Turbine Shaft Part III


The power turbine shaft is completed!

  The pinion end was screwcut 12-24, and the turbine end of the shaft was cut 1/4-28. Before doing this, I created both nuts out of 316 SS hex stock to act as guages for the screwcutting operation, as I cut the nuts with a tap. The nuts become my "test fit" as I approach the final dimensions while cutting the shaft.
With both shaft ends screw cut, the nuts are put in place to test. Both nuts have a fairly tight fit, as we want them.
One machining operation remains... the turbine end of the shaft must be milled or filed for a spanner wrench. Mike uses the simple method of filing a pair of flats. I decided to use a mill jig, and also decided that cutting a hex would be just as easy as a pair of flats. The mill device shown here is a Hardinge 5C collet fixture which provides for division by 24, or any number thereof. Note the spindle of the device has the proprietary Hardinge taper lock, which allows me to use my lathe chucks in the mill. Very handy.
The shaft is chucked and milled for a 3/16" hex socket wrench. Just a tiny bit of thread groove remains on the flats... this won't hurt anything.
Final pinion end shaft assembly. I polished both the bearing and pinion diameters for a press fit of perhaps 0.0004", light but beyond any hand press. First, I degreased everything and then applied sleeve retainer Loctite. Probably not needed for the press fit, but it can't hurt anything. The shaft is assembled with the bearing, oil thrower, and pinion, in order. A small hydraulic press was used, but a mill vise would work as well with a hollow tube acting as a pushrod. The bearing is fully seated, then the oil thrower installed. Lastly, on went the pinion.
The completed pinion end of the turbine shaft...
...and the entire shaft ready for installation!

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