My Attempt to Keep Unused Blast Gates Closed

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Forum topic by JBrow posted 07-09-2016 09:45 PM 600 views 1 time favorited 6 replies Add to Favorites Watch
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740 posts in 337 days

07-09-2016 09:45 PM

Topic tags/keywords: blast gates sensor low voltage dust collection

I really appreciate the CV1800 cyclone dust collector setting in my shop. However, I really do not like dancing through the shop opening and closing blast gates. I know there are automated blast gate systems, but I am too cheap and lazy to install these, so I will keep dancing.

The problem I seem to have is that I sometimes leave one or more unused blast gates open. This diminishes the dust collection that would otherwise be available if those unused blast gates were closed. So the problem was how to quickly and easily identify those open blast gates. In a two car garage it is easy enough to simply walk around the shop to the nine dust collection drops and look at the blast gates. Unfortunately, not being the brightest bulb on the tree, I can look right at blast gate and not even realize that it is open. I thought I could benefit from a more reliable system for identifying all open blast gates at one time.

My solution was to install a shop made low voltage Blast Gate Sensor System. It consists of an Information Panel Box, low voltage components and wiring, and Blast Gate Switches. A quick look at the Information Panel Box reveals those open blast gates. This is done with a column of lights, numbered to correspond to various blast gates throughout the shop. Only those lights corresponding to open blast gates are illuminated; otherwise the lights are off. It works really well, but only when I look at the Information Panel Box before starting the dust collector (which I sometimes fail to do).

The total cost was under $100 and all components were purchased from the home center. For anyone who shares my problem and is interested in my solution, here is what I did…

This is a low voltage fused system. Obviously building a system using line voltage would be really dangerous and a super bad idea! Also, in my view, incorporating an electronics fuse is an added margin of safety. All components are electrically isolated from piping and other electrically conductive materials.

The Information Panel Box is a simple two compartment shallow box with a series of holes drilled in a column and numbered. The holes are sized to allow Lighted Door Bell Buttons to seat with a friction fit. The holes are numbered.

Information Panel Box…

I used a 120V/12V plug-in transformer (which I had laying around), but a low voltage doorbell transformer would probably also have worked. For added safety I figured an electronics fuse would be a good idea. The fuse was spliced into one low voltage leg from the transformer. The other low voltage leg from the transformer remained un-spliced. The fuse was housed in a separate add-on compartment attached to the side of the Information Panel Box. The transformer line voltage side is switched so that the system can be shut down when not in use.

The two low voltage transformer leads ran from the fuse box into the splice compartment of the Information Panel Box. One lead was connected to a Terminal Grounding Bar while the other was spliced to several low voltage telephone conductors. Each of these pigtailed conductors was then attached to separate terminals of a Multi-Terminal Connecting Block.

Lighted Door Bell Buttons, each with a pair of low voltage telephone wires, were pressed into holes drilled in a column in the front of the Information Panel Box. One lead was connected from the Lighted Door Bell Button to the Terminal Grounding Bar. The other lead was connected to a terminal on the Multi-Terminal Connecting Block. As a result of these two connections, each Lighted Door Bell Button had continuity to the transformer once the circuit was closed. Each Lighted Door Bell Button operates as a separate circuit.

Low voltage single pair telephone cable was run from the Information Panel Box to each blast gate. One conductor in the telephone cable was connected to the Terminal Grounding Bar. The other conductor was connected to a terminal in the Multi-Terminal Terminal Block. These were made in the Information Panel Box. At the blast gate, the pair of the conductors in the telephone cable was connected to each side of the Blast Gate Switch.

Information Panel Box Connections…

The Blast Gate Switch is a two part switch. One side of the switch is mounted to a small piece of ½” plywood. The plywood is screwed to the dust collection pipe. Then two ¾” wide pieces of Galvanized Pipe Hanging Strap were mounted parallel to the Blast Gate sliding door on the ½” plywood and spaced apart. The screws that secured the Pipe Hanging Strap are separate from the plywood mounting screws. A terminal screw was added to each piece of Pipe Hanging Strap. The only screws that contact the dust collection piping are those holding the ½” plywood in place. There is no electrical continuity between the Pipe Hanging Straps and the duct work. Each conductor from the telephone cable was secured to to each of the parallel Pipe Hanging Straps’ terminal screws.

