Linear Actuator Blast Gate (12v DC)

Meta Description: Looking for a cheaper alternative to iVAC Blast Gates? Simple, reliable, easy to install, lowcost? 12 volt DC Linear Actuators are the answer!

Photo: Linear Actuator Blast Gate (blast_gate_linear_00)

Linear Actuator Blast Gate

Looking for a cheaper alternative to iVAC Blast Gates? Simple, reliable, easy to install, low cost? 12 volt DC Linear Actuators are the answer!

Here is my sad story about how I found Linear Actuators the hard way. I tried iVAC Pro Blast Gates and Servo Blast Gates. They cost to much and were not reliable. Then I found 12 volt DC Linear Actuators and used them to automate my existing blast gates. They are low cost, 100% reliable, and easy to install. They are the answer!

Photo: Linear Actuator Blast Gate Video (blast_gate_linear_youtube) Linear Actuator Blast Gate Video

Everyone seems to need a video these days. Here is a little 30 second video that shows my Linear Actuator Blast Gate in action.


Make Your Own

Photo: Make Your Own (blast_gate_linear_11)

Here is how I made my own Linear Actuator Blast Gates.

Easy to Install, 100% Reliable

Cost: Roughly $50 per gate. $40 for actuator + $6 for DPDT switch & case + roughly $4 for wire.

Plus $23 for a 12 volt DC power supply. If you don't already have one in your spare parts box. You only need one power supply for all of your gates.

Photo: Linear Actuator from Amazon (actuator_amazon) Linear Actuator from Amazon

I purchased a linear actuator from Amazon. "Mini Electric Linear Actuator Stroke 4"–Force 4.5 lbs–12V | High-Speed 0.6"/sec–Weight 0.25KG …"

I picked this one because it has 4" of stroke (like my 4" blast gates) and it moves in/out relatively fast (when compared to the other ones on Amazon).

I have found that the speed of the actuator is good. Not as fast as my iVAC gates. But, not to slow. My blast gates open in about the same amount of time it takes for my big 2HP dust collector to come up to speed.

Photo: Linear Actuator from Ebay (actuator_ebay) Linear Actuator from Ebay

I recently found what appears to be the same actuator on Ebay for $30 with free slow shipping.

I ordered some of the Ebay actuators and they are the same as the above Amazon actuator. 100% identical. They work ok. Shipping from China takes a few weeks.

Are they second quality with flaws inside that I can not see? I don't know. Buyer beware!

Photo: Linear Actuator Motor (actuator_motor) Linear Actuator Motor

This photo shows what is inside of a linear actuator. A small 12 volt DC motor. A small gear box. Limit switches (intelligent protection chip in photo).

The motor is 12 volts DC. I love this! A hell of a lot simpler than the "compressed air" blast gate systems on the web. Wires are easier to run than little air tubes that do not easily go around corners and may get squashed, etc. Electrical switches are cheaper and easier to install then air switches. Etc.

The gear box drives a threaded rod that moves the linear actuator in and out. I really like this. It means the connection to my blast gate can be DIRECT DRIVE. i.e. rock solid. Works 100% of the time. No crazy linkages and springs like you have with the "servo" blast gate systems on Youtube, etc.

The standard for linear actuators is ONLY 2 wires and 12 volts DC. A black and a white wire. When you connect the wires to a 12v DC battery or power supply the actuator moves OUT. If you reverse the wires it moves IN. Thus you can easily control the actuator with a DPDT reversing switch. Just like 12 DC model trains or any DC motor. DPDT = Double Pull, Double Throw.

The built in limit switches are really nice! They stop (cut off the power) when the actuator moves all the way in or all the way out. I REALLY love this! It means you DO NOT have to worry about burning out the motor. You can just leave the power always on! Thus you can just use a simple DPDT switch. A center off position is NOT needed.

If you leave the power always on a "servo" blast gate and the gate jams or does not move all the way in/out then you going to burn out cheap hobby servos that do not have built in limit switches. Adding your own external limit switches adds a lot of pain and cost.

