12-15000 cuts per minute is a good speed for jointing,
so if your cutterhead has 3 knives, you want about 5000 rpms
on the cutterhead.
Those specs are BS. You'll get better jointer performance
running a 3450rpm motor. If the cutterhead pulley is 2"
then a 4" pulley on a 3450 motor gets the cutterhead
moving fast enough for clean jointing.
Just my opinion, understand. I've set up a lot of jointers
with motors over the years.
With a 1725 rpm motor you need a 7" or 8" pulley. I know
because I have such a big old motor in my yard I pulled off
a jointer and I cannot get the big pulley off the shaft. I
was going to throw the motor away (big old repulsion
motor) but desire to possess the pulley stayed my hand.