So… I’ll be up front with you. This article is probably my longest yet. I really must get better at culling images. With most things I post, if it is going to have much more than 20 or so photos, I try to break it up into multiple posts. However, this is already a series and I didn’t want to write a four part post on how to make your own blast gates for you dust collection system. So here it is… One giant post… 108 images.
Also, you could just buy blast gates from Rockler (they’re $13 each). I think my design is better, but buying them would save you a lot of time. But… this is a hobby not a profession for me, and I enjoyed making them.
I’ve added captions to all the photos, so there won’t be much need for text in between.
Again, I went to my scrap wood bin for the plywood needed to make all these parts. During this whole dust collection series, I haven’t had to buy any wood. Admittedly, my sheet storage bin was overflowing with leftover plywood from various projects. ½-sheets and ¾-sheets a-plenty. I’ve used up a good portion of that now.
These 16 blanks will each make up one half of a blast gate. They will have thinner ¼-inch pieces of ply glued in between along the edges to act as spacers, and a ¼-inch thick gate that will slide back and forth to open and close air flow.
I needed to cut a hole in the center of each of these pieces. 4-inch PVC pipe has an inner diameter of 4″. The outer diameter is 4 3/16″. I want the pipe to fit snugly into the hole with very little play. These holes need to be very accurate and identical in all 16 pieces. this calls for a jig. I grabbed some scrap plywood and clamped one of the blanks to it. I then screwed three pieces around the edges of the blank and added a toggle clamp to hold the blanks in place. I found the center and drew a 4 3/16th circle.
I drilled a pilot hole and then cut out the circle with a jigsaw. I kept away from the line and then finished the circle using a sanding drum on the drill press. I periodically checked the fit, but despite repeated checking made the hole a hair too big. I added a layer of masking tape and the fit was perfect. The jig was ready for use.
I then got into repetitive mode and made a bunch of sawdust.
The next step in this project is to cut up some PVC. I bought some straight coupling pieces for this next part. They have an inner diameter of 4 3/16″ and fit over the outside of the PVC pipe. I could have used a whole one on each side of the blast gate, but that would have been a little bulkier and would have doubled the cost of the parts. Instead I cut the couplings in half. I was very careful to cut the coupling exactly in half and make sure the cut was square. PVC cuts very well on the bandsaw.
To glue the PVC to the wood, I used PL375 construction adhesive. I love this stuff. I buy it at Home Depot and it is considerably cheaper than liquid nails.
I used ¼-inch ply for the gate that will slide back and forth inside the assembly. This means that I needed to separate the two halves that I just built, by the same ¼”.
I also cut ¼” ply to make the gates. These were 4 7/16″ wide by about 12″ long. This with equals the width of the overall blast gates (6 11/16) minus the two 5/8″ spacers.
I needed to cut the holes in the ¼” plywood for when the gates are in the open position. I’ll use the same jig to do this, but with a few modifications. First, I had to move the top fence of the jig up by ¾” to account for the portion of the ¼” ply that will go into the handle. Also I want the hole in the gate itself to be the same size as the inner diameter of the pipe not the outer. Since the jig is currently sized to route the outer diameter, I simply pushed a small piece of pipe into the jig. Now the router bit bearing will follow the inside of the pipe. Lastly, I cut two pieces of ply, 5/8 wide to “shrink” the effective width of the jig.
I routed the holes in the gates using the same method as above.
Since I am using the same ¼” ply for the gate as the spacers, things might be a little too tight. I thinned the gates very, very slightly at the drum sander.
To avoid getting any glue on the inner gates, I used a scrap of the same width for assembly.
Next, on to the handles and stop-blocks that will attach to each end of the gate.
Before starting with the assembly, I wanted to come up with a way of temporarily immobilizing the blast gate in the open position. This will allow me to install the handles so that when they are pushed all the way in, the holes in the gate are perfectly aligned with the dust collector pipe. To do this, I cut down some PVC pipe little by little, until it just fit inside another piece of pipe.
Here’s how it will be used:
Next I cut some small pieces of Sapele to fill the grooves in the handles and stop-blocks.
Time to glue the handles on.
Yes, I still use handtools.
The handles are glued on for a permanent joint, but the stop-blocks need to be removable. If I ever have to take the gate out of its housing, this end will have to be removed first. I’ll hold them on with screws.
Below you can see how well the hole in the gate aligns with the pipe:
Alright…. 8 blast gates done! I installed them in the PVC duct lines that lead to my various tools. In the photo below, the left gate (closed) leads to my bandsaw, the center gate (open) to my tablesaw, and the right gate (closed) to my jointer. I’ve installed 4 gates and have 4 spare for future expansion.
I also installed a gate in the vertical section of pipe that comes off the back of my planer.
Well, I’m sure that this is more than you ever wanted to know about how to make blast gates. Have a go at making some, it was a fun project.
– Jonathan White
If you would like to see all of my blog posts about installing my dust collection system, you can find them here:
- Dust Collector Project – Part 1 (mounting the dust collector on the wall)
- Dust Collector Project – Part 2 (installing a shop made wireless remote system)
- Dust Collector Project – Part 3 (designing and making brackets to hang 4″ PVC pipe)
- Dust Collector Project – Part 4 (Cantilevering a section of pipe under the garage door)
- Dust Collector Project – Part 5 (Making blast gates for the dust collection system)