Photo: Manual Blast Gate (blast_gate_linear_01) Manual Blast Gate

This photo shows a blast gate installed up near the ceiling in my studio BEFORE, I installed a linear actuator.

I have a big 2 HP dust collector in my studio. It is turned on/off by little micro switches on each blast gate. See red circle in photo.

The micro switches are part of an old "Penn State Industries Long Ranger" system. The micro switches trigger a relay that triggers a magnetic motor starter.

Over time the micro switches have failed and given me trouble. I have replaced them with better micro switches. I recommend doing this BEFORE you install linear actuators. See my "Better Blast Gate Micro Switch" blog entry.

If you don't have micro switches and you don't want to install them. Then you could open/close your gates via a "3 pole, double throw" switch, rather than "double pole, double throw" switch. The third pole would be use to trigger a relay that triggers a magnetic motor starter or power relay. See "3 Pole Switch" below.

I REALLY like the micro switch solution. It means that my 12 volt DC linear actuator wiring is NEVER in the same box as my 24 volt AC control and 220 volt AC motor starter wiring. Thus, no accidental cross over is possible. I can't burn things out.

Photo: Automated Linear Actuator Blast Gate (blast_gate_linear_02) Automated Linear Actuator Blast Gate

This photo shows the same blast gate with a linear actuator installed.

Note: The ceilings are low in my studio. Thus I had to rotate the gate 90 degrees in this photo. Otherwise, the actuator would hit me in the head. Rotating the gate was the hardest part!

The installation is easy. You just add a piece of 1/4" plywood, some wiring and a DPDT switch (switch not shown in photo).

The gray wire coming in on the left is 12 volts DC power. Red arrow in photo. All of the gates in my studio are powered by a single 40 watt plug in 12 volt DC power supply. See Digikey order below.

The white wire coming in on the right is 4 wires going to my DPDT switch (switch not shown in photo). Green arrow in photo. Two 12 volt DC Power wires go to the switch. Two 12 volt DC control wires come back from the switch and go to the linear actuator. Blue arrow in photo.

Photo: The Front on Workbench (blast_gate_linear_04) The Front on Workbench

I recommend you set up and test things on a workbench before dorking around over our head.

This photo shows the front after I got things working. See photos below for more details.

I got the little white terminal strip on Amazon. You do NOT need one of these. You could use little orange wire nuts.

Photo: The Back on Workbench (blast_gate_linear_06) The Back on Workbench

This photo shows that I attached the linear actuator to my plywood with black wire ties. After I got everything working. I added some insurance. I removed the wire ties. Added some 5 min epoxy between the actuator and plywood. Then I reinstalled the wire ties.

The plywood is attached to the blast gate with standard #10-24 x 3/4" machine screws. I just replaced the existing blast gate screws with longer ones.

Photo: Attach Gate (blast_gate_linear_07) Attach Gate

I attached the sliding part of the blast gate to the linear actuator with a standard #8-32 x 1-1/4" machine screw. I removed the spring machine screw and replaced it with a longer one.

I REALLY love how simple this is! A 1000 times simpler than all of the crazy "servo" blast gate linkage solutions on the web.

I carefully adjusted things here, so the gate does not drag on things when it opens and closes. The linear actuator is probably strong enough to overcome any problems. But, I like to avoid extra wear and tear. You may also need to adjust things so the gate does not rattle when closed.

Photo: Close up of Micro Switch (blast_gate_linear_05) Close up of Micro Switch

This photo shows my micro switch that turns my big 2HP dust collector on/off. It is definitely off when the gate closes.

See "Manual Blast Gate" above for more micro switch details.

Photo: Plywood with Dimensions (blast_gate_linear_09) Plywood with Dimensions

This photo shows the 1/4" plywood with dimensions.

The red arrows in the photo, point to the 1/4" holes that I use to attach the plywood to the gate.

The green arrows, point to the 1/4" holes that I use to attach the linear actuator to the plywood.

The blue arrows, point to the 1/4" holes that I use to attach wires with wire ties.

Beware! The photo is NOT dead on. Thus it is NOT to scale. You can NOT use it as a template.


