Needle Bearings in a model

[Philipintexas]

My Corliss engine had very large bronze bearings for its 3/4" shaft that produced lots of friction along with the many other parts all dragging on the free operation of the engine. To reduce the friction I modified both bearing holders to hide 1" X 3/4" X 3/8" needle bearings. I used commercial bronze flange bushings to make things look authentic from the outside. The needle bearings cost around $3.75 each but Boy what a difference. The shaft spins effortlessly supported on both ends by the needles. Please forgive the out-of-focus photos, but you get the idea.
I've built several hit-n-miss engines and if I do another I may incorporate this idea to get them to run as slow as possible.

 

[gbritnell]

Great execution. I'm sure if they had needle bearings in the 1800's they'd have put them on their machines.
gbritnell

 

[pete]

Yep I'd agree, very clever way to hide a modern style of bearing. I've thought of doing the same for eccentrics also and just build the eccentric in two halves and then press them together with the needle or roller bearing between the halves. Invisible, yet you still get the friction reduction. Bearings with seals or a grease lubrication would probably increase the friction to a higher level than a standard bronze sleeve type bearing though.

Pete

 

[deverett]

Very good idea that Philip, but don't needle bearings (and ball bearings) need to run on hardened shafts? Would un-hardened silver steel (drill rod) be acceptable, particularly for hit 'n' miss engines that were suggested by you?

Dave
The Emerald Isle

 

[Philipintexas]

The bearings I used roll effortlessly on the shaft and are 1/2" on one side of the flywheel and 3/4" on the other side. I imagine they will run the rest of my life without needing a hard shaft. For an engine that will run continuously it might become a problem. I think, given the nature of our hobby engines, it is more than adequate. Definitely something to consider before departing from a true scale model. The Corliss has so many points of friction I really needed to reduce everywhere I could.