Stuart Triple Assembly Question

[atomarcParticipant @atomarc]

I’m in the close to final assembly stages of my Stuart triple build, and have hit a snag I haven’t been able to figure out. I’m going to use the component terms supplied by Stuart as I attempt to explain my conundrum.

When the drag links are assembled, they cannot pass the little 7BA fastener that holds the steam chest valve rod to the reversing eccentric..they need to be spread out more, for lack of a better explanation. The parts are build to the drawing, but there is absolutely no way that I can see it would work without either making new drag links with thicker offsets on the ends, or making small spacers to space the drag links apart so they won’t contact the cross-head bolt that goes through the eccentric.

I’ve looked at a bunch of pictures, have watched Keith Appleton’s videos and I see nothing obvious other than the drag links in those pictures have thicker spacers on them. My print sheet calls out one end at 3/16″ thick and the other end at 5/32″. The item I’m blabbing about is #31 on my print sheet, which is dated 1981.

Thanks,

Stuart Miller

Eureka, CA USA

[David George 1Participant @davidgeorge1]

Hi Stuart a picture of your engine would help.

David

[JasonBModerator @jasonb]

Would reducing the bolt head and nut height help.

Snip of the drawings for others to see the point of contact

[atomarcParticipant @atomarc]

Gentlemen,

Thank you for those comments, I’ll try to post a photo. As an update, Andy from Stuart Models replied to my questions and stated the drawings I was working off of were from ’77, and the updated drawings indicated the ends of the drag links should be 1/4″ and 7/32″ on the ends versus the old measurements of 3/16″ and 5/32″. Making small spacers seems like a fiddly pain so I’ll just make six new drag links with adequate end dimensions to clear that cross-head bolt.

Jason’s comment about reducing the total length of the cross-head bolt is valid, but for some reason, in my case it would result in almost a total loss of the fastener, and thanks for posting that drawing, that’s exactly where the problem is.

Stuart

[JasonBModerator @jasonb]

 

Ah it will be a bit tight with those dimensions, should be OK with the new as below, I was thinking your figures were after the 1/16″ had been deducted.

[atomarcParticipant @atomarc]

Jason,

 

Thanks. I’m actually going to make the dimensions fatter than even the new call out, just to make some comfortable clearance between the moving components.

I’ve looked at quite a few of these triple builds and realize that some of the builders put their own ‘take’ on the design of many of the non critical items.

 

Stuart

[JasonBModerator @jasonb]

I’m guilty of that, using just one or two castings and doing my own thing with the rest. Others where castings are no longer available I do it all from scratch.

[atomarcParticipant @atomarc]

Gentlemen,

I modified the drag links and nuts and bolts and now all is good. The engine is finished, runs both directions nicely, albeit using only the HP cylinder on compressed air, but that’s fine with me..I’m not going to run steam. I’ve included some pictures of the finished product and I hope the images aren’t too big. There is a wood base, freshly lacquered sitting in the shop that will be added when it dries. Although the engine is not perfect, I’m happy with it and am proud of how it turned out. I started the project in 1981 and it only took me 43 years to finish it…wow!

Stuart Miller

Eureka, CAL  USA

 

 

[Chris GunnParticipant @chrisgunn36534]

Nice job Stuart, what is next?

Chris Gunn

[atomarcParticipant @atomarc]

Chris,

 

Thanks, my next project is to sit in my easy chair and read a book and do some cross word puzzles. This project was interesting in that it got me back in the shop and I utilized many of the tools and such that I’ve built up over the last 45 years. I found stuff I didn’t even know I had.

I have another smaller, simpler Stuart engine that was given to me that I may build….don’t know yet. At the ripe old age of almost 78, it’s hard to stay upright for hour after hour hunched over a lathe or milling machine.

Stuart Miller

Eureka, CAL USA

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