Open/Close Switch for Blast Gate

Photo: Blast Gate Open/Close Switch on Drill Press (blast_gate_linear_14) Blast Gate Open/Close Switch on Drill Press

This photo shows the switch that opens or closes the blast gate attached to my drill press. See red box in photo. I use similar switches on my bandsaw, tablesaw, etc.

I LIKE hard wired switches. I am not big on wireless remotes and I definitely don't want anything to do with current sensing switches and/or other fancy electronics crap. Keep it simple! More about this latter.

The hard wired blast gate switch is next to the power on switch. Were it is easy to turn on IF AND ONLY IF I need it for a big job!

If I am just going to drill a little hole or make a small cut on the band saw I don't need to short cycle my big dust collector on/off. The next time I do a big job and turn the dust collector on it will almost instantly suck up any little saw dust left over from a small job. Thus, I do NOT want my dust collector to automatically come on, any time a tool is powered on!

Photo: Blast Gate Open/Close Switch on Big Gulp Dust Hood (blast_gate_linear_13) Blast Gate Open/Close Switch on Big Gulp Dust Hood

On my big lathes the switch is located on the side of the Big Gulp Dust Hood on each lathe. See red box in photo. This works really good!

Manual Open/Close switches are definitely the way to go here! I only use the dust collector while sanding and painting on the lathe. Turning a green bowl or hollow form, creates huge long wood shaving that are to much for any dust collector. Thus, I do NOT want my dust collector to automatically come on, any time a lathe is powered on.

Photo: Wiring The Switch (blast_gate_linear_08) Wiring The Switch

The standard for linear actuators is ONLY 2 wires and 12 volts DC. A black and a white wire. When you connect the wires to a 12v DC battery or power supply the actuator moves OUT. If you reverse the wires it moves IN. Thus you can easily control the actuator with a DPDT reversing switch. Just like 12 DC model trains or any DC motor. DPDT = Double Pull, Double Throw.

Any DPDT switch will do the job. You do NOT need a center off switch because the linear actuator has built in limit switches that cut off the power when the linear actuator is all the way open or closed. However, I like to use a DPDT switch with a center off position for the added piece of mind.

The photo shows the back of two DPDT rocker switches. The top switch in photo shows how to wire the switch to make it a reversing switch. The red and yellow wires cross over the outside pins.

The bottom switch in photo shows how to connect the power and linear actuator wires. The red and black wires are 12 volts DC power in from your power supply or battery. They connect to the left (or right) set of outside pins on the switch in the photo. The green and white wires go to the linear actuator. They connect to the center pins on the switch. On the other end of the cable the green and white wires connect to the black and white wires on the linear actuator via the terminal block on the gate. See "The Front on Workbench" above.

Remember we are only dealing with 12 volts DC here. Thus you can play around until you get it right. If you stick both 12 volt DC wires in your mouth it will give you a nice little jolt. But, it will not kill you. Well, it did not kill me when I was a kid playing with model trains. Now that I am an old fart, maybe it would kill me.

BEWARE! If you want to use the switch box and switch I list below then YOU need to grind off the pins on the bottom of the switch a little BEFORE you solder on the wires!

Note: I DO NOT worry about open vs closed when wiring the switch. If the gate opens when the switch says closed. Then I just reverse the black and white wires going to the linear actuator at the terminal block on the gate. See "The Front on Workbench" above.

Photo: Switch, Switch Box, Wire, and Power Supply (digikey_dpdt_switch) Switch, Switch Box, Wire, and Power Supply

Finding a nice little box for the switch is not easy. I got the box in the photos from Digi-Key (www.digikey.com). Digi-Key part number 377-2289-ND. $3.80 each on 3/2021.

Any DPDT switch and wire will do. You can get from local store or Amazon.

HOWEVER, the above switch box is only 1.161" tall. Thus your DPDT switch needs to be not to tall! I known that Digi-Key part number EG1541-ND works if you grind the pins on the bottom down a little on a belt sander or grinder wheel. This switch also has two sets of holes in each pin that makes soldering on the cross over wires easy.

