Thompstone Engine

[geoff walker 1Participant @geoffwalker1]

Hi James,

Just add my congrats, very nice indeed and for me one Jason's best designs.

I too love the colour, it looks like my favourite, Halfords industry grey?

Geoff

[JasonBModerator @jasonb]

I must get round to writing up another engine for the mag, this vertical is the most likely candidate.

My usual 24mm bore and again with a soldered cylinder though a little simpler than the Thompstone. The standard is also silver soldered from 3 bits of steel, base is a "box" from screwed and JBWelded aluminium. It's a similar size to a Stuart No7 (before it became the 7A) and materials would be about 1/3rd the cost of a Stuart casting set, few quid more if you wanted to use a spoked flywheel casting.

[paul raynerParticipant @paulrayner36054]

oooh looks nice, another one to add to my retirement list!

have you any plans to do a tangye or twin victoria style?

or maybe even a bottle engine or am I asking too much

 

Edited By paul rayner on 14/02/2023 18:41:06

[JasonBModerator @jasonb]

I suppose my Filer & Stow is not too far removed from the design usually associated with "Tangye" with a slightly different trunk guide.

Or for a simple quick project my version of the Stuart "One One" is the same sort of layout. Bothe could easily be built as back to back pairs for that "Double Tangye" look

I do have quite a few images and details of the Tangye "Colonial" engine which is one on the to do list but not near the top

I did draw up a Victoria Look Alike to be made from barstock but ended up making one from a Casting Set with a few alterations, again could be made as a twin fairly easily just a case of pressing "mirror" on the CAD file

Or for a slightly simpler project a reworking of the Clarkson as the Lark and Son cross compound which could either be done by modifying the Clarkson castings or better still cut from solid

Bottle engines are nice and something to think about, should be interesting carving the bottle from solid. Probably have to split it in half horizontally so the insides can be hollowed out and then after joining cut the pockets in each side. The James Begg one that Anthony Mount designed was a nice engine but not available now that Cotswold Models are no more and I'm not so keen on the PM Research one.

[paul raynerParticipant @paulrayner36054]

Hi Jason

I know what you mean about the PM bottle, It just doesn't just look right, maybe a bit skinny?

I do have 1 set of them clarkson castings squirreled away, Blackgates are stocking all clarksons castings and plans if anybody is interested.

I've never heard of Lark & Son. looks a nice engine. I will have to google it.

Paul

[James Smith 24Participant @jamessmith24]

Thanks all for the positive feedback, much appreciated.

The colour is Rustoleum Sage Green, was about the only colour the local hardware shop had that came close to what I was looking for, and now its on I do like it. I have plenty left in the can so I can guess what colour the next one will be !

Thanks to Jason for the series, it was a good build with plenty of learning along the way, so I think I have gained a lot of experience during the build.

[paul raynerParticipant @paulrayner36054]

Hi all, Just a quick one i'm back on the Thompstone decided to splash out and buy some PB for the cylinder rather than use CA, Stupid question but on the drawings on page 491 the valve block is 22mm wide but the steam chest is 20 mm wide, I presume this is a printing error and should read 20mm? also the text states on page 562 tap the steam chest M4 but the drawings state M5, I presume the M5 is correct? as the valve nut is also M5 & M4 would make it rather thin walled.

Sorry for daft questions, but I just want to clarify before I cock something up.

thanks for all reply"s in advance

Paul

[JasonBModerator @jasonb]

Several of the components that make up the cylinder are shown with a machining allowance on my drawing No2 so that they can be taken down to finished size after they have all been soldered together as drawing No3.

There is 1mm down each side of the valve block to come off and also 1mm off it's face to bring it down to 2,5mm thick from the individual parts 3.5mm thickness. Similar with the two "washers" that make up the end flanges which are over thickness and over diameter,

If you look at thes ecouple of photos you can see th ebrighter freshley machined surfacs compared with the darker ones of the pickled assembly.

Text is wrong, the chest gland hole should be tapped M5, preferably M5 x 0.5 metric fine but 0.8mm pitch metric coarse would do

J

[paul raynerParticipant @paulrayner36054]

Cheers Jason, I've just read about machining the cylinder and I get it now. I new it would be a stupid question!

having said that, I have not machined the cylinder yet as i've a poorly lathe (waiting for parts). Just thought I would do what I could on the mill while I have the chance.

Thank you

Paul

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