24" planer electrical question.

[Jonathan Spool]

I have the opportunity to purchase a 24" Delta Rockwell planer for $1700.
Problem is that it is 3 phase 7.5hp, and I don't have 3 phase, or the wiring available for a 7.5hp machine. Is it possible to run a 7.5hp 3phase motor through a VFD, from a 30 amp supply, and just pull 5hp from the motor. I may be barking up a tree here, and might be better off seeing what a new 5hp 1ph motor will cost???? Can anyone with a 24" planer let me know their opinion as to whether 5hp will be sufficient?

[Chip Lindley]

Thats one BIG planer! The price is right, but are you sure you need that much machine? The VFD aficianados can chime in, but IMO, that is not the way to go for a large 7.5hp motor. First of all, you can probably replace your motor with a single-phase for the price of a 7.5hp VFD. IF you are limited to a 30A circuit, a 5hp motor is your usable maximum.

Most RPCs that would power a 7.5hp motor work on 40A circuits. My ARCO Model R does. But the 7.5hp single-phase motor on my Woodmaster double drum sander pulls 30A. max but runs on a 40A circuit! Repowering with a single-phase 5hp motor would be doable, but would leave that big 24" planer a bit underpowered. Unless you plan on planing maximum width often, you may never notice. Big commercial planers are "over-powered" so that the motors are never pushed to their max except in extreme circumstances. Most RC63s I have seen have a 10hp 3-ph motor.

Too bad you're not closer. I have a 5hp 20" Shop Fox I would swap you for it! I still kick myself for not buying a pristine Rockwell RC63 for $1500 back about '93! Oh, well!

~Chip~

[Jeff Duncan]

I'm with Chip, I had a 5hp 20" a few years back and it was really underpowered. Now of course it depends on what you do with it, and I know there are many who will say they have a 5hp 20" that works fine. But I'm used to using industrial machinery and if your trying to do any real work 5 hp is not enough for a 24" machine. My current 20" machine has 9hp motor and runs like a champ. For a 24" I'd shoot for 10 Hp+ to have a decent amount of power to work with.

I don't know enough about what you do to give you advice whether or not to buy, but my guess is you may be better served looking for something that will work within your power supply. There's certainly no lack of machinery on the market.

good luck,
JeffD

[Stephen Cherry]

All good advice so far. I have a 7.5 hp saw that I use with a rotary phase converter with a 15 hp idler. I have it on a 30 amp breaker right now, just to be conservative, but it has popped the breaker while running my shaper. 40 amps would be the more appropriate size. I scrounged heavily for my phase converter, and it was not cheap. I used all industrial quality parts- many of the phase converters on the market are a little low on the quality scale.. To buy something good off of the shelf would be about the price of the planer. Even the wire is far from cheap. The great thing about a phase converter is that it will open things up for industrial machinery.

For a vfd, you can generally use a 15 hp vfd to run a 7.5 hp motor off of single phase power.

Another option would be a 7.5 hp single phase motor. These are used sometimes in compressors.

[Scott T Smith]

I've had a 7.5 hp, 3-phase 20" spiral cutterhead planer and operated it off of an RPC, and I don't think that a 30 amp service will be adequate; probably 40 or 50 amp minimum. In my instance, I was running mine off of a 30 hp RPC, so it required much more than 30A, but even then it would still trip a circuit breaker on the planer itself when planing wide boards (and taking off more than 1/8").

I would also not suggest reducing the motor HP; I felt that my 20" was underpowered with the 7.5 hp motor.

[Jonathan Spool]

I was thinking that running a 24" planer on a 5hp motor wouldn't be any different than running a 20" planer with a 5hp motor, as long as the stock was only 20" wide. Any wider, and one would need to take lighter cuts.
There's an awful lot of 5hp 20" planers out there, and as I am not a production shop, I won't be taking 1/4" bites! Or I could look at a 18" wedge bed Rockwell that already is set up with a 1ph 5hp motor, and has been rebuilt.
My thinking is that I will have a better chance of ending up with a snipe free planer if I go with old good machines rather than trying to get a four poster adjusted well.

[Chip Lindley]

Well, the Rockwell RC-63 is heavier in every respect than those Chinese 4-posters. The Rockwell has a massive 4" diameter, 4-knife cutterhead. A 5hp motor was not a factory option, BUT, you can surely mount one on your RC-63. If it does what you need to do, all is well. It's still a free country!

[Stephen Cherry]

maybe something like this:
http://cgi.ebay.com/ELECTRIC-MOTOR-7-5-HP-COMPRESSOR-213T-SINGLE-PHASE-/180602988433?pt=LH_DefaultDomain_0&hash=item2a0cc6e791

[Rod Sheridan]

Jonathan, many 15 inch planers came with 2 or 3 HP motors.

A 24 inch machine will be fine for home use with a 5 HP motor, you're just not going to be able to take full depth of cut on 24" wide material.

For any less strenuous work (depth of cut or full depth at reduced width) you'll be just fine.

Regards, Rod.

[J.R. Rutter]

My RC-63 has the 7.5 hp motor with a Byrd head. The only time it works hard is on close to full width passes taking off 1/10" or more". You should be fine with 5 hp if you don't push it too hard and keep the table waxed.

[David Castor]

I assume you've verified the motor is 230 V and not 460 V - or dual-voltage that can be connected for 230 V. Regarding the VFD - a VFD can certainly take care of the single-phase to three-phase issue and give you a variable-speed planer motor as part of the bargain.

I would figure on at least a 40 A single-phase 240 V circuit. And as already mentioned, you'll need an oversized VFD or one specifically made for single-phase input. Whether or not a smaller motor would work, I can't say. Generally, the manufacturer doesn't go out of their way to oversize the motor too much.