dust collection for small drum sander

[miguel bernardo]

Sorry for yet another question re: dust collection, but i´m having an hard time making sense of all the info available (this and other forums, Mr. Bill Pentz site, on-line retailers,...). I have a Jet 10-20 drum sander, Jet says i need at least 400 CFM for it. So i ordered an 500 CFM, 0.5 bp unit. Then i understood i´d need a finer filter, as the original only filtered particles above 30 microns. SO now i have a 5 micron filters, seemed OK - but then i discovered that particular filter/DC unit combo had a flow inferior to the recommended 400 CFM. So now i want more CFM - i thought i´d go for a 2 hp unit but then realised here (as in europe) i can´t seem to find fine enough filters for such DC, the lowest i could find is 1 micron. As lots of dust is of inferior dimensions and travels easily to your lungs and no cyclone system big enough is to be found around here, i´m a bit confused. What DC system should i buy for my drum sander? Should i go with a big powered DC, forget the canister filter and try to find/build a decent cyclone unit? should i just go with an 1hp DC with an 1 micron canister filter? am i overthinking this?

I will sand mostly spruce and east indian rosewood, and i´m not able to vent the DC outside. i also don´t plan on doing a lot of sanding, maybe just a couple of times each month.

Thanks in advance,
Miguel.

[David Kumm]

You do need more like the 2 hp bagger and you don't want a cartridge but a bag. Most good bags are rated at 1 miicron but do get a little better when the dust cake inside forms. Your sander doesn't create much dust below 2 microns so the bag is as good as you can get. Order and oversized bag from either American Fabric Filter Co or Beane filter co. I'm a Beane guy. You have to beng on the bag periodically to get the dust cake to drop off but way easier to clean than a cartridge. Once a cartridge gets jammed with fine dust your cfm drops and your lungs become the filter. Dave

[miguel bernardo]

You do need more like the 2 hp bagger and you don't want a cartridge but a bag. Most good bags are rated at 1 miicron but do get a little better when the dust cake inside forms. Your sander doesn't create much dust below 2 microns so the bag is as good as you can get. Order and oversized bag from either American Fabric Filter Co or Beane filter co. I'm a Beane guy. You have to beng on the bag periodically to get the dust cake to drop off but way easier to clean than a cartridge. Once a cartridge gets jammed with fine dust your cfm drops and your lungs become the filter. Dave

Thanks for the reply.
You mean i should skip the canister filter and go with a bag? That would be super, but leaves me with one question. If a bag is good enouigh and will take particles down to one micron what´s the reason for expensive canister filters?

thanks again,
Miguel.

[David Kumm]

Cartridge filters with a preseparator allow for more sq ft of filter in much less space. More filter area means better filtration and more airflow due to reduced back pressure. Even one oversized 24x60" bag takes up room. There are some real benefits for relatively low usage hobby systems with a cyclone or a Thein separator in front of it but a lot of it is more marketing than science. Sanding dust with no separator is not where a cartridge excels. A 5 hp cyclone works better with two or three cartridges than 5 or 6 12" x96" cloth tubes from a cfm standpoint. Dave

[Jim Andrew]

Miguel, I think you will be disappointed if you just go for the minimum cfm's.

[Phil Thien]

Miguel, I think you will be disappointed if you just go for the minimum cfm's.

Oh I don't know, I used a shop-vac based system on a 16/32 sander for two years, and it did a great job. I'd imagine something flowing 400+ CFM (my shop vac unit maybe did 125?) would be terrific.

[miguel bernardo]

Oh I don't know, I used a shop-vac based system on a 16/32 sander for two years, and it did a great job. I'd imagine something flowing 400+ CFM (my shop vac unit maybe did 125?) would be terrific.

1st thing, many thanks for your work and generosity on the separator. i´m considering building one when i´ll get the time (not any time soon, though). 2nd thing, why does so many people call you Thein instead of Thien ? (joking... )
Now, seriously, you think so? because i already have a 0.5hp, allegedly 500 CFM unit with a cartridge canister filter (5 microns) and i´ll only be using a 10-20 sparingly - it´s for guitar tops and backs, but just for the final stages, as most of the thicknessing of the plates is done with planes/scrapers.

BTW, will a felt polyester bag remove much CFM "horsepower" from a 2hp DC?
oh decisions, decisions....

anyway, thanks very much for your replies guys!

cheers,
Miguel.

[David Kumm]

Miguel, by all means try what you have first. Our advice is only valid after what you have tried has failed. No substitute for real world experience. The reason for putting the oversize fine dust bag on a 2 hp is to compensate for the pressure drop of the finer filter material with extra square feet of surface. You can even do as Phil suggests and try the shop vac too. I would not buy one to try but would certainly test what I all ready had. Dave

[Phil Thien]

Miguel, by all means try what you have first. Our advice is only valid after what you have tried has failed. No substitute for real world experience. The reason for putting the oversize fine dust bag on a 2 hp is to compensate for the pressure drop of the finer filter material with extra square feet of surface. You can even do as Phil suggests and try the shop vac too. I would not buy one to try but would certainly test what I all ready had. Dave

Exactly.

The 16/32 sander I had was the Ryobi. It actually came with a 2-1/2" port, not a 4" port like newer Jet units. But the dust hood was actually pretty well thought out and the shop vac did a pretty good job controlling the dust. Not GREAT, mind you. But if you are only going to use the sander occasionally, try what you have FIRST, then come back and let us know how it worked.

