I managed to weld up the clutch basket / shaft for the lathe I am repairing okay fine. Didn't damage the threaded sections and it is still straight if we can trust my tenths indicator.
I used the fiberglass tape suggestion in an earlier threads, wrapped tin foil around mounted bearings that I couldn't get of non destructively.
Welding, I put opposite strips weld on the fill and non fill side to keep distortions minimized. I took my time too.
I used the short bapps of weld on opposite sides.
One trick that helped was I set my 3W LED maglight positioned so that I could really see what I was doing from under the hood.
Decided the section could stand losing 0.015" on diameter, I have to bush the pulley anyway so I'm taking the easy route on this.
Now I'm down to putting a woodruff key in. I can't exactly tell what was in it due to the damage. The pulley groove is 3/16" and a fragment of key was 3/4" long but I wouldn't bet it wasn't 7/8" or 1" too, those see to be sizes I can get a key in.`
So I started calculating things. A 3HP motor puts out ~4.4 lb/ft of torque at3600, doubled if the motor is half that rpm, I can't remember what it is atm.
There is a pulley ratio of 1:2 motor:driven clutch so now I have 8.8 lb/ft at the pulley / shaft interface that is a ratio based on diameter of shaft of 24.34 giving 214 lb of force on the key at the shear line.
A 3/4 x 3/16 key has .140 sq/in in shear. Using 60Ksi that would mean I'd have to generate 8437 lbs at the shear line to shear the key.
So the questions are:
Is there a standard shear value in KSI for woodruff keys? I'd think we would want them to give rather than the expensive parts but my assumption could be wrong.
What kind of safety margin is typically used in this kind of application?
Thanks in advance,