Advice on piecing together dust collection - Jet horizontal motor to Clearvue mating

[Carl Beckett]

I happened to have a dust collector like this:

222865

And then went out and bought one of these which just showed up:

222866

So now I have to decide how to piece it together. As you can see, the motor mounts horizontally with a horizontal blower. Im not sure what the bearings are, so wonder if I mounted this vertically on top of the cyclone if they would wearout. (option A)

The alternative is to mount the blower horizontally in a loft (have a nice spot that will put it at the proper height), and then a short elbow to the inlet of the cyclone (the blower will exhaust to the outside). (option B)

(note this original DC was basically free - but with the stock bags it creates more airborne dust than it prevents, so long overdue to upgrade the system) I would like to try and get the hardware at hand to work - unless you can convince me its just NOT possible and then I would consider purchasing different equipment.


Im inclined to go with option B - knowing that it might cause additional pressure drop - it runs the motor/blower in the orientation it was designed for, and in many ways simplifies install (mounting, etc).

But simple install isnt a huge criteria (would do more work for better performance)

Opinions?

[Brian Loran]

That motor is going to be undersized. I would sell the old DC and buy the proper motor.

[Carl Beckett]

Ok - that is one vote for purchasing new hardware (and the very first advice at that!)

I will have to check the model number again - I believe this is a 2HP motor (on 220V), with the blower rated at 1200 CFM (yes.... unloaded and at the outlet I assume)

So no way to piece together a system that would work with this relatively lower powered hw?

[Bill White]

Keep as many elbows out as possible. I have seen motors mounted horizontally in applications using a Harbor Frt. unit.
I'd look at several installations (maybe Google "woodworking dust collector installation?), then decide. Couldn't tell from the pics how big the cyclone is. Does it have specific ratings needs?
Bill

[David Kumm]

You can attach a stand alone blower and motor, in fact they make them separate in many commercial systems. Mine is in the attic above my cyclone. Your impeller and motor are too small however to give you satisfactory results. The cyclone itself in addition to the piping needed for the remote installation will restrict the airflow to less than what you have now. Look for a 3hp 14" impeller or a 5 hp 15-16" fan so the components are matched well enough to give you a first class system. They come up on ebay and CL periodically and Penn State and Oneida both sell them. Dave

[ian maybury]

It's kind of hard to correlate CFMs and pressure drops between systems, but for sure 1.5 HP is all being equal going to be highly marginal on airflow. Bill Pentz discusses cyclone considerations when running smaller fans somewhere in his pages (maybe the section on building your own cyclone) - the cyclone would probably work all right, but as Dave says it will cost you some extra pressure drop. (hard to know how much at lower CFM, but Bill i think mentions about 2.5in WG at higher CFM)

The big issue with 1.5 HP is that it'll pick up chips if the filter is clean and it's on a short hose as in the case of a mobile unit. By building it in you will probably lengthen the runs, and be forced to install some extra bends too. There's very little room to maneuver with a 12in or so impeller - unless it's some highly unusual type it'll literally in CFM terms stop pulling not too much above 8in WG. (which is why dirty filters, restrictions and extra hose/ducting impact them so badly)

You might think of going for larger ducting to increase the flow, but apart from the possibility of running into transportation issues due to lowish CFM a 1.5HP motor would likely overload pretty quickly much below roughly 6 WG total pressure drop.

Run at 3,450 rpm as David says a 13 or 14in impeller should get you half as much pressure capability again - and this is what determines if a fan can still pull reasonable CFM through longer duct runs (of a given size).

Step up to a 15 or 16in impeller and it's still going to be hauling right up to 16in WG or even a bit more - to the point where depending on your set up you may even have enough suction for it to start causing some issues in some situations. (like sucking up small work pieces) Easily dealt with....

This actually is an aspect of blowers that gets missed in the debate about fans and CFM. Larger diameter impellers don't just deliver higher CFM (for a given pressure drop), they keep on doing so up to much higher pressure drops. Which means that if for whatever reason your machine hooding or ducting is a little restrictive it's going to do much better on it.

Here's a typical fan curve: http://blog.mechguru.com/machine-design/understanding-fan-curves/ The sudden drop off in output of fans running near their peak pressure output and at much lower CFM than they are capable of if unrestricted is explained by the shape of the curve. (and this generalised one has a much less sharp shoulder than many smaller low pressure centrifugal impellers of the sort we use) By the time the highest (pressure) part of the curve to the LHS of the graph is reached it's almost horizontal. Meaning that a tiny increase in pressure produces a massive reduction in airflow/CFM. (marked Q in this chart)

Against that a larger fan running out nearer to the RHS of the curve where it starts to dip down will do much better if restricted by the same amount. (inWG) Because the curve rises much more steeply in this area the effect of increasing the pressure is to produce a much smaller reduction in Q. ( = CFM)...

:) Pardon my going techie, but it beats being accused of making unfounded claims based on generalities....

ian