Dust Collection Air Filter

[SpiderDave]

I'd wondered if the ratings on the HFDC was under optimal conditions or not. The specs were suspiciously vague. I'm think I'm seeing the big picture, thanks!

Excellent. I'd been wondering if I could use insulated flex duct or not? That's great! Should the exhaust ducting be larger or smaller than the intake? And still stay clean?

Maybe I should go the cyclone route then, especially if it's more efficient? If I'm understanding it right. The cyclone applies (more or less) downward pressure to the particles where as the Thein type allows the particles to move downward through the crescent slot as it' pushes them outward? Still trying to get my head around it. Gettin' close! HA! Seems like the cyclone has more of a vacuum effect?

There is a ad with someone selling a couple of Shop Fox W1687 Dust Collectors here locally. Only has a single intlet, instead of the four way like the website. It holds two bags/filters. Would one of these work? If so, can I just use one side of the bag filters and cap off the other side? Or should I use both so I don't create back pressure on the motor? It seems more fitted for what I'm trying to do, and has actual specs listed. For $100 more to get something that works might be worth choking down the extra cost in the end? Maybe I can save money other places to make up that extra cost. I'm a bit worried about spending all the time & remaining money to find the system is just or barely adequate in the end. So I really appreciate all of the input and sharing of your knowledge & experience. A slight but not huge overkill is preferred over just adequate dust collection. So maybe the Shop Fox would be better? Sorry for all the questions. I have a lot riding on this, another chance won't come to change or correct things anytime soon, while paying off the loan. I'm kinda feeling like the HFDC is more of a maybe/probably when I could find something that's more of a solid bet? Not to say the HF unit is bad, I'm just not sure if I should take the chance on it or not given my situation? I'm sure most people have been there before and know what I'm talking about.

Shop Fox W1687 Dust Collector  Here's the shop fox:   https://www.factoryauthorizedoutlet.com/...gLPBfD_BwE

[SpiderDave]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.

A cyclone simply forces the air flow into a downward spiral within the body, with the dust flying to the outside of the helical flow pattern as it descends.  As the air gets near the bottom of the cylindrical part, it starts to turn inward toward (and eventually into) the exit tube in the middle, while the dust continues to spiral downward along the walls of the conical bottom section, into the lower tube and on down to the collection bin.  It's a centrifuge for small particles, to separate them from the air.

A well designed cyclone unit will remove almost all of the dust, including very fine dust (wood flour), leaving very little of the finest particles to be captured by the filters or exhausted directly outside.


I plopped my HFDC on top of my Pentz cyclone, after opening the blower cover's inlet from 5" dia. to 9" dia. (half the cyclone body diameter).  Made a big difference in reducing the losses.  Even with all that exhaust hose, and 6" trunk line along the wall, I can get it to pull around 1000 cfm, based on the increased current draw.  I don't remember what it flows with the largest blast gate open, though I did measure it once.  That blower wheel is tiny, so it can't move much air through a high restriction (max SP was about 7" WG), but opening it up to let it breathe helps move more air than it was designed to.  Gotta watch the current draw, though, as the motor doesn't actually have a nameplate, and I don't know what it's capable of without unduly shortening the insulation life inside.





Oh, and a ventilation fan is always a good idea.  

Oh, by the way, That belt driven blower I have was for open air duct ventilation. It's an (straight blade) impeller not a squirrel cage type of fan. Or does that make much difference in this circumstance? I can take a pic if needed? I was considering putting a larger motor in and changing pulleys. But probably end up spinning my wheels on that one, right? I do have other uses for it later. So it won't disappoint me not to use it. Mostly just curious what my options are. But if the Shop Fox is better (definitely spend a lot less time fiddling with builds and mods) then I'd rather get that one. I'll wait until I hear from you guys before I jump on that though.

[SpiderDave]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.

A cyclone simply forces the air flow into a downward spiral within the body, with the dust flying to the outside of the helical flow pattern as it descends.  As the air gets near the bottom of the cylindrical part, it starts to turn inward toward (and eventually into) the exit tube in the middle, while the dust continues to spiral downward along the walls of the conical bottom section, into the lower tube and on down to the collection bin.  It's a centrifuge for small particles, to separate them from the air.

A well designed cyclone unit will remove almost all of the dust, including very fine dust (wood flour), leaving very little of the finest particles to be captured by the filters or exhausted directly outside.


