Wanted - 1.5 HP Motor for Delta 8in Jointer Restoration - Found

tijmt

Jared
User
I was able to grab an 8in Delta jointer to restore, but unfortunately (for me) it came with a 3 Phase motor.

I was wondering if anyone had a 1.5 HP 1PH 1725RPM motor (the ideal would be TEFC and with manual protector) that they would be willing to sell or trade?

The motor that came with it is a 1953-1954 Delta 1.5HP 3 Phase 1725RPM with dual 3/4 arbors. I was not able to test it as I do not have 3 phase power.
 

Oka

Oka
Corporate Member
see if the motor is invertable, if so a 100.00 inverter vfd will allow you to run on 220 single phase
 

Pop Golden

Pop
Corporate Member
I'm using Harbor Fright motors. They seem to hold up well to wood shop use. I'm not sure if they have a 1-1/2 hp. I'm using a 2 hp. in place of a 1-1/2 hp.

Pop
 

Alan in Little Washington

Alan Schaffter
Corporate Member
Besides being 3 phase, the RPM of your motor is a little low. My 1980's DJ-20 came with an open frame, 1.5 hp 3450 rpm motor (cutting head RPM of 5,500). When I put a Shelix head on it, I replaced the motor with a 2 hp, 3450 RPM TFEC.
 

tijmt

Jared
User
@Oka I think it can be inverted to phase 1, but I read that I would lose 1/3 of the horsepower. I figured I might as well just get a 1PH motor so I did not go down to 1HP.

@Pop Golden I did look into a HF motor but given all of the work it will take to restore the jointer, I wanted to stick with a USA made motor. (I know, I am a bit crazy)

@Alan in Little Washington I never thought about changing the RPM on the motor. Did you have to change the pulley size when you increased the RPM? I need to replace the pull either way since most modern motors do not have 3/4 arbor so definitely something to think about.

One other question, I have heard that the helical heads need a bit more power, but does it also need greater speed? Either way, is there any easy way to estimate speed of your cutter head based on say motor, pulleys, and belts?
 

Alan in Little Washington

Alan Schaffter
Corporate Member
I didn't increase the RPM- the originally supplied Delta motor was 3450 RPM. I used the same pulleys, so there was no change in the approx 5000+ cutter head RPM which is the proper speed for almost every jointer with straight or helical-segmented cutter heads. You can verify online, check the specs- some examples (cutter head RPM): Grizzly 8"(4800), Jet 8" (5500), Powermatic 8" (6000-7000). So unless you have a pretty large diameter pulley* on the motor and a pretty small one on the cutter head you really should have a 3450 RPM motor.

Multiply pulley ratio times motor RPM to determine cutterhead RPM

* I used the ratio of cutterhead RPM and motor RPM to determine pulley sizes you might need= 5400 / 1725 = 3.13 which means if you use a 1725 RPM motor, you'll need a 6.26" diam. pulley on the motor and a 2" diam. pulley on the cutter head to achieve 5400 RPM at the cutterhead. (note- changing the pulleys alone will result in less power to the cutterhead.)

It is a common misunderstanding/misreading of inverter specs- inverters do not decrease the motor hp- most inverters are designed to run on higher voltages (240V (and higher) / 3 phase power source), but many can also produce 3ph / 240V from single phase / 240V input, and some from a 120V input. It all depends on the inverter and specs- they are built differently and have different specs. You may need to derate the inverter to protect the inverter circuitry, not the motor, e.g. if an inverter, while supplied with single phase / 240 V, is primarily designed to operate a 2 hp motor, it may also operate on 120V but may only be rated for a 1.5 hp motor when supplied with 120V. It should say in the inverter specs. (often a table)
 

tijmt

Jared
User
@Alan in Little Washington Thanks for the great write up.

From what I understand looking at the old catalogs and owwm.org, in the 50s Delta did ship their jointers with 1725 RPM motors. As you suspected, the pulley on the cutterhead is 1.5-2 in (I would need to go out and measure) and the pulley on the motor is 6in. Thanks for the formulas. I will grab the exact sizes and work out the speed.

I really have not looked at upgrading to 2HP since the max delta suggested was 1.5HP (but that might be because 2HP motors were too expensive in the 50s), but maybe with the helical head it would be better to upgrade it.

Thanks for the info on the inverter. The more I think about it, I am not sure I want to use a 220 for 1.5HP, but if I don’t replace the motor and decide to use the original, it is great to know this is an option I need to research more!
 

Oka

Oka
Corporate Member
No That's not true for VFD's on a rotary 1 phase to 3 phase converter you do lose 1/3 of your output, but with a 1 phase input VFD to run a 3 phase motor via the VFD you only lose 2-4%. So, essentially, your do not de-rate the motor's nameplate ratings.

BUT, you do want to derate the VFD. So, if the you have a 1hp or 2 hp motor you want to use a 1-3 hp rated VFD. But if it was a 3 hp motor, you would get a 5 hp rated VFD.

:cool:


@Oka I think it can be inverted to phase 1, but I read that I would lose 1/3 of the horsepower. I figured I might as well just get a 1PH motor so I did not go down to 1HP.
 

tijmt

Jared
User
@Oka Thanks for the clarification! If I decide to keep the old motor I will go down that route! I am just not sure it is worth going to 220 for 1.5HP. If I go to 220 and my Jointer can handle it, I might go to 2HP.
 

Oka

Oka
Corporate Member
Motors are a science of themselves ........ in general 1750rpm motors normally have 4 windings vs 2 windings for 3450rpm motors, ergo the higher cost. Usually the 1750 motor will perform better than the 3450rpm motors using a VFD. Higher RPM motors will heat up down around 10-15% .

Best recommendation- if you buy 3ph motors make sure they are inverter ready.
 

bob vaughan

Bob Vaughan
Senior User
Probably the best case will be to use a 1.5 HP TEFC 3450 RPM single phase motor. Half the pulley size. Connect the motor to run on 230 volts single phase. A 1.5 HP motor on 120 volts sucks up a lot of juice and challenges most existing residential wiring. Using 230 volts has the added advantage of requiring a switch and cord that aren't nearly as heavy as that needed for 120 volts.
 

tijmt

Jared
User
Thanks everyone! Someone on the site sent me a PM and had a motor that matched the specs I was looking for. I might try something different in the future (and there were lots of great suggestions!), but for now, I think I will just use this motor with an identically sized new pulley with a 5/8 bore. (To match the new motor)

Thanks again for all of your thoughts and comments!
 

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