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

Hi guys, as a newbie in machining steam engine,  I have a question about mine:   is it possible to run a pmr 1 engine at virtually no psi or is my mesuring method false ?  I know that my engine is pretty well setup, but a bit sceptical about this result...



Here it is at 3.5 psi !

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Ok!  So I suppose that the reading on the manometer is pretty accurate.  I was thinking that some air effect in internal pressure can cause false reading in any way...  I can now pass to the next step, finition of the piping, paint and some details...  I didn't decide yet what I will drive with it,  I'm dreaming of some machine shop tools 🙄.  But I'm a so slow maker...

  I have a pmr #1 that runs but feels stiff - not the rod or crankshaft,
they are good.  It almost feels like there are 'O' rings....on the piston?
Could this be so?  And if so, how many should there be?  The builder
put three rings on the feed pump ram, more than the instructions,
but it worked with some fussing.  BTB - I'm not removing the head
to check the piston assembly until I know what to expect inside.
After all, it is a …….runner.

  Anyhow, if you could shoot me a page or two of the plans that show
the piston assembly and installation it would help.  More than one
motorhead agrees that the stiffness is, almost, rubbery.  It runs off
the pm vertical boiler but not for very long.

Thanks from Brooklyn,
Wayne

vertical boiler but not for very long.  If I could get it to tick over
on lung power, well, I'd feel like I was living in the tall cotton.

  I have a pmr #1 that runs but feels stiff - not the rod or crankshaft,
they are good.  It almost feels like there are 'O' rings....on the piston?
Could this be so?  And if so, how many should there be?  The builder
put three rings on the feed pump ram, more than the instructions,
but it worked with some fussing.

The problem can be o'rings, but it can also come from some misalignment of internal parts of the engine.  Did the builder make a good "break-in" ?  PMR provide teflon rings instead of o'rings, but the builder could choose for any reasons to put o'rings,  that work too.  For myself, I think your best way is to look inside for some wear and alignment of the piston and rod.
And I agree about the copyright, but can give you the dimensions you need...

graphite yarn or teflon yarn for rings available at local plumbing supply works well in small steam engines as well, and really no break-in period.
crazydoug

Yep!  But the engine itself, after machining, need break-in period.  If his engine feels "stiff",  I imagine it can origin from some mechanical friction caused by no or bad break-in.  Same thing if the builder choose to use, for any reason, o'rings instead of teflon or graphite...