pneumatic blast gates

[Kieran Kammerer]

Has anybody here made these? I assume your source of air would be your compressor? I would like to try to reduce noise and not need my compressor cycling off and on to power these. I have also been experimenting a bit with an Arduino and servos. Any thoughts/suggestions appreciated. I know I can drop $500.00+ and get the automatic gates, however what fun would that be. My searches have provided a few leads but then seem to die off without getting to the real information

Thanks in advance

[Dan Friedrichs]

Alan Schaffter has what is probably the nicest design for these. Check out his post about half-way down this thread:
http://www.sawmillcreek.org/showthre...es-very-clever

The air usage is very minimal. You likely could just use something like a 12V portable tire inflator pump.

I toyed around with electrically-actuated gates (using a 12V motor to spin a long threaded rod that pulled the gate along). It didn't really work - it would bind and stall, etc. There are some other designs with "butterfly" style closure that use solenoids and springs, etc, but Alan's design is really quite elegant and effective. Given the low price of pneumatic cylinders and valves, it would be a real challenge to come up with anything cheaper/better.

[Kieran Kammerer]

Thanks Dan. I will take a look.

[Andrew J. Coholic]

http://www.sawmillcreek.org/showthre...heap&styleid=3

[Brian W Smith]

Kieran,we use pneumatic controls for fixturing and obvious fastening solutions.We don't have a blast gates that require them.So,we have plenty of"shop air" available.But hold that thought.

In our machine shop we have a cpl $$$ air/hyd vises.Years ago as an expedient (laziness),instead of running hard lines to those vises,snagged a really small CH compressor from Walmart of all places.This thing "might" have enough power to run a brad nailer?It functions beautifully with the vise's.

Just sayin,if we were running pneumatics on blast gates,can almost guarantee it wouldn't be through one of the big compressors.Id snag a cheap small oiless,hide it somewhere quiet,out of the dust....good luck with your project.

Edit to add;you could also hard line in a 1 or 2 G reservoir tank.Filling it from your large compressor with a ball valve.Filling it as needed.

[Peter Aeschliman]

Every time I read about these DIY pneumatic blast gates, I start with a high degree of excitement that I can make them for my shop, and end discouraged and confused by all of the technical engineering speak.

I would love it if somebody could boil it all down into layman's terms, but can certainly understand if it's too much work to explain to knuckleheads like myself.

[Andrew J. Coholic]

Every time I read about these DIY pneumatic blast gates, I start with a high degree of excitement that I can make them for my shop, and end discouraged and confused by all of the technical engineering speak.

I would love it if somebody could boil it all down into layman's terms, but can certainly understand if it's too much work to explain to knuckleheads like myself.

Did you look at my thread? It is far from "technical". Basically, you want to find an air cylinder (I prefer double acting, that uses air to force the piston to travel both directions, no spring return) that has a stroke that matches the size your blast gate has to travel. Then, select a valve to control the air flow. A 5/2 way valve has 5 ports (two go to the cylinder, two are exhausts and one is where the air feed goes) and controls the air flow to either extend or retract the cylinder's shaft.

All you need to complete the set up is to mechanically connect the cylinder to your gate, and hose to plumb up the valve to the cylinder, and air feed to the valve.

Most cylinders have threaded holes at the end, which will accept standard pipe taper fittings. Also, you can buy fittings that allow the smaller diameter tubing to be pushed in and are easy to hook up and disconnect if necessary.

You will also want some sort of needle valve, or in line restrictor to allow the cylinder to move from one extreme to the other in a controlled manner, and not go "bang" "bang" from one end to the other. Can be as fancy as a purchased restrictor/needle valve that goes in line with the supply to the cylinder (one for each input) or a home made restrictor that you can shove into the lines - I made mine from a small plug of brass that I drilled a small hole into.

It really isnt that difficult.

[Kieran Kammerer]

Thanks for all the suggestions/input. I think I have a fun project ahead of me.

[Malcolm McLeod]

There are electrical alternatives as well. Electrical actuators are used in an ever increasing array of products - from pop-up car spoilers to TV lifts. Based on a quick search, the (6" stroke) actuators themselves can run from $35 to >$150, with a range of available force, stroke, and speed options. I suspect this will be a classic get-what-you-pay-for situation. Generally speaking, anywhere you can physically mount a pneumatic cylinder, there is an electrical equal.

