Another new build – I’m in information paralysis

[nj_mike]

Hi everyone, 
There is a lot of good information on here....maybe too much.  I have a HF 2hp dust collector.  I want to add a top hat separator to it so I have been reading and reading on the design.  I think I am over complicating it and in information paralysis.  I scored a free 15gal fiber drum that has a 16" diameter and that's I want to use.  I'm putting the drum and collector on a cart so I can move it around.  Space is at a premium - my shop is a one car garage that is currently sharing space with the snow blower, lawn equipment plus some other things.  I'm using 4" fittings.  I'll be running one machine at a time – 10" contractor table saw, 6" jointer, 12" planer, router table, saving for a 14" band saw.  I know you can go crazy building this but I'm trying to keep it simple and cheap as possible.  I'm a hobby shop and I make and sell pieces from time to time to help support my habit.
Here's my idea based off of what I have read and the guideline pdf I found:
The inlet will be a 4" rectangle and located close to the top cover.
The height of the separator (from the baffle to the top cover) will be 4 ½ -5".
The outlet will be 4" and will project into the separator so it is 2" from the baffle.  If I read it correctly the outlet pipe should stop above the baffle half the diameter of the outlet pipe. (Outlet pipe is 4", half of that is 2" so it should stop 2" up from the baffle)
The baffle will be made out of 1/4" or 1/8" hardboard - forget what I have on hand.
The top cover will most likely be made from plywood – 1/2" or 3/4" - forget what I have on hand.
The drop slot for the baffle will be 1 ½" wide with a chamfer and go around 240 degrees.
I see that people like to use poly carbonate for the walls...that hard to bend?  I was thinking of using sheet metal or formica.  To attach the wall to the baffle what's the best thing to do?  Just route a groove and bend it into place?  Any ideas or comments are greatly appreciated. 
Thanks in advance for any help and make it a great day,
Mike

[Jack]

I am in the same place as you are and have settled on the same specs, but I am not sure of the walls.  When this darn snow ends I plan to cruse HD and Lowes to find something.  I have even thought of bending 1/8 inch hardboard and screwing it to the sides to the rings.  You can have a dado on the top for the wall, but from what I have read, you can't have a dado at the bottom, because that will leave an edge next to the "C" on the baffle.  There must be something that is bendable and screwable.  The laminate idea will work, but will the Contact Cement stand up to the suction/abuse?  I am stuck in "wall hell".  I need a push.

[tvman44]

Thanks for the idea of using Formica for the walls.  I have built 2 separators that are in the barrel but want to build a top hat and having trouble finding lexan long enough and reasonably priced.  I happen to have 2 large pieces of Formica laying around in my storage and had never considered using that but now I think I may just do that. :)

[retired2]

Jack and NJ Mike,

If you are trying to keep your build inexpensive, simple, and functional, here are my suggestions:

First, forget about using anything transparent for the walls.  The see-thru options are expensive, hard to work with, and add NOTHING to the functionality.  I would recommend light gage sheet metal.  If you use my design, which has a top and bottom collar for attaching the walls, you can simply attach the sheet metal with pan head or truss head screws, and then seal the outside with silicone caulk.  My design also avoids any lip at the drop slot.  You may notice that my build has a dado that houses the top edge of the wall material, but I pointed out in my thread that this dado serves absolutely no purpose.  You do not need to incorporate it in your build.  I added it simply because my wall material was 1/8" too high and I did not want to try to cut that small amount off the entire length of my plastic wall material.

Also, in the interest of simplicity, you could use a 4" round inlet.  Plenty of top-hat separators have been built this way and work very well.  However, the rectangular inlet might work a little better with a small diameter waste drum.  The rectangular inlet will keep your incoming waste stream a little farther away from the outlet pipe.  That should help minimize waste by-pass.  If you build a rectangular inlet, make sure the area of the rectangle is a little larger than the area of the 4" diameter inlet pipe. 

