# Metal vs Plastic Duct



## Santa's Workshop (May 16, 2011)

Moving to a new house so I get to build a new basement shop. My current DC system uses 4" PVC ducts. I ran a ground wire through it. So my questions are:

Is there a performance difference between metal and PVC?

If PVC is used, what are your thoughts on the need for the ground wire? There were lots of conflicting opinions on line, so I ran the ground wire to be on the safe side with the current system.

Thanks in advance for your opinions.


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## Fred Hargis (Apr 28, 2012)

There is probably a performance difference, but I'd bet it's so slight that you would need laboratory instruments to measure it. I have PVC, and went with it because of cost and availability....kinda hard to find metal wyes locally. As for the ground wire, my very first system had it and it was such a PITA to deal with every time I made a change I finally tore it out and have not replaced it. There is an article that debunks the need for grounding, if I can figure out where I put the link to it I'll post back. I think even the mythbusters show debunked it, at least from a fire/explosion standpoint. It may help some if you have a static problem and want to put it in for personal comfort.


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## rrbrown (Feb 15, 2009)

Fred is right it will be a slight advantage with metal but You will not be able to tell. Supposedly the PVC will have enough static to slow the airspeed some but Proving that is the problem.

I have PVC with no static problems. However Santa's workshop might be in cold and dry air which might cause more static electricity problems then down here in South Louisiana.

I will add a little helpful info. 

If you don't have a canister filter I would add one they increase the efficiency by 50% and are 1 micron filters. Wynn Environmental has a kit for $109, $153 for a slightly better one and another one for $168 that is not that good.

If your DC can support a larger main trunk line do it because I got another 50% increase by increasing mine to 6" and reducing down at the tools. That will allow you to have better suction on tools that require 2 dust ports. Usually a 4" and a 1 1/2" - 2 1/2" ports like for a band saw or a table saw with overarm.

Thien Baffle's are also a good substitute for expensive Cyclones. Just remember if you use a larger trunk line you need to use that size ports on the Thien Baffle ports.


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## tvman44 (Dec 8, 2011)

rrbrown, which filter are you using? Been eyeballing the $153.00 thinking about ordering that one for my HF 2hP DC.


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## Santa's Workshop (May 16, 2011)

This branch of Santa's Workshop is in the midwest where dry air is NOT a problem in the summer and a controllable problem in the winter. 

My DC is Craftsman which appears to be identical to Jet--at this moment, I can't remember the motor HP. I plan to order the new filter after the move--been thinking about it before--but now I have the perfect reason. I guess I'll take all the existing pvc pipe, fittings, blast gates, etc. Probably barely worth the trouble for the cost of the material, but why not.


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## jgt1942 (Mar 15, 2012)

Take a look at Bill's site (http://billpentz.com/woodworking/cyclone/index.cfm) he has a BUNCH of info and I think it will answer all of your questions. PVC is actually better than metal mainly because it is much easier to work with. BTW 4" is really too small (sorry). Also the ground wire is not necessary, I was surprised to learn this myself (I think there is an article on Bill's site about this).


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## Lost 81c10 (Jul 14, 2012)

rrbrown said:


> Fred is right it will be a slight advantage with metal but You will not be able to tell. Supposedly the PVC will have enough static to slow the airspeed some but Proving that is the problem.
> 
> I have PVC with no static problems. However Santa's workshop might be in cold and dry air which might cause more static electricity problems then down here in South Louisiana.
> 
> ...


rrbrown,

you mention that the wynn filter that sells for 168 (the .5 mic NANO filter) is not that good. i debated this trying to decide which filter to get when i was looking at buying one and decided to get the NANO one. can you let me know why that one is not that good, as i have not used mine yet and would like to know if i might need to exchange it. thanks for the info.


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## dbhost (Jan 28, 2008)

For what it's worth, on the Wynn Filters. Even though the Nano fiber filter spec's out at .5 microns, the spun bond poly is the one Bill Pentz, AND Richard Wynn both recommend. The specs for the spun bond at %99.99 at 1 micron, and something like %99.9 at .5 micron. I can live with .09% being missed on the first pass, my ambient filter certainly will catch it... As I read it, the difference in ratings has to do with testing methodologies used at the time of rating the different filters. The spun bond are also FAR superior to the Nano in the fact that they can be washed out, and are basically a lifetime filter. Worthwhile investment for sure!

To the original question, metal duct is preferrable to PVC in the fact it doesn't build up static. The threat of a dust explosion in a home woodshop dust system is theoretical at worst. Your odds of being smashed to bits by an unexpectedly de-orbiting hunk of space trash are MUCH higher... About the only reason I would want to duct with metal is to get sizes PVC doesn't come in, like 5"...


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## TMA Woodworks (Apr 23, 2010)

jgt1942 said:


> Take a look at Bill's site (http://billpentz.com/woodworking/cyclone/index.cfm) he has a BUNCH of info and I think it will answer all of your questions. PVC is actually better than metal mainly because it is much easier to work with. BTW 4" is really too small (sorry). Also the ground wire is not necessary, I was surprised to learn this myself (I think there is an article on Bill's site about this).


Bill website really gives all the information you may or may not want. PVC is easy to work with. I used 4" for mine and it seems to do the job. I did run the ground wire on mine, this was only because I was tired on the monster shocks every time I ran the thickness plainer. I actually used Bill site to build my cyclone. I have a picture in my album. Fun project. The only reasons I would go to metal is the ease of taking it apart to reconfigure and the sweeps are a lot more gradual than the pvc.
Bob


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