# Dust collection in new shop - a blend of above and below ?



## loupitou06 (Apr 17, 2009)

Hi all,

First of all I know this topic has been discussed many times and I did spend the better part of the last week reading all former topics on dust collection on LJ forum but I still need some help.

I am about to break ground on my dream shop, a dedicated 25×30' - one story workshop with A/C, build in dust collection and dedicated power. The days of the garage shop are soon over.

One of my biggest complain about my garage workshop is the dust collection, I have to constantly move the 4" flexible hose of my Oneida Gorilla DC from machines to machines. In the new shop I want to install a dedicated DC piping and blast gates.

Like most shops, my layout is a simple rectangle with power tools on the edges (band saw, drill press, jointer, planer,..) and a central table saw/router table.

I would really like to have no extension cords or dust collection hole anywhere so I initially thought of burying DC and power under the slab but most of the comments on previous forum posts are steering me away from this solution. I will rather have a ceiling-based piping for DC and power for the peripheral power tools but I'm thinking of keeping the underground just for the table saw.

Does anyone ever tried this idea? I realize I might have to fish some debris from that underground line leading to the TS but it's well worth the effort I believe.

I plan to use my 2HP Oneida gorilla for a little bit after I build the shop and if DC is inefficient I might upgrade to a more powerful unit.

Any thoughts or ideas welcomed.

Pierre


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## shipwright (Sep 27, 2010)

I have underfloor dust piping and electrical for my major tools and while I can access the piping, I really never have had to. Check out this blog to see how mine is set up.
http://lumberjocks.com/shipwright/blog/31966
I really recommend a wood floor over a crawl space if you can possibly accommodate it. Easier on your legs. Access to the piping and wiring, warmer, and storage space to boot.


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## JBrow (Nov 18, 2015)

loupitou06,

It would certainly be nice to have nothing hanging from the ceiling to get in the way. Burying dust collection pipe and floor mounted receptacles has its issues; some of which could be overcome with good planning and during construction. The problems with dust collection pipe buried in or under concrete and floor mounted electric receptacles are inflexibility, maintenance, and safety.

At some point you may determine that a 2 hp dust collector is insufficient and/or you may decide to install an over the table saw dust port in addition to the under the table collection. 4" pipe would restrict air flow and could only be upgraded by abandoning the in-floor piping. 6" pipe installed now may not offer enough airflow with a 2 hp system. It would also restrict where a new table saw could be placed, though probably not by much assuming you now have a cabinet saw. If you ever took a notion to clean the shop floor with water and a mop or garden hose (or just spilled some water), the buried dust collection pipe (and electric receptacles) could be a problem.

Maintenance beyond simply removing a block of wood from the pipe may be required down the road. If the pipe is metal and moisture exists under the slab, the pipe will eventually rot. If the joints are not water proof and standing water makes it under the slab, it could enter the dust collection pipe. The in-ground pipe will probably be cooler than the air rushing through the pipe and thus condensation could form inside the pipe.

In floor electric receptacles present safety concerns. If not properly located, plugs could become a trip point. If little people enter the shop, the receptacles are within easy reach. Water, dust, and debris can find its way into the receptacles, if flush with the floor. There may be some National Electric Code or local code requirements governing in-floor receptacles. The circuit can only be upgraded if the conductors are run in oversized conduit. If the shop is ever re-configured, the fixed locations of the electric and dust collection would be constraints on the new layout.

Many of these problems could be overcome by making these utilities fully accessible. This could be done by including a floor chase in the pour. It would be a trench of poured concrete (or block) with ledges along each wall of the trench onto which removable floor panels that are flush with the finished floor are placed. The panels could consist of ¾" plywood mounted to 2" x 4" cross members. These removable panels would offer from-above access to the utilities run the trench. This feature would likely add to the construction costs and still required good planning.


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## loupitou06 (Apr 17, 2009)

> I have underfloor dust piping and electrical for my major tools and while I can access the piping, I really never have had to. Check out this blog to see how mine is set up.
> http://lumberjocks.com/shipwright/blog/31966
> I really recommend a wood floor over a crawl space if you can possibly accommodate it. Easier on your legs. Access to the piping and wiring, warmer, and storage space to boot.
> 
> - shipwright


Hi Shipwright, I have spent a long time looking at your shop and some of your posts. Thanks a lot for sharing. Unfortunately here in Florida I do not have the option to have a crawlspace under the shop as you do (since the shop must "blend-in" with the house we are building as well. I did thought about having a wooden sub floor - but it would raise the floor by ~7" (to accommodate for a 6" main pipe) and then I would have to make ramps to come in/out of the shop and I'm worried about load bearing if I ever want to bring a car in the shop or heavy equipment (I'm thinking buying used metalworking machines mill and lathe as well in the future).