The most recent innovation that gets some support, is the double high unit.  I'm reserving opinion on the benefit of this enhancement since I have not seen any hard data to support its value, but like other enhancements I think the most that could be hoped for is a very marginal improvement.

In my opinion, the basic top-hat design with none of the upgrades that have evolved, will probably give you 90% of the efficiency and functionality of the more elaborate units.  So, don't knock yourself out fretting over the design.  Build something quick and start getting the significant improvements that even a basic unit will provide.  When you get more money, add a Wynn style pleated filter.  It will take almost no time, and will provide more benefit that the other separator enhancements.

Then when you have nothing better to do with your time or money, build a new separator with every wiz-bang feature you can think of, but just make sure your expectations for improved performance are not too high.

[nj_mike]

Thanks for the input retired2.  Do you have a link or some pictures of your build?  I'm looking around but can't find any.

[jdon]

I'm yet another neo-builder with the dilemma of what material to use for the separator wall, so let me jump into this thread, too. I'm planning on ~20" diameter, to fit on top of a Brute can, based in large part on retired2's design.

I have scrounged both a good length of 1/8" hardboard, and one of Formica. It seems that the hardboard would be easier to fasten, but does anyone have experience with hardboard durability: would incoming chips scrubbing the wall erode the surface.

On the other hand, I figure Formica would be more durable than hardboard, but I'm not sure of how best to use. My only experience with Formica/laminates has been the traditional countertop installs, cemented to a solid substrate. Can Formica "stand alone", that is, can it work as a separator wall, supported only by mdf rings at the edges, with several vertical ribs (a la retired2) spaced between the rings. Or, does Formica need a continuous substrate for adequate strength?

Probably the strongest install would be a hardboard outer ring (substrate) with a Formica lining, but thinking of bonding Formica to the inside of a cylinder with contact cement gives me a headache- how to get a good bond with matching seams, without disaster. Does anyone have experience with partially supported Formica, or with more forgiving adhesives? I can't find any info on Formica walled separators, either in this forum, or a general Google search, so any advice would be greatly appreciated. This is a great forum :D

[tvman44]

Never tried the Formica yet myself but fully intend to as I have some Formica on hand, but it may be awhile before I get around to it.  If you try it before I do, please report back your results and I will do the same.  8)  I have made a couple of top feed separators in the barrel but anxious to try a top hat when ever I get a chance.  This time of year we do a lot of camping so it will be awhile before I get to it.  8)

[Jack]

Thanks Retired2,

I have all I need now.  I have on hand a roll of 8 inch metal so with your advise, that is what I will use for the wall.  All the necessary wood is in my scrap bin.  I even have some plexiglass left over from the door window on my router cabinet build, which I  might inlay into the bottom of the top of the hat.  For sure I will make the inlet a rectangle.  I have your plans and photos to use as my guide and I can't thank you enough for the help.  I use this link for your plans http://www.jpthien.com/smf/index.php?topic=563.0.  By the way, your hand drawing really helped in showing details which the  photos only implied.
Jack

[retired2]

Thanks for the input retired2.  Do you have a link or some pictures of your build?  I'm looking around but can't find any.

Here you go:

http://www.jpthien.com/smf/index.php?topic=563.0

[retired2]

I'm yet another neo-builder with the dilemma of what material to use for the separator wall, so let me jump into this thread, too. I'm planning on ~20" diameter, to fit on top of a Brute can, based in large part on retired2's design.

I have scrounged both a good length of 1/8" hardboard, and one of Formica. It seems that the hardboard would be easier to fasten, but does anyone have experience with hardboard durability: would incoming chips scrubbing the wall erode the surface.

On the other hand, I figure Formica would be more durable than hardboard, but I'm not sure of how best to use. My only experience with Formica/laminates has been the traditional countertop installs, cemented to a solid substrate. Can Formica "stand alone", that is, can it work as a separator wall, supported only by mdf rings at the edges, with several vertical ribs (a la retired2) spaced between the rings. Or, does Formica need a continuous substrate for adequate strength?

