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So, I'm kind of re-doing my shop at the moment and I'm thinking about a few runs of rigid ducting to get dust collection out so some places in the shop I need it and don't have it and to improve the performance where I do have it. I also don't want to blow too big a crapload of cash on this as I'm currently blowing a crapload of cash on other shop related things. My DC is a 1HP Penn State Jobbie (I know it's not much but it's what I have). Don't know the CFM, not listed on the sticker.

The cheapest ducting I've found is the split kind oat home despot for $7.99 for 5'. Anything wrong with using that for my main runs? The Y-joints and "valves" I'll probably get from woodcraft or something like that.

Anyone know of any other sources for ducting?

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Andy I don't see why that won't work. Be careful with buying the fittings they may not fit. I had to adapt quite a bit. I would up buying a crimping tool and made some of my own adapters. Bought a heavier gauge pipe from a AC/furnace supply house.
Got a friends wholesale pricing. Not sure about your DC. Sounds under powered.

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I put in a duct system using the split kind from Lowes. I would highly suggest using duct tape to seal all the joints- or even caulk. Also, if you go to lowes rather than home depot, they have y-joints there that will be cheaper than woodcraft or grizzly or the like. Best of luck.

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Andy,

I just spent the past two weeks relocating machines and revamping the dust collection ducting in my shop. Contrary to all the great advice Bill Pentz offers on his site, I've found that there are much more economical ways of doing it with excellent results. I used the 4" ID sewer pipe from HD at under $8 a 10' stick and it only took 4 sticks plus a few fittings for the whole setup. The key is good grounding to minimize the static to virtually zero. I do have a 2hp collector with the filter canister from Grizzly and additional air filtration in the shop so I'm with Bob that you might want to think upgrade on your DC. Another great support to maintain good suction should you use less than a 3hp DC unit is to make sure you have good blast gates to cut off each machine at the main line, and keep the shortest possible runs. Go with the rigid lines all the way to each machine if possible and use the flex ducts to create long radius elbows where you need instead of regular elbows. My system splits off to each side of the machine area (unorthodox I know but it works well) so I also have gates to isolate the side of the room I'll be using at the time. I reworked my entire system for under $150. Having so many blast gates is not the most ideal setup because you have to consciously make sure and close or open only the ones you need for the specific machine you'll be operating at the time. But, in a small one man shop on a tight budget, it works just fine for me because it doesn't take that much time and is essentially second nature to me now. I currently have the best suction I've ever had in my little 460 sqft shop here at home since I set it up and couldn't be more pleased. Again, grounding is extremely important if you go with plastic pipe because you don't want to get zapped by static while your hand is in the vicinity of a moving sharp object. In regard to grounding, I've found that it's not necessary to run wire through the pipe (which can cause clogs), but rather, I add 3/4" lath screws piercing through to the inside of the pipes at about 8" intervals on either side staggering so that actual exposure in the pipe is about every 4". Then I wrap the exterior of the pipe with bare copper wire in a long spiral fashion connecting all the screws for the length of all the runs and grounding to the machine at the end of each run. Don't forget to ground to the DC as well. I can post a few pics of it if you're interested, and if not, well, that's what I did and it works great for me. The shop is virtually dust free now when resawing exotic billets, or bolts of spruce.

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Bill Hodge


One does not simply, own enough guitars!

I've used PVC sewer and drain in the past, it worked OK, but was a lot harder to modify when new equipment was added or changes needed made. It was also a nightmare when a clog occurred due to the lengths of the pieces of pipe. If you go that route, take the grounding very seriously. Shocking your fingers is not the main reason for grounding, it's to prevent explosions! Seriously, this can and does happen. I can think of at least three fairly large shops that had their collectors explode in this area in the past 15 or so years. The wire inside the pipe is to relieve the static charge in the wood dust itself and prevents potential explosions, the one on the outside keeps you from getting shocked. The screws through the pipe may or may not discharge the dust, I don't know. The latest system at the cabinet shop I run was done with standard round metal HVAC ducting. I found taping the seems on the pipes was not necessary, but recommend taping every joint with aluminum tape. We even used the HVAC elbows, the trick is to use 2 of them to make a 90 so as to keep the corner as rounded as possible, every seam on each elbow is also taped with aluminum tape. It is self grounding when properly fastened to the collector and equipment( assuming your equipment is properly grounded to start with). And of course flex pipe should only be as long as absolutely necessary to connect from the duct to the equipment when needed and properly grounded itself.
Brian

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Brian

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Brian, I'm well aware that the grounding is not just to prevent static shock to the operator (my bad if it came across that way ), there was a study done on the screw through the pipe method and the purpose was to see if indeed it would eliminate static inside the pipe when using the method I described. This is the reason I switched to this method because it virtually eliminates clogging if designed according to my description and used with an adequate layout and DC. They found that the static discharge distance in an evac system is an average of 4-3/8". Thus, the every 4" coverage in the pipe. I've been at this (woodworking) for over 35 years much of it professionally and in a large shop environment, absolutely metal is the way to go. In a small shop if it's in your budget, it's the way to go as well. That said, in the average small one man shop, no more than one machine is being used at a time that requires dust collection and if done correctly, the system I described is perfectly efficient, and safe. In a multi-person shop I would never advise anything less than metal ducting and a minimum of 5hp for dust collection. Again, with emphasis on proper grounding for plastic or PVC!!! The key to what you mentioned is "large shop", lot's and lot's of dust being moved very rapidly in large volumes at very high speed (i.e 4000+ cfm). No comparison whatsoever to that of a small one man shop. I've run a lot of volume through mine with the thickness planer hogging away and no clogs. It's the biggest culprit for potential clogs in a small shop. Another big culprit for clogs is moving the dust and chips at less than 800 cfm. A large bandsaw needs a minimum of 800 cfm to move the waste efficiently and a 12" thickness planer needs around 600 cfm with a table saw at about 400 cfm. These are minimum for efficiency and to help prevent clogging. The longer the runs you have and the more turns, the less efficient the line becomes. Thus the need for better isolation in the typical small shop using one machine at a time.

