Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Update:

Success!!...I have not corrected the geometry (squareness) of the "L" brackets yet, but this morning have just been gentle "running in" the D12 on aquarium pump low pressure. I don't really know if it is "better" to run a steam engine in on "steam" power? But it is certainly more relaxing to run in on aquarium pump...it is just humming away in background and I stop it frequently to add oil...it has been running for about 3.5 hours now on 2.32 PSI and on the last stop I noticed it picked up quite a bit of RPM this time after I oiled it...so I took a toothpick and carefully removed the "helper" counter spring while it was running....bingo! The valve port plates have run in well enough that she runs on Full stock spring pressure at 2.32 PSI!
  As a test I dripped some runny MMO on the running outer cylinders right at the friction point, my outboard cylinder looks totally sealed but I am getting just a few tiny air bubbles on my inboard cylinder so perhaps I will do my tear down now and see why the Inboard cylinder is taking longer, I expect I will find a tiny flaw, but I feel sure just a bit more running in would do the job as well.

Photo of D12 running on air pump with no "helper" spring.

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Close up of the stock springs:

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