I need a H/P recommendation for a 6" Jointer

[D Gobby]

I'm currently in the process of rebuilding a 6" Jointer that I purchased off of e-bay. This is an old Pryor Jointer with a 4 blade cutterhead, and a 54" bed. The old motor is not in very good shape and the darn thing has been painted over so as not to be able to tell the H/P or the RPM. I'm thinking that 3/4 hp should be fine. What says thee?

Darrel

[landlocked sailor]

Mine has a 1 HP that has given yeoman service for nearly 20 years. Rick

[Mrleft8]

1hp might be fine, but...... How big (Diameter) is this 4 blade cutterhead? My old 6" jointer had a 1hp motor, but the cutterhead was only about 2 1/2" in diameter.
On a side note.... This 4 blade cutterhead isn't one of those square ones is it?

[D Gobby]

The cutterhead is round and is 4" in Dia. I think I can figure out the rpm of the existing motor based off of the current pulley sizes. I'm thinking about using a 1725 rpm motor, motor pulley of 5" dia. and a cutter pulley of 3" dia. With a 4 blade cutter head this should produce 11,500 cuts per minute with a shaft speed of 2875 rpm. I'm just trying to figure out what is enough hp for this machine without going overboard.

Darrel

[Canoeyawl]

I would probably double that rpm...using a 3600 rpm motor. For example, my table saw is about 10,000 sfpm. Your plans will only get about 3000 sfpm (surface feet per minute) I think the finish will be disappointing.

[ricardo de oliveira]

Mrleft8,
Don't want to hijack the thread but I found an used jointer around here, good shape, brand new 1 hp motor and with a square four blade cutter. Fair price. What's the deal about the square cutter? I'm really ignorant about it.

[katiedobe]

Having used square head cutterhead jointers I am in a position to speak on this subject. They can take your whole hand off faster than a round head cutter due to the fact that the opening formed when the square cutterhead passes by the infeed mouth table edge changes in dimension radiacally. A round cutter head stays the same and it is more likely that you will be able to pull your hand away. Sure you will lose part of your fingertips and probably have to have the whole first bone of your finger removed to the first joint, this happened to a friend of mine. But a square cutterhead has a higher chance of grabbing your whole hand and yanking it into the opening. I have also seen it grab a piece of wood that splintered off of the bottom of the wood I was jointing and jamb it in the opening, causing all sorts of events to happen quickly. Namely the piece of wood I was pushing through flew up and bonked me on the head. You also want to make sure that you tighten the bolts down well that hold the knife in place.

As far as hp goes get a 1hp motor. It don't cost much more than a 3/4Hp and it is always nice when you are jointing a very hard piece of lumber like white oak.

[ricardo de oliveira]

Thanks, katiedobe. That's scary enough.
I'd rather chop off only my fingertips not my whole hand, so I'll keep searching a round cutter jointer plane.

[PeterSibley]

Good Ricardo, square head jointers should be hit very hard with a big hammer ,very big ....so the don't run...ever.

Fine Woodworking magazine did a comparison on all the current 6" jointers a few years ago ,Chinese and US. The normal speed was expressed in cuts per minute.The range was between 12000 and 13500 per minute.

[Mrleft8]

As stated above, square cutterheads are very dangerous. As far as RPM/SFPM.... I wouldn't ask your jointer to go any faster than it's currently set up for. A guy in a shop I used to work in decided to speed up his jointer "To make it cut smoother". He was out of work for two weeks. He's lucky he wasn't killed.

[katiedobe]

That being said about square head jointers I agree with. I just fondly remember the fence system on the old Oliver 12" I was using that had that square cutterhead. You could skew the fence so that when you wanted to you could take an angled cut across the knives and still push it tight up against the fence.
I was always careful about making sure that my fingers never passed over the knife area.

[Robmill0605]

I'll throw in my 2 cents, since I just restored a 1950 8" Northfield jointer.
A new 6" powermatic jointer uses a 1hp motor spinning a 4" round cutterhead. The speed of the cutterhead will be determined by the pulley sizes. Foe example, my jointer has a motor speed of 3850 rpm. With the pulley's that I have it has a cutterhead speed of 15,000 rpm.
These older machines are the awesome. Not to hijack this thread but you can see my jointer restoration under Restoring Vintage Machines.
I'd recommend the 1 hp motor.
Let me know if I can help you as I've just been through the process.

[PeterSibley]

I'll throw in my 2 cents, since I just restored a 1950 8" Northfield jointer.
A new 6" powermatic jointer uses a 1hp motor spinning a 4" round cutterhead. The speed of the cutterhead will be determined by the pulley sizes. Foe example, my jointer has a motor speed of 3850 rpm. With the pulley's that I have it has a cutterhead speed of 15,000 rpm.
These older machines are the awesome. Not to hijack this thread but you can see my jointer restoration under Restoring Vintage Machines.
I'd recommend the 1 hp motor.
Let me know if I can help you as I've just been through the process.

15000 rpm ! That's extremely fast ! It must beautifully balanced .

[Ron Williamson]

Robmill
I guessing you meant cpm,cuts per minute.
15000/4 knives=3750 rpm

[PeterSibley]

That would make me feel better

[Robmill0605]

opps, sorry , you are correct cuts per min.

[katiedobe]

But there is something about those old, heavy, cast iron machines. I mean the inherent stability of a machine that weighs 500 to 700 pounds is wonderful. I sure miss the old shop that I rented that had the machines from the late 1800's.

[katiedobe]

But there is something about those old, heavy, cast iron machines. I mean the inherent stability of a machine that weighs 500 to 700 pounds is wonderful. I sure miss the old shop that I rented that had the machines from the late 1800's.

[ricardo de oliveira]

take a bow:

[Robmill0605]

1950 8" Northield jointer I just restored. 1150lbs.

[img]