Jointer problem

[Jaromir Svoboda]

I bought old jointer few months ago.Work good but cutter head is spining at only 3,393 RPM.Its 3 blade cutter head.I did replace cutter head pulley for a smaller one.Now its spining at 4,524 RPM.The problem I do have now is jointer will turn off itself after about 3 minutes.Then I have to wait a little and press reset buttom and it will start again.
I do not understand why smaller pulley can do this.
Any idea?

Thank you.

[Ole Anderson]

Not enough horsepower to spin the head faster? Shutting off after 3 minutes indicates that the motor is likely overheating from being pushed too hard. It's like having rear end gears on a car that are too tall for a small engine. Pully size changes your gear ratio.

[John TenEyck]

You should check to see what that jointer speed was intended to be. It could be that 3400 rpm is what it was designed to run at. If so, running it faster could kill the bearings at the least, or be disasterous at the most. If the motor on the machine looks like it is original that would be a clue that it was intended to run at the lower rpm. Why not tell us what machine you have and maybe you'll get some help, or go over to the OWWM.org website and ask those guys.

[Jaromir Svoboda]

Someone replaced motor,bearing and cutter head.I do not know brand.I did look at all pictures at OWWM ,but didn't find same jointer.

[Jeff Duncan]

That may be a little fast for an older jointer. The guys at OWWM are definitely where you want to go for advice. I can't tell you why the motor is kicking out thought.

good luck,
JeffD

[Chip Lindley]

Jaromir, we need to know the horsepower and RPM of the motor on your jointer, and the diameter of the original cutterhead pulley. PHOTOS would be quite helpful!

If your motor is too small--1/3hp, 1725 rpm, that is not nearly adequate. A 1725 rpm motor looses twice it's torque, compared to a 3450 rpm motor, trying to run the jointer at a faster speed--around 4500 rpm. In your case, adding a smaller cutterhead pulley reduced your motor's torque by 25 %. 3393rpm/4524rpm=.75

The smaller pulley you installed may be binding the v-belt, helping to cause the motor to overload. A cutterhead pulley is usually already optimized for adequate belt traction. It is better advised to replace the motor pulley with a larger one for added RPMs. If the cutterhead turns smoothly, without strange noises or binding, I doubt if bearings are an issue.

The motor on your jointer could be any that was on hand, in order to sell the jointer with a motor. My rule of thumb--a 6" jointer's minimum usable motor is 1/2hp, but 3/4hp or 1hp is much better for face-jointing boards close to the jointer's full width.

[Jaromir Svoboda]

Motor is 2HP, 1,740 RPM.Original cutterhead pulley was 5".Motor pulley is 9.75".I installed 3.75" cutterhead pulley.