Options for automated blast gates

[Anthony Whitesell]

Based on my research I have found a few options for automated blast gates. There may be more, if so, please link.
1. Pneumatic linear - pnuematic cylinder to open a linear slide gate (us-duct)
2. Motor driven linear leadscrew - similar to pnuematic linear using a leadscrew instead of cylinder rod (sorry, I couldn't find a mfr)
3. Motor driven linear rack and pinon - use a motor to drive a rank and pinon gear setup to move the gate (iVac)
4. Motor driven swing gate rack and pinon - use a motor to drive a a rack an pinon on a gate the rocks from a pivot point oppposite the motor (ecogate and grngate)

I can and plan to build my own. The manufacturers listed are only for reference (sorry, pictures not working, don't know why).

Both the pnuematic and motor leadscrew have options of inline with the gate (us-duct ro nordfab) or on the side of the gate (nordfab, has both options)

I am trying to decide on the design and drive I'm about to delve into. Being a EE I am leaning towards the motor driven and away from the pneumatic (easier to find a broken wire than a leaking airline ).

Which design did you use or do you prefer? Which design should I avoid?

[Tom Bender]

As an ME my leaning is toward pneumatic. Motors contain precious smoke that can leak out. Fire is also a possibility in a dust handling system. Intrinsicly Safe might lack might. When a blast gate gets stuck will the motor just keep trying?

How about water power? Or maybe a windmill on the roof with belts and pulleys? Hamsters will work for peanuts. Lots of other options.

[Anthony Whitesell]

As an ME my leaning is toward pneumatic. Motors contain precious smoke that can leak out. Fire is also a possibility in a dust handling system. Intrinsicly Safe might lack might. When a blast gate gets stuck will the motor just keep trying?

How about water power? Or maybe a windmill on the roof with belts and pulleys? Hamsters will work for peanuts. Lots of other options.

The electronics/electrical are no in the, possibly but doubtfully (I didn't do the calculations since the predominant particle size is more than 10x wood flour size) C2-D1-G6 classified area. The electrical controls is outside the ductwork (outside any C2 area) in the unclassified space.

The circuit for the motor drive contains limit switch with built in cut-off. The programmign could easily contain a timer such that if the limit switch signal is not detected in the amount of time, the motor stops.

Motors do have the potential to let out the magic smoke. That point is valid to the OP question.

[Andrew Seemann]

Spiral Manufacturing has electrically controlled pneumatic blast gates. They are listed in the high pressure section on their home page under blast gates (I can never remember the TOS rules on links).

Having fixed lots of things built by engineers, I would lean towards pneumatic, mostly because you can hear leaking air, but those leaking electrons are darned sneaky to find.

Based on your last post, it sounds like this isn't for a hobby shop?

[Anthony Whitesell]

Oh, it is for a hobby shop. I just have more knowledge of electronics, electrical systems, and classified hazardous than the average person.

[Jim Becker]

You have to balance the cost/complexity with an automated gate system vs whether or not you would actually benefit from it vs just plain enjoying building it out. There have been some pretty kewel setups folks have built over the years to automate gates.

Honestly, I even abandoned a "remote control" on/off switch for my DC and just use a centrally located wall switch. It's simple. It works. And I also have found over the years that I don't bounce around between machines all that frequently when working a project...flattening, thicknessing, cutting all gets done in batches.

[Andrew Seemann]

Since I like doing that sort of thing, I had a cool system all planned out for triggering the cyclone when I open up a blast gate, with micro switches on the gates and a 24V relay for the contactor, etc. I had even set up a couple gates with microswitches as a POC. Then when I bought my cyclone, Oneida had a deal where if you bought an extra remote, you could buy as many more as you wanted for $10 a piece. I ended up ordering 5 extra remotes and attached them to the walls around the shop near the machines. It wasn't as fun as wiring up the control system, but it was a whole lot faster (and cheaper). I haven't regretted it in the least.

Right now my automated method for opening and closing the ceiling mounted blast gate for my table saw is a 4 foot stick. It is inconvenient, but not enough to have changed it for the last 10 years. I'll probably mount a blast gate on the saw when I get around to adding overhead dust collection to the guard.

[Paul F Franklin]

I have the remote on my apron, so turning the DC on and off is no issue, but I could see the value of automatic blast gates. I recently made a bunch of solid wood edge banding. Starting with wide stock of the proper thickness I would route the profile on each long edge, then go to the bandsaw to rip off two strips, then to the jointer to joint each edge, then repeat, and repeat and repeat.