I plopped my HFDC on top of my Pentz cyclone, after opening the blower cover's inlet from 5" dia. to 9" dia. (half the cyclone body diameter).  Made a big difference in reducing the losses.  Even with all that exhaust hose, and 6" trunk line along the wall, I can get it to pull around 1000 cfm, based on the increased current draw.  I don't remember what it flows with the largest blast gate open, though I did measure it once.  That blower wheel is tiny, so it can't move much air through a high restriction (max SP was about 7" WG), but opening it up to let it breathe helps move more air than it was designed to.  Gotta watch the current draw, though, as the motor doesn't actually have a nameplate, and I don't know what it's capable of without unduly shortening the insulation life inside.





Oh, and a ventilation fan is always a good idea.  

Bill Pentz/Cleavue Style Cyclone P2- Harbor Freight Dust Collector- Woodworking with Stumpy Nubs 29 --->  https://www.youtube.com/watch?v=XX_naeLwv8E

At 1:54 mins into this video, there's a chart for size ratios. Very fuzzy and only partially readable on my end. I looked up Bill Pentz you recommended and found this video. Does anyone know where I could find a chart like this to go by for building a cyclone separator?  I didn't find it anywhere on his actual site. I'm hoping to find out what the correct size would be, once I get a blower so it's done reasonably right. Otherwise I'll just guess by looking at everyone else's videos and photos. Heh. I'll be making mine from with either steel or plastic, not sure yet.

I've found tons of literature on grounding for sparks now. That's been another issue to address. I'm trying to decide whether to run a wire down all of the ducts if I use plastic? Or use metal and ground it that way? If I use plastic or PVC. Why couldn't i just drill a small hole in the pipe every so many feet and put the tip of copper wire in the pipes air flow? Like a spark plug, but in reverse? Seems like it'd have less drag and not provide a place for dust to build up against. Or does it require more surface that an occasion wire tap to ground the friction? I have lots of copper wire handy. And PVC's cheaper, so that's my first thought. But if metal is better I'd like to hear about it. 

Sorry if you guys're gettin' sick of me. I'll be out of your hair soon and putting some photos up of what I ended up with. That's a promise! Ha!

[fredhargis]

The Pentz website has more info about DCs and cyclones than most folks can digest. You might check there and start with the FAQ section to avoid spinning your wheels. I didn't watch the utube video you linked, but Pentz has a chart on his site (right here, check the cyclone sizing section, #11).  About that dust collector. That would be a fairly high performance model, bear in mind if you reduce the filtration are (remove 1/2 the bags) it will reduce the CFM somewhat....but that wouldn't put more strain on the motor, it would actually work less hard. What loads the motor is moving air, do anything to restrict it and the motor can loaf a little more. My opinion on grounding is that's it's a colossal waste of time, effort, and money. I did it with my first system 20 years ago and found it to be such a PITA every time I accessed the ductwork (and you will access the ducts for some reason) it got removed pretty quickly. There is no from explosion in these systems so I skip it altogether.

[SpiderDave]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.

The Pentz website has more info about DCs and cyclones than most folks can digest. You might check there and start with the FAQ section to avoid spinning your wheels. I didn't watch the utube video you linked, but Pentz has a chart on his site (right here, check the cyclone sizing section, #11).  About that dust collector. That would be a fairly high performance model, bear in mind if you reduce the filtration are (remove 1/2 the bags) it will reduce the CFM somewhat....but that wouldn't put more strain on the motor, it would actually work less hard. What loads the motor is moving air, do anything to restrict it and the motor can loaf a little more. My opinion on grounding is that's it's a colossal waste of time, effort, and money. I did it with my first system 20 years ago and found it to be such a PITA every time I accessed the ductwork (and you will access the ducts for some reason) it got removed pretty quickly. There is no from explosion in these systems so I skip it altogether.

 Perfect! Thank you. That last DC might be a bit over kill by comparison. Good to hear about that motor, I thought the back pressure, limited flow or resistance of only one bag would cause it to get hot or ramp up like some ventilation/duct fans. I may still keep both bags, but wanted the option without harm to the system. So I'm going to go for the second DC. Not being at the edge of it's limitations, It'll leave me with options later that the HF unit won't. It also dawned on me this morning that it's 220 and I have a plug available for it in a great location - no wiring to do that way. If I decide to change my piping or add on down the road, I won't be looking for another blower any time soon. I appreciate you all getting me on the right path. Maybe some pics when I'm done.

