Twin mill engine progress

[AStroudParticipant @astroud]

This started with the fabricated flywheel, a first for me and which I asked the forum for advice.

The model is obviously inspired by the Twin Victoria which I liked the look of but I like to do my own designs and kits don’t really do it for me though I certainly admire seeing other peoples’ examples. It is all fabricated and remaining are the eccentrics and straps and a fair amount of fitting to achieve alignments and running clearances.

[JasonBModerator @jasonb]

That is coming together nicely, the squarer cylinders give it the look of a corless. Look forward to seeing it running.

[DiogenesParticipant @diogenes]

Yes, nice to see a bit of freelancing, do you make detailed plans before you start, or make a start with a general picture in mind and develop it as you go along?

I like the ‘industrial’ heft of it.

[AStroudParticipant @astroud]

Thanks for the comments.

I make a GA to get overall sizes and allow me to order the material in one go and I will make some detailed drawings. Other smaller parts are made to fit other parts so if something doesn’t go to plan then the next part can be made to suit. In the workshop I will also sometimes notice that a part does not look right, often too chunky so I will change it,  the dimensions being worked out on scrap paper. Making a twin though made the process a bit more disciplined so the 2 engines will end up looking the same.

[AStroudParticipant @astroud]

I am calling my twin mill engine finished after a few days chasing alignment issues, air leaks and mechanical noises. Hissing is still evident, hoping that is via the sliders and will reduce as they bed in. The noises are probably amplified by the base which being hollow probably acts as a sounding board. Generally pleased with the appearance and how it runs.

Here is a run, a bit short due to my small compressor size.

https://youtu.be/6pQd_rFI65U

 

[Andrew CrowParticipant @andrewcrow91475]

And very nice it is to!

Andy

[roy entwistleParticipant @royentwistle24699]

Very nice. Andy. Just a small point, Mill engines generallyturn over the opposite way

Roy

[JasonBModerator @jasonb]

That has turned out well, who neds a set of Stuart castings! Will you paint it or leave it in the flesh?

[AStroudParticipant @astroud]

Thanks, no plans to paint it, never enjoyed painting and I think I would forever be fretting about chipping the paint.

Just a small point, Mill engines generallyturn over the opposite way.

Roy

Are you sure Roy? When I put up my Corliss running in the opposite direction I was told that was wrong, the connecting rod should always be pulling the crankshaft down onto the main bearings/foundations.

[JasonBModerator @jasonb]

It is not the crankshaft where it matters but the cross head guides. It should push the cross head down on the outstroke and pull it down on the instroke

If you look at your engine as the piston moves further into the cylinder with the pully or flywheel under load if you were to have no guide bars then the cross head would tend to lift as the piston rod and conrod want to straighten. But if you rotate it the other way it will get pushed down.

Same as the piston moves towards the crank, if there were no guide bars the piston rod and conrod would tend to kink and the force go down if running the opposite way.

[roy entwistleParticipant @royentwistle24699]

Andy.  Bolton steam museum have over 20 mill engines they all run the same way. The opposite to yours. Ive lived in Lancashire for over 90 years and Ive seen a lot of mill engines.

Roy

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