Make Your Own Blast Gates

Make Your Own
Blast Gates

They’re cheap! All you
need is some PVC and
plastic laminate.

By Alan Schaffter

A central dust collection system is a big improvement to any shop, but
the cost can really add up. With commercial gates going from $4 to over $50 each,
building your own can help lower the bill. I make my own gates from a little bit
of MDF, some PVC pipe or coupling, a few scraps of plastic laminate and plastic
laminate adhesive. This design will work for 4", 5" or 6" blast gates (the dimensions
below are for 4" gates).

Before you begin, note the diameter of the hoses or pipes that you’re planning
to hook up to the gate. With this design, you can make the inlets and outlets of each
gate any diameter you wish, to fit your system. On most commercial gates, the inlet
and outlet sides are the same diameter.

In my shop, I run 4" or 6" flex hose between each machine and the gate. That
means that the PVC inlet side of the gate must fit inside a hose. I've found that flex
hose with plastic reinforcing works best. (If the fit is too tight, try warming the end
of the hose with a heat gun to stretch it.) The outlet side of my blast gates is a larger
diameter. I use PVC pipe between the blast gate and the dust collector, so I made the
outlet side from a short piece of PVC coupling, which fits around the PVC pipe.

 

Make the gate bodies

1. Cut two 6" x 6" squares of 1/2" or 3/4" MDF for the gate body halves. You can
also use plywood that’s flat and smooth or melamine-covered particle board.

2. Drill an access hole and use a jigsaw to cut holes in the center of each gate
body to fit your inlet and outlet (Fig. A). My inlet is a piece of 4" PVC pipe, which
requires a 4-3/16" dia. hole. My outlet is a piece of 4" PVC coupling, which requires a
4-1/2" dia. hole. Use a spindle sander or file to achieve a good fit.

3. Apply laminate adhesive to the backs of two 6-1/4" x 6-1/4" pieces of laminate
and one face of each gate body. When the adhesive is dry to the touch, apply the
laminate to the gate bodies. Trim the edges with a router and flush-trim bit, but
don’t open the hole yet.

4. Cut the inlet and outlet pieces to length (Photo 1). Make a large V-shaped cradle
to hold the pieces of PVC, and attach the cradle to your tablesaw’s miter gauge.
Raise the saw’s blade so it barely cuts through the PVC’s wall. Push the cradle into
the blade and rotate the PVC to cut it apart.

5. Roughen the PVC, then use epoxy or polyurethane glue to secure each piece in the
cutout in each gate body. Make sure the pipe pieces bottom out against the laminate.

6. When the glue has hardened, drill a hole through the laminate. Use a drill
bit that’s about 1/4" larger in diameter than your flush-trim router bit. Use your
router to enlarge the hole (Photo 2).

 

Make the blade and sides

7. Make the gate's blade by joining two 7" x 14" pieces of laminate back to
back with laminate adhesive. Cut this piece to 5-15/16" x 13".

8. Use double-faced tape to temporarily attach the blade to the laminated
face of the inlet gate body. Position the end of the blade 1" past the 6" square
(the 1" margin leaves room for a handle). Drill a hole in the blade and use a
flush-trim bit to enlarge the hole, as you did in Step 6.

9. Make the gate sides from two 1-1/2" x 6-1/2" pieces of laminate. Apply a
1/8" wide strip of tape to the middle of the back of each piece. The tape prevents
adhesive from sticking to this area.

10. Soften the sharp edges of all laminate pieces with a file or sandpaper.

 

Assembly

11. To create clearance for the blade when you assemble the gate, put two
layers of painter’s tape near the edges of one face of the blade (Photo 3). Rub
paste wax on the faces of the gate halves. Apply strips of tape down the middle
of the side pieces, to prevent the pieces from adhering to the blade.

12. Carefully apply laminate adhesive to the backs of the gate sides and two
edges of each gate body. Avoid getting adhesive on the faces of the gate halves.
Remove the strips of tape from the gate sides before the adhesive sets up.

13. Once the laminate is dry to the touch, position the blade between the
gate halves. Lightly clamp everything together and apply the side strips (Photo
4). Be careful: You only get one chance to position the sides. Use a roller or rubber
mallet to ensure the sides make a good bond with the gate halves. Trim the
sides flush with a router.

14. Remove the blade from the gate and peel off the tape. Clean and wax the
blade. Screw handles to each end of the blade.

Fig. A

Click any image to view a larger version.

1. Cut short lengths of PVC using the
tablesaw. Caution: To prevent kickback,
use a V-shaped cradle and raise the blade
just enough to cut through the pipe’s wall.

2. Glue the PVC into two pieces of MDF
covered with plastic laminate. This creates
each half of the gate body. Use a flush-trim
bit to finish off the holes in the laminate.

3. Make the gate’s blade and sides from
plastic laminate. Add tape to the blade
to provide clearance during assembly.
Assemble the gate with glue.

4. Clamp the gate body together and
add the sides. Once the sides are secure,
remove the clamps and blade. Add a handle
to the blade, and you’re ready to go!

This story originally appeared in American Woodworker June/July 2010, issue #148.



June/July 2010, issue #148


Purchase this back issue.