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Bill Hodge


One does not simply, own enough guitars!

Some very good advice Bill. I ran a 6" HVAC pipe main trunk with wye's off each side to connect my machines. 6 in all.
The unorthodox part of my system is 2 - 3hp double canister Grizzly's and lots of blast gates to control isolation.

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Thanks Bob, that means a lot to me coming from you!

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Bill Hodge


One does not simply, own enough guitars!

I used HVAC sealant on the joints. It's a brush on paste and works well. Only problem is changing things around. Takes a bit of work to get the pipe/fittings apart

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Beautiful and unusual tone woods at a reasonable price.
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The Zootman
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Kenmore, NY 14217
(716) 874-1498

Brian, I'd be interested to see any documentation of those explosions, the cause, and the size of the system. This is a hotly debated issue but all the searching I've done has indicated that DC explosions in a small shop system are, as Todd implied, essentially a physical impossibility. Fires are a real hazard but not ones started by static sparks.

Here's one article. http://www.thewoodnerd.com/articles/dustExplosion.html

I don't claim to know either way but I would expect that there would be some well documented cases if it has happened. So far, I haven't found them.

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Thanks for all the advice guys. Right now I'm thinking of going with the metal stuff but we'll see. The idea of driving screws every 4" doesn't sound that all appealing I'll tell you that. If I do go with PVC pipe, I'll probably just run the bare wire on the inside.

I'm going to look for an HVAC supply place and see if they'll sell me ducting if not, I'll probably hit bLowe's for the split piping.

As to the strength, or should I say, weakness of my DC, it looks like 2HP DCs aren't all that crazy expensive so I'll look into it. I think the key is that I'm going to try with what I have first and if it don't work, I'll consider moving up to a 2HP. 3HP seems just crazy overkill for a little shop like mine.

Any opinions on these DC's:

http://www.pennstateind.com/store/DC2000BCF.html

http://www.pennstateind.com/store/DC2000B.html

They've also got a nice 1.5hp models that run on 110v http://www.pennstateind.com/store/DC2V3CF.html but I'm thinking that extra 1/2 horse might be worth running another circuit for. Sure would be easier if it wasn't necessary.

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Andy, if you're going to upgrade your DC, don't go with a two bagger, go with the filter canister type. The cloth bags do not filter well and it's the fine dust in the air that will get you over time. Also, This unit will give you more bang for your buck, and IMO is a much better quality, more powerful unit. Just something to consider.

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Bill Hodge


One does not simply, own enough guitars!

Also, if you are going to upgrade your DC, don't waste your money on 4" ducting. You'll need 6" mains for a DC that produces CFM's in the 1,000+ range.

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Hmm... now that could be a serious issue. I'm sure my 1HP doesn't need 6" mains but I won't know if it's completely inadequate until I try it out with rigid lines.

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A good collector can collapse that pipe. But you may be safe with the 1hp.

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Two of the cases I know of were Amish shops, they run all their equipment with air motors. I don't think that made a difference though, but I do not know. You won't find any official documentation of these things as the Amish generally don't operate that way. They generally don't follow OSHA or many other safety precautions either. Grounding is a foreign concept to folks who don't use electricity. The other was a pallet mfg. company in Thompsontown. Late 80's or early 90's. I looked but could not find anything on the web on this incident. Perhaps "explosion" was not the word to have used, rather a very hot and fast burning fire in the system. That pallet co burnt to the ground in short order. The fire Marshall said it started in the dust collection system. I remember it well as my employer made us re-wire our grounding on the PVC system we were using at the time. Grain mills use dust collection systems similar to what we use in woodworking only on a vastly larger scale. ADM in Mechanicsburg averages a serious collector fire every 2-3 years. Don't think a static spark can start a flash fire? A young man blew up at a gas pump in Mechanicsburg last year, most likely cause was a static spark. While I am not a safety-crat by any means, I see no reason to take a risk just to save a few bucks. While the risks surely escalate with scale, that does not mean they are nonexistent on a small scale operation. Otherwise they would tell you not to worry about grounding systems under a certain size at all. I'll spend the time and money to set up a proper dust collector and sleep well at night knowing my place won't burn down. As for the screws in the PVC, If someone published a report stating it is safe then so be it, as I said I had no idea if it was good enough or not.
Brian

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Hmm... Perhaps my best bet then is to put off central unless I can justify upgrading to the 2hp unit. Question though - does anyone know of a site that has some guidelines on how long your runs can be with what size collector? If I did go with a 2HP it would be nice to put it outside the shop to free up a little space IF it has the juice to pull the chips that far. I'm thinking that the longest run would be between 20 and 30 feet piping.

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Andy - here's a tutorial on Oneida's site that might help http://www.oneida-air.com/shop_plan_design/ductwork_tutorial01.php

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