Stuart Triple Steam Engine

[steamlaser]

I have been trying to make sense of the drawings supplied for my Stuart  Triple! (Mine are from the 1950s and lack any sort of clarity)
I am about to fabricate a crankshaft for the engine. I have made webs and worked out that the total length of the Crankshaft as 9.1/8 inches. However I am confused as to the distance between the individual webs. i.e. What are the lengths of the journals between the webs? Are they different or all the same.
Many thanks

[tghs]

stuart list 3 pages of plans for that engine,, you might want to contact them, the webs placement would be directly set by the cylinder centers, and the connecting rod bottom width.. I would make the crank longer on both ends an trim to final size later..

[Alyn Foundry]

Perhaps this will help?

http://www.modelenginemaker.com/index.php/topic,5354.0.html

Cheers Graham.

[Jasonb]

1/2" for all three journals

[Jo]

Would you like you to introduce yourself and your interest in making model engines    (before you use us to solve your problems  )

Jo

[Mcgyver]

stuart list 3 pages of plans for that engine,, you might want to contact them, the webs placement would be directly set by the cylinder centers, and the connecting rod bottom width..

Three drawings?  I only had two....maybe that;s why it was such bear!  (j/j, there are three sheets, but only two are drawings, the third is more of a rendering)

Those drawings were done in the day when draftsmen hated both lettering and machinists and vigorously fought avoid even a single superfluous character.  As tghs suggests, the key is in the cylinder spacing.  Everything can be worked out from the drawings, but if one of my guys turned one out like that today (where its cheap and easy to add info) they'd for sure hear about it

[steamlaser]

stuart list 3 pages of plans for that engine,, you might want to contact them, the webs placement would be directly set by the cylinder centers, and the connecting rod bottom width.. I would make the crank longer on both ends an trim to final size later..

When  I bought the pile of bits there were only two poor print quality plans.
I have much time sorting out the dimensions for the individual components.
I have had to change some of the ancient Imperial threads to Metric equivalents .
Also thanks to all those who have responded!

[steamlaser]

Would you like you to introduce yourself and your interest in making model engines    (before you use us to solve your problems  )

Jo

I make sundials and other related items. I am am moving towards making small engines and besides the Stuart  Triple there is in the pipeline a small four stroke engine made from scrap materials. Eventually I intend to make a "Flame gulper" and a Stirling engine. (For these I have good quality plans so things should procced with fewer problems.

[Jasonb]

Do you have your cylinders machined yet? If not I would hold off on making the crankshaft in case your castings won't allow for the Ctr to Ctr distances shown (on the later drawing). It is then a simple job to work out the lengths of shaft required between each pair of webs by subtraction crank pin and web thickness sizes. Possibly why they may not be shown on your drawing.

[Jo]

From Stuarts: There are two big drawings for the Triple and three General Arrangement Drawings (exploded views). The Drawings use horrible Imperial fractional measurements without any tolerances shown. The tolerances are measure the castings/your machined assembled bits and adjust accordingly. 

The Model Engineer published a series of articles on building the Triple by Doug English in 1995. As you can see it provides some of the drawings. 


Now for a bit of a warning: This is not an engine for a beginner I would recommend you build your flame gulper and other engines first  And Graham has pointed you to my build.

Jo

[steamlaser]

Do you have your cylinders machined yet? If not I would hold off on making the crankshaft in case your castings won't allow for the Ctr to Ctr distances shown (on the later drawing). It is then a simple job to work out the lengths of shaft required between each pair of webs by subtraction crank pin and web thickness sizes. Possibly why they may not be shown on your drawing.

Thanks for your feedback.
The Cylinders had already been machined, as was the base. The rest was a pile of rust bits and castings.
As advised, I will go back and carefully measure up the cylinder head.

[steamlaser]

From Stuarts: There are two big drawings for the Triple and three General Arrangement Drawings (exploded views). The Drawings use horrible Imperial fractional measurements without any tolerances shown. The tolerances are measure the castings/your machined assembled bits and adjust accordingly. 

The Model Engineer published a series of articles on building the Triple by Doug English in 1995. As you can see it provides some of the drawings. 


Now for a bit of a warning: This is not an engine for a beginner I would recommend you build your flame gulper and other engines first  And Graham has pointed you to my build.

Jo

Thank you for your response.
I did realise that this would not be a trivial project. I also understood it would not be finished in a short time scale! I am slowly ploughing through the drawings and  machining up the various components. I am now reaching the stage where there will need to be some careful "fitting" required.

[Mcgyver]

Thank you for your response.
I did realise that this would not be a trivial project. I also understood it would not be finished in a short time scale! I am slowly ploughing through the drawings and  machining up the various components. I am now reaching the stage where there will need to be some careful "fitting" required.

My outlook its usually 'if another human can, so can I'; there is no reason you can't make it....but I do kind of agree with Jo.  It could well be a frustrating beginner project.  otoh you may be a beginner at engines, but the best machinist on the site and would have no trouble.  Its a longer build with  some parts that are demanding to make properly - crank, double start small thread, tight tube bends come to mind.

I found the kit crank and counter weights toss-worthy.  The springy brazed up crank is a pain - made mine from the solid which worked well.   After machining the counter weights, I tried to peen them onto the crank, and with what seemed like very little force, managed to crack one (the peening in a count countersunk hole creates an outward force).  Remade them in steel and have had no issue.

Still working on it....its picked up and put down from time to time.  Currently challenge is a perfect 5/16 bend in 5/16 tube....for which I'm just finishing Ian Hunts very substantial mandrel tube bender.  Story off my shop life...make a tool to make a tool to make a tool and then forget where you are and what the goal is

[Jo]

Still working on it....its picked up and put down from time to time. 

  I know the feeling. Sometimes you feel like doing a bit of your triple (s  ), sometimes something else. If you are one of those people who has to start a thing and will not allow themselves to do anything else until it is finished I would advise them against doing a Triple, stick to simple engines

Jo