36" Northfield Bandsaw: What size motor?

[Sal Kurban]

Fellow Creekers,
I am working on a 36" 1959 Northfield bandsaw. It has been converted to belt drive. It came with a 2 HP single phase, which I intend to upgrade. The saw has 16" resaw capacity. I currently have two spare electric motors: a 5 HP Dayton TEFC single phase 1740 rpm and another 10 HP 3 phase 1700 rpm TEFC motor. Am leaning towards the 5 HP single phase based on the resaw capacity as the 10 HP would be an overkill... As always, thanks for any feedback...
Sal.

[Andrew Fleck]

Sal,
You get your hands on some awfully big bandsaws. I saw your other ones in the classifieds a while back.

Most 36" saws I see usually have a 5hp motor on them. 7.5hp might be perfect, but I think a 5hp will do the trick. I can't imagine slowing one down even while resawing 16".

[Judson Green]

Quite a while ago I had a old crescent 30" with a 2hp DMD. No slowing it down but it was also a big motor for only 2hp.

[Sal Kurban]

Sal,
You get your hands on some awfully big bandsaws. I saw your other ones in the classifieds a while back.

Most 36" saws I see usually have a 5hp motor on them. 7.5hp might be perfect, but I think a 5hp will do the trick. I can't imagine slowing one down even while resawing 16".

Yeah, the bandsaws disappeared. I think there have been very good boys and Santa snatched the bandsaws for them ;) When I see old cast arn, cannot help it. This is the first 36" that I laid my hands onto though... This is definitely a keeper. Currently I have the Centauro 700 (a 27.5" cast iron beast) and a vintage Powermatic 141 and that is all.
Cheers,
Sal.

[David Kumm]

Generally the 5 hp should be fine. Most old cast iron saws were direct drive and 700 RPM so they had lots of torque. Most 36" had 21" resaw capability but northfield made saws with both more and less. I would prefer three phase as the saw is hard starting but if the 5 hp is a stout frame quality motor you should be golden. Dave

[Stephen Cherry]

One thing to think about is that in starting heavy loads; a little belt slip can be your friend. It can make it easier on the motor, with less chance of overloading the circuit.

[jack forsberg]

had a 2 hp! wow that pathetic. 5 hp is light for a 36" saw and the 10 would not be over kill by any means. I have 5hp on a 30" wadkin and at times is lacking.

[Judson Green]

had a 2 hp! wow that pathetic. 5 hp is light for a 36" saw and the 10 would not be over kill by any means. I have 5hp on a 30" wadkin and at times is lacking.

Only 2hp that's what I thought. But that was a big 2hp, probably 16 inches diameter maybe more. Plenty tough. Lots of torque.

[Ed Griner]

I put a 2hp on my Delta 14" and my Bridgewood/ACM 20" has 5hp Marathon motor. Both are more than up to any task. Nothing worse than an under powered bandsaw! I think 5/7.5hp would be in the ballpark for a 36" bandsaw.

[Ben Martin]

Fellow Creekers,
I am working on a 36" 1959 Northfield bandsaw. It has been converted to belt drive. It came with a 2 HP single phase, which I intend to upgrade. The saw has 16" resaw capacity. I currently have two spare electric motors: a 5 HP Dayton TEFC single phase 1740 rpm and another 10 HP 3 phase 1700 rpm TEFC motor. Am leaning towards the 5 HP single phase based on the resaw capacity as the 10 HP would be an overkill... As always, thanks for any feedback...
Sal.

Sal,

Hopefully the conversion to belt drive was done by somebody who knew what they were doing. Northfield sits the direct drive motors in babbit to get all of the adjustments fine tuned, the conversion could have potentially thrown everything out of whack...

What final SFPM are you shooting for? Will this saw be sat up specifically for resawing or general use? Are your wheels AL like most Northfield saws?

My 20" Northfield has a 900 RPM motor and thus is a bit too fast for solely resawing work, but it does work. The 2HP Crescent that Judson is talking about might be the version that had basically a flywheel as a lower wheel, so you could get away with a under powered saw...

A little more info would help for people to give you an educated answer. :D

Ben

[David Kumm]

Most of the old 30" saws ran 900 rpm motors and 6700 fpm. Not too fast for resawing and much faster than a 20" wheel at that rpm. That speed helps with the feed speed and is a reason the old saws ran smaller motors ( in addition to the motors being huge cast iron frame ones ). Tanny used 900 rpm motors on their 36" ( 8400 fpm ) although most others used 700 which dropped the speed to 6700. It is not the size of the wheels but the resaw height that is relevant here. 16" means the saw was a special short version and closer to the 30" in height. 20" saws ran 1-2 hp motors with 10-12" resaw, 30" ran 3 hp with 15" resaw and larger saws ran 5 hp and higher. While I think the 5 hp will serve just fine, I like three phase enough that I'd be tempted to go with the 10 hp and a vfd to dial in the fpm to the application. Sal, you've done that before so it should be easy. Dave

[Steve Rozmiarek]

I run 5hp in my 36" Oliver, it works great. However, the speed was off as several of the guys mentioned when I changed out the 2hp to the new 5. No big deal on my saw, just different pulleys to get where I wanted. If it was me, I agree with David, 10hp and VFD. Soft start and variable speed would be pretty cool.

