# what size pulley for old delta



## GROOVY (Apr 27, 2008)

I have an old model Delta 6" jointer
the motor is 1740 RPM the pully arrangement looks like it has been replaced there is an 1 1/2" on driven and a step pully on drive.
I would like to replace the set before mounting motor.....


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## JohnK007 (Nov 14, 2009)

There's a 7 inch pulley on the motor of my Delta 37-220 6" jointer. My motor is also 1740 rpm. It is the stock motor and pulley. Can't get to the pulley on the cutterhead because I'd have to take apart the guard. If you need that info I can try to get at it later.


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## woodnthings (Jan 24, 2009)

*Based on this*

14,4000 cuts per minute with 3 knives at 4800 RPM:
*Specifications:*
Motor: 1 HP, 110V, single-phase
Maximum stock width: 6"
Maximum depth of cut: 1/8"
Maximum rabbeting capacity: 1/2"
Cutterhead diameter: 2 1/2"
*Number of knives: 3*
*Cutterhead speed: 4800 RPM*
Table size: 6" x 46"
Table height from floor: 32 1/2"
*Cuts per minute: 14, 400*
Fence size: 5"H x 35"L
Fence adjustment: positive stops @ +/- 45º & 90º
Overall dimensions: 46"L x 27-1/2"W x 49"H
Approximate shipping weight: 272 lbs.
Free pair of safety blocks 


I find that a 1 to 1 ratio with a 3450 RPM motor is not the case.
It's usually a 1/2" or so larger on the motor to give the 4800 RPMs. So with a 1750 RPM motor 1/1/2" on the cutter head, which is very small, I'd go to 5" or 6" on the motor and 2" or 2 1/2" on the cutter. 
You can do the math back from 4800 RPM if you start with the motor. 4800/3450 = 1.39 ratio 4800/1750 = 2.75 ratio or roughly 3 to 1. 6" motor/2.2" cutter = 2.72" close enough....
 bill


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## GROOVY (Apr 27, 2008)

Thanks is the 7" on the rim of the pully?
its a 1/3 hp motor. 3 blade cutter head


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## JohnK007 (Nov 14, 2009)

GROOVY said:


> Thanks is the 7" on the rim of the pully?
> its a 1/3 hp motor. 3 blade cutter head


It's 7" rim to rim. The motor is 3/4 hp 1725 rpm. 3 blade cutterhead like yours. I'll remove the guard and measure the pulley on the cutterhead for you later today.


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## woodnthings (Jan 24, 2009)

*1/3 hp?*



GROOVY said:


> Thanks is the 7" on the rim of the pully?
> its a 1/3 hp motor. 3 blade cutter head


That oughta be just enough to create a gentle breeze in the shop :thumbdown: You gotta be kiddin us. If it works more power to you....if it doesn't...more power to you.... about 2 more oughta do it.  bill


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## GROOVY (Apr 27, 2008)

yes 1/3 old school motor babbit bearings and was home to some small critters rus well shaft straight.... the drive largest choice was 4" 
It for sure is too slow as it is........ thinking about cruising craigslist for more power and RPMs


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## JohnK007 (Nov 14, 2009)

Measured the pulley on the cutterhead for ya. It's 2 7/8" rim to rim. Like I said, my motor is also 1725 rpm and the cutter spins plenty fast but I think you'll get better performance with a beefier hp motor. Using an online pulley calculator, my 7" drive pulley going at 1725 rpm's is twirling a 2.875" cutterhead pulley at 4200 rpm's. Times 3 knives in the head and that's 12,600 cuts per minute.

If you put that 4" pulley you have on a 3450 rpm motor and belt it to a 3" pulley on the cutter, it should turn at 4600 rpm. A 2 7/8" driven pulley, like on mine, would yield 4800 rpm. I'd be careful going much faster at the cutterhead. I don't know what the gibs holding those knives in are rated for. If it were me I'd just try to find a 3/4 hp 1725 rpm motor and get pulleys sized like I have on mine. As far as I can tell everything on mine is stock the way it came from Delta. I'm sure they engineered it with that pulley ratio for a reason.

In any case, good luck Groovy! Let us know how it works out.


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