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I'm planning to put a chip collector in line before the bag. I now have a squirrel cage rated @ 1800 CFM. Would it benefit to add this in line to add a bit of oomph to the system?
 

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My impulse is no. The HF blower is pretty strong, and I'm not sure another blower in line will add--you are only going to move so much air through the HF blower, and I can see that it might undo the action of the chip collector by creating too much turbulence. That's my thinking anyhow. But if you already have a blower, try it out and see and then publish your finding.
 

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I'm planning to put a chip collector in line before the bag. I now have a squirrel cage rated @ 1800 CFM. Would it benefit to add this in line to add a bit of oomph to the system?
That's interesting . I have this type of squirrel fan looking thing that I use to evacuate fumes from my laser .
Never thought of using one further upstream from my DC ?
 

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I agree with Tom. When I bought my HF DC, I was also trying to come up with making use of my old DC motor+fan. Fortunately, I sold it. But had i not, instead of in line (or in series), I believe it would work a lot better to add it in parallel. The downside is that this might require some pretty fancy duct work.

When I first read your post, I interpreted it as you wanted to add the chip collector between the fan and the bag. That's a bad idea, too.
 

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Discussion Starter #5
Thanks guys, I'll hook things up and see what kind of suction I end up with. If things are not up to snuff, I'll put my noggin to work & come up with some alternate ideas.
 

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Y'know, enclosing the DC system in a closet arrangement, and putting the exhaust fan on the closet to greatly reduce the air pressure on the outflow side of the system might actually help with the efficiency, by reducing the backpressure(?)...
 

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Y'know, enclosing the DC system in a closet arrangement, and putting the exhaust fan on the closet to greatly reduce the air pressure on the outflow side of the system might actually help with the efficiency, by reducing the backpressure(?)...
I agree. But the closet would have to be well sealed, in order to maintain the reduced pressure. My hunch is that even the leaks around a standard closet door would be enough to bring the pressure in the closet back to ambient. I'm also not sure how well the original motor+fan will handle the increase in flow speed.

I still believe a parallel setup would be a lot simpler. If you ignore ducting losses, 2 motors gives 2 times the CFM, with each motor+fan seeing its original CFM (flow speed). But of course, you will have ducting losses.

Just to be clear, a simple example of "in parallel" is to add another exhaust port to the chip collector, ducted to another motor. Then take the exhaust duct from each motor and merge with a wye, ducted into the bag/filter.

Whether someone can overcome the ducting losses to make it worth it, I look forward to hearing about :smile:

An even simpler parallel arrangement would be to buy a second HF DC, add a second chip collector for it, and hook it all up with a wye split in the original inlet side.
 

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I'd use the DC without a booster to determine whether I really needed it in the first place. My setup has a 30 gallon chip collector in line ahead of the the HF unit and the combination works fine, particularly the one with the Wynn filter on it. The folded filter significantly increases the air flow, certainly better than the cloth bag. Why fix it if it's not broke.

Here is a discussion of modifying the HF impeller. Anyone try upgrading their HF DC impeller? - by Sarit @ LumberJocks.com ~ woodworking community. One of the comments discusses the impact of adding pressure and why the impeller angle of the HF unit will back up and reduce pressure.

Some years ago, I read about increasing the height of the blades in the impeller, and in the discussion in the link, they talk about replacing the impeller with a somewhat larger unit. As I recall, using the modified impeller without a chip collector dinged the blades because the air is moving chips (and nails or screws) pretty fast. A well sealed chip collector should not really affect total flow since, and it will drop potentially damaging object into the chip unit so it doesn't hit the impeller. My first DC was just a blower and bag and I was amazed how many dings and pings there were without the chip collector.

I'm no expert on dust collectors, blower engineering and CFPM rates, but I have gone through a lot of (expensive) practical experiments trying to handle this nasty dust problem.
 

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Tom, if someone has the energy to experiment around, I'm all for them going for it. For myself, I'd rather spend my free time doing woodworking. But then I'm not retired, yet, either.

The link on the impeller issue is pretty interesting...thanks for that.

Adding a chip collector will increase the drag (or pressure loss) in the system, no matter how well sealed it is. How much, I have no idea. I might take the time to build a simple manometer to see the difference. Regardless, I agree that it's well worth it. Right now, I cringe every time I hear a chip hit the impeller. So I've ordered the drum you found from amazon.
 

