Jointer cutter head RPM

[Jaromir Svoboda]

Few week back I bough old 16" jointer with 2 hp ,3 ph motor.I am looking for bigger motor 5 hp,1 ph.Can someone tell me how fast is cutter head spining? Motor : 1,740 RPM with 9.75" pulley,cutter head pulley is 5".
Also if I get 3,600 RPM motor what size pulley I need to keep same RPM of cutter head?
Thank you.

[Chip Lindley]

...Can someone tell me how fast is cutter head spining? Motor : 1,740 RPM with 9.75" pulley,cutter head pulley is 5".
Also if I get 3,600 RPM motor what size pulley I need to keep same RPM of cutter head?

Hi Jaromir! Let's do the math:

9.75" / 5" = 1.95 X 1740 = 3393 (your current cutterhead rpm.)

3393 rpm is about right for a big 16" jointer with babbit bearing journals.

If your jointer has modern ball bearing journals, you can go faster to about 5000 rpm.

5000 / 3600 = 1.3888 X 5" = 6.944" (7" motor pulley gives a cutterhead speed of 5040 rpm.)

[Steve Jenkins]

Chip's math looks good however I have a 16" direct drive jointer. it spins at about 3300 rpm. If you just slow down your feed rate you can get just as good a finish as a higher speed cutterhead

[Jaromir Svoboda]

It does have ball bearing jurnals.
Thank you.

[Josiah Bartlett]

A 2 pole induction motor actually spins at 3450 RPM on 60 Hz, due to the slip angle required to induce the field in the rotor. Only synchronous motors spin at 3600 RPM, and those are rare in small horsepower configuration.