Dust Collector Motor change question

Grimmy2016

Board of Directors, Development Director
Scott
Staff member
Corporate Member
I have a 2hp Harbor Freight Dust collector and I am thinking of replacing it with a 3 or 5hp motor, but the ones I keep finding online are called electric compressor motors. They seem to have the correct shaft size for the impeller but I am not sure if there are other specifications that I need to be thinking about to make this switch.

Does anyone have any insights as to what I should be considering when looking for motors?

ANd no I do not want to buy a whole dust collection system for the same price... I am putting up a dust collection system using 5" or 6" piping with 4" drops to the tools. I just need the more powerful motor to ensure adequate pull as the main line will run 3 sides of my 15x15' shop. So 45 ft in all.
 

chris_goris

Chris
Senior User
You need a totally enclosed fan cooled (TEFC) motor, a 3 HP motor, 220v TEFC is about $400 , delivered. Plus , you will probably need a Mag starter for that motor, another $75 plus . Now, with that being said, you may have other engineering hurdles to overcome. What mkaes you think simply upsizing the motor will do what you need?. Typoically, a larger motor uses a larger impeller, housing etc. Simply bolting on a larger motor to the existing impeller will only ensure the motor is not working as hard as the 2HP current motor, Its not going to spin faster, but it will ramp up to speed faster and that may not be good either.
 

Grimmy2016

Board of Directors, Development Director
Scott
Staff member
Corporate Member
You need a totally enclosed fan cooled (TEFC) motor, a 3 HP motor, 220v TEFC is about $400 , delivered. Plus , you will probably need a Mag starter for that motor, another $75 plus . Now, with that being said, you may have other engineering hurdles to overcome. What mkaes you think simply upsizing the motor will do what you need?. Typoically, a larger motor uses a larger impeller, housing etc. Simply bolting on a larger motor to the existing impeller will only ensure the motor is not working as hard as the 2HP current motor, Its not going to spin faster, but it will ramp up to speed faster and that may not be good either.
I have already placed an order for the upsides impeller that Rikon uses to also pull the extra air. I have been reading much about dust collection by Pentz as well as info on the HF w/rikon and 6" pipes being pretty close to ideal.

Future state will have a Wen canister and a dust deputy cyclone on the system, so even though those will reduce some of the CFM it should keep the static pressure at a place where suction remains strong.

@chris_goris anything with using something like this? Shop Tools and Machinery at Grizzly.com or this General 3 HP 2P 182T 1Ph 115/208-230 V 60 Hz IC01 - ODP - Foot-mounted | ODP Standard Efficiency | ODP Cast Iron | ODP | General Purpose ODP/TEFC | AC Motors - NEMA | Electric Motors | WEG - Products
 
Last edited:

Pop Golden

Pop
Corporate Member
The Dust Deputy will actually increase flow. I am putting in a dust collection system and I find the HF 2 hp. motor to be all that's needed. How will the DD increase flow? My son has a HF/DD system in his shop. The DD gets everything. He has had this system several years now and has yet to clean out the HF DC. This means that the DC has no cake in the upper bag to slow things down and that increases flow.

Pop
 

chris_goris

Chris
Senior User
I have already placed an order for the upsides impeller that Rikon uses to also pull the extra air. I have been reading much about dust collection by Pentz as well as info on the HF w/rikon and 6" pipes being pretty close to ideal.

Future state will have a Wen canister and a dust deputy cyclone on the system, so even though those will reduce some of the CFM it should keep the static pressure at a place where suction remains strong.

@chris_goris anything with using something like this? Shop Tools and Machinery at Grizzly.com or this General 3 HP 2P 182T 1Ph 115/208-230 V 60 Hz IC01 - ODP - Foot-mounted | ODP Standard Efficiency | ODP Cast Iron | ODP | General Purpose ODP/TEFC | AC Motors - NEMA | Electric Motors | WEG - Products
Youll have to compare your mounting arrangement, many dust colectors are flange mounted motors.

MAybe this one?
 

Grimmy2016

Board of Directors, Development Director
Scott
Staff member
Corporate Member
The Dust Deputy will actually increase flow. I am putting in a dust collection system and I find the HF 2 hp. motor to be all that's needed. How will the DD increase flow? My son has a HF/DD system in his shop. The DD gets everything. He has had this system several years now and has yet to clean out the HF DC. This means that the DC has no cake in the upper bag to slow things down and that increases flow.

Pop
What size pipes are you running straight from the dust deputy? I am debating 5 or 6" and which size DD are you using? The XL or regular?
 

riggsp

Phil
Corporate Member
I've got a buddy that did the same conversion you're doing...he kept the original 2hp motor and everything works as it should, no problems.
 

UncleJoe

Joe
Senior User
Since you have the larger impeller already I suggest that you run it with the existing motor and see if that works, I think, based on reading others that have done the same that you will be fine. If not then you can source a larger motor.
 

Dee2

Gene
Corporate Member
A larger motor is not the panacea you think it might be. If you have the horses to pull the rotor, going bigger (more hp) won't make a more efficient system. Size the system (rotor) for the intended use. You should be able to find guidelines that will size a motor for you; or a manufacturer, or a fluids specialist - not my calling.
 

Grimmy2016

Board of Directors, Development Director
Scott
Staff member
Corporate Member
Since you have the larger impeller already I suggest that you run it with the existing motor and see if that works, I think, based on reading others that have done the same that you will be fine. If not then you can source a larger motor.
@UncleJoe @Dee2 - THanks for the replies. I have ordered the Rikon but have not received YET! But everything I have read about adding larger impeller to the motor means more strain on it to getup to speed and maintain the revolutions per minute it was designed for. I have also read that even with the new impeller, there is still not enough power/air flow to pull air 45' through a 6" tube and pull all of the dust and debri in. My whole goal is that not only will I be adding the impeller, and hopefully the motor, so that I can overcome any loss of pressue I might get when adding in the Wen air filter.

