Replies

1. 
   Drew1house | Oct 17, 2007 06:53pm | #1

   The pros are less noise... nothing to trip over, no overhanging ductwork... really it would be a dream... make sure the radius on the turns is really correct as there is no going back... now that is the issue... no going back. The con is just that. What if you get a new machine or find your shop configuration is not to your liking... changing where the ducts are is gonna be tough. When you get to schools (university level) where they have build big work shops it is usually still overhead due to the fact that 20 years down the road you may want to change something.

   Drew

1. 
   KiddervilleAcres | Oct 17, 2007 08:21pm | #2

   Drew & orange,

   Gawd awful if a line gets clogged too! 

   Judicious placement of machines can alleviate a lot of duct work, think center island of tools, downdraft for outfeed table, router in TS extension table, etc.

   Regards,

   Bob @ Kidderville Acres

    

   A Woodworkers mind should be the sharpest tool in the shop!

   Edited 10/17/2007 1:21 pm ET by KiddervilleAcres

2. 
   KeithNewton | Oct 18, 2007 01:34am | #3

   I have some runs down through my shop which are about about a foot deep and 10" across. When I formed the sides, I had a 1'x 3/4" cleat along the top of the form, so when it was poured, and the forms removed, this leaves a little ledge for the plywood top to sit on, and bridge the gap.

   I can always get into the whole ditch to change air-lines, electrical, vacuum, or anything else that you choose to put in there with it

1. 
   orangedoc | Oct 18, 2007 03:54am | #4

   I've read online about creating a "valley" with a cleat on the top which you describe. I'm assuming you either have to do this, or put the ducting below the concrete/rebar, given that the ducting is 4-6" and so is the thickness of the concrete. Is this correct? Also, I'm planning on PVC ducting, thinking that will be stronger, and better able to hold the weight of the concrete above it. Any reason to use metal ducting? One more question: I did find a diagram in an old "Tools and Shops" which shows placing styrofoam with a vapor barrier below the ducting. Is that necessary?

3. 
   tinkerer2 | Oct 18, 2007 05:01am | #5

   I can't tell you which works best, only what I plan on doing.  My shop is just about built.  I have two holes in the concrete leading to the basement.  I was going to put the dust collector in the basement with ducts going through the floor to the machines.  I haven't decided how to arrange the tools or the ductwork yet though.  I might run some of the ductwork overhead yet.  I suppose that I will either have to open the basement door or put in a return for the collector.  I don't know how that is done.

4. 
   terryb | Oct 19, 2007 05:50am | #6

   You'll lose a lot of shop heat unless the pipes are insulated