You would need a suitable power supply for 12VDC or 24VDC (at least my recommendation for a home shop) to match the actuator voltage. ...A simple 'wall wart' might be enough. A larger supply could power the whole shop.

You need a control device to turn the actuator on/off. The actuator may have options for "extend with power on", "retract with power off". If so, then all you need for control is a current sensor for the station where its installed. The sensor closes when the tool starts, power flows to the actuator, actuator opens blast gate. Reverse on stop.

I have not priced this out, but for a small system an electrical solution could be cheaper - especially if you include the cost of a compressor (excluding the throw-aways). I'm sure for larger (10-12 gate systems?) the pneumatic control will be cheaper. ...No idea where they cross. Yet.

I am where I can ditch the 1hp, single-stage, delta dust spreader and finally looking at DC options and this blast gate automation has me intrigued. Stay tuned.

[Dan Friedrichs]

The thing I worry about with the electrical actuators is binding or stalling. With pneumatics, if you have a stuck gate, it just sits there under pressure until maybe, eventually, vibration (or something) wiggles it free and it moves again - there is no harm in "stalling" the actuator. With electric actuators, if the motor stalls (because of sawdust build-up or excessive suction or whatever), you may be able to overload it and damage it.

[Malcolm McLeod]

...With electric actuators, if the motor stalls (because of sawdust build-up or excessive suction or whatever), you may be able to overload it and damage it.

I thought the same thing, and had dismissed any home shop electrical option several years ago. As you start adding components and interlocks, the part count, complexity, and cost climbs pretty steeply. But that was then.

Still reading, but several actuator manufacturers indicate built in end-of-travel limits to stop the motor. And also, overloads to deal with the motor stalling. Of course, the get-what-you-pay-for factor kicks in - - but at the moment concept seems feasible.....?

[Ben Rivel]

If I could find electrical actuators with at least a 5" and 6" travel and were as cheap as the pneumatic kind I'd start working on an automated system right away as Im really getting tired of having to juggle blast gates all the time when jumping back and forth between tools. I dont really like the idea of having to have a compressor on just to run my blastgates, even if it is small and all those air tubes running everywhere seems like it would be a lot more of a rats nest than small gauge wires.

[Peter Aeschliman]

Did you look at my thread? It is far from "technical". Basically, you want to find an air cylinder (I prefer double acting, that uses air to force the piston to travel both directions, no spring return) that has a stroke that matches the size your blast gate has to travel. Then, select a valve to control the air flow. A 5/2 way valve has 5 ports (two go to the cylinder, two are exhausts and one is where the air feed goes) and controls the air flow to either extend or retract the cylinder's shaft.

All you need to complete the set up is to mechanically connect the cylinder to your gate, and hose to plumb up the valve to the cylinder, and air feed to the valve.

Most cylinders have threaded holes at the end, which will accept standard pipe taper fittings. Also, you can buy fittings that allow the smaller diameter tubing to be pushed in and are easy to hook up and disconnect if necessary.

You will also want some sort of needle valve, or in line restrictor to allow the cylinder to move from one extreme to the other in a controlled manner, and not go "bang" "bang" from one end to the other. Can be as fancy as a purchased restrictor/needle valve that goes in line with the supply to the cylinder (one for each input) or a home made restrictor that you can shove into the lines - I made mine from a small plug of brass that I drilled a small hole into.

It really isnt that difficult.

Thanks Andrew. I guess I just need to study. Still seems pretty complex to me, but I'll figure it out.

[Rick Fisher]

I just built 5 of them and have a few more to go. They've had a few months use, and nothing bad has happened.

I used 6" Aluminum Blast gates from Lee Valley.. Bought 160mm pneumatic pistons from Ali-Express. cost about $13.00 each.

The rest is hardware store stuff.

I hope to eventually automate them .. but right now .. they are just on switches.

[Bob Cooper]

I'm not quite following what the 5 ports r hooked up to -- the wiring diagram per se -- or what tells the valve to open and close.