Joa wrote:

Pardon my ignorance but how exactly is this "taper" machined into the shaft?
Are these inserts, if so how many?  What is the dished out portion?

Thanks.

Joa
______________________
PIW Engraving and Milling
      "Affordable CNC"

This PSRU is not something you want to make unless you have a pretty
good machine shop or have access to one. The PSRU shown on the ACRE NL web site 
would be easier to make. No taper is required and the shaft is larger and
stronger.

To cut a taper you stick the shaft in a lathe, set the taper attachment 
angle and start cutting. You do the same for the flange. The shallower
the taper angle the stronger the joint up to a point but the harder it is 
to get it apart. 

The four keyway slots need
to be broached or milled. No mention is made of this in the plans.
You will need to send this out in any event. 
 
Virg recommends lapping the two together with valve grinding
compound which is a real good idea.

Those dished out things are two Woodruff keys 180 degrees apart. The same 
type of key and taper is used on the Mazda 13B e-shaft for the flywheel.

Without the taper, built as the plans show, this PSRU is dangerous.
All loads go through a 1.25 diameter tube with 5/8th threads cut on the
inside and keyway slots cut on the outside. A sure way to start a 
fatigue crack and lose the prop.

Paul Lamar
 
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