I need a new 3 HP motor for my Powermatic 100 planer. The motor compartment & mount allow for either 3450 or 1725, and a manual for a 1965 version of this planer gives pulley sizes for both speeds.
The newer manual for my 1987 version calls for a 3600 rpm motor ( ! ) with no mention of any other rpm.
Obviously, both will get me to the proper head rpm, and I suppose I should use a 3450 to keep things more "stock" (is there such a thing as a 3600?) -but it seems to me there are three minor reasons to choose 1725 instead, even though the bigger pulley will cost a lot more:
1: The wider diameter pulley would give less strain to the belts. I suppose I could get link-belts, but the vintage guys over at OWWM are vehemently against this,and they've kind of swayed me. Plus, why spend the money if I don't have to?
2: The wider diameter pulley would give more contact area to the belts.
3: The significantly larger pulley needed on a 1725 rpm motor is a lot heavier, so it should be more stable AND add a small amount of smoothness and resistance to speed change. Very minor, of course, but it's surely a factor.
So it seems logical to me to go with 1725., except that the company chose to go with 3600, when they decided to offer / recommend only one speed, and I'm wondering if there was a good reason, or was it just convenient somehow?
Also, the smaller pulley for a 3450 would save me $45.
Your thoughts?