[miguel bernardo]

thanks once more! i appreciate all inputs. well, i´ve been "trying" for a while now - what prompted me to want to change in the 1st place was the discovery that the smallest dust particles were the more harmful ones and - precisely - the ones i could not see. my actual "system" - Jet 10/20, axminster´s AWED2 0.5 hp 500 CFM dust extractor and 5 micron cartridge filter - does a nice job of taking all the visible dust from the sander and putting it in the plastic bag. where i´m not that sure is with the sub 10/20 micron particles that i´m not able to see and assume are being expelled all over the shop. that´s why i thought a more hp DC/finer filter would help.
when you start to (over) think this stuff, you can get really paranoid!
also, Dave, thanks for pointing out that my drum sander produces dust down to 2 microns - i din´t knew that!

once more,
thanks everybody!

[David Kumm]

Just remeber Miguel that when measuring big stuff vs little stuff relative % might not tell the whole story. A 5 micron bag isn't ideal for a sander. Dave

[miguel bernardo]

A 5 micron bag isn't ideal for a sander. Dave

Please excuse my ignorance (again...), but why? because there is the dust between 2 and 5 microns that gets away or am i missing something?

thanks!

[Phil Thien]

So many times the right advice is to invest in a particle counter.

If your DC has enough CFM to capture the larger particles, it will also catch the smaller ones, too. But David is right, 5-micron filtration means at least some of them may be making it past the bag and back into the air you breath. It is hard to know unless you have a way of testing.

The key is to make sure your filter (whether bag or cartridge) is capable of hanging onto the finest dust you're generating. As long as your filter is up to the task, then you should be all set.

Some people assume (well, I guess maybe a lot of people have read or been told) that their DC catches the chips, but not the finest dust. That is (IMHO) a myth that anyone with basic reasoning skills can sort through.

Here, let me relate a story...

Last XMAS I was drilling a bunch of larger (1-1/4" I think) holes in hard maple using a carbide-tipped Forstner bit. I was going about 1-1/2" deep, so I was making a lot of chips, and I expected that.

My drill press has a light that was doing a good job of backlighting all the fine dust I was also generating. I could see this fine dust floating off in all directions. After the 2nd hole I thought, "well, that is a lot of fine dust." I don't drill a lot of large holes at my drill press, so I never really did anything to bring DC to the drill press.

So I grabbed the 15' long Fein hose that is connected to my 2.5" piping (I use this hose for general cleanup) and draped the hose over the back of the drill press table's fence.

The nozzle for the hose was approx. 6" to 8" from the drill bit. I turned on my shop vac. Now, when I was drilling, I could see the fine dust that was being generated head right for the nozzle. All of it.

While that little 1-1/4" hose doesn't move a ton of air, it really doesn't have to move much in order to get all the fine dust.

Let's say that little hose only flows about 30 CFM (it is probably more, but let's just say). That means that for every single second the vac is running, the hose is evacuating a sphere (approximately) of air 1' in diameter. The makeup air outside of that 1' sphere now moves in to replace that missing air and the next second, the process happens again.

It doesn't take an atom-splitting scientist to figure out that the finest dust is not going to escape. It just doesn't have the mass or velocity (momentum). That finest dust rides in the air, and goes wherever the air is going.

Contrast that to larger chips, like the big chips the Forstner was throwing. Those big chips were going EVERYWHERE. The back of the drill press table. The floor. My pockets. Those chips do have both mass and velocity (and therefor momentum) that exceed the ability of the vac to capture them. And no big deal, they will not escape my floor wand later on.

But the point of my story is that catching fines at the source is actually easier than catching big chips (at the source). A 10" table saw blade is going to toss big chips at a high enough velocity that they will absolutely escape the pull of the DC (sometimes even when you have a blade guard with collection attached). But as dust gets finer and finer (the kind that hangs in the air for a while), it will get caught in the virtual tractor beam (sorry, trying to make this sound more interesting) that is your DC.

So when you hear that fine dust is more difficult to collect, think "fine dust is more difficult to CONTAIN." You need filters that, once you have the fine dust, hang onto it.

Now, I've seen bag filters that claim 5-micron and others that claim 1-micron and quite honestly I'm not sure if I've observed much of a difference in the fabric (type or thickness). I'm no expert on filter bags. I have seen 30-micron and can absolutely tell the difference between those and better felt bags.

It could be an engineering or marketing difference, I don't know. That is why having a particle counter would be helpful. If you have a particle counter and find that by running your DC and sander together that the counts are spiking, you'd have your answer. You could replace the bag with 1-micron bags and retest, and if that works better, then you'd know for sure.

My that was long. Sorry.

[David Kumm]

Please excuse my ignorance (again...), but why? because there is the dust between 2 and 5 microns that gets away or am i missing something?

thanks!

While woodworking might not generate much <5 micron dust a collector is still forcing air with a lot of velocity back through the bags. A 5 micron bag may be rated when new or when seasoned which means it is tested after a cake of dust has formed inside the bag. In the meantime your lungs are the filter. Since no one really knows how much fine dust it takes to hurt you or how much you are generating it just doesn't make sense in my world to go to the effort to collect the stuff that doesn't get deep into your lungs and not try to get the small stuff. the cost difference between a crap bag and a good one is only a few dollars. I buy Beane bags for under $50. A Dylos type monitor is a big help. I got pretty good numbers with my cloth bags, better with my spun bond cartridges and better yet with my nano cartridges. Still I prefer the bags for dust as they are easier to clean. All gave me numbers comparable to what was inside my house- if I was pretty good at collecting at the source. Dave