Can a Unimat SL be used for a Stuart Sirius steam engine build?

[Ken S.Participant @kens-57619]

[Ken S.Participant @kens-57619]

Hello Group:

If I get extension blocks for my Unimat SL would it be possible to to go from unfinished castings to a functioning Sirius steam engine with this mini lathe set-up? I do have the milling attachment and would consider hand boring the cylinder blocks. What work might I need to outsource to a larger lathe? I thought I would do the Stuart Twin but I believe the Sirius would be a better choice for me. All opinions/input (other than "your daft&quot is appreciated. I would especially like to hear from individuals who have had experience machining the Stuart Sirius.

Regards,

Ken S.

NYC-USA

[Ady1Participant @ady1]

A Unimat SL is a bit rubbery for doing serious work

If you're skillful enough no doubt most things are possible on a SL though

(I'm not very skillful and upgraded)

[John OlsenParticipant @johnolsen79199]

I did a Stuart V10 on a Unimat 3 back in the 80's. That had its moments…the casting set came free with the lathe, but it was right on the maximum size. The main problem that I could see for you would be machining the cylinder block. You want to get both of the cylinder bores and the vertical shaft parallel , and square to the top face, as well as being square to the crankshaft bearings and the top face of the block. It would be easier to decide if you had the castings and could play with setups before committing yourself.

regards

John

[JasonBModerator @jasonb]

Like John I did a 10V on a U3

For the cylinder block on the Sirius I would use your milling attachment to machine the top and bottom surfaces flat and then do the crankshaft hole using a between centres boring bar. For the cylinder bores and vertical shaft an angle plate on teh cross slide would allow boring with the lathe and if the angle plate were not moved all would be parallel.

Either way you will need a reasonable size clamping plate to go onto the topslide to give a surface to fix the crankcase to.

[Brian GParticipant @briang]

Hi Ken

I don't think anybody on the Unimat group has attempted that engine, but several members have made and used riser blocks, extended motor mounts etc, so if you hit problems it might be worth asking there. The general attitude seems to be that if it can be made to fit an SL or DB it can be made on one.

**LINK**

Brian

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