Wierd dust collector idea

[LCHIEN]

The difference is the amount of suction generated. Two 1.5HP units in parallel don't generate any more suction pressure than one; they simply can consume more airflow at the same suction pressure. Thus, to get double the airflow at the same pressure differential, you need less restriction, and that means larger pipes.
....

that's right. Thx, dwk.

Very, very roughly speaking, to get 1/2 the restriction at the same airflow,
OR the same restriction at twice the air flow, you'd have to go up 1.5 times the diameter (with the same length).

So, 5" to 8" would be about right.

[thestinker]

Russianwolf, now thats a good idea! I might just have to try that.

[TheRic]

If your going to do that, don't buy off ebay. Go to Harbor Freight and buy it direct and save. Also have a chance to return it if you have a problem with it.

[thestinker]

How well do the pvc inlet / out let home made cyclones work? Something that small I could almost put underneath my work bench and my pipe rud would be like 1 or 2 feet long. I know those aren't half as poweful as the full sized ones, but hooked up almost directly to the equipment..... thoughts here fellas. 1hp small DC with homemade cyclone like the Jet or the shop vac hooked up to an actual cyclone. Both seem about the same price, and seem to take up about the same space. I could prabably put all that under the bench, which would limit my runs length, and what size runs with the small unit? 2.5in....3in...4???

[Russianwolf]

If your going to do that, don't buy off ebay. Go to Harbor Freight and buy it direct and save. Also have a chance to return it if you have a problem with it.

I agree, but I couldn't get the HF links to work. The unit I pointed to looks very similar in picture and stats to one made by Penn State Ind. for $199. Supposedly the impellor is the reason it's rated higher than some higher HP units.

[TheRic]

I saw the ebay link / picture and it screamed HF. The specs are the same in the same order. Same picture. I looked at the other items being sold, HF all over them. Didn't know about Penn State version.


I think the little one might do you to start with. It's better than using nothing at all, or a shopvac for the bigger items (jointer, planer, etc). But not as good as a big one.

For little items like sanders, circular saws, etc. a shop vac is suppose to work better then a big DC. The way I understand it a shopvac is better at fine dust, where a DC is better at large chips. Has to do with high air speed (shopvac) VS. large airflow (DC). I'm sure someone will be happy to correct me if I'm wrong.

[LCHIEN]

I'll correct you.
A SV pulling 100 CFM, which would be a very good SV, on a 2.5" hose would achieve an air velocity of 2880 ft/minute

A DC pulling a lowly 500 CFM on a 4" pipe would achieve an air velocity of 5732 ft/minute, more than twice the SV.

Typically high velocity is associated with carrying chips, the speed is necessary so that they don't fall out of the airstream and clog the pipe on corner elbows and upgoing runs.
HIgh CFMs are desirable because
1) capture mores dust and chips at the source
2) need higher CFM to maintain velocity is larger diameter pipes which are required to keep the restriction (loss) down so that a high velocity and high speed are possible simultaneously.

You can always neck down a pipe to a smaller dia. to get faster velocity, but that assumes the blower has sufficient head to work against the restriction of the smaller pipe. Usually, that's not the case.

Basically the impellor design is a threeway tradeoff of air flow vs head vs. power. A DC is designed to get the most flow for a practical head loss so for each DC there's an idea pipe size. Hopefully the pipe is big enuf to do the job and not cause too much loss yet still small enuf to keep the particles moving (velocity). When it can't happen (e.g. too long a run of pipe) then you need more power.

[dwk]

[thinking out loud here, sorry for the rambling]

That Penn State version looks interesting. It uses a universal motor at 6400 rpm rather than an induction motor at the more normal 3400, which apparently accounts for the better CFM rating at lower HP. Probably really loud, though.

I've been really struggling with what to do for DC. I currently have a Jet DC 650 which is the worst of all possible worlds - takes up space, but not enough HP/CFM to really do a decent job (and too small to fit a good canister filter anyway). I'm very limited on space and don't have particularly good power in my shop, so a real cyclone needing 220V is definately out.

The Mini clear-vue cyclone/shop vac system discussed in another thread looks interesting, but as Loring points out no shopvac really has enough flow to work well for most normal shop DC applications, particularly a TS or a CMS.

I'm wondering whether the Penn State mini unit plus the mini clear-vue cyclone might actually work together as a small portable unit. The 2.5" ports on the cyclone might be too much restriction, but if you only used it dedicated to a single tool at a time with short hook-up runs, it might net out OK. Is there any way to estimate the SP requriement of the mini clear vue to determine whether it's viable? I suppose even if it's not, a trash-can mount similar to the integrated Jet might work, but as Pentz points out you might simply scrub the trashcan clean at the higher flow rates.

Of course you'd still need to adapt some sort of sub-micron filter canister to the Penn State unit similar to the way the Jet unit does.

[thestinker]

Exaust Filters

I,m not sure the pore size, but for the small 1 hp DC, how would the filters for shop vacs work. Say 2 or 3 in a row to form a long tube, kinda like the wynn canister filters. This may not work, having never fooled with these and not knowing how they are set up...I will do some looking into the poor size of these filters.