Oh, and when I was doing the motor change, several people told me that the old 2hp rated motors actually produced power more similar to a bigger motor by today's rating system.

[Erik Loza]

The three-phase motor would be my choice on a saw that size. Good luck,

Erik Loza
Minimax USA

[David Kumm]

As a frame of reference, the 5 hp motor on my Oliver 116 DD is 19.6 FLA. Dave

[Sal Kurban]

Sal,

Hopefully the conversion to belt drive was done by somebody who knew what they were doing. Northfield sits the direct drive motors in babbit to get all of the adjustments fine tuned, the conversion could have potentially thrown everything out of whack...

What final SFPM are you shooting for? Will this saw be sat up specifically for resawing or general use? Are your wheels AL like most Northfield saws?

My 20" Northfield has a 900 RPM motor and thus is a bit too fast for solely resawing work, but it does work. The 2HP Crescent that Judson is talking about might be the version that had basically a flywheel as a lower wheel, so you could get away with a under powered saw...

A little more info would help for people to give you an educated answer. :D

Ben



I think the conversion was decent. They used pillow block bearings and a 11.25" double belt cast iron balanced pulley. I intend to use a 3.75" pulley which would give me a gear ratio of 1/3. With 1740 rpm, the SFPM is 5463. The fellow at Northfield suggested about 6000 SFPM for resawing. Below are some pictures.

First picture is the conversion. Secon picture is a brand new Dayton single phase 5 HP 1740 RPM motor. 3rd picture is a US Motors (Division of Emerson Electric) 3 PH 10 HP 1440 RPM motor. The last picture is the 2 HP 1750 RPM Century Electric Single phase motor. Notice how the 2 HP Century Electric dwarfs the 5 HP Dayton motor.

Now If I use the 10 HP, I will achieve 4521 SFPM. Is that adequate?
Thanks to all for the input,

Sal.



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[Sal Kurban]

Just for clarification, the original direct drive on this Northfield was a 3 HP, 900 RPM motor. That translates to 8478 SFPM and Northfield apparently did not mind that.
Sal

[mreza Salav]

I agree a 3-phase with VFD would be nice on a bandsaw. For a recent task I installed my powerfeeder on my smaller (24") bandsaw to resaw hundres of feet. The resaw job was small height (only at 4") but the speed of powerfeed was a tad too fast. So I increased the speed of the saw (by about 10%) to keep up. It worked fine. I imagine it works euqaully good to run it slower if one needs.

[Steve Rozmiarek]

Just for clarification, the original direct drive on this Northfield was a 3 HP, 900 RPM motor. That translates to 8478 SFPM and Northfield apparently did not mind that.
Sal


Wow thats fast. My saw was running in that range before I changed pulleys. It sure cut, but it just felt too fast to me. No objective reason, it just made me uneasy.

[jack forsberg]

5000 sfm is the target range for resawing. faster has proven bad on the tooth set for deep cuts . the high speeds saws are curvy cut saws You need HP to resaw too. this is my Wadkin with a 5 hp 1200 rpm DD motor and is a high speed saw and i wish it had a 10 hp one it. As for VFD you still want a slow speed motor and 600 rpm would be ideal. you can lower the speed of motors but as you drop hzs hp is also lost. you lower the hzs and the cooling fan runs slower on the motor too. some just add a fan to cool the motor if there working them hard and at less than 60 hz.

5 HP is not that powerful for a saw that size IMHO

https://www.youtube.com/watch?v=fYVqoiWFeBg

[David Kumm]

Generally a VFD will provide almost full power down to about 30 hz. Even less but the fan cooling becomes an issue then. If you use a vfd to speed up a motor you lose power at a rate of about 1% per HZ. Better to slow a motor 30 hz than speed one up 30 hz if you want full power. When running a resaw blade fast, the Lenox CT 1.3 is a good choice as fewer teeth compensate for the speed to some extent. Old bandsaws were production machines and nothing was run as slowly as we hobby guys tend to do. Look at the old vertical borers that ran at 3500 rpm. Scares you to death at that speed but common back when fingers were considered optional. Dave

[jack forsberg]

