Wanting to Automate dust collection blast gates

[oceanslider]

I would like to automate dust collection blast gates on a series of two wheel buffing machines.  My buffers are "Baldor 332B".  They are 120vac 60htz.

I saw a Facebook post where a guy did this with a few relays and on/off/on switches for each of the two buffing machine wheels.  And I would like a similar setup.

My plan is to modify existing aluminum blast gates with a 12vdc Linear Actuator (Amazon: "Mini Electric Linear Actuator Stroke 2"–Force 4.5 lbs–12V") . 

I want to do this for 3 buffing machines, each two-wheel buffing machine having dust shrouds and blast gate for each wheel.  I have three buffing machines, so that is six wheels in all, each with a dust shroud and dust port blast gate operated by its own linear actuator.  So that is six blast gate actuators. 

What I would like is an on/off/on switch in front of each two-wheel buffer (each wheel having its own dust shroud and blast gate port).  So that when the buffer was running if the on/off/on switch was in the center position that both blast gates for each wheel dust shroud would be open and sucking dust debris.  If moved to the left "on" position, the right blast gate would close and the left would be open. And vise versa, if the on/off/on switch was moved to the right on position, the left gate would close while the right blast gate would be open.

But here is a twist.  If the 120vac buffer was turned off both 12vdc linear actuated blast gates for each of the two wheels would close.  That way I could go to the next buffer and operate it in a similar fashion with the on/off/on switch controlling the two blast gates for that buffer.  So that only the buffer running would have blast gates open via the on/off/on toggle switch.  Any other buffer would have closed blast gates when the on/off switch of the 120vac buffer was turned off and not running.

So how should I wire up such a setup?

[oceanslider]

Here is a picture of what the modified blast gate would look like with the 12vdc linear actuator.

[SmallCog]

Can your extractor supply enough suction to suck from both buffing wheels of the same machine? That would simplify the control and you'd only need 3 automated gates rather than 6.

You could sense the machine running using a current sense relays, it removes the need to actually play with AC mains power. You can DIY a solution for this rather than using a premade module as well.

If you're not familiar with them these relays use non contact methods to sense when your machine is running and then close (or open) a relay contact in response.
 
I've only gotten so far as getting the vaccuum pump for my extraction system, but I intend to control my various machine gates using the system above with current sense relays. Therefore I'm only sharing an idea, not a proven solution... I was intending to use car central locking actuators but I've not yet tested them to see if they have the neccessary force.

If you need the suction to be directed left and right you could use a switch to simply choose which gate is actuated by the current sense relay OR you could do it a little smarter by using radar or PIR sensors to sense you working at each wheel.

Alternatively you could break into the machine and wire a traditional relay across the on switch or motor, one with a coil voltage to match your local mains power, and use it to switch DC to actuate your blast gates.

[donlisms]

I pondered this for a few minutes.  I had the following thoughts -- no answers, but thoughts!

I wonder if the actuators you've chosen have enough guts to move to blast gates.  Mine were always kinda sticky; maybe it's okay because they're geared down, and maybe your gates are better than mine (!), but were it me, I think I'd do some tests with a fish scale or something before I spent money for six of those.  (As I said... just a thought!)

If the problem was something simple like... turning on a light, it would be pretty easy to wire it up with relays.  On/off/on/off, simple.  But then I assume the actuators can't turn themselves off when they get to the end -- we need gizmos to do that.  So we need:

• On closing direction
• Off closing direction
• On opening direction
• Off opening direction

and suddenly the relay logic and switching states get more complicated.  This actuator-actuating logic sits alongside the three-position user-interface switch.

I think the project is intriguing, and not as simple as it might seem on the surface.  I think using actual wires is a reasonable alternative to current-sensing; when the motor's switch is on, there is a 120v available that isn't available otherwise, and it could be used as a master "on" signal -- it could open a relay that turns on the 12 volts (which you're going to have to get from somewhere... right?).

Then there's switching and relay logic, and I suppose it could be solid-state relays (though I've never used those, and I do understand (cheap surplus) hardware relays).  But in any case, it looks like limit switches are going to be required, so overall, the actuator can only run until it hits the end.  And then there's some direction-switching to take care of, which I assume is a matter of the polarity of the voltage feeding the actuator.  The three-position user-interface switch is easy, with a little bit of inverted logic (off is on).

There are other ways to frame the design, i.e. just put a button on each side, and push it when you want that gate open.  That signal could be used to close the other one.  I don't think you have to worry about any connections between the machines; just turn the other ones off if you don't want to use them.  (I am a little confused about wanting two of them open on the same machine, but I guess that's for something like going back and forth or something.)

Some things will require some more thinking.  Are you sure you want to do it this way?  Since "simple is good," there might be ways to redo the design to make it easier to implement.  I think I'd start with figuring out how to have a button that opens the gate without the actuator motor running off the end of its track.  Then thinking about the logic, which is easy but complicated.

[oceanslider]

For a buffer with an on/off/off toggle switch in front of it, whenever you turn the buffer off both gates close so that you can go to the next buffer and have full dust collection suction.

If you turn the buffer on, in the center "off" position both gates open, to the left "on" the left gate is open but the right closes.  And vise versa, for move the switch all the way to the right "on" position and that right gate opens and the left gate closes. 

Here is the setup of the guy who automated multiple blast gates on his buffers. But this setup pictured also has a DPDT switch to make sure the compressor does not come on when using a buffer as this setup runs off a generator, and too big motors running at the same time is a bit hard on the genset.  So keep that in mind when looking at this setup.  He also added time delays, not exactly what that does.  But the top 4 relays are for the 4 blast gates he has switching.

I want 6 blast gates to work like this.

I have seen on YouTube a guy using an Andrino but that just looks like too much work.

[donlisms]

That's kinda what I would expect - there's a lot of stuff there,  not just wiring together a few parts.  What I was trying to get at, without having time to do a full design of this, is that there are some basic problems that must be solved before the rest of the design can happen.

Let me give one of those as an example.  Suppose we have an actuator that has a motor that can be turned on in one direction, on in the other, or off.  Now suppose it's at the "open" end of the travel.  We want to turn it on n the right direction and make it move to the "closed" end.  If we use a switch (or relay) to turn it on... who's going to turn it off when it gets to the end?  With a light switch, or a saw's motor switch, you turn it on, use the thing, and turn it off.  Easy.   But with the gate, this seemingly simple problem introduces a fair bit of complexity: somehow the system has to know when the actuator has reached the end, and when it does, to turn the thing back off.

I think the right way to do that is with a limit switch, physically "bonked" when the actuator gets there.  You mentioned timers - that would be another approach that might sorta work, but I would not trust it.  The idea would be to turn on the actuator for, like, seven seconds, because that's how long it takes to open or  lose the gate. Usually.   If it would be like saying "hold the gas pedal down for three seconds to get the car from the garage to the middle of the driveway."  Sometimes that might work, but there are variables, and you might end up halfway out, or in the street getting run into by the ice cream van.

The bottom line is... this is not a simple thing to do properly.  Your request was essentially "please solve this for me", and I suspect it will be difficult to find someone with both the time and desire to do all the design work.  There would probably be a LOT of back and forth about the details, and you would have to be prepared to invest a lot more effort than you've got in it so far.  Maybe there's someone who would be willing to go down that road with you.

Alternately, your best bet would be finding an existing design that tells you everything you need to know in a way that makes sense to you.