A Stuart Twin Oscillator

[Sanjay F]

I've run out of BA nuts and bolts to finish my Clarkson engine so am going to take a look at a new build whilst I wait for Postman Pat. There seems to be a few oscillators being built atm, so I thought I'd jump on the bandwagon and go for ride on this Stuart Twin oscillator. I have restored both a Stuart ST and Progress engine but this will be the first time building one

I've had a cursory glance at the drawings and my initial thoughts are, it may be small, but it looks quite fiddly, and some accurate measurement and machining will be the order of the day(s).

I always like opening the box and seeing what's inside, not a huge amount ..........a piece of paper with a drawing mod floated to the floor......... I'm glad I spotted it and didn't chuck it in the bin! 

[55fairlane]

Oh that looks like fun.....

[CI]

Nice kit.
I don't often see V-steam engines.

.

[Sanjay F]

Right, time to start on the Twin and I'm not not starting with machining the standard as is usual with this engine according to the various build logs I have read. The reason being is I've treated myself to a couple of new gadgets, a face mill and a box angle plate, both of which I've never owned. They both look really useful and according to a build in an old ME will make the job easier (I can see that having looked at the various holes and angles required) and give the lovely smooth precision finish which is required; I'm also sure they'll come in useful in future....

I'm going to start with the crankshaft and again like some who have built this before, am going to build it in parts rather than from a single piece of stock

[Sanjay F]

Finished the crankshaft and starting to understand the size & scale of what I'm building here! 

PS. I haven't got giant hands 

[CI]

 

[Chipswitheverything]

That crankshaft is certainly very dinky!   I've got a couple of box angle plates that I've used from time to time and found useful. Funnily enough, I can remember the late George Thomas showing me three or more pristine box angle plates in his workshop, and saying that he had bought them very many years ago and never found any application for them!   One of mine is an inspection grade larger one, about 6" by 5", which I bought s/h on a tool stall for a tenner, and it has been helpful for making checks on alignments when fiddling with the machines.
( When I bought the plate, and another large standard angle plate, the dealer, whom I know, had just bought them from someone who had fished them out of the boot of a car, and he'd given the chap £18 for the two. The dealer said to me, " don't know why I ever bought these, I'll never see my money back on them!" I bunged £18 into his hand and immediately took them away! )

If you find that the various tee-nuts and bolts that you have are not a match for the tee slots in the box, it's worth making up a set of nuts to fit properly. I ended up having to do that for the box plates I use, and it does promote using them readily.  Dave

[Jeff123]

Hi Sanjay,

Following this thread with interest.
Never made a stuart engine, about time I did and I certainly like this one

Quite like the "fiddly bits". I bought a Sherline some years ago which perfect for them
Geoff

[Sanjay F]

I'm hoping the new bits arrive in time for the Bank Holiday weekend so I get some hours in the workshop.

The builder in the ME magazine thread capped off the steam passages using bolts and washers rather than plugs (see photo) - he stated it was for access should it be required, I quite like that idea and similar to the pump I built a while ago.........hmmmm, decisions, decisions 

[Sanjay F]

Finished the flywheel and 'jazzed' it up a bit so it wasn't looking just a flat disk and more like the single cylinder oscillator (ST) I restored some time ago. Given that I will make this one in a similar vein so will use blanking plugs rather than bolts and washers to seal the steam passage ends

[Michael S.]

Looks good 👍.

A start has been made.


Michael

[Sanjay F]

These are the crossheads which I think are amongst some of the smallest and most fiddly things I've made; the piston rod spigot looks offset, but it isn't, it's where the crankshaft bearing is undercut - if you don't like small and fiddly, this is not the engine for you! 

[crueby]

Definitely a little engine!  What is the bore/stroke on that one? Looks to be a bit bigger than a Tiny oscillator.

[Sanjay F]

It's a HUGE 7/16" Bore. 7/16" stroke  ...........same as the single cylinder version.

[crueby]

It's a HUGE 7/16" Bore. 7/16" stroke  ...........same as the single cylinder version.

Oh, thats MASSIVE!      You'll have to do Elmer's Tiny next, only a 3/16" bore as I recall. Or just put a 2x scale penny next to this one!