Probably the strongest install would be a hardboard outer ring (substrate) with a Formica lining, but thinking of bonding Formica to the inside of a cylinder with contact cement gives me a headache- how to get a good bond with matching seams, without disaster. Does anyone have experience with partially supported Formica, or with more forgiving adhesives? I can't find any info on Formica walled separators, either in this forum, or a general Google search, so any advice would be greatly appreciated. This is a great forum :D

I've never tried Formica or hardboard for the separator wall, but I doubt you would ever wear a hole through either one.  I have a feeling you might find hardwood, a little too stiff to work with.   Formica is thinner and probably easier to bend into shape.  If necessary, hit it with a hair dryer to make it a little more flexible, that is what I did with my plexiglass.  I definitely would not use contact cement, i.e. unless you are interested in giving up your place in heaven.  Personally, I would just use a construction adhesive that is slow setting.  Once dry, I would add a few screws to make sure it stays put.  Then go around all the outside edges and caulk with silicone to make sure it is air tight.   

Be aware that if you are using a DC with very high SP, more like what you would find with a really good shop vac or dust extractor, it is possible to collapse piping, waste drums, and I suppose even a poorly attached separator wall.  Some people have built spring loaded relief valves to prevent this.  I have never had that problem, even when I intentionally deadheaded my system.  I doubt you will ever have the problem if you are using a 1-1/2 HP or 2 HP DC because they just don't generate that much SP.   

[jdon]

First, apologies to nj_mike, if I've hijacked the link- the questions you had were the same as mine. Second, thanks to all for replies and info. Thanks esp. to retired2. I'm planning on wholesale borrowing of your build.

As of now, I'm planning on using Formica for the cylinder wall (it's actually a scrap of Wilsonart I picked up), without any substrate. I figure that I'll add more vertical ribs (?8) between the upper and lower rings, to provide more support. Construction adhesive is a great idea- the though of using contact cement gave me the willies in this application. Bending the laminate to ~20 inch diameter shouldn't be a problem, since it's already wrapped in a 14" roll.

My collector is an older model (blue paint) Jet DC 1200. Specs sheet says static pressure is 11.44 inches of water. FWIW, that translates to about 0.4 psi. I'm hoping that with bracing the Wilsonart will be strong enough.

My earlier question about dust particles eating away at the wall was based on some comments that Bill Pentz made on his site, saying that wood, esp. species high in silica, effectively sandblasted commercial cyclones, causing rust through. He suggested adding a rubberized coating at the impact area. In hindsight, for my application it seems like overkill.

One final (for the moment, anyway) question/thought about retired2's design of a "sandwich" baffle. You have a picture showing a chamfered mdf disc attached to the under side of your baffle, I assume to improve rigidity. What do you think of cutting the bottom ring (between the baffle and the waste container), so that a "tongue" projects into the center, below the baffle, in the sector where there's no slot. That is, instead of an mdf "island" beneath the baffle, have a "peninsula". I figure it would give better support, and might eliminate the need for a baffle support in the separation chamber. Just a thought... see attachment of a very crude drawing.

[retired2]

First, apologies to nj_mike, if I've hijacked the link- the questions you had were the same as mine. Second, thanks to all for replies and info. Thanks esp. to retired2. I'm planning on wholesale borrowing of your build.

As of now, I'm planning on using Formica for the cylinder wall (it's actually a scrap of Wilsonart I picked up), without any substrate. I figure that I'll add more vertical ribs (?8) between the upper and lower rings, to provide more support. Construction adhesive is a great idea- the though of using contact cement gave me the willies in this application. Bending the laminate to ~20 inch diameter shouldn't be a problem, since it's already wrapped in a 14" roll.

My collector is an older model (blue paint) Jet DC 1200. Specs sheet says static pressure is 11.44 inches of water. FWIW, that translates to about 0.4 psi. I'm hoping that with bracing the Wilsonart will be strong enough.