Generally a VFD will provide almost full power down to about 30 hz. Even less but the fan cooling becomes an issue then. If you use a vfd to speed up a motor you lose power at a rate of about 1% per HZ. Better to slow a motor 30 hz than speed one up 30 hz if you want full power. When running a resaw blade fast, the Lenox CT 1.3 is a good choice as fewer teeth compensate for the speed to some extent. Old bandsaws were production machines and nothing was run as slowly as we hobby guys tend to do. Look at the old vertical borers that ran at 3500 rpm. Scares you to death at that speed but common back when fingers were considered optional. Dave

Dave you are mixing up torque with HP with a VFD HP is constant above 60hz and drops proportionally below 60hz. so a motor of 10 HP would only be 5 HP at 30hz . Hp is what does the work not torque Dave. so its better to over run a motor if you want power or over size the motor like many machine makers do it you wish to lower it and maintain a HP at a given speed.

[David Kumm]

Jack, this stuff is over my pay grade but I thought torque was relevant when running bandsaws, saws, shapers etc. HP drops when rpm drops and torque stays constant when a motor is slowed but hp drops as the motor is speeded up over its rated speed as torque remains the constant. For the motor to run at full power over 60 hz the voltage would need to increase in the power supply proportionately. I lost this argument with an electrical guy who told me to always use a larger motor and slow it rather than the other way around. Dave

[jack forsberg]

Jack, this stuff is over my pay grade but I thought torque was relevant when running bandsaws, saws, shapers etc. HP drops when rpm drops and torque stays constant when a motor is slowed but hp drops as the motor is speeded up over its rated speed as torque remains the constant. For the motor to run at full power over 60 hz the voltage would need to increase in the power supply proportionately. I lost this argument with an electrical guy who told me to always use a larger motor and slow it rather than the other way around. Dave

much of what the electrical guy was saying is true but it based on the motor its self as a machine . Most motors in the industry are 2 poll (3450 RPM) and 4 pool (1750 RPM). If you over run a 2 poll motor its hard on the bearings and motors where made special from this case when frequency changer where the motor speed control of the day. It was not uncommon to run these motors at speed of 10,000 rpm with these rotary frequency changers and special bearings. these motors were generally rated to 120 hzs. If you start with a slow motor with more polls like the 4 pool and run it at 120 hz there is no problem it just running at the speed of the the 2 poll motor and the bearing are fine with that. this is way i recommend a slow speed motor is best. slow speed motors are very large so they can cool the winding at slow speed that's is the reason there large in most cases.

[David Kumm]

Jack, we are kind of off topic but assuming that you are not taking gearing into effect, it is safe to say a 5 hp 3450 rpm motor at 60hz will provide the same torque at 30hz but the hp will be approx 2.5 so a 5 hp 1750 motor is a better choice. A 5 hp 1750 rpm motor at 60 hz will hold it's torque and thus increase hp for a limited range 60-70 hz or so but then the lack of additional voltage negates and reduces the power of the motor such that at 3450 that motor will no longer be near 5 hp even at the additional rpm. Both torque and hp are going down faster than rpms are increasing. When speeding up a motor it needs to be oversized at the start to compensate. Dave

[Larry Edgerton]

Sal, I converted my 36" Oliver from flat belt to Vbelt and used a 5Hp Baldor. Did everything that I wanted to do.

Wish I had known, I have a new 5 Hp 3ph Baldor on the shelf from my Porter jointer that I sold. Still has a flat belt pulley on it.

Larry

[Keith Hankins]

Call Northfield. They are still in business and they will put you to a guy there that deals with the old stuff that's still out there. He will tell you exactly what was original and make a recommendation. I have an early 60's planer and they made a dust hood for me and provided me with original decals and owners manual.

[Sal Kurban]

Call Northfield. They are still in business and they will put you to a guy there that deals with the old stuff that's still out there. He will tell you exactly what was original and make a recommendation. I have an early 60's planer and they made a dust hood for me and provided me with original decals and owners manual.

That was the first thing I did. Not only did they gave me their recommendation, (they said 5 HP is fine, max blade width 1 1/4 1.3 tpi, 6000 SFPM blade speed) they provided me with the original configuration: 3 HP direct drive, 900 rpm, 3 PH motor, etc. They also gave me the history based on their registry: The machine was purchased by Meramec Mining of Potosi, MO in 1959. They also listed 4 other owners prior to me. They are incredible; they also stock all the parts. They also said this machine retails for nearly $18 K at the moment. One sticker shock is the tires: If I needed to replace mine, they would cost $1200 for a set!
Sal.

[David Kumm]

Call bobby at Woodworkers Tool Works in Wisconsin about the tires. If the saw has Carter wheels you for sure don't want to screw them up. Really expensive. Dave