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Tom, if someone has the energy to experiment around, I'm all for them going for it. For myself, I'd rather spend my free time doing woodworking. But then I'm not retired, yet, either.

The link on the impeller issue is pretty interesting...thanks for that.

Adding a chip collector will increase the drag (or pressure loss) in the system, no matter how well sealed it is. How much, I have no idea. I might take the time to build a simple manometer to see the difference. Regardless, I agree that it's well worth it. Right now, I cringe every time I hear a chip hit the impeller. So I've ordered the drum you found from amazon.
Rob, the first DC system I set up had the fan inline with the suction where everything went through the fan into the cyclone. Like you said I could hear a large chip or screw hit the fan.
The set up I have now has the fan sucking directly out of the cyclone and blowing into the filters. In this set up the chips are removed before the air gets to the fan,so Nothing but air and fine dust goes through the fan.
Herb
 

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You don't want the squirrel cage in the airflow but if you were to add it upstream from the vac and blew the air from it into a Y facing towards the vac you would induce an extra vacuum on the other side of the Y. In power engineering this is known as an induced draft fan meaning it's not directly in the flow. Dan is also correct when he says that reducing air pressure around the main vac will make it more efficient. This is somewhat similar to the way a helicopter works. The rotor on the helicopter compress the air below it, increasing it to the point where it is capable of floating the helicopter. A vac will do the same thing, even in an open space. The space around it will pressurize as the air it is moving tries to get away but runs into other air molecules which slow them down.
 

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Discussion Starter #12
If I understand correctly, this is what I was originally planning.

Hose from table saw to chip collector
chip collector to squirrel cage
squirrel cage to HF DC
HF DC to dust bin

Is that what you are envisioning?
 

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If you can eliminate all but the fines going through it then it should be fine. How much it will help, if at all, you'll only know by trying it.
 

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Discussion Starter #14
I'll probably try just the HF DC 1st, if I don't get good results, I'll add the extra fan. I get the fans for free from my friend that's an AC guy so I figure it won't hurt to experiment. If it works any better we will all know!
 

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I have a separator upstream of my HF dust collector. As long as I remember to empty the drum every now and then, the system works pretty good.:surprise::grin: Good enough that I don't think about it.

I only have two 4 inch ports. One is plumbed to the table saw. The other comes off a "Y" in the line to provide a connection for a hose that I connect to the mobile tools (drum sander, planer, jointer).

Note that I added a Wynn cannister filter to help capture the fine dust.

Good luck.
Mike
 

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I have a separator upstream of my HF dust collector. As long as I remember to empty the drum every now and then, the system works pretty good.:surprise::grin: Good enough that I don't think about it.

I only have two 4 inch ports. One is plumbed to the table saw. The other comes off a "Y" in the line to provide a connection for a hose that I connect to the mobile tools (drum sander, planer, jointer).

Note that I added a Wynn cannister filter to help capture the fine dust.

Good luck.
Mike
Wow, I really like that ply insert in the chip collector. The heavier chips and particles are going to spin to the outside and drop through the cut away.

One thing I've thought about cutting a 1X6 strip into the side of the chip collector and putting in a plastic window so I can see clearly when it's full without having to open it. Or, I saw that someone put a dowel through the top with a pad on the bottom so you can rest the foot on top of the sawdust. Mark the stick at the full level. A grommet in the lid would seal the top of this probe but let it slide. Every time I open the chip collector I know some sawdust is going to launch. I think the stick approach sounds more practical.
 

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Wow, I really like that ply insert in the chip collector. The heavier chips and particles are going to spin to the outside and drop through the cut away.

One thing I've thought about cutting a 1X6 strip into the side of the chip collector and putting in a plastic window so I can see clearly when it's full without having to open it. Or, I saw that someone put a dowel through the top with a pad on the bottom so you can rest the foot on top of the sawdust. Mark the stick at the full level. A grommet in the lid would seal the top of this probe but let it slide. Every time I open the chip collector I know some sawdust is going to launch. I think the stick approach sounds more practical.
The drum is translucent.:surprise: I can see the level if I look close at it. I bought it specifically for that reason.
 

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Discussion Starter #18
Nice work, how functional is the wood insert. Do you notice much dust build up on top of it when you open it?
 

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Rob - Mike may have a different answer but I made one for a 5 gallon pail that is attached to my shop vac. The lower platform on mine is just above the bottom of the inlet elbow and works well. Not much gets through to the vac and filter as most dust, chips etc. fall to the bottom of the pail.
 
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