My earlier question about dust particles eating away at the wall was based on some comments that Bill Pentz made on his site, saying that wood, esp. species high in silica, effectively sandblasted commercial cyclones, causing rust through. He suggested adding a rubberized coating at the impact area. In hindsight, for my application it seems like overkill.

One final (for the moment, anyway) question/thought about retired2's design of a "sandwich" baffle. You have a picture showing a chamfered mdf disc attached to the under side of your baffle, I assume to improve rigidity. What do you think of cutting the bottom ring (between the baffle and the waste container), so that a "tongue" projects into the center, below the baffle, in the sector where there's no slot. That is, instead of an mdf "island" beneath the baffle, have a "peninsula". I figure it would give better support, and might eliminate the need for a baffle support in the separation chamber. Just a thought... see attachment of a very crude drawing.

Frankly, I think the MDF stiffener I added is overkill, but as I pointed out in my thread it was scrap material and could do no harm.  But in the end, I still felt it was necessary to add the support rod to avoid having the baffle "flapping up and down" in the turbulence.  Flapping is an exaggeration of what would actually happen, but you get the point.

So, on to your question of a peninsula style support.  It might work if stiff or thick enough.  And therein lies my concern.  Remember there is spinning air above and below the baffle, and that is why you want to keep the baffle thin, especially at the rim. If you add any thickness to the baffle between the start and end of the drop slot you might just introduce some unwanted turbulence.  I doubt that it would be a serious hit on performance, but you don't want to give anything away.

People seem to shy away from using a support rod as I did, but if you keep it set back from the drop slot I don't think it has any impact on performance.  It is largely out of the waste stream, so nothing ever hangs up on it, and I also doubt it introduces any performance robbing turbulence since it is also out of the fastest moving air stream.

[revwarguy]

I agree with just about everything retired2 said in his 1st post on this thread.  Until there is a way to actually measure "better separation of fines," most of those enhancements based on it are just unknown, and a slight improvement at best.

I would beg to differ, with utmost respect to retired2, about the transparent sides, though - I think it is an advantage to be able to see if anything is clogging inside, and, well, I just love looking at the swirl.  Maybe that's not worth the expense to some (it didn't cost me anything as I had the stuff already) but I would have paid for the plastic sheet anyway.  Just don't use plexiglass (acrylic) as it will be an exercise in frustration.  My Lowe's carries Lexan and you can find it at sign makers or online.  You don't have to get one long, narrow piece - the walls can be done in sections.  Since you are going to seal the walls in place, you don't need to screw into it, either - it just has to be cut with a tight enough fit to stay in place until the caulk sets up.

Having a transparent wall on the inside of the separator has shown me that with about 1 year's use, there is NO wear, scratching, or dulling of the window from the dust against the material, and I believe that worrying about the walls wearing down is unnecessary.  I have only been collecting sawdust however, not cleaning up after sandblasting equipment.  In that case, you should probably worry more about your hose.

Retired2 is right, though - just doing a basic one will get you very close and one you will be happy with every time you look in your bin.

[retired2]

I would beg to differ, with utmost respect to retired2, about the transparent sides, though - I think it is an advantage to be able to see if anything is clogging inside, and, well, I just love looking at the swirl.  Maybe that's not worth the expense to some (it didn't cost me anything as I had the stuff already) but I would have paid for the plastic sheet anyway.  Just don't use plexiglass (acrylic) as it will be an exercise in frustration.  My Lowe's carries Lexan and you can find it at sign makers or online. 

I guess whether we agree on wall material or not, comes down to your definition of "functionality".  I meant it to mean only how well the separator works, not seeing how well it works. 

I can honestly say that after using my separator for more than a year now, I no longer bother to even look at it.  That is a good thing because watching swirling waste in a separator can be a hazardous pasttime when your running power tools.  The last thing I want to see is one of my fingers spinning around inside my separator.  Secondly, I've never had a jam or plug in my separator, so I just take for granted that it is working.  If it ever did jam I suspect it would become obvious in a matter of minutes.

[revwarguy]

Jeez, retired2.  What ever made you think I look at the sep while sawing?  I use a camera.