Why a Duck?

[Bruce Seidner]

In planing the route for my 6" pvc ductwork the most straight forward line is straight down the middle of the shop with a few wyes, wheres, and one big but for. The 2x10" 50 year old rough sawed hardwood joists milled on the property run perpendicular to the proposed route. I need to run through about 20 of them.

The fastest method of work would be my chain saw. Chaulk mark two lines 6" apart and cut straight up to the floor. Use a temporary brace between the joists. And sledge hammer the piece out. Once out. I could use a band saw to remove the 6" hole I need and glue the corners to the PVC and as best as I can back to their original spots. Then use some thin ply squares with the hole cut oversize sides covering the cuts to mend the joist.

Like I need 20 holes in my head. Anyone want to commiserate or lend sage advice

Or I could drill, route, jigsaw a 6"hole in each of the joists. I don't suppose they make a circle saw drill that is 6". But i routers anf jig sawa ann

Is one preferred for a structural reason or is just personal taste, Excerpt during the holidays 2x a year at most there a 6 adults. It is a quiet residence. Also is there a more elegant way to achieve this line. I just can't afford to loose six inchea from my ceilinh hight and know I will smack my head ongingly.

[John Coloccia]

I want to say you're allowed something like a 30% hole in your joists, so for a 10" joist I think you're allowed a maximum of about a 3" hole. I'm pretty rusty on this, but I have to say that a 6" hole in a 10" joist, just as a gut feeling, seems like a bad idea. I had this printed out somewhere at one point because I was contemplating doing some work in a house I owned some years ago, and that 30% number sticks in my head, but I can't seem to find that reference at the moment.

[Leo Graywacz]

Don't do it.

[Roger Jensen]

+1 on the don't do it vote. Can I vote twice?

[Rick Potter]

Another +1 here. Don't do it. Is it possible to run the main along one side wall and run branches between the joists? Not as efficient, but compromise may have to be made. You would have a lot of trouble trying to sell that house if you do it. As others have said...probably illegal.

Rick Potter

[Scott Holmes]

Bad idea...

[Dave MacArthur]

I'll vote again for you, don't do it!

This is a perfect case where the engineering answer is this: spend $150 extra and save yourself untold hours of labor and destroying your floor. Whatever you were going to buy as a DC, buy one HP size up, and run your duct around the walls. Honestly, look at the cost of a 2HP Oneida vs. the 5HP models:
3HP V-3000 $1195
2HP Dust Gorilla: $1380
3HP Dust Gorilla: $1585
5HP Dust Gorilla: $1690
3HP Pro 1500: $1695
5HP Pro 2000: $1895

Just bump up 1 HP and and be done with it.

[Bruce Seidner]

So basically my idea of routing down the middle of the shop through the joists sucks. I must plead temporary insanity after reading too much about CFM loss, etc. In truth I have a silly huge industrial blower that will suck a golf ball through a garden hose, the chrome off a bumper, you get the idea.

Reason will prevail and I will locate the blower/cyclone towards the side of the shop wall and out of the way. It will make some machines happy and some less happy but that is life.

Thank you all for your sage and collective wisdom.

[glenn bradley]

Temporary insanity after trying to work out your DC needs is a common occurrence. I had a complicated overhead layout conceived and then ended up going low instead. Plastic duct makes it really easy to change things around so I lucked out on that decision when it was time to add a leg for a planer.

You don't want anything laying across a walkway or robbing you of any more floorspace than necessary. Sometimes the addition of a DC is a good time to re-think your whole layout. Your ceiling height sounds like a driving force to give that a chance. Sketchup, graph paper, coffee and a sense of humor help too ;-)

[David Thompson 27577]

In planing the route for my 6" pvc ductwork the most straight forward line is straight down the middle of the shop with a few wyes, wheres, and one big but for. The 2x10" 50 year old rough sawed hardwood joists milled on the property run perpendicular to the proposed route. I need to run through about 20 of them.

The fastest method of work would be my chain saw. Chaulk mark two lines 6" apart and cut straight up to the floor. Use a temporary brace between the joists. And sledge hammer the piece out. Once out. I could use a band saw to remove the 6" hole I need and glue the corners to the PVC and as best as I can back to their original spots. Then use some thin ply squares with the hole cut oversize sides covering the cuts to mend the joist.

Like I need 20 holes in my head. Anyone want to commiserate or lend sage advice

Or I could drill, route, jigsaw a 6"hole in each of the joists. I don't suppose they make a circle saw drill that is 6". But i routers anf jig sawa ann

Is one preferred for a structural reason or is just personal taste, Excerpt during the holidays 2x a year at most there a 6 adults. It is a quiet residence. Also is there a more elegant way to achieve this line. I just can't afford to loose six inchea from my ceilinh hight and know I will smack my head ongingly.

Either method will leave with a significantly weakened floor system. Assuming your rough sawn 2X10 is actually 10", then a 6" hole leaves you with 2X4 framing.

And 2X4's won't carry the weight -- they are only considered structural in the vertical, and then only in approved-design wall systems.

If you really need to hide the pipe in the floor system, you should find a structural engineer who can help you figure out how to add steel plates surrounding those holes. The engineer can tell you how thick, and how long the steel needs to be, and whether or not it's needed on both sides of each joist or not.

[Thomas Bank]

Here is a quick reference for boring holes in floor joists and wall studs:
http://www.bloominggrovetownship.com...ughintable.pdf

[Lee Schierer]

Go above or below, but definitely not through a 10" joist or stud with a 6" hole and you absolutely do not want to cut a section out and try to splice a piece back in place.

[Bruce Seidner]

I had a complicated overhead layout conceived and then ended up going low instead.

That is clever. Going down the middle between machines. Now that I had never seen.

[Dan Friedrichs]

Another idea: instead of a 6" round main duct, you could build a square duct (out of melamine, etc) that was not as tall, but wider, and mount that to the ceiling (saving the height you're trying to avoid loosing). As an example, a 6" round duct could be replaced with a 2.5" tall, 11" wide rectangular duct and still get about the same CFM.

[Joe A Faulkner]

Maybe you can configure your tools in an island around the DC. Checkout this shop:

http://www.finewoodworking.com/Works....aspx?id=23974