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Heath Fitts
10-24-2017, 4:26 PM
I've been thinking about dust collection a lot lately. My current dust collection method is wait until it settles and clean it up with a shopvac and broom. But I want to improve that with a decent system. I've been looking at the Harbor Freight dust collector with the intention of converting it with a cyclone for separation. But I have also been looking at DIY systems built with shop made impeller (Matthias Wandel and others have good videos on YouTube).

I have an old Hitachi M12V router that someone gave me. It's in rough shape - handles are missing, height adjust knob is broken, I don't have collets for it, etc. But the 3-1/4 HP motor is still good. So I got to thinking... could I use that router motor to drive a shop built impeller for a dust collector? I'd have to use a belt drive with a small pulley on the motor and a large pulley on the impeller. But it seems like it would be plenty strong.

Any reason it wouldn't work?

Doug Garson
10-24-2017, 10:27 PM
Try posting the question on the comment section of Mathias's video, would be interesting to get his input.

Brice Rogers
10-25-2017, 12:12 AM
I'm guessing that there would be better choices for the motor.

Some routers run at around 20,000 rpms. So, if you put a 1 foot diameter impeller, the outside perimeter speed would be about 60,000 feet per minute or 1000 feet per second. So the outside of the impeller would be supersonic. Liable to sound like a siren. But I doubt that it would be able to run at that speed because of air resistance. The load on the router is likely to be very high and it is likely that it'll get pretty hot pretty fast.

The 2 HP HF (when on sale) is a good value for its price, but lower in performance than ones costing 2X or more as much. (Funny how that works). I have a 2 HP HF DC that is vented outside and which uses a thien baffle separator. It works a WHOLE lot better than sweeping up the dust. But, I'm sure that there will be people with larger units and more expensive separators who will comment that this setup isn't worth having (it cost me under $200) and that I'd be better off with a $2000 system.

Heath Fitts
10-25-2017, 12:48 AM
Of course there are better options, but I'm trying to work with what I have.

The lowest speed setting on this router is 8,000 rpm. As I mentioned, I would use pulleys, not direct drive of the impeller. If I put a 2" pulley on the router, and an 8" pulley on the impeller, the impeller would be rotating at 2,000 RPM (slower than the 3,450 RPM of your Harbor Freight motor) with a perimeter speed of 4,188.8 ft / min. The load on the motor is one of my primary concerns, though. Although this is a pretty beefy motor made for big routing jobs, I don't know how turning an impeller compares to turning a big router bit through hard wood. I'm not quite sure how the 3-1/4 HP motor of the router compares to a typical 2 HP induction motor like on the HF dust collector.

Curt Harms
10-25-2017, 7:17 AM
The first thing that would come to my mind would be durability. I can't think of an application that uses universal motors - the kind used on routers, circle saws etc. where the motor runs for more than a few minutes at a time then has time to cool. I'd think a universal motor under load would get pretty hot pretty quick. Though routers are used on some CNC machines so perhaps not. The second item would be fabrication - how do you mount a pulley to the router motor? Fabricate an impeller? I'm sure it has been done but getting the balance right and the design to create an efficient air mover yet durable enough seems like no small trick.

John K Jordan
10-25-2017, 7:34 AM
I'm having trouble imagining using a router motor to turn an impeller, even assuming you can reduce the speed enough. Are DYI dust collector builders using router motors?

First, does the router truly have a 3-1/4" HP motor? Some HP ratings are misleading - some advertise numbers based on startup currents under load, some shamelessly deceive. (HP ratings for shop vacs are a prime example - I have one advertised at 6.5HP!.) A more useful number than HP is the amperage value that should be listed on a plate on the motor. I assume the router is 115v. Look at the full load amperage in the 115v column in the chart on this page: https://www.engineeringtoolbox.com/elctrical-motor-full-load-current-d_1499.html All the motors in my shop greater than 1 HP are powered by 230v (nominal) to provide power. The 3HP motor in my table saw is a heavy monster compared to any router I've seen.