The second part of the Blast Gate Switch mounts to the open-side of the blast gate tab. A piece of ¼” plywood mounts to the open-side tab of the blast gate. A mounting block is attached to this ¼” plywood. The pair of Side Tension Springs for Window Screens is attached to the mounting block parallel to one another and in alignment with the pair of Pipe Hanging Straps mounted on the dust collection pipe. A piece of Pipe Hanging Strap is used to hold the Window Side Tension Springs in place and establish electrical continuity between the two Window Side Tension Springs. When the blast gate is open, the Window Side Tension Springs ride up onto the Pipe Hanging Straps at the dust collection pipe. Since the Window Side Tension Springs are electrically connected via a Pipe Hanging Strap, when the blast gate is open, the circuit to the Information Panel Box is closed.

Blast Gate Switch…

System Wiring Diagram…

6 replies so far

View woodbutcherbynight's profile


2295 posts in 1826 days

#1 posted 07-10-2016 07:28 PM

Interesting solution to the problem you had. Very detailed with pictures and diagrams how you did it. Nice work.

-- Live to tell the stories, they sound better that way.

View Polhub's profile


2 posts in 239 days

#2 posted 08-22-2016 06:15 PM

Now that you have wire to each blast gate add a solenoid. Add current sensors on each tool and do a bit of programming on an Arduino and viola, an automated blast gate system.

Sounds easy doesn’t it?

View MrRon's profile


3888 posts in 2660 days

#3 posted 08-22-2016 08:36 PM

You could have used mercury switches or magnetic sensors as used on window/door alarm systems; just a thought.

View JBrow's profile (online now)


740 posts in 337 days

#4 posted 08-23-2016 01:10 AM


Thanks for the comments. The automatic blast gate system sounds like it would convenient. But I am not smart enough to tackle the system you suggest. Even if I was dumb enough to undertake such a project, the wife would quickly end the project, at least until her kitchen cabinets are done.

It would be interesting hear from those with the commercially available automatic blast gate systems as to how well those work. I figured that the expense of an automated blast gate system in a 2 car garage workshop would be difficult to justify. But I do wonder how well these systems priced at the lower end of the market actually work.

I image that blast gate maintenance and occasional failure would eventually overcome any convenience offered by the automatic systems –but really do not know. I also wonder whether such systems can be programmed to keep the dust collector operating for some period after the tool is shut off. I like to clear the line by running the dust collector for a few seconds after the tool is turned off. But I have to admit, an automatic system would be more convenient than the poor man’s blast gate management system I described. When I am preparing stock, I sometimes feel like I am dancing from one blast gate to another.


Thanks for the ideas.

I gave serious thought to a magnetic switch. However, I was uncertain how well the magnetic switch would have worked on the aluminum blast gates. Even though non-magnetic, I feared the aluminum might interfere with the magnetic field and would fail to properly operate (but I suspect my fears are unfounded). Additionally, the cost would have been more that I was willing to pay for 10 blast gates. As a result I never purchased a magnetic switch and therefore did not figure out whether it would work.

I suspect the mercury switch could both work. When I was puzzling through the design, the blast gate switches were the biggest challenge. I never considered the mercury switch but had I thought of it, I probably would have rejected that option. My fear would be that I would bang the switch and mercury would spill into the shop. This is a hazard I think is best avoided.

I also considered a plunger switch and a toggle switch. But I could not figure a reliable way to energize and de-energize the switch. However, I did not consider this problem very much primarily due to the cost.

View Kelly's profile


1039 posts in 2361 days

#5 posted 08-23-2016 02:23 AM

I took a whole different approach. Instead, I go to the cyclone and just swap hoses. I have eye hooks in the ceiling and a rope running through each one. At shoulder level, the ropes tie to, for example, the sand station, the jointer, the floor vac / lathe collection hose and the table saw.

The rope keeps all the items at shoulder height and allows me to just reach over and swap to the hose I need.

Without the gates on the system, the efficiency stays higher.

View Bill7255's profile


344 posts in 1702 days

#6 posted 08-23-2016 11:30 PM

JBrow, that’s a great idea. I’m going to try to incorporate something like that in my system.

-- Bill R

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