Any wire will do. Thermostat wire or phone line, etc. However, DC power does not like long cable runs. i.e. 12 volts DC goes in one end comes out as 10 volts on the other end. If you power all the gates in your shop from a single 12v DC power supply then I recommend at least #18 wire. I prefer #16 wire. I like Digi-Key part number BEL1266-100-ND.

The wire that goes from the gate down to the switch may run by or near some big motors. Thus I prefer good shielded wire rather than thermostat wire, etc. A shielded wire has aluminum foil wrapped around the 4 wires in the cable to block or lessen the effects of magnetic field noise created by AC motors. I like Digi-Key part number CE2204W-50-ND. However, this may be over kill. Thermostat or phone wire from a local store may be good enough. I DO NOT connect the shield wire to ground or anything. Why? Because the ground in my studio may be polluted by magnetic field noise from lots of big AC motors in my studio.

Any 12 volt DC power supply on Amazon, etc will do. I wanted one that was big enough to power all of the gates in my studio over long wire runs thus I went with Digi-Key part number 1866-4539-ND. It is 40 watts.

Photo: 3 Pole Switch (digikey_3pdt_switch) 3 Pole Switch

I have micro switches on each blast gate that turn on/off my big dust collectors. If you don't have micro switches and you don't want to install them. Then you could open/close your gates via a "3 pole, double throw" switch, rather than "double pole, double throw" switch. The third pole would be used to trigger a relay that triggers a magnetic motor starter or power relay.

3 poles switches are hard to find. I found one on Digi-Key for some one. Digi-Key part number ET310E12-Z. Beware! This switch is to tall for the switch box above. You will have to find your own box.

You will also need 6 wire (rather than 4 wire) cable down to the switch. Digi-Key part number CE2206W-50-ND.

Sorry, I don't have time to get involved beyond what I have written here. You are on your own.

Photo: 4 Pin Connectors (4pin_connectors_amazon) 4 Pin Connectors

I wanted to add blast gate open/close switches to some of the 4" dust hose lines in my shop that can be quick disconnected and moved around. To make this possible I needed to find some 4 pin connectors.

In the past I have used "Molex" connectors. They work good. But soldering on the little pins and assembling them, really tests my patience. I looked around on Amazon and found some screw on connectors that work ok. Not great, but ok. They are "Cerrxian 3.5mm 4 Pole Female Jack Stereo Audio Video to 4 Screw Terminal Female …" and "Cerrxian 3.5mm 4 Pole Stereo TRRS Audio Video Male to 4 Screw Terminal Female ..".


Master Kill Switch for Dust Collector

Photo: Master Kill Switch for Dust Collector (master_kill_switch)

Have you ever woken up in the middle of the night and realized your BIG dust collector is running? Well I have.

Does it run while you are on vacation? Just imagine the sky high electric bill you are going to get!

What happens when the power goes out and then comes back on. Will a dust gate FALSELY open and turn on your dust collector?

If you have wired things up so any time you open a blast gate it will turn on your big dust collector. Then any FALSE opening of an automated dust gate while your are sleeping, etc, will turn on your big dust collector. Thus I recommend you install a master kill switch for you dust collector.

My kill switch is next to the light switch for my studio. It has a big red indicator light that reminds me it is on and it needs to be turned off when I turn off the lights.

My kill switch is wired into the 24 volt AC line that connects all of the micro switches on the dust gates in my studio. When the switch is off the micro switches are disconnected from the magnetic motor starter for my big dust collector. i.e. the kill switch is connected to the 24 volt AC input on my magnetic motor starter.

A cheap on/off light switch from your local hardware store can be used as a kill switch. Any switch that can handle 110 volts AC can easily handle 24 volts AC. You can get a 24 volt AC red LED indicator light on Amazon or www.mcmaster.com item #5339T13.


Wireless Remote Control for Blast Gate

Photo: Wireless Remote Control for Blast Gate (no_remote_control)

I personally REALLY do not like wireless remote controls. They seem to be all the rage on Youtube, etc. But, I really don't understand why! Because iVAC gates offer remote control?

I really DO NOT like wireless remote controls because they get lost. Are never in the right place, etc. If, I have to walk around looking for the remote control or go get it off some other tool then what is the point? I could just walk over to the main dust collector switch and turn it on!

