And the dust collection saga continues. I have a feeling that once I get the dust collection completely setup I might get a new dust collector that will require a change to the entire system. That’s normally the way things go. But anyway, one more shop project before I get back to making actual projects. This time some easy to make blast gates for 4” PVC pipe.
The design for these blast gates calls for a piece of pipe on one side and half of a coupling on the other. This allows them to be used at any PVC fitting which is quite handy as you almost always need to use a fitting to branch off to a machine. Because half of a coupling is required per blast gate it’s naturally fitting that these should be made in pairs. To make one pair of blast gates you will need six 6” x 6” pieces of plywood (any thickness will work), one 4” PVC coupling, one section of pipe that is at least as long as the coupling, a scrap block to use as a handle, and some construction adhesive. Here you can see me doing my best Vanna White impression while showcasing a piece of plywood.
The coupling needs to be cut in half and the easiest method is with the table saw. The miter gauge with a stop block will keep the coupling where it needs to be as you rotate it. You could also use a bandsaw but be mindful of blade drift as the blade my make the resulting cut not quite square.
The pipe is also cut the same way.
With the pipe and coupling cut you can lay them out on the plywood squares. The pipe should be 7/8” from the edges and the coupling should be just shy of ¾” from the edges.
Next, drill a hole through all of the pieces of plywood on the inside of the circle. The hole needs to be large enough for a jigsaw blade.
And rough cut the interior with a jigsaw. Make sure you don’t touch the circle. This will be trimmed up in just a bit.
To secure the PVC to the plywood a bead of construction adhesive is used. You will have to roughen up the sides of the PVC with sandpaper first though. That will give the construction adhesive something to grab a hold of. Also make sure the cut side of the plywood is down and the factory edge is facing up. This is important because the coupling has a taper on the inside to make the pipe tighter as it is inserted.
Then smooth the bead of construction adhesive. I used a relatively quick setting construction adhesive so I pretty much made an ugly mess here. A slow setting adhesive would have been a better choice. But looks are relatively insignificant on this project. These will function just they way they were intended to function regardless of how ugly I made them.
After the construction adhesive has cured overnight the insides can be trimmed with a flush trim bit in a router. I actually just clamped my laminate router into my sliding moxon vise and it worked great.
The remaining plywood squares need to be cut. Two 5/8” strips are removed from each square. Then the larger piece is centered on the blast gate and the smaller strips are glued and clamped in place on the sides. It’s a good idea to remove the center section once the strips are clamped down. That way it doesn’t accidentally get glued into place.
To give the center section, or gate, a handle a dado is cut in the center of a scrap piece of wood. In this case I used a piece of 3/4” plywood. The gate is then glued into place.
Once the glue has setup on the two smaller strips the second half of the blast gate body is glued on.
Because no shims are used in the construction of the blast gate body the thickness of the gate itself needs to be reduced. I used my ¼ sheet sander for this step and it worked great.
The resulting fit should be smooth without any obstructions. You can also see in this picture that I added a painters tape flap that will cover the other side of the blast gate when suction is applied to the pipe. I used something flexible such as tape so that any debris that may be in the gate path will be pushed out once the gate is closed.
I hope you were able to find this shop project useful and are able to incorporate it into your dust collection setup. If you have any questions, comments, or thoughts on the project I’d love to hear them. Take care folks.