Dust Collection Advice Sought

[BOB OLINGER]

I sincerely apologize as this has likely been discussed previously, but to avoid searching through the past posts, I would like to request any advice. I'm going to redo my present dust collection -

* I have a Delta 50-760 single bag unit
* I have installed a Thein collector/seperator
* I just ordered a Wynn canister (best model) to replace the upper bag
* I currently have about 12-14' of main trunk of 4" sewer drain PVC that runs parallel to a beam (basement shop)
* I have drops using 4" PVC and/or 4" flex hose to the table saw, jointer, planer, and miter saw.

I was thinking about replacing the 4" PVC with 6" as I recollect that bigger diameter is better. While doing this, is 6" metal (heat duct material) better than 7" PVC? Metal duct materials is much easier to get (at all borgs), but my focus is on what's best and I'll get the PVC if better.

Thanks in advance for any input.

[Matt Day]

I sincerely apologize as this has likely been discussed previously, but to avoid searching through the past posts, I would like to request any advice.

It has been discussed before, many times. Not sure I understand your logic about not searching for posts (use the search function!).

Anyway, I used to have that same setup. That 50-760 doesn’t have the CFM to support 6”. Keep the 4”.

And if you were going to go to 6”, the metal pipe at home centers isn’t thick enough and could implode. It’s designed for pushing air not pulling it.

[Andrew More]

I don't think it matters much which material you use. You should go with whatever you find cheapest, and easiest to use. PVC can be a bit easier to reuse, and it won't cut you, so there's that. OTOH, it starts to build up a charge, and no you cannot ground an insulator. It's also heavier, which is a problem when you're up on a ladder, by yourself, trying to hang a 10' section.

Metal duct is easy to get at the big box stores, but I like HVAC suppliers. The costs are usually lower, and they have more unusual fittings. For example, I've got a 6", 5", 4" WYE on my table saw they happened to have in stock. Doing that at the borgs would probably have been difficult at best, because of the 5" is an odd size. Your HVAC supplier should also be able to hook you up with some 26 guage ducting, instead of the 30 guage at the home centers. They also often have uncrimped fittings, which is nice, because a dust collector goes in the opposite direction of a normal furnace.

I find the fittings for metal to be more flexible, and cheaper. It's also lighter. The fittings themselves make it very easy to put in sweeping curves, while PVC is designed to work in cramped spaces, and makes very sharp corners. OTOH, metal requires a way to cut it, and you're likely going to need to coat all the seems with mastic. It can also be painful to assemble, vs PVC which just slips into place. If you do assemble it without gloves, be prepared to come out looking like your hands lost an arm wrestling contest with Edward Scissorhands.

And yes, bigger is better, exponentially so. 6" duct has an area of 28.27 sq in vs 4" which is 12.5 sq in, or about a third of the size.

[Andrew More]

And if you were going to go to 6”, the metal pipe at home centers isn’t thick enough and could implode. It’s designed for pushing air not pulling it.

This seems unlikely with a small single stage unit.

[Frank Pratt]

Personally, I like spiral metal duct. It's very strong, much more so than the snap lock duct, even in heavier gauge. Metal also come in long sweep elbows, which is much better for airflow.

As far as size goes, you don't want to go to big for the size of your blower. If you do, then the spoil will tend to settle out in the duct, or may not even make it up vertical runs. I would say that 4" is about as big as you want to go for that little blower.

[Robert Engel]

Based on experience with my own system, I am confident you're 1 1/2HP blower will perform better with 6" pipe.

When I revamped my dc system, I originally planned to upgrade to a 3HP blower. I quickly discovered that is a rare animal, so as a stop gap I threw my old 1 1/2HP Jet blower on a Super Dust Deputy cyclone, hooked it up and was quite surprised at how well it performed. 3 years later its still there and works well enough to please me.

The longest duct run is my tablesaw (24'). While I know the CFM's at my table saw could be better, it does a good enough job to suit me.

While I know I could do with a better system & mine wouldn't Bill Pentz test, reality is all I can talk about.

So I say go for it!

[Bob Riefer]

I agree that some initial searching before posting is generally a good idea, especially on a common topic like this one. Water under the bridge :-)

On the first page of this subform, there's a post I recently put up that contains my "recipe" that has worked out really well, and is based on being frustrated trying to do exactly what you're doing now (and finding lackluster results, wasting a lot of time and energy,when I really should have gone straight to the recipe), and then feeling lost in the beautiful mind of Pentz.

Not saying my recipe is perfect (it's not!) but it would significantly advance your learning curve on this topic, and it's based on having read all Pentz, and all posts from the knowledgeable contributors on this forum (honestly... these guys are brilliant and helpful too).

(all that to say this... small blower and small pipe is going to be frustrating as can be... )

[BOB OLINGER]

Personally, I like spiral metal duct. It's very strong, much more so than the snap lock duct, even in heavier gauge. Metal also come in long sweep elbows, which is much better for airflow.

As far as size goes, you don't want to go to big for the size of your blower. If you do, then the spoil will tend to settle out in the duct, or may not even make it up vertical runs. I would say that 4" is about as big as you want to go for that little blower.

By spiral do you mean the semi rigid flexible - such as at Lowes?

[BOB OLINGER]

Thanks for the replies. FWIW, I have read a good number of the past posts, but wanted to assure answers were as applicable to my situation as possible.

[jeff norris 2011]

6" is better IF you can get the FPM high enough to keep the dust moving. With 1.5HP it think you are pushing it. Going too little means you don't get max CFM, go to big means you have a system that does not work at all.

I went 5' on my 2hp system.

[David L Morse]

I think the Thein separator probably is the highest loss part of your system. Changing duct size won't have much effect. Can you post a pic of your separator?

[Steve Wurster]

I own the same DC, also with a Wynn filter, but I have a Super Dust Deputy mounted under it instead of using a Thien Baffle. The output of my Super Dust Deputy is a 5" port, so I'm using 5" HVAC pieces for the solid piping (maybe 10 feet total, but after a short takeoff from the unit it drops down to the floor and continues from there). Part of the pipe is "hard wired" into the back of my table saw, while the remainder goes to a 5" flex hose that I hook up to my router table, jointer/planer, and bandsaw as needed (also a basement shop, with barely 7 foot to the beams and tons of house HVAC overhead, so no ability to do overhead drops). The main parts of my HVAC pieces are from the BORG, while a 5"->5" splitter and a couple adapters are from Oneida. I want to say the blast gate is also from Oneida, but I might have bought that somewhere else.

I've run 4" pipe and hoses with this unit before, both before I had the Super Dust Deputy and for a while after. I'm pretty sure it works a lot better with 5" pipe and hoses. The DC has a 5" output on its own, after you remove the double 4" splitter it comes with. I'm not sure it gets enough performance from its fan to go with 6", especially after going through a Thien baffle or cyclone separator. I want to say somebody out there has done some performance analysis with this exact DC, but don't quote me on that.

[David L Morse]

I want to say somebody out there has done some performance analysis with this exact DC, but don't quote me on that.

Are you thinking of this one from Wood Magazine?

Various5InchMagazinePic.jpg

[Steve Wurster]

Are you thinking of this one from Wood Magazine?

Maybe... good find, although of course you gotta do the math yourself on the pipe loss.

[Larry Frank]

With that dust collector and losses due to the Thien baffle, I think you are best off with the 4" duct. You already have the 4" installed, just use it.