Martin Evans, Royal Scot in gauge 0 - Walkerite sheet?

Looking at Martin's ME articles (1969) about building Royal Scot in gauge 0, I am puzzled about the use of Walkerite sheet joint between frames and cylinders.

Never seen anything like this before?

Can anyone, please explain what is it for?

Chris

I believe that it is a insulation gasket material probably to prevent heat transfer to the frames.

David

Regarding the earlier response of "gasket material". There is a company called James Walker that manufacture gaskets and related components and materials. From their website, their UK office is in Cheshire but a search on Walkerite does not provide any results. Possibly an enquiry may result in the current equivalent material being identified.

Thank you guys,

@ David G.

Heat transfer prevention seems the only plausible explanation, but I have never seen it in any other design (whether in G0 or G1) so I am puzzled as to why Martin Evans thought it "important" ?

@David M.

Yes, James Walker is the original manufacturer of "Golden Walkerite"

"...In 1882, Scottish engineer James Walker founded a company
to sell engineering accessories to ships in the Port of London.
...and followed this with Golden Walkerite® high
pressure jointing..."

I guess it is no longer available because of it's asbestos content...

Question for me is why use it, though?

and has it been used in any other loco design?

Edited By Chris Kaminski on 15/02/2021 08:28:19

Not my area of interest or expertise; but I note that the drawing asserts its insertion to be Important

... Presumably because of its thermal properties, and/or its mechanical ones.

One would hope that Martin Evans included a textual explanation ... somewhere !

MichaelG.

.

Edit for clarity: __ If Mr Evans only included it as a convenient ‘packer’ then its important characteristic might be the 1/64” thickness.

Edited By Michael Gilligan on 15/02/2021 08:49:18

no such hope - both his drawings and texts (usually) leave a lot to guess

at least I couldn't find it anywhere...

I agree the gasket is intended to prevent heat transfer in this small engine,Why not use gasket paper,might have to use nearest metric equivalent for thickness,a local motor accessory shop sells a gasket paper which is very tough,it resists tearing much better than the old type gasket paper,or try to get some of the graphite coated,grey colour gasket material which has been asbestos free for many years,suppliers to the vintage vehicle owners is also good source ,I would suggest a visit to an auto jumble but thats not on at the moment with cov 19 lockdown.

Success or failure in this gauge can rest on the rate at which heat is lost in the cylinders.

Personally , I would make as much of the frames as possible in that area 'disappear', ie a hole.

The 'gasket' material thickness is probably vital to stop 'clashing ' somewhere.

I guess that is the thinking behind it.

Having said so, the real gauge O live steam experts like Clarry Edwards and Eddie Cooke (who BTW designed and built many more locos in this gauge than Martin Evans) never mention any thermal insulation of cylinders...?

As for "...'gasket' material thickness is probably vital to stop 'clashing ' somewhere..."

that cannot be so - simply increase the cylinder body by 1/64" instead of adding 1/64" gasket and you will avoid any "clashing"

This is the other half of the OP's drawing:-

As the only dimension shown is the thickness of the gasket material, one must assume that this is necessary for motion clearances.

Reasons for including it might be a. the original drawing of the cylinders was incorrect or b. that the cylinder castings, originally meant for a different design, would not clean up to the size required here.

Having read many of Martin Evans's articles I conclude he would appear not to find it easy to acknowledge a mistake and would either ignore it or suggest an 'improvement' had been pointed out to him - and at least two other well known authors would seem to not offer any corrections at all!

I would think that commercial gasket material would be best here being less compressible than my goto oiled braille paper.

Edited By Nick Clarke 3 on 15/02/2021 09:56:05

I often use company called Kennions for materials. Having checked their website, they stock a gasket material (16 thou in thickness). So I assume that Martin Evans is not the only person to specify a "gasket material" on drawings.

@ Nick

Cynic in me tends to agree with your views about Martin Evans's mistakes

but I must give him credit were it is due - elsewhere in this series he acknowledges a mistake in the drawings of tranverse stays in the boiler "...Slight slip by draughtsman!..."

Yes, gasket materials are used where appropriate and needed...

but not for use between frames and cylinders?

But not by him!

Cynical, Moi?

There are 'a few' , who I would tie to a ball and chain and only release them when they had constructed what they had drawn !

While normally I would agree wholeheartedly with you, in this case the loco was designed by Martin Evans and built by Severn Lamb for a French customer in 1965 although the design was not published in ME until 4 years later.

Martin Evans, in his book "Manual of Steam Locomotive Construction" suggests putting thermal insulation between frames and cylinders of smaller models, adding to the effect of lagging the outsides of outer cylnders.

The material he mentions in his book is "Hallite". Similar to Walkerite AFAIK.

Well spotted Clive

on page 75 of 1983 edition of his "The Model Steam Locomotive" he says:

"...Sometimes gaskets made of some kind of heat-insulating material are used between cylinder and frames, to reduce as far as possible heat loss from the cylinders. A sheet steam packing material such as Messrs James Walker's "Walkerite" or "Golden Walkerite" is ideal for this purpose..."

So, I guess mystery solved and my question is answered

If you did want to try an insulator sheet to reduce heat transfer from cyls to frames, you could try a sheet of printed circuit board FR4 material with the copper removed. Quite a good insulator and mechanically very sturdy, no very compressible either. Just a thought. As others have said it is likely not needed as seen my many existing O scale steam locomotives without it.

Another thought - if Martin Evans had milled away the material around the cyl screw holes and other openings by 1/64", leaving the holes as islands, it would leave an air gap in the majority of the cyl face which likely would reduce heat transfer significantly without reducing strength and with no effect on alignment.