Motor Question 1725 versus 3450 rpm?

[Doug Hepler]

Guys,

My reasoning was faulty but I think that my conclusion was correct nonetheless. I did not recognize that the HP of a motor is directly proportional to the RPM, so for a given torque doubling the rpm doubles the HP. The formula is approximately HP=(torque x rpm)/5252. So for a given HP (say 2 HP) doubling the rpm would halve the torque. That was my original point, although badly argued.

Doug

[Mark R Webster]

Thanks Doug... I think my brain is hurting ;-)

[Doug Hepler]

Mark,

"I think my brain is hurting" Mine, too. This is pretty much hijacking your thread with an esoteric discussion. Unless you buy a low-powered motor relative to the work you plan to do, I doubt the difference in torque will matter much to you. There are too many other practical variables like price, value for money, availability, etc. I love a good argument but I think I am done.

All best wishes

Doug

[Mark R Webster]

Thanks Doug

[Rick Lizek]

Sears Park planers were sold with a 1750 rpm motor and the cutter head speed was listed around 4000 to 4500 rpm.

[lowell holmes]

Intuitively, I always replace the motor with the size and rpm of the motor I am replacing.

That is assuming the old motor has been satisfactory in performance. Why would you change?

[Mark R Webster]

Yes, mine is a Sears Parks planer and the 1 hp on it is a 1750. I have decided to go with the 1750 in a 2 hp. Thanks guys