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Discussion Starter #1
Hey folks,

I'm putting together my dust collection system using 6" 3034 pvc and now have my first run between my shop and the adjacent room where the DC will be set, but I've run into a problem.

When I go to attach the first 45 I am finding that I am not able to get it connected to the straight run. The 45 has a rubber gasket (see pic below) and no matter what force I use I cant get it fully on the straight pipe, it just seems like the straight pipe is a bit too big.





I should clarify that I am attempting to connect the 45 to an end of a straight run that I cut with the jigsaw, not a bell end. I tried putting some pipe lubricant on the end but it doesnt seem to want to get on there.
All pipe and fittings came from the same vendor.

I tried some other fittings like a coupler and in each case it seems like the addition of the rubber gasket makes the fitting too big to fit on the end of the pipe. I'm wondering if I shouldn't be taking the gasket off and screwing each connection together with sheet metal screws and foil tape, but I wanted to check here before I started removing the gaskets. Or is there something else I am missing?

One other unrelated question: Folks here have strongly recommended going with 6" as much as possible throughout the system. I am planning on ordering this 2HP Grizzly, non cyclone:
http://www.grizzly.com/products/2HP...h-Aluminum-Impeller-Polar-Bear-Series/G0548ZP

and this seperator:

http://www.grizzly.com/products/30-Gallon-Dust-Collection-2-Stage-Cyclone-Separator/W1049

I noticed that the seperator accepts 4" hose. I assume that means that the pipe from the seperator to the dust collector will be 4". Wont that negate the benefit of using 6" pipe to begin with since on a critical connection at the end of the run I am using 4" or is it just a small part of the system and I will still be getting the benefit of the 6" runs so I shouldnt worry about it?

Thanks.

Nathan
 

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I'd take the rubber out and see what happens. I'm also thinking you bought the wrong fittings for what you're doing.
 

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Discussion Starter #3
Paarker said:
I'd take the rubber out and see what happens. I'm also thinking you bought the wrong fittings for what you're doing.
Uh oh. How did I buy the wrong fittings? I told the schedule 35 & since they gave me all the stuff together I'm assuming everything goes together. What do you know that I don't?
 

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where's my table saw?
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do not use a 4" ported separator

It will dramatically affect your performance in a 6" main. If you want to have a separator you can make a simple one with 2 6" 90 degree elbows on a lid mounted in opposing directions. Like this, only with 6" fittings:
http://www.ptreeusa.com/dustacces.htm#399

4" Cyclone Dust Separator Kit


Barrel and hose NOT included



Make your own cyclonic action dust separator

 

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Have you tried beveling the edge of your pipe? We used to do it on water pipe with a trim router mounted on a plate and a 22.5-degree bearing guided bit. It can be really hard for the o-ring to make the initial jump over an abrupt edge.

You can look up how much friction loss you will have with different sizes of lines, fittings, transitions , and various expansions and contractions online. They just add together. I personally would be more concerned with frictional losses at the separator than any where else. Typically cyclone separators shave less loss.
 

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Using a 45 reduces the debris speed in the pipe. A long 45 or two 22.5 fittings together work better. I think you have to thick of a pipe but I could be wrong.
I bought thin wall drain pipe and fittings 6" fittings were pricey but nothing had o-rings.

With a 6" duct as mentioned that seperator will not work properly. That style alone is not the best to begin with. Search the DC section gor Thien Seperators. They will be more efficient and you can build one using 6" ports.
 

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You almost certainly have the wrong fittings, and I'll bet those cost more than the ones you actually need. Pipe sizing is confusing to a lot of people, but more to (for some reason) to Skippy Stockboy at the local borg ( I'm guessing that's where you got it). BTW, yes, if you choke your 6" ducting down to 4" it will have an impact, reducing air flow.
 

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I hate that type pipe however it is the correct pipe. You just have to put a block of wood against the end of the pipe and use a sledge hammer to get the joint together. You need the rubber gasket to make it air tight. If you would heat the rubber seal that might also help. If it's cold where you are that can make it more difficult.
 

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where's my table saw?
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just remove the gasket

If the straight pipe is a sloppy fit, wrap the end with several layers of duct tape or other heavy bodied tape. It's not carrying fluid like the pipe was designed to do, only air, so it doesn't have to be a "perfect" fit. A small bead of silicon can be pressed in around the fitting afterward if that's necessary. This ain't rocket science, just dust collection. :yes:
 

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I want to come back to those being the wrong fittings. I've not seen anyone use gasketed fittings on a DC system, not to say it hasn't been done. But the ones you want are "solvent weld" (no gasket) though you won't glue them....or at least I suggest you don't glue them. They will almost certainly be cheaper and you won't have to muscle the stuff together.
 

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I want to come back to those being the wrong fittings. I've not seen anyone use gasketed fittings on a DC system, not to say it hasn't been done. But the ones you want are "solvent weld" (no gasket) though you won't glue them....or at least I suggest you don't glue them. They will almost certainly be cheaper and you won't have to muscle the stuff together.

I got to agree with this one for sure. Not that I use PVC pipe every day but every time I've used it it never had a rubber gasket in the fittings.
 

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If the pipe reads ASTM 3034 SDR-35, the uncut straight sections should have a bell and gasket on one end and a chamfer on the other. Like jigs-n-fixtures said, chamfer the cut ends and use some lube. Those gasketed fittings are a tight fit.
 
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