Thanks a lot for your inputs


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## loupitou06 (Apr 17, 2009)

Hi JBrow, thanks for your inputs



> loupitou06,
> 
> It would certainly be nice to have nothing hanging from the ceiling to get in the way. Burying dust collection pipe and floor mounted receptacles has its issues; some of which could be overcome with good planning and during construction. The problems with dust collection pipe buried in or under concrete and floor mounted electric receptacles are inflexibility, maintenance, and safety.
> 
> At some point you may determine that a 2 hp dust collector is insufficient and/or you may decide to install an over the table saw dust port in addition to the under the table collection. 4" pipe would restrict air flow and could only be upgraded by abandoning the in-floor piping. 6" pipe installed now may not offer enough airflow with a 2 hp system. It would also restrict where a new table saw could be placed, though probably not by much assuming you now have a cabinet saw. If you ever took a notion to clean the shop floor with water and a mop or garden hose (or just spilled some water), the buried dust collection pipe (and electric receptacles) could be a problem.


You are correct, the position of the TS is pretty much fixed with this option but I have a large cabinet saw now and I think I can leave with a fix position and nice outfeed table.
I was thinking 6" for the main pipe and 4" drops to the machines. I agree that 2HP DC might not be good enough (actually the intake of the DC is 6") but if I do mix and match in-floor and ceiling pipes I could have blast gates right at the DC (with a remote system).



> Maintenance beyond simply removing a block of wood from the pipe may be required down the road. If the pipe is metal and moisture exists under the slab, the pipe will eventually rot. If the joints are not water proof and standing water makes it under the slab, it could enter the dust collection pipe. The in-ground pipe will probably be cooler than the air rushing through the pipe and thus condensation could form inside the pipe.


I was thinking PVD for in-floor and metal for ceiling to avoid these concerns. Agree that condensation might form in the in-floor pipes but would that damage the DC, I have a cyclone so I presume the moisture will go with the debris in the bin rather than being sucked in the filter ? Perhaps a wrong assumption.



> In floor electric receptacles present safety concerns. If not properly located, plugs could become a trip point. If little people enter the shop, the receptacles are within easy reach. Water, dust, and debris can find its way into the receptacles, if flush with the floor. There may be some National Electric Code or local code requirements governing in-floor receptacles. The circuit can only be upgraded if the conductors are run in oversized conduit. If the shop is ever re-configured, the fixed locations of the electric and dust collection would be constraints on the new layout.


To avoid these issues I was thinking to raise both electrical and DC outlets 1' of the ground. Definitely not asthetics if the room is empty but when filled with machines….



> Many of these problems could be overcome by making these utilities fully accessible. This could be done by including a floor chase in the pour. It would be a trench of poured concrete (or block) with ledges along each wall of the trench onto which removable floor panels that are flush with the finished floor are placed. The panels could consist of ¾" plywood mounted to 2" x 4" cross members. These removable panels would offer from-above access to the utilities run the trench. This feature would likely add to the construction costs and still required good planning.
> - JBrow


I spoke with my contractor about that I really liked the idea of a trench as well but he recommended against it because here in central FL typical slabs are 4" "floating type slabs and a trench will weaken the slab. Thicker slab would be much more expensive.

Thanks a lot for your inputs again


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## JBrow (Nov 18, 2015)

loupitou06

With a cabinet saw in the more or less center of the workshop, it will probably never be moved. In my case, once the cabinet table saw was set, it was never moved. While I have considered moving other equipment, I have never considered moving the table saw. You mentioned no other tools that might be grouped near the table saw. In my 2 car garage workshop, I have 3 6" dust collection drops clustered together at the end of the table saw (right hand end) that service the planer and bandsaw. I assume that if you likewise have a cluster of some kind at the end of the table saw, multiple in-floor piping and power are planned or branches and blast gates from the single in-floor pipe near the clustered machines will be used.

Running 6" PVD, not familiar with that term but assume it is plastic pipe, is a good thing. Upgrading to a 3hp - 5 hp dust collector should work fine with this size pipe. It sounds like all 4" pipe is accessible. I am not sure to what extent condensation in the pipes would pose a problem. I mentioned this potential problem not out of fear over the dust collector or filter issues but rather concern that moisture in the in-floor duct work could make dust and debris stick together and build-up a crust over time. If my condensation fear is justified, the problem is easily avoided during construction by insulating the pipe with a moisture resistant insulation. I mention this condensation issue because I recall the dealer from whom I purchased a central vac system for the house recommending that I insulate the PVC piping that I ran in the attic to avoid any condensation issues.

Bringing piping and electric up from the floor is also good planning, avoiding potential problems I mentioned.

I understand the point of your contractor. I assume the floating 4" slab is supported on the perimeter by a lip formed on the foundation. If a trench interrupts the monolithic pour, I can see that the slab could crack near the trench. If the pour is supported by foundations constructed on both side of the trench (which would then form the walls of the trench, I would think the floating slab would be fully supported. But then, adding a pair of foundation walls to support the slab would add to building costs. Also bear in mind I am not a concrete guy and would therefore defer to the opinion of the experts.


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