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An unfinished Stuart 10h Mk I

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Sanjay F:
This is the Mark I version of the Stuart 10h. It does not have a tubular trunk guide, but has a single-sided cross head. Not sure when it changed to the tubular version?

There are several odd things about it:

- The crosshead guides are missing but have clearly never been there as there are no holes.
- The cylinder does not mate correctly with the soleplate
- Someone has got a bit trigger happy when drilling the holes in the cylinder
- There's a huge blob of solder holding the exhaust in place
- The entire engine has never had a primer or paint on it
- The piston rod end has been beaten over to try and keep it fixed to the piston (it didn't work!) - see video
- The valve chest cover has never been machined to size and it never had the 'S' on it, so must be a later addition

In my humble opinion this engine was never a runner, although I did try pumping some air through it  :)

I think I'll start with trying to get the cylinder sorted before moving onto the crosshead guides, new piston and rod. I cleaned up the soleplate and it looks like a brand new casting, I even had to file away some flashing; I may actually paint this one given the fact it was never finished......

I have a couple of questions.

1. Has anyone got the drawings for a Stuart 10h Mark I?
2. How do I sort the messy solder out; is it soft solder and will just melt away nicely......?

https://youtube.com/shorts/rbw4oq6WAsg?feature=share

internal_fire:

--- Quote from: redhouseluv on October 02, 2025, 09:09:26 PM ---- The crosshead guides are missing but have clearly never been there as there are no holes.

--- End quote ---

The important part of the crosshead function works as long as the rotation is clockwise, as viewed in the first photo. In either movement of the piston the force is downward onto the "crosshead" platform. Lateral restraint is not very important.

Gene

Sanjay F:
That's great, thanks Gene, I never knew that  :ThumbsUp:

Jasonb:
Looks like soft solder so it can be melted out. A damp cotton (not manmade) cloth will allow you to wipe the liquid solder off the surface which will leave very little and that can be removed with Emery.

No Drawings but looks like the bars just had a single fixing at each end. 1/8" x 1/4" would probably do depending on how thick the lip on teh bottom of the crosshead is. Mill a rebate into the bottom corners to retain the crosshead.

Sanjay F:
Excellent thank you, I'm hoping there's nothing nasty under the solder! You're right about the way the guides are fixed, I found the picture below of a complete engine

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