[TheRic]

Loring thanks for correcting me. I could have sworn I read somewhere, probably this website, that a shop vac works better than a dust collector on small items like sanders. Must have been another dimension.

[Russianwolf]

here's the other links

From penn state
http://www.pennstateind.com/store/dc5.html

from HF
http://www.harborfreight.com/cpi/cta...emnumber=94029

pics and specs nearly identical. now the fit and finish may be a bit lower on the HF, but then again the fit and finish on the penn state lathes isn't exactly top notch.

{shrugs}

as far as putting sv filters together. I guess you could, as long as you get good connection between them so you don't lose dust. I'd keep an eye on ebay for a torit filter though as they are really designed for the use.

[dwk]

here's the other links

pics and specs nearly identical. now the fit and finish may be a bit lower on the HF, but then again the fit and finish on the penn state lathes isn't exactly top notch.

I think it's highly likely that they're effectively identical. Not really enough margin to rework them. I was originally confused on the HF side as they have a similar portable unit that's a 1HP induction unit that I've looked at before.

as far as putting sv filters together. I guess you could, as long as you get good connection between them so you don't lose dust. I'd keep an eye on ebay for a torit filter though as they are really designed for the use.

Looking last night, there is actually someone on the clearvue forum that stacked 3 SV filters for use with the mini-cyclone. I'll have to refresh my understanding of what HEPA filters, but given that 3 of the HEPA filters will run ~$90, and a Wynns .5 micron runs $70, I'm not sure I see the value.

Of course you'd really need TWO of the Wynns (or two hepa stacks) to handle ~800 cfm, if you buy into Pentz's view. Suddenly this isn't looking so small and portable anymore......

[thestinker]

Great Ideas...just help me put them togather now

The HEPA shop vac are .3 micron according to Rigids site. I assumed a couple of HEPAs would be cheaper, but it seems as though thats not the case. The goal of all this was to get good dust collection for less than a couple of hundred bucks. I have a 40 or so gallon steel container with a lid held on by a metal snap ring. Make a homemade cyclone out of that, with the 1hp harborfreight dc mounted on the wall above it (maybe..I'll need to check the logistics of this once I start rounding stuff up). Put a filter of some kind to catch the small dust the cyclone doesn't get (sounds like the .5 microns from wynn would be ok for this and cheaper) and pipe everything in. My longest run would be 6 or 7 feet with 1 90 degree elbow, level with the cyclone / DC without a lot of up and down drops and virtualy no flex lines in the system. According to BP's site, its best to just leve the runs like 5" or 6" in diameter up to your tools. So for the BT I guess just run the pipe strait up to the 2.5" conncetion behind the saw and call it good?? Now trying to figure out the whole smaller diameter pipe to keep velocity up is confusing me some. Since this is a smaller unit, would it be better to run like 4" to everything, since the inlets on the DC are 4"? Also the only place I would think to reduce would be to the router table for the above the table collection, or would it be better to keep the 4"run to the router box under the table and hook the 2.5" SV to the top of the table and run them both??? Also, and most important....am I over thinking this??? Right now my DC is nothin, so anything would be better than that right?

[LCHIEN]

The HEPA shop vac are .3 micron according to Rigids site. I assumed a couple of HEPAs would be cheaper, but it seems as though thats not the case. The goal of all this was to get good dust collection for less than a couple of hundred bucks. I have a 40 or so gallon steel container with a lid held on by a metal snap ring. Make a homemade cyclone out of that, with the 1hp harborfreight dc mounted on the wall above it (maybe..I'll need to check the logistics of this once I start rounding stuff up). Put a filter of some kind to catch the small dust the cyclone doesn't get (sounds like the .5 microns from wynn would be ok for this and cheaper) and pipe everything in. My longest run would be 6 or 7 feet with 1 90 degree elbow, level with the cyclone / DC without a lot of up and down drops and virtualy no flex lines in the system. According to BP's site, its best to just leve the runs like 5" or 6" in diameter up to your tools. So for the BT I guess just run the pipe strait up to the 2.5" conncetion behind the saw and call it good?? Now trying to figure out the whole smaller diameter pipe to keep velocity up is confusing me some. Since this is a smaller unit, would it be better to run like 4" to everything, since the inlets on the DC are 4"? Also the only place I would think to reduce would be to the router table for the above the table collection, or would it be better to keep the 4"run to the router box under the table and hook the 2.5" SV to the top of the table and run them both??? Also, and most important....am I over thinking this??? Right now my DC is nothin, so anything would be better than that right?

If you really want to collect dust from your saw, 2.5" won't get it all.
I connected one 4" hose to one Y off the DC and that to the 2.5" port on the back of the BT. I connected another hose to a 4" belly pan port I put in the bottom of my BT. This by placing a piece of plywood under the saw and putting a 12" x 12" pan with a 4" port in the center the pan/port are readily sold (I think mine came with the HF DC accessory kit ITEM 93601-2VGA ). That really ges most of the dust. I think a 2" hose Y's with the hose to the back port of the BT, to the sharkguard port will get the rest that comes off the top.
Somewhere I have pics...

[thestinker]

Belly Pan

I will add a belly pan to the saw to catch more loose dust...what do you think about the main runs. With that size blower will 4" be big enough for the main runs?