I ended up leaving all 4 blast gates open (router table, jointer/planer, and 2 for the bandsaw) because it was such a huge pain to keep opening and closing them. Dust collection was just OK (3 HP Oneida). Not nearly as good as it would have been with only the appropriate gate(s) open.

Granted, I don't do that particular operation often, but there are other times when a similar sequence happens, like making shop sawn veneer.

I don't see myself ever actually getting around to doing it, but I can appreciate the usefulness.

[Dan Friedrichs]

I tried building some electronic ones (the leadscrew variety) a few years ago. I built boxes that would plug in-line with the tool, which would sense the current drawn by the tool (when it was turned on) and output +12VDC that would drive the motor to open the gate. When the tool turned off, after some brief delay, the box would output -12VDC to reverse the motor direction and close the gate.

Note that for an motor-driven design, you need to account for detecting the end of travel. The way I did it was with limit switches. With 2 limit switches and 2 diodes, you can configure it to drive the motor forward until it hits the end-of-travel and opens the circuit, then reverse the voltage polarity for the reverse, and only use a single pair of conductors.

Ultimately, I threw it all away, though. The gates (necessarily home-built) were sticky. The leadscrews accumulated dust. The motors would stall and get hot. The motors I selected were far less torquey than I expected (given their size). It caused more hassle than it solved. If you're worried about the gate binding, is automating it really helping you any?

If I were to do it again, I'd do pneumatic. There are so many advantages: self-wiping (no sawdust accumulation), can be safely stalled, high force-to-size, easy to add pneumatic cylinders to off-the-shelf blast gates (much easier than building your own blast gates), etc.

If the EE in you needs some fun, though, you can use electrically-actuated air valves and build current sense circuits to trigger them.

[Anthony Whitesell]

The lead screw accumulating dust, I had not thought of (hence the thread). My concern with the side driven gates (whether pneumatic or electric) if the toque placed on the gate slide to open. But the inline system appears to be much larger (longer), so I not sure I'm a fan of that either. The rack and pinion drive is an interesting option (either linear or swing gate).

I am NOT looking for auto gates or auto DC start/stop. Push button selection and turn on/off is fine. I'm looking at this because in my latest re-org, three gates are terribly inaccessible to open-close. Not all of my projects execute in a batched order (flattening, thicknessing, cutting). My current projects has had two rounds of jointing, resaw, and thicknessing already and one, maybe two, more rounds to go.

[Alan Lightstone]

My biggest problem has been forgetting to open a blast gate, or leaving another one open. With a 5 HP Oneida it's not the end of the world (although forgetting to open a blast gate or turn on the cyclone for the wide-belt sander is both messy and creates one heck of a large dust cloud), but I would love for things to go automatically.

Periodically I look at the Ecogate system, but with mainly 6" ducts, and Nordfab ones to boot, the cost is huge.

DIY pneumatic is tempting, but sounds like a ton of work.

[George Yetka]

Has anyone seen an option to open when powered with a spring return to close? My plan is to run a 4" gate up high to cover a wall mount cnc. I energize a power strip which powers controller, display, and water cooling. If I plug a gate into this strip it could open when energized and close when I shut it down.

[Ron Selzer]

Has anyone seen an option to open when powered with a spring return to close? My plan is to run a 4" gate up high to cover a wall mount cnc. I energize a power strip which powers controller, display, and water cooling. If I plug a gate into this strip it could open when energized and close when I shut it down.

George you could build something using a Johnson Controls M9208-BAC-3 with a remote mount kit M9209-100 buying it off of eBay. This actuator has aux switches that could be used to start/stop the equipment based on gate open/closed. Spring return when powered off, 120v input, two position, would not need remote mount kit if you could utilize rotary motion instead of linear action. Shuts off when stalled so doesn't burn motor up. Designed as an actuator for HVAC damper/ valve operation.

[George Yetka]

George you could build something using a Johnson Controls M9208-BAC-3 with a remote mount kit M9209-100 buying it off of eBay. This actuator has aux switches that could be used to start/stop the equipment based on gate open/closed. Spring return when powered off, 120v input, two position, would not need remote mount kit if you could utilize rotary motion instead of linear action. Shuts off when stalled so doesn't burn motor up. Designed as an actuator for HVAC damper/ valve operation.

Thats not a bad option and I have a few dozen actuators lying around. I spent some time thinking about it in the middle of the night last night and I was thinking I may try an IVAC gate with the wired remote and instead of the switch I'll put a dry contact on it. I watched a video on youtube a couple weeks ago about a power strip that has a contact built in. Ive been searching for it for the past hour trying to find it. So basically my operation would be to turn on the power strip that energizes everything but the spindle vfd and would open the gate. Im thinking this may be easier than fabricating