6" Blast Gates for Sheet Metal Ductwork

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Project by English posted 103 days ago 1695 views 22 times favorited 8 comments Add to Favorites Watch
6" Blast Gates for Sheet Metal Ductwork
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When I prepared to install my new Dust collection system, 6” gates were a premium item. I looked around the internet for a good homemade solution and found many that used PVC pipe. I planed to install 6” 26 gauge snap lock pipe so I wanted something that fit correctly, that would seal up easy. So I decided to use parts from others peoples designs and finish with my own. Below is what ended up with.

I cut 22 – 3/4”x 8 1/4” x 8 1/4” pieces of plywood, I was making 11 gates. I was able to get this out of left over small cuts from my shop. I then centered the first piece up on my drill press and cut out a 6” hole with a circle cutter. I had to cut from both sides to get through the 3/4” plywood. So I set a stop box to keep all the holes the same.

After all of the holes were cut I glued left over Wilsonart laminate to each of the halves and routed out the holes.

I used 6” HVAC starter collars to transition from the plywood to the duct system. 2 halves are needed for each gate. You have to cut off the crimped section on the female half.

You also need to cut 1/4” off each of the tabs to keep them out of the gates slide.

Then insert the collar into the plywood half and nail or staple each tab down to the plywood.

This is a finished half.

Then cut 2 – 3/4” x 8 1/4” pieces of 1/8” hard board for each gate, cover each piece with thick tape on both sides. The tape will provide space for the slide to move. Nail these strip to one half of each gate.

Then cut a piece of 1/8” hard board that will fit between the strips from the last step but will completely cover the 6” hole in the gate. Make the piece 1” longer on each end of the gate so that the side will extend past the gate halves to provide self cleaning.

Take two of the gate halves, one with strips nailed on and one without strips. Be sure that there is one male half and one female half. The screw the two halves together.

Seal each side of the assembled gate with silicone.

Let your finished gates sit until the silicone dries. You can make and install any type handle you wish. I plan to just drill a finger hole in each slide.

The finished gates seal very well. They do open a 1/8” x 6 1/2” opening on the back side of the gate when open. But this only when the gate is open and does not affect the performance of the system.

-- John, Suffolk Virgina

8 comments so far

View Jim Finn's profile

Jim Finn

1656 posts in 1553 days

#1 posted 103 days ago

I made six of these much like yours. I am a retired sheet metal worker so I made my own starter collars and made the tabs long enough to reach to the far side of the wood and bend over the edge of it. I also caulked it. Good post and great photos.

-- In God We Trust

View kdc68's profile


1964 posts in 908 days

#2 posted 103 days ago

Great work here…very informative and detailed…..well done !

-- Measure "at least" twice and cut once

View dbhost's profile


5378 posts in 1863 days

#3 posted 103 days ago

Very nicely done. Can’t wait to see them installed.

I am curious why you chose not to extend the gate panel all the way through with a stop on the end. Seems like they would pull completely out, and like you mentioned, you have that gap at the end when it is open…

-- My workshop blog can be found at

View English's profile


189 posts in 109 days

#4 posted 103 days ago


Thanks for the comment. Sometimes the slides do pull all the way out. I chose not to use long slide to save space. Most of my gates are installed against the wall and a long slide took up to much room. The way I have them they are still self cleaning and not in the way. The small opening when open is not a problem with the suction I have from the Tempest DC I have. I did use long slides on two gates that are installed on the positive pressure side on my DC at the filters. I use these to reverse the flow through the filters for cleaning. Short slides there would have allowed fine dust to be blown back into the shop.

You can see some of the gates installed at:

-- John, Suffolk Virgina

View HillbillyShooter's profile


4506 posts in 924 days

#5 posted 103 days ago

Looks a lot better than the plastic gates I have on some of my connections. Also, if I might suggest, don’t forget to run a wire from the top to the bottom pipe to have continuity in your static electricity discharge from the machine to the DC.

-- John C. -- "Firearms are second only to the Constitution in importance; they are the peoples' liberty's teeth." George Washington

View Bob Current 's profile

Bob Current

312 posts in 249 days

#6 posted 103 days ago

Thank you for the detailed explanation of the assembly of your gates. I have a feeling this will get favorited many times.
Bob Current

-- When you are wrong admit it, when you are right forget it.

View JesseTutt's profile


803 posts in 742 days

#7 posted 103 days ago

Thanks, I was debating either to make my own or buy gates.

-- Jesse, Saint Louis, Missouri

View Holbs's profile


515 posts in 661 days

#8 posted 74 days ago

i REALLY like your idea of 6” blast gates. cutting tabs and air nailing solves the problem of the metal shifting forward to rub against the gate material

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