Upgrade DC motor from 2HP to 3HP

[Joe Shinall]

I just turned my Grizzly 2HP DC into a cyclone with the Super Dust Deputy XL. Really happy with the results, but I was wondering if changing the motor itself to a 3HP would be that much better? My dad works on electric motors so I can get one for next to nothing, but just wanted to make sure there wouldn't be any hinderence on something like the impeller size or something.

It has a 12" steel impeller.

Also Grizzly rates the 2HP motor at 3450 RPM. The 3HP motors I'm looking at are 3450 RPM. Is Grizzly really giving the correct RPM on their motor?

[Andy Giddings]

Might be wrong on this but I think unless you change the impeller to a larger size the motor upgrade won't make any difference to your flow

[Malcolm McLeod]

... I was wondering if changing the motor itself to a 3HP would be that much better?

Seems like everything from lipstick to leaf rakes are advertised as a "system" these days, so I hate to even insinuate that your DC is such, but....

I don't know the specific design you have, but if Griz engineers did their job, then all the components in your system match; i.e. the impeller is sized to the motor AND to the inlet and outlet port sizes. Changing one component may not necessarily yield better performance.

In this case, if the existing 2 Hp spins the impeller at 3450 RPM, then installing more Hp at the same RPM achieves nothing. Your would probably need to increase the inlet size, then the outlet, then a bigger impeller, then more filter... ...maybe.

Bottom line, the 3 Hp motor is probably a crap shoot, and you might be just as well off buying a 3 Hp system (doh! I said it again!).

[Joe Shinall]

That's kind of what I was thinking which is why I asked. I was looking on Clearvue at the housing, impellers, and motors they have but by the time you're done, it's $1k for all 3.

[Joe Shinall]

Malcolm, I know exactly what you mean and also had the same thoughts. Just figured I might be missing something and would be able to up it on the cheap. Guess I'll stick to what I have for now and upgrade the whole thing later.

[Mike Henderson]

I don't know if this would work, but if your 3Hp motor was a 3 phase motor and you used a VFD, you could overspeed it beyond 3450RPM and get some additional air movement. But that's a kluge and you'd probably do better to get a system that was designed for a 3Hp motor running at 3450RPM.

BTW, the reason an induction motor runs at about 3450RPM under full load is that it's a two pole motor and the input Hertz is 60. If it was a synchronous motor, it would run at 3600RPM, but since an induction motor must have slip between the rotor speed and the speed of rotation of the magnetic field, the motor runs slower than 3600RPM. Thus 3450RPM. Unloaded, a two pole induction motor at 60hz runs close to 3600RPM.

The size of the motor - 1Hp, 2HP, 3HP, 50HP - doesn't matter. It's all related to the number of poles and the input Hertz. Also, it doesn't matter whether it's a 3 phase motor or a single phase motor. Both work the same way. The only difference is in how they get started (up to speed).

Mike

[A four pole motor is usually spec'ed at 1725RPM under full load.]

[Carl Kona]

Joe,

I am looking at all the same things you are and as already stated the 3HP will not change anything until you increase the impeller. Since you can get a cheap motor you could make a new blower housing. The Bill pentz design is made for a 14" impeller, just print out the plans. You can still get the Jet 14" impeller through http://www.toolpartspro.com/powermat...31006-impeller for $105. Add a good pleated filter and you got a great little system.

BTW how is your separation? Do you have a sander or router? Wondering how much fine dust gets through the XL.

Let us know what you do,

Carl

[Joe Shinall]

Carl, I'm venting outside which is great. I do not have a sander but I have gone almost a month without dust collection while building this new one and moving things around and I had a lot of fine dust on the ground and I can tell you that having my dad vacuum the floor while I watched outside, I could see a very small amount of fine dust going outside but could definitely tell it was only very fine stuff. I also believe a good amount of that fine dust was from us cutting the hardie siding and the dust getting on the floor.

I haven't used it a whole lot, just mainly on a few machines just to test it out but am very happy with my decision for the SDD XL and 6" piping. Just one of those things that I think can always be better was my only reason for upgrading motor size. I really like your idea and I think I'm going to definitely look into that.

[James Gunning]

Without increasing the impeller size (or efficiency) the only advantage of putting a 3HP in place of the 2HP motor would only give you a cooler running motor. With a 12" impeller, the motor should already be spinning at its full rated speed.

[Ole Anderson]

Check your amperage draw on the existing motor with the most gates open you will ever have. As long as the amperage is less than the amount stamped on the motor, no reason to upgrade the motor alone.