Depending on the motor and means of speed control, a variable-speed motor running at reduced speed might not produce as much horsepower as when running wide open.

Another issue would be devising a way to connect a strong pulley to the motor. Assuming you could connect an impeller and drive it at a useful speed I would still be concerned about how long the motor and bearings would last.

If I wanted to build a DC I might look for a used motor with a heavy shaft. Maybe look for the type of motor the DYIers are using.

JKJ

Alan Schwabacher
10-25-2017, 7:34 PM
I don't think a "3 1/4 HP" universal motor from a router will come close to the actual power output of an actual 2 HP induction motor. Let's skip the reasons universal motors are rated in such a fantastical way, and look at some numbers.

The Hitachi M12V is listed as running on 15 amps at 120V. According to this reference https://www.engineeringtoolbox.com/elctrical-motor-full-load-current-d_1499.html
a 2 HP induction motor should draw a full load current of 24 amps at 115 V. If you used a pulley to slow down the router motor you would also lose power to that, and I suspect the induction motor is more efficient as well. So the 2 HP motor should deliver well over twice as much power as the "3 1/4 HP" universal motor.

In my area people frequently sell motors and older machines with induction motors for next to nothing on craigslist. Wandel and others have videos showing how they scrounge old motors and other parts for their projects. If you want to make your own blower, I strongly urge you to find an induction motor to use.

It looks as if others have made the same points already in this thread, but I'll leave it worded this way anyway.

Brice Rogers
10-25-2017, 10:32 PM
Heath, I think that you should build your dust collector using your router motor. If it works, come back and report it. If it doesn't work to your satisfaction, then you will have learned something. Sometimes it isn't about the "distination" but it is about the "journey" and learning experience.

Heath Fitts
10-26-2017, 1:42 AM
In my area people frequently sell motors and older machines with induction motors for next to nothing on craigslist. Wandel and others have videos showing how they scrounge old motors and other parts for their projects. If you want to make your own blower, I strongly urge you to find an induction motor to use.

I'm not so lucky in my area. I've been stalking Craigslist and other sources for old "arn" for years and have had very little luck. What does pop up is usually way overpriced. I have a small collection of induction motors. Most of them are well beyond usable or repairable and not even worth holding on to. The ones that do work, are dedicated to machines.


Heath, I think that you should build your dust collector using your router motor. If it works, come back and report it. If it doesn't work to your satisfaction, then you will have learned something. Sometimes it isn't about the "distination" but it is about the "journey" and learning experience.

After more research, I agree with the consensus that the router motor is not suitable. However, like you say, I may just do it anyway. It may work for a little while and perhaps I'll learn things along the way.

William Hodge
10-28-2017, 9:06 PM
With enough encouragement from enough people, Matthias Wandel just might build a router powered dust collector. For me, remembering not to ever do anything like that is like trying to remember to not store hammers over the visor in my truck.

I bought a 3 hp Penn State dust collector. I tossed the bags and dolly, and mounted the blower on the wall. It has a 6" inlet, and a 5" output that goes right through the wall into a sawdust trailer. $225.

Brice Rogers
10-29-2017, 1:08 AM
William, you came up with a good solution. I did something similar but added a separator. Reason? the long curly shavings and brillo-pad like wads of shavings will plug up the impeller. But for small particles like sawdust, you system will work fine w/o a separator.

Tom Bender
01-03-2018, 1:46 PM
I wrestled with DIY designs for a couple years. Finally I bought a Dust Cobra and never looked back. It's made a huge difference in my shop.

Art Mann
01-03-2018, 6:12 PM
My opinion is that a router motor is singularly inappropriate as the drive for a dust collector. I have a Hitachi M12V and the slowest it will go is 10,000 rpm. At that speed, the motor is not putting out its maximum horsepower. It is going to take a huge pulley on the fan side to slow the output down enough to spin a typical squirrel cage fan. Routers don't have good starting torque. Their power comes from speed rather than torque. It is likely that the motor will eventually burn up trying to overcome the inertia of heavy fan, especially one that is home made.