[TDKPE]

Good to hear about that motor, I thought the back pressure, limited flow or resistance of only one bag would cause it to get hot or ramp up like some ventilation/duct fans.

Axial (propeller) fans work that way.  Centrifugal fans (and pumps) work the opposite way.  Like your vacuum cleaner, which speeds up dramatically when you block the hose.  But then, universal motor speed is very sensitive to load, whereas induction motor speeds only vary a little more than 4% between full and no load.  So you won't be able to tell what's going on with a DC by the sound, other than less noise when you block the air.

In either case, always check the current draw of the motor under operating conditions.

[fredhargis]

If you get that Shop Fox DC and want a remote for it (which is a good idea) you can buy them, but you can make an even better one. One of our members has done a good write up on how to do it. Linky....

[SpiderDave]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.

If you get that Shop Fox DC and want a remote for it (which is a good idea) you can buy them, but you can make an even better one. One of our members has done a good write up on how to do it. Linky....

Oh man, for only around $14.00? I'm going to do this! Thank you Fred that's going to be handy and save me from tripping over things back and forth. I went and got it today. Very nice unit, nice guy.. excellent condition. I haven't hooked it up, but I have ran it with some hose etc. and I'm sooo pleased with it. I'm really feeling like it was a far smarter purchase for my needs than I would've done on my own - thanks to everyone here. 

I am wondering though, why is it a guy can't use one of these in a separate system - and I'm just talking about the motor and blower housing section, not bags or anything else - for metal dust collection??? In short- using a cyclone separator and filter with a set up designed for metal. That's something I've been wanting for a while. Grinding or working metal on a disk sander, flap disk, wheels etc gets dusty too. A tank vac just doesn't cut it. A wall fan helps, but only for the less direct particles that're drifting about. The site says NOT for metal dust but it does handle silica from sand paper. These come up for sale now and then. Maybe I could score a beat up one that's a project. Scrap everything but the blower/motor part itself and use that? Or is this a bad idea? The motor wouldn't be exposed to the elements of the dust at all. The impellers the same, I can't find any difference except maybe something to do with the motor housing or the seals? Any ideas there? 

I do have that other old blower I mentioned earlier.  I was planning on using that,... maybe. I'm hoping I may get some insight on the idea or learn the difference between blowers?

[SpiderDave]

Just a comment about that 1550 CFM. Those numbers are less accurate than the 6.5 HP your shop vac has. DCs sometimes measure air flow with no restrictions at all, and that number drops drastically once the blower is hooked to almost anything. My DC is a true 5 HP with a 14.25" impeller and it pulls a measured 1150 CFM through 6" duct ( a little over 550CFM in 4"). The HF is about 1.5 HP with a roughly 10" impeller....so the 1550 is a pipe dream. This isn't a criticism of that DC (maybe the specs) since a lot of folks have it and get satisfactory performance from it, but to compare it to others on the basis of that info is really not realistic.

Axial (propeller) fans work that way.  Centrifugal fans (and pumps) work the opposite way.  Like your vacuum cleaner, which speeds up dramatically when you block the hose.  But then, universal motor speed is very sensitive to load, whereas induction motor speeds only vary a little more than 4% between full and no load.  So you won't be able to tell what's going on with a DC by the sound, other than less noise when you block the air.

In either case, always check the current draw of the motor under operating conditions.

Okay, that makes sense. One of my 220v squirrel cage fans will react by ramping up when I put my hand even a foot away from it. I had never seen that before. Haven't wanted to use it until I understood it first. Didn't want to use it wrong and damage it. 

I did want to check the load etc once I got my new DC all hooked up - or test as I go to see where I'm at as I add more. Is there a formula, chart or a guideline I can use for that? 

Also, I asked about that Shop Fox DC (blower only) for metal in the previous response, if you wish to read it? Would you know anything about that while we're at it? Could another blower unit the same or similar to this one be used (a totally separate one - not both wood and metal) for metal dust and grinding? If not what would I look for a motor/blower for that type of work? I apologize if that's frowned upon asking that on a wood forum. I just assumed you might know what to avoid for wood dust collection that works for metal? Really keeping you fella's busy aren't I? Sorry about that. ha! Gotta say, it feels good to learn though.