I strongly prefer hard wired switches that are ALWAYS next to the power switch on a tool.

Wireless RF remotes in a studio with lots of big AC motors is just a recipe for UNRELIABLE operation! Noise from the AC motors can easily false trigger anything that receives wireless remote signals.

Photo: Wireless Linear Actuator Remote (amazon_motor_remote) Wireless Linear Actuator Remote

If you want a wireless remote there is one available on Amazon. It is "ECO-WORTHY Wireless Motor Controller, Wireless Remote Positive Inversion Control Kit for Linear Actuator …".

Can you use more than one of these remotes on multiple linear actuators? I don't no. Probably not. If you want to do that then you are probably going to have set up something like an Arduino Uno micro computer. Trigger the Arduino with a remote. Google "How Do You Control a Linear Actuator with an Arduino" and "Sparkfun Remote Control". It is going to get real ugly and expensive fast!

Sorry, I don't have time to get involved beyond what I have written here. You are on your own.


Current Sensing for Blast Gate

Photo: Current Sensing for Blast Gate (no_current_sensing)

The web is full of crazy current sensing stuff that will automatically open your blast gates when you turn on the power to a tool.

There is NO WAY on the face of the earth I want to mess with current sensing!

I am an electrical engineer. I known more about computers, than I do about power. But, I known enough about power to tell you that current sensing is really difficult to get right! It's black magic that is just a recipe for UNRELIABLE operation!

I don't want to waste my time with unreliable electronics circuits. Mixing low voltage electronics with 110 or 220 volts AC is a great way to electrocute yourself!

I strongly prefer hard wired switches that are SIMPLE and 100% RELIABLE.


Multi Gate Control for Blast Gates

Photo: Multi Gate Control for Blast Gates (multi_gate_control)

The web is also full of multi gate control for blast gates. When you open one gate then all other gates automatically close. I think this is an iVAC marketing gimmick in my not so humble onion. I don't understand why DIY people spend time and money on implementing this.

In my studio I DO NOT leave tools running when not in use. I turn off a tool when I am done with it for safety reasons. When I turn the tool off, I close the dust gate via the hard wired dust gate switch next to the power switch for the tool. Easy, simple and cheap! Thus, there would never be another gate open that needs to be closed when I move to the next tool.

I don't need a lot of fancy expensive electronic stuff that will sooner or latter fail. I don't want to run a lot of dust gate switch wires to a central location. I don't want to deal with wireless RF remote noise problems created by big AC motors.

I really prefer to have all of my gates operate independently. Stand a lone! If another gate needs to be closed, I will walk over and flip the switch manually. A cheap and easy solution. How often will, I need to do this? Almost never?

We often open multiple dust gates in my studio when I have students. Student A on lathe A is sanding. Student C on lathe C is also sanding. They both have a dust gate open. My dust collector is big enough to handle 2 or 3 gates open. I really don't want students A gate to close when student C decides he wants to open his gate and start sanding.


iVAC Blast Gates

Photo: iVAC Blast Gates (ivac_blast_gate_failure)

Here is my iVAC Blast Gate experience. In a nutshell. No happy ending! My iVAC gates are an expensive pile of junk!

The iVAC gates oscillate open, close, open, close, etc in noisy environments. If you have lots of big AC lathe motors in your studio then the noise from them will make the iVAC gates unreliable! The iVAC gates cost to much. Then they don't work right!

My quest to automate the opening and closing of the blast gates in my studio started a couple of years back when I decided to treat myself to a iVAC Pro Blast Gate for Christmas. I wanted to automate just ONE gate in my studio. The one on my bandsaw. I was sick and tired of cleaning up the bandsaw saw dust mess after each class in my studio.

The first iVAC gate, I installed worked ok. No problems with false trigging of the gate due to AC motor noise in my studio. The iVAC gate was opened or closed via a manual open/close switch next to bandsaw power switch. I supplied my own open/close switch and plugged it into the "Manual Wired Remote" jack on the iVAC gate.

