Looking to upgrade my dust collection - motor specs confuse me!

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Forum topic by gtbuzz posted 03-16-2013 12:56 AM 2636 views 0 times favorited 6 replies Add to Favorites Watch
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427 posts in 2469 days

03-16-2013 12:56 AM

My current dust collection setup consists of a motor from a Jet DC1100 (rated at 1.5hp) that I mounted on top of a cyclone that I got off eBay . I use a single nano cartridge from Wynn .

Since I’ve got most of the workings of a “real” cyclone, I’ve been looking to upgrade the motor to a 2hp-3hp unit to increase performance. It’s proving rather difficult to find anyone that sells just the motor, so I’m left with the option of just harvesting a regular single stage dust collector for the parts. What I’m finding though, is that specs for motors and performance are really confusing me!

I know HP ratings are a rather poor indicator of true performance, but I’ve been using them just to group together “classes” of dust collectors. Take for example these dust collectors:

Grizzly G1029Z2P – 2HP, 9A at 220V, 1550 CFM
Grizzly G1030Z2P – 3HP, 12A at 220V, 2300 CFM
Shop Fox W1666 – 2HP, 12A at 220V, 1550 CFM

The Grizzly 3hp claims to pull quite a few more CFM (numbers are in line if you assume about 750cfm/HP), but the Shop Fox in comparison, which is the same 2HP as the Grizzly and CFM, draws 12A – the same as the 3HP Grizzly. What’s with the increased amp draw? Is it just a cheaper, less efficient motor? Or is it likely to be more powerful than the Grizzly 2HP that pulls 9 amps?

I also know impeller size may play a factor too – the Shop Fox has a 12” impeller, while the 2 Grizzly’s have a 12.75” impeller. All of them claim to run at 3450rpm, but I’m going to assume that that speed is the max speed and will bog down under load. Otherwise, wouldn’t we not care about the horsepower at all and only be concerned with the impeller diameter and the speed? Either way, I’m trying to ignore this factor right now since there’s already so many variables.

Thanks for any clarifications anyone can give. Also, if anyone has any suggestions on where I could get just a motor and impeller without exceeding the cost of a new single stage dust collector, I’m all ears. Looking out on Craigslist right now too.

6 replies so far

View Holbs's profile


1878 posts in 2057 days

#1 posted 03-16-2013 01:03 AM

my non-z grizzly (not the polar bear version) 3hp 220v pulls 18amps, according to the motor badge

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

View gtbuzz's profile


427 posts in 2469 days

#2 posted 03-16-2013 01:41 AM

Yeah, that’s even an additional point of confusion. I’ve seen other 3HP dust collectors say they pull 18A as well, including other Griz models like yours, as well as the 3HP Shop Fox. I thought perhaps the two Grizzly units were understating their amp draw, but then I looked at table saw motors as well for comparison.

Powermatic PM2000 and Sawstop PCS both say 13A for a 3HP motor.

Needless to say, I’m confused!

View Holbs's profile


1878 posts in 2057 days

#3 posted 03-16-2013 02:01 AM

i am no electrical engineer… but i would suspect a 13amp motor moving the same amount of CFM’s that the 18amp does… would put alot of strain on said 13amp motor (with same impeller size). granted, i have a dual bag, not a single bag. that also might make a difference as the force needed to intake the air has to have nearly the same output.

electrical stuff doesnt make sense after drinking vodka :)

-- The Carpenter Bee is derived from the Ancient Greek word wood-cutter

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2658 posts in 2305 days

#4 posted 03-16-2013 03:42 AM

gtbuzz…...I’m like you…I know enough, but not near enough…I agree, the info from your DC research is confusing. I don’t have an answer. I have asked elecrticians questions like you have asked here and got answers that vary…

here’s a couple of links….it’s from the internet…so take it at face value

-- Measure "at least" twice and cut once

View MonteCristo's profile


2099 posts in 2216 days

#5 posted 03-16-2013 05:40 PM

Dust collection is like gas mileage. Most of what you hear it’s true. As for HP, that is usually wildly overstated too. Your best bet is to buy a quality motor, looking at the AMP draw. At best you will get 1 HP for every 746 watts, about 7 AMPS with 110V power. I say “at best” because there are motor inefficiencies that reduce the true power output. (Double the voltage to 220V and you get about 1 HP for every 3.5 AMPS.)

My strategy is to used a number of relatively low HP collectors and keep the runs as short as possible, avoiding bends in the line as much as possible, using an appropriate diameter line. After that, it’s time to pick up a broom.

-- Dwight - "Free legal advice available - contact Dewey, Cheetam & Howe""

View Fred Hargis's profile

Fred Hargis

5001 posts in 2521 days

#6 posted 03-16-2013 06:01 PM

Impeller size does indeed play into this. Unless your Jet motor is seriously oveloaded (in which case it would burn out) your impeller is turning at ~3400 RPM. Now, if you put a larger motor on that same impeller, guess what speed it will turn at….the rated motor speed, which would be ~3400 rpm. That won’t move more air. To do so would require a larger impeller, which would also probably require a larger motor. But here is another factor to consider…if your duct work is only 4”, you won’t increase the air flow at all (or only an amount a laboratory instrument will measure). 4” is going to allow ~400 CFM, regardless of what pulling on it. If you have 6” ducts, the increase with a larger fan/motor will be quite noticeable. Back to the factory CFM ratings, in many cases they are about as accurate as the 6.5 HP your shop vac has. Generally what you see are “free flow” CFM, nothing to hinder air flow. But put filters and ductwork on one, and those numbers come down dramatically….often more than 1/2. When you see a number that says”XXXcfm @ y” SP”, those numbers are usually good to trust.

-- Our village hasn't lost it's idiot, he was elected to congress.

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