March 9, 2013

Under Floor Dust Collection

[Click the pics for larger view]

My wood shop is in the basement of our house, and with very few exceptions, I consider this ideal.  It is heated and air conditioned 24 x 7 x 365 at no extra cost, I have hot and cold running water in a shop sink, a full bathroom with a shower, telephone, internet, and plenty of AC power.  I can be in my shop in 15 seconds from anywhere in the house, in my underwear if I want.  From my wife's point of view, there are some drawbacks--in a nutshell, they boil down to noise, dust, and odors.  While we've come to some understandings on these points, she does acknowledge that it is handy to have me accessible for dire domestic emergencies like, say, a spider in the sink.  

One drawback I see is the concrete floor.  If I ever built a detached shop, and this isn't likely, I'd have a crawlspace, or at least a false floor to allow underfloor routing of AC power and dust collection ducts.  The concrete floor makes this harder--harder, but not impossible.  When I got a new table saw ten or so years ago, I tried for a while to make overhead dust collection ducts work.  The ducts were unsightly, always in the way, and just generally a hassle.  Likewise with the power cord.

I finally took what many (including me at the time) would consider an extreme measure:  I broke up enough of the basement floor to install a dust collection duct and AC power to the table saw.  The job took a few days, and while a little dirty at times, wasn't all that hard or complicated.  I ended up considering it time and effort well worth it.  

When I got a new Delta RC33 planer (new to me--it's 30 years old [here's a link to the rebuild of the machine]), I wanted to put it and my jointer in the middle of the floor.  Since these thing each can put out prodigious amounts of wood dust and shavings, they really need good dust collection, and I decided without hesitation to extend the underfloor system.  The following is a story about the experience.

Here is the area I cleared out to put the planer and jointer.  It's about six feet from the table saw, which has an underfloor duct that I would tap into.  I marked out on the floor where the concrete would have to be broken out.

I broke quite a bit of it out with just a small sledge, but since I wanted to do the whole thing while my wife was gone for the weekend, I rented a small jack hammer that finished the rest pretty quickly.

Here is where I had to tap into the existing duct and conduits.  One conduit is for AC power, and the other is for low voltage control wires to remotely turn the vacuum system on.

Cleaned up the debris, and leveled the bottom of the trench at the right depth.  The near end of the trench is where the floor access box will be.

There wasn't a good way to glue the joints of the "Y", so I assembled them dry with slip couplings and taped them.

Then ran the conduits.  I used a double box for the AC so I could plug in both the jointer and the planer, and a single box for the control circuit.

I set the duct and boxes in concrete that would form the floor of the access box, then set an angle iron frame to form a lip for a cover for the access box.  I backfilled the trench   part way with gravel and some rubble from the demolition...

...and then poured concrete to the floor level.  I got to this point in a single two-day weekend.

Installed two 20 amp, 220 volt recepticles.  They are wired in parallel on the same circuit.

Decided to paint the entire floor while I was at it.

Added cover plates and a floor cover for the access box.  There wasn't clearance for the power plugs on the machines, so I swapped them out for right angle ones.

Moved the machines into place.  I had to move the power cord of the jointer so it exited on the chute end of the machine.  

I made some little control boxes to turn the collection system on and off.  I had a switch on a far wall before.  This will be better.  The box on the planer has magnets inside so it just sticks to the belt guard.  The one on the table saw is attached to the existing control box with nylon hardware.

This is the custom duct transition I made for the table saw years ago.  Normally there are little clips that hold it tighter against the cabinet.  The transition for the jointer is obviously different.

For some reason, I still remember how to do sheet metal transition design from drafting class in highschool.  It's a skill that's come in handy a number of times.


Since the table saw, jointer, and planer are all on the same duct, I have to have a way to block individual machines.  I had a few blast gates around from my previous overhead system.  I modified one slightly to use here.

The jointer is hooked up.  The planer goes on the other branch.  

The dust chute exit on the planer is very clodse to a standard 2-1/4 x 12 rectangular duct size, and it's pretty common to just use a standard sheet metal register boot to transition to a round outlet to one side or the other.

That was my first plan, but all my usual sources only had transitions to 6" round duct, and by the time I put a reducer on it to 4", it made the angle for the flex hose kind of awkward, and the whole setup was looking pretty kludgy.  I decided it wasn't that much work to make the transition, so I sketched out something that would work.  It would be a transition from 2-1/4 x 12 rectangular to 4" round on the right side, but the round outlet would be facing 45 degrees down to help the hose connection.  

The layout of this transition was a lot more complicated that the one for the jointer because it is asymmetrical.  A paper pattern ensures that the drafting was correct.

Then transfer to som thin galvanized sheet, cut it out, and fold it like the paper pattern.  It is hard to visualize without a paper model that some of the folds have to be reverse.  I cut the end off a PVC fitting and fitted it to the round outl;et to serve as the attachment point for the flex hose.

This is the metal frame to attach the transition to the planer using the existing holes.  One sort of background rule I have for adding accessories to machines, especially old ones,  is to not make any irreversible changes like drilling holes or welding if at all possible.  The last pic is a trial fitup of the components.

I had to rivet a little piece of sheet metal to the frame to serve as the bottom of the exit duct from the planer, then riveted the transition to the frame.  Some foam weatherstripping tape seals the joints.

Here is the planer all hooked up to the in-floor system through a blast gate.

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