Then I decided I wanted to add a second iVAC gate on my big lathe. The one, I use all the time. This is when I ran into all kinds of trouble. The gate would randomly close itself. Then open itself. Then close it self, then open itself. The iVAC gate would oscillate between open and close. This was COMPLETELY and TOTALLY UNACCEPTABLE because each time the gate oscillated it would turn my big dust collector on/off. i.e it would short cycle the big 2HP motor on my dust collector. Short cycling burns out motors. NO GOOD!

I contacted the iVAC people. They responded, but were of no help.

I played around and found the following:

  1. The manual says you should set the iVAC mode switch to "Close" when using a "Manual Wired Remote". This does NOT put the iVAC gate into a manual mode. The RF remote is still enabled. Thus any RF noise from big AC motors can trigger the gate. No good!

    I removed (cut out) the RF receiver. This improved things, but did not completely fix things.
  2. Good electrical engineering practice says that any electrical switch (toggle switch, rocker switch, etc) should be de-bounded and electrical noise resistant.

    The iVAC gate "Manual Wired Remote" port is NOT de-bounded and noise resistant! It should be opto isolated. But, it is not. Opto isolators are a dime a dozen. The iVAC people saved what? A few cents?

    The software that controls the gear motor on the iVAC gate should de-bounce the switch and prevent gate open/close oscillation. But, it does not! De-bounceing is easy to implement in software. Why did the iVAC leave it out?
  3. You can not run the "Manual Wired Remote" wire next to the power lines for your lathes, etc in your studio. The wire will pick up AC motor noise and false trigger the iVAC gate or oscillate the gate between open and close.

    Using a shielded wire, run down the outside of your 4" dust hose, away from all electrical lines, improves things. But, does not completely eliminate the noise problem. I still ran into UNACCEPTABLE gate open/close oscillation problems.
Eventually, I had to give up. I paid to much for iVAC gates and now they are an expensive pile of junk!

I looked for a cheaper solution and found Servo Blast Gates on the web. See next section. Then I found Linear Actuators. They are 100% reliable. No noise problems. Rock solid. Go with Linear Actuators!

Servo Blast Gates

Photo: Servo Blast Gates (blast_gate_servo_failure)

If you search the web for iVAC Blast Gate alternatives. The first thing you will find is lots of people opening and closing their blast gates with hobby servo motors. You can get MG995 servo motors for $5 on Amazon, etc. The price looks right!

You can see in the photo that I really went a long way down the servo motor blast gate path before I decided to give up and switch to SIMPLE 12 volt DC Linear Actuators. I wasted a lot of time and money. Why?

Controlling a servo is not simple. They use pulse width modulation to control the rotation of the servo. You CAN NOT just hook up a servo to a simple toggle switch and power supply. You need to use a servo controller. A little computer circuit board that generates the pulse width modulation BS.

I started out by developing a system that used an "Arduino Nano" as my servo controller. I went a long way down this path. Before I discovered the simpler "SparkFun Servo Trigger". The red board in the photo. I then went all the way to end of the SparkFun path, before giving up. Why?

I ran into numerous problems:

  1. By the time you add all the stuff you need to control the servo (servo control board, pots, resistors, terminal blocks, rocker switch, mounting box, etc) the price goes up to around $50 per blast gate.

    Note: "Off the shelf" 12 volt DC Linear Actuators are $40 on Amazon. All you need to add is a rocker switch, mounting box and some wire. Roughly $10 per gate. Thus the total Linear Actuator solution cost is $50 per blast gate. You get a "turn key", "off the self", 100% reliable solution for the same money!
  2. You need to convert the rotary motion of the servo to a in/out motion for blast gate. A DIRECT DRIVE solution via a screw shaft is NOT POSSIBLE. You have to come up with some sliding channel method that is not 100% reliable. It has to be a compromise that may (will) bind up from time to time and it is not real strong. It can not apply a lot of force to over come a jam in the linkage or the suction of a running dust collector.