Art Mann
01-03-2018, 6:22 PM
My opinion is that a router motor is not suitable as the drive for a dust collector. I have a Hitachi M12V and the slowest it will go is 10,000 rpm. At that speed, the motor is not putting out its maximum horsepower. It is going to take a huge pulley on the fan side to slow the output down enough to spin a typical squirrel cage fan. Routers don't have good starting torque. Their power comes from speed rather than torque. It is likely that the motor will eventually burn up trying to overcome the inertia of a heavy fan, especially one that is home made.

Brice Rogers
01-08-2018, 8:30 PM
I was hoping that the original poster would come back and report what he found.

I suspect that a router connected to a blower or fan cage might sound like a siren when running. But it would be fun to know what the OP found.

Malcolm McLeod
01-08-2018, 9:20 PM
My opinion is that a router motor is not suitable as the drive for a dust collector. I have a Hitachi M12V and the slowest it will go is 10,000 rpm. At that speed, the motor is not putting out its maximum horsepower. It is going to take a huge pulley on the fan side to slow the output down enough to spin a typical squirrel cage fan. Routers don't have good starting torque. Their power comes from speed rather than torque. It is likely that the motor will eventually burn up trying to overcome the inertia of a heavy fan, especially one that is home made.

DCs operate at 3600 RPM; routers at 10,000->25,000 RPM; turbochargers at ~20,000->200,000 RPM; turbine engines at 10,000->500,000 RPM. All move air by means of 'impellers'.

I'd think Heath's motor would work just as well as any other motor, IF it's operated within its design envelope. As several have pointed out, this is at rather higher speeds than a typical 3600 RPM motor on a typical direct-drive blower impeller. Squirrel cage fans are designed for even lower RPM, suitable high-volume, low pressure work, but payback is that they are whisper-quite (relatively). However, if one were to spend the time and resources to spec, locate, and purchase an impeller that matches the router motor's RPM, peak power, and duty cycle, there is no reason it wouldn't function.

I use 'function' intentionally - - to mean it wouldn't fail prematurely and it would move air. How much CFM @ SP? I have no idea. Suitable for a dust collector? See Dyson ads. Easy to build? :Dteehee, teehee:D ...Maybe not, but it would be fun to try.

Lots of things are possible for those who dream, even if they have to make-do with less than ideal equipment.

Heath, good luck and post how it turns out!

Rod Sheridan
01-09-2018, 2:09 PM
Heath, that's actually a 1 HP motor that's not very efficient and built for intermittent load.

It's exactly the opposite of what you want for a dust collector..............Regards, Rod.

Daniel Dupius
03-29-2018, 11:08 AM
Router motors are designed for RPM's and are low on torque, it would have difficulty spinning an impeller. It like the difference between a 2 stroke and 4 stroke engines. Two stokes are light, build quick RPMs but lack in torque.

marlin adams
04-21-2018, 8:22 PM
I wish I could remember where I read it since it been a few years ago but a lady wood worker actually made a dust collection system starting with a motor from a washing machine and a old force air pump volute the part that has the input and output connections and some 55 gallon plastic barrels.

Marshall Harrison
04-21-2018, 8:28 PM
Maybe pick up an old saw off of CL and salvage the motor from that. But not sure how long it would run continuously before overheating as table saw don't have long duty cycles.

Kevin Beitz
04-23-2018, 2:32 PM
To many sparks....

Osvaldo Cristo
04-30-2018, 7:30 PM
Router motors are not appropriate for continuous use - it is the reason they usually pack a lot of power in a small size. Additionally they are rated for (very) high speed.

I wouldn't go with router motor to drive dust collection or any fan.

All the best,