DC Motor Upgrade? Yay or Nay?

[®smpr_fi_mac®]

For now I'm running a flex house to the three tools it services: planer, jointer, table saw. I want to add PVC ducting around my shop in the coming months. I don't think the motor is powerful enough for that, though.

Current motor is a 56 frame 3/4hp 3450rpm on what I think is a 10" impeller. If I were to replace the motor with a 2hp (220v) would that improve its performance? Does the impeller diameter limit it enough that I shouldn't bother?

[TDKPE]

It won't make any difference at all.  The motor is 3600 rpm, and any new motor will also be 3600 rpm, so the impeller speed won't change, and if it doesn't change, the load on the motor doesn't change.  You could put 100 hp on there and it'll still perform exactly the same.

What you need, if you want to increase performance, is a larger blower with a higher hp motor.  You may be able to replace just the blower wheel, and the motor of course, but that's not necessarily going to be a good match for the scroll housing.  

Best to just replace the whole blower assembly, IMO.

[®smpr_fi_mac®]

I figured that would be the case but was hopeful!

[TDKPE]

If you wanted to do a bit of backyard engineering, you could mount the blower wheel on its own shaft and bearings, and belt drive to another motor with a speed increase through the sheave ratios.  

If you do that, just remember that the input power changes as the cube of the speed ratio.  So a 25% speed increase results in just shy of a 100% increase in input power.

You also get a sound pressure change as the square of the speed ratio, and air flow in proportion to the speed ratio. So that's a lot more hp for a small increase in flow. It's really better to go to a larger blower, for a number of reasons.

[iclark]

TDKPE did a good job of explaining why changing the motor would not help.

The one thing that he skipped over was your saying that you wanted to switch over to PVS ducting around the walls of your shop. You should actually gain some flow by the transition from the flex tubing to the smooth wall pipe as long as you do not have any 90* elbows anywhere. Whether or not that improvement in flow will make up for the longer transport distance or not is a more complicated question than I have the experience to address.

It looks like you currently have a decent exhaust filter. One option might be to add another blower with a thien filter and catch barrel in an upstream corner. This would give you the 90* turn at the corner, added transport capability, and not need more floor space for a 2nd exhaust filter. Adding a moderate-sized 2nd blower might also be cheaper than up-sizing your current system to one big enough to handle everything. Just thinking out loud here. I am sure that someone will come along soon to tell us both what I got wrong.

[®smpr_fi_mac®]

I'll contemplate possibly increasing the speed with pulleys and another motor.

I want PVC ducting around so that I can run dedicated drops to my RAS and lathe along with the gain through the reduction in friction caused by the ribbed flex tube.

My wife and I recently started a small furniture business and sales are already pretty good. For months to come, all profits are being plowed back into tools and shop upgrades. One of those early upgrades will likely be a bigger DC and ducting.

[Stwood_]

Pull that cover and see what size impeller you actually have. 12? or so.
See how much room is around the housing. You may be able to put in a 13".
Of all the collector I've had previous to my current one, they all had room for bigger impellers.
Then you can justify using a bigger hp motor.

[TDKPE]

Pull that cover and see what size impeller you actually have. 12? or so.

He said it was 10” in his first post.  That’s pretty puny, but it does have a 3/4 hp motor.  I was thinking extending the vanes, which people do, but it would certainly be easier to just buy one.

That housing, compared to the NEMA 56 motor in the second photo, looks loads bigger than what I would expect for a 10” blower wheel.  A 56 frame is 3-1/2” from the feet to the shaft center (56/16), which usually results in a 7” OD motor or thereabouts.  

But again, the OP wasn’t sure exactly what the blower wheel size is.

For reference, my 2 hp HFDC blower that sits on top of my cyclone has a 9.85” diameter blower wheel. And I wring every bit of its 2 hp out of it by opening up the inlet (to 9”) and outlet (got rid of the adapter) and I use a 6” trunk line and 8” outlet flex to a window with no filters.

[JDuke]

He said it was 10” in his first post.  That’s pretty puny, but it does have a 3/4 hp motor.  I was thinking extending the vanes, which people do, but it would certainly be easier to just buy one.

That housing, compared to the NEMA 56 motor in the second photo, looks loads bigger than what I would expect for a 10” blower wheel.  A 56 frame is 3-1/2” from the feet to the shaft center (56/16), which usually results in a 7” OD motor or thereabouts.  

But again, the OP wasn’t sure exactly what the blower wheel size is.

For reference, my 2 hp HFDC blower that sits on top of my cyclone has a 9.85” diameter blower wheel.  And I wring every bit of its 2 hp out of it by opening up the inlet (to 9”) and outlet (got rid of the adapter) and I use a 6” trunk line and 8” outlet flex to a window with no filters.

Several years ago, I extended the blades of a dc impeller, and riveted the extensions on.

Every time I turned it on, I worried that one would turn loose. 

They never did, but I did remove them before I gave that dc away.

[fredhargis]

Brad, you can spend some money and a lot of time trying to make that blower work...and it will still be a sub par blower. Sorry to be blunt, but it just isn't going to be up to the task. Time to go with something better suited for the purpose.