    Note: Linear Actuators use a direct drive screw shaft. They can apply a lot of force. They move the gate in/out like you do when you do it by hand!
  3. Creating all of the linkage parts, soldering things together, etc takes a lot of time and effort. Soldering tiny wires into tiny holes with out overheating the adjacent computer chips, requires nimble fingers and really good soldering skills.

    Note: Linear Actuators are turn key, "off the self" solution. No soldering necessary.
  4. You have to adjust the in/out limit pots for the servo position just right. This is really difficult to get right. If you get it wrong then you will burn out the servo motor. I known from experience.

    If you don't use pots then you have to change the limits in your computer program, recompile it and then down load it to your servo controller board. Ugly!

    The pots may be shaken by the opening and closing of blast gates. They then need to be adjust all over again. Err…
  5. It is easy to burn out a servo. I did it twice. Once while testing and once with a gate installed. If a linkage between the servo and blast gate binds then a gate may not open all the way or close all the way. This will leave the servo powered on trying to move the gate. SOONER or latter the servo burns out.

    The "off the self" programs for Sparkfun Servo Trigger or Arduino chips DO NOT detect a stuck servo and cut the power. Adding this function is not an easy change!
  6. If a servo does not close a gate all the way then it does not turn off my micro switches that turn off my BIG dust collector. If my big dust collector is left running with little or no airflow then it will burn out the motor on my big dust collector. This is a HUGE problem.

    This turned out to be a MAJOR road block that I could not solve.

    When I started installing the servo gates in my studio some of them worked ok. Well they only got stuck almost closed once in a while. Not good.

    Then I, installed a servo gate in a location that had lots of suction from the dust collector. I could not get this gate to close. The suction pulled the sliding metal part of the dust gate down tight in the sliding gate slot. The servo was not strong enough to over come the suction from the dust collector.

    I looked for a stronger servo and realized they cost to much and I would still have to live with gates that did not close all the way once in a while. NO GOOD. I gave up and looked for a better solution. I found gear motors. Which lead to Linear Actuators and rest is history. See next section.
Note: My Servo Blast Gate system was based on the info I found on the www.siliconsawdust.com web site under "Arduino Controlled Electronic Blast Gate System".

I gave up on my Arduino Nano board based system because: Soldering all of the pots and wires directly to the really small Arduino Nano board was to changeling. Adding a socket for the Arduino Nano added to much to the cost. This solution also required two power supplies or the use of a Bust Buck Converter. More cost. The Arduino Nano requires 7.7 volts DC for reliable operation. The MG995 servo is 6 volts DC MAX.

The SparkFun Servo Trigger solution requires just one 5 volt DC power supply. It comes with the servo limit pots built in.

AC motor noise protection and de-bouncing of rocker switch has to be down by you in your Arduino Nano program. De-bouncing is built into the SparkFun. However it does not have adequate AC motor noise protection. Noise will cause the SparkFun to falsely open/close and it may oscillate between open and close. Not acceptable! Changing the SparkFun program to add noise protection, etc is possible with additional hardware, but not easy!

The switch de-bouncing and nose protection built into the 12 volt DC Linear Actuators is good. No false switching or open/close oscillation problems!

Gear Motor for Blast Gates (aka Linear Actuators)

Photo: Gear Motor for Blast Gates (aka Linear Actuators) (blast_gate_gear_motor)

Using a gear motor or stepper motor to open/close your blast gates is a great way to go! The connection to the blast gate can be direct drive via a screw shaft. i.e. rock solid. 100% reliable. However, DIY may not be fun. You need a little computer board to control the gear motor. Limit switches, etc.

I stumbled across "off the shelf" 12 volt DC Linear Actuators on the web while looking for a gear motor control board. Linear Actuators are gear motors, with a control board, and limit switches, all rolled up in an easy to install, easy to control, "off the shelf" package. They are the way to go! See "Linear Actuator Motor" photo above.

Note: There is a good DIY gear motor presentation on Imgur web site at https://imgur.com/a/Hxu9Iaj#EGDjE9q with a title of "Automated Blast Gate System". I would like to give the person who wrote this up a lot of credit. Because it was the inspiration that lead me to my Linear Actuator Dust Gate solution. However, I can not find the person's name. Thus, I can't give him credit.

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