PM Research #4 - Quarter Horse Vertical Steam Engine

[RReid]

I'll second and third what Chris and Mike said. I do both things fairly often. I tend to prefer boring to reaming whenever possible. Not only is it cheaper (and I'm cheap), but I can (try to) get the exact fit I want (tight, snug, running, loose,whatever). Besides, what better way to exercise your newly hot-rodded lathe?

[propforward]

Well that settles it!

I may have been a bit gun shy after my last boring adventure, but today every cut I made that I finished with a spring cut came out at the dimension I was shooting for, so given that I should just keep going. The finish in the bore right now is pretty reasonable, so with a bit more care should end up just fine.

Thanks everyone for your comments - very helpful and greatly appreciated!

[crueby]

Spring cuts are your friend!   When boring out, one thing I like to do (when I remember anyway) is to test out speeds of turning/feed and depth of cut before reaching final dimension, to see if changing anything slightly will give a smoother finish. Sometimes need to adjust the boring bar up/down slightly or put in a fresh insert - better to find out before that final pass! With proper setup its normally possible to get a nice shiny smooth finish.
 

[larry_g]

A couple of things that worked well for me on my engine.

On the eccentric strap the print has you drill through the threaded rod connection point and into the strap so that the hole in the strap becomes an oil hole.  I moved this oil hole around so that it is between the rod and the connecting bolt.  This allows easier oiling and access to the grub screw in the eccentric so one can adjust the timing without removing the eccentric strap. ( Thank you Keith Appleton)  Also with mod you can line up the grub screw hole with the oil port and fill it with oil, making it somewhat a reservoir.

On the valverod to the flex joint connection I deleted the pin and made this connection threaded. I extended the length of the coupling so that it had plenty of thread length. My thinking was that as designed you could only adjust the valve position by one thread pitch at the eccentric strap and I wanted something finer.  Once running I could adjust the valve position, while running, by turning the valve rod by hand and getting the best running that I could. 

These two changes made getting the valve timing and position very easy and for me it was a success.

lg
no neat sig line

[propforward]

Hi Larry,

Thanks for those suggestions. They are solid improvements and I think I will implement both of them. The threaded connection you mention for the valve rod is a lot like the design on the PMR#1, so I'm sort of surprised PMR didn't already include it here. Thanks for mentioning it. I am also planning on making a tapered lock collar for securing the flywheel to the crank shaft, copying Stan Shires on that one.

No work on the engine last week - crunch time at work on a big project. Lots of overtime, then we had a weekend away. Hopefully get back in the shop this week.

Dratted work. Got to pay for the hobby somehow though, and have money available for materials in retirement. Ho hum.

[propforward]

Haven't been in the shed much the last 2 weeks, what with trips, overtime and a night at the opera thrown in. What time I did get in was mostly making some jigs and fixtures. But I did get this finished today.





 Not very much to say about it. I have plans for more interesting parts in the coming weekends, so I'm looking forward to that.