THough it says I shouldnt lose much, all the videos on YouTube do show a drop in air flow when you add in the Dust Deputy and Filter together. A lot of my research has been done based on info from Bill Pentz.

He has a lot to say about the subject. Long read but interesting to us woodworkers. Dust Collection Research - Home

Thanks guys
 

Charlie

Charlie
Corporate Member
Fans are designed to move as much air as possible with the existing motor at the rated max amp draw. If air flow is increased in any way, ie., larger impeller, RPM increase, etc., the existing motor will be over amped.
Google "Fan Laws". The Third Fan Law: Power: For an airflow increase of a little over 18% the power needed has risen by nearly 45%.
I would install a larger fan/system. You may get a little increase in airflow with the impeller change, but it will be very little.
Not wanting to get into a debate of 6" vs 4" duct, I will say that I have (2) 2HP HF collector blowers,
(I exhaust directly outside with no filters) on my lathe. Each has it's own 4"exhaust duct 75' long.
There are (3) other 2HP blowers and (1) 3HP blower, all with 4" exhaust ducts, shortest run being 50'. In 30 years I have yet to have any plugging.
It takes a minimum velocity/FPM (35-4000 FPM) to keep sawdust suspended in the air flow. As you increase pipe diameter, velocity/FPM decreases and the sawdust drops out and plugs the system.

The problem with home dust collection systems is a fan/collector is purchased and then the system is designed. That is backwards. The ductwork should be designed first and that will dictate the required fan size.




 

Grimmy2016

Board of Directors, Development Director
Scott
Staff member
Corporate Member
Fans are designed to move as much air as possible with the existing motor at the rated max amp draw. If air flow is increased in any way, ie., larger impeller, RPM increase, etc., the existing motor will be over amped.
Google "Fan Laws". The Third Fan Law: Power: For an airflow increase of a little over 18% the power needed has risen by nearly 45%.
I would install a larger fan/system. You may get a little increase in airflow with the impeller change, but it will be very little.
Not wanting to get into a debate of 6" vs 4" duct, I will say that I have (2) 2HP HF collector blowers,
(I exhaust directly outside with no filters) on my lathe. Each has it's own 4"exhaust duct 75' long.
There are (3) other 2HP blowers and (1) 3HP blower, all with 4" exhaust ducts, shortest run being 50'. In 30 years I have yet to have any plugging.
It takes a minimum velocity/FPM (35-4000 FPM) to keep sawdust suspended in the air flow. As you increase pipe diameter, velocity/FPM decreases and the sawdust drops out and plugs the system.

The problem with home dust collection systems is a fan/collector is purchased and then the system is designed. That is backwards. The ductwork should be designed first and that will dictate the required fan size.
Great info Charlie! Thank you.

In this case I originally intended to just use the standard setup from HF with their bag filter. Since I have added 4 new machines I decided it was time to upgrade to a dust collection system. I did a lot of research and most of what I was reading said 4" wasnt big enough for that many machines and that I should go with 6" for more airflow and less resistance... I also wanted to add in a separator and less than 1 micron filter due to how dangerous the dust could be long term. So thats when I decided the dust deputy and the Wen filter would be the next consideration to add. The last piece, which is the one we are discusssing, is what size fan (HP and Impeller size) should I go with for my system.

My room is 15 x 15 and I can only run the ducting along the walls as I have other obstacles onthe ceiling in the middle. That means I have to run three 15' runs to have enough reach to all of the machines. My thought was to drop down a 4 or 5 inch pipe as each machine to fit their ports. I would add blast gates at each machine to help reduce loss.

Knowing all that ... do you think the 3hp, with bigger Rikon impeller, would work just fine with 4" main line instead of 6"?!?
 

Pop Golden

Pop
Corporate Member
The loss in flow is most likely the filter. My son bought one and installed it. His flow died. He took it off and returned it. His flow is now ok. I am using 4 inch pipe for most of the shop, however for my sanding machines (I have 4 stand alone) I am dropping to 3 in. (fine dust & no large chips) 2 points: I have 2 books on dust collection systems. One is by Sandor Nagyszalanczy the other by Woodstock Sandor's book is a intense in depth discussion of the subject. The little handbook by Woodstock is the direct approach it's thin, small and tells you just about everything you need to know. I have based my system on Woodstock's book. The 2nd. point is on the need to ground plastic pipe in a system. Forget it! There is really no way to ground plastic pipe. The Myth Busters tried everything they could to create a dust explosion in a 4 in. plastic pipe. They even put a spark plug in the pipe. No cigar. There is also a gentleman at MIT who published a research paper on the subject. The final answer, THERE'S NO WAY FOR A STATIC DUST EXPLOSION IN A 4 INCH PLASTIC PIPE.

Pop
 

Charlie

Charlie
Corporate Member
Scott, 6" may be required if you have several machines operating at the same time, which of course will require a lot more air flow than a 2HP can supply. Also, with 6" it is required to have a minimum velocity to operate properly, which means several pickups will need to be open at all times, which again, will require more air flow. 4" is adequate for any single machine.
We sometimes over complicate things. Hook up 4" with slide gates at each machine and start making sawdust. Lol.
If I was in your position I would purchase another HF system. It is cheaper than a new motor.
Years ago I purchased (4) used 2HP Woodtech collectors for $150. I tossed everything except the blowers. I have a blower on my TS, one on my RS, one in my planer and another, using slide gates on my sanders, jointer, shaper, etc.
You have seen my shop and know the system works.
 

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