordon, thanks for reply. I do not have a problem sourcing 5” OUTSIDE diameter tubes. What surprised me is that the boiler design for the Sweet Pea in Jack Buckler’s book specifies 5” INSIDE diameter. (Boiler drawing on p.102). To my knowledge all copper tubes are specified by there outside diameters.

I was hoping someone who has built the Sweet Pea could throw some light on wether this is a drawing error and should have been dimensioned to the outside of the tube.

Thanks very much for the M metal suppliers, they will be very useful I’m sure, and they do list a 5 1/4” o.d x 10 S.W.G tube which would be close to a 5”” nominal I.D tube.

but a 5” I.d x 14 swg (0.080&rdquo would be a pretty weird size of 5.16” nominal outside diameter. This is what is drawn in Jack Buckler’s book.

I was considering making a Sweet Pea. Any other part I wouldn’t worry about it but due to the problem of deviating from an established / published boiler design I wanted to clarify this.

So is it a drawing mistake? Any help appreciated.

Graham

Looking at some of my paper catalogues Blackgates and Reeves list some copper tube by ID, the nearest is 5" ID x 10swg from Blackgates. Though being a few years old that may no longer be available

GordonH, sorry just reread your post.

Thanks JasonB, I looked at Blackgates and had missed there listing of 5" i.d x 10swg...thanks.

Further reading of Jack Buckler's Sweet Pea book, looking at smoke box details and the spacer ring dimensions work out to a 5 3/16" (5.1875" which would slide over a 5.16" o.d boiler tube. Therefore boiler drawing must be as intended so can only assume a 5" I.D x 14swg tube was available in the past.

I've just seen a Metremaid (0-6-0 version of SweetPea) boiler being constructed on YouTube and I'm now pretty sure that 5" I.D x 10swg is now being used for both Firebox inner and Boiler Tube.

Thanks

Graham