How to Make a (Free) Tactical Pressure Switch





Introduction: How to Make a (Free) Tactical Pressure Switch

This Instructable details how to make a professional-grade (waterproof) tactical pressure switch for activating rifle-mounted lasers, scopes, TacLights, scopes, etc.

I found that quite frequently I accidentally left the laser on my red dot sight turned on. This led to more than one dead battery when I needed it most. With this remote pressure switch, the dot only turns on when I need it, instead of running down before it's necessary. It also adds a professional "look" to my paintball marker, adding to the "milsim" theme.

The principle of operation is quite simple. There are two conductive pieces of copper foil that are separated by a spongy foam, and when the foil is pressed together, they connect through a hole in the middle of the foam.

I was able to make this switch and wire it into my scope in under two hours, using only materials I had on hand. Granted, had I not been documenting the process, it probably would have taken an hour or less.

Also note that the accessory can be returned to its normal operating mode by simply removing the battery isolator, shorting the switch.

Step 1: Materials

Here are the parts you need:

+A scope/laser/light/etc of your choice

+An old car cell phone charger cord - If you prefer a curly cord, just like the commercial ones have, that is. Bonus points if the cable is colored black. An old telephone cable should work, too, but having a straight segment at the switch end makes life a lot easier. Also, you only need two wires to make the switch work.

+A small rectangle of plastic stock 1.5" x 0.5" - The rectangle will form the semi-rigid switch body. This can be anything from part of an old credit card to a cutout from a Chubs Wipes container. I used the latter.

+Heat shrink tubing - Black is best, as it doesn't stand out as much. You'll need at least 0.75" tubing to cover the switch itself and some smaller sizes to seal the cord end. I used a piece about 2" long and trimmed it once it was shrunk. This can be found anywhere from Fry's electronics (they have a great variety box) to Radio Shack.

+Light-duty epoxy to seal the seams between tubing segments (thanks Spork) or (in my case) super glue, if nothing else is available. Note that if you will need the switch to be completely flexible, super glue will crack, allowing moisture inside the switch.

+Copper tape - Two strips of tape form the switch contacts. I used some leftover tape from shielding my bass guitar. Aluminum could be used, except that it doesn't solder. Any conductive, solder-able tape or foil will work.

+Thin packing foam - This is what keeps the switch off when there's no pressure on it. I used a leftover sheet of pink foam, the kind that is made of very small bubbles. Whatever you use, it has to be thick enough to hold the conductive tape apart but thick enough to not need too much force to activate.

+Small strip of paper - Depending on the model of scope/sight/laser/light you're using, it might be necessary to isolate the sides of the battery from the compartment. The idea is to only have the battery connected when the switch is pressed.

+Solder of your choice

Step 2: Tools

Here's what you need:

+Power drill

+Drill bit the diameter of the cord you're using


+Needle-nosed pliers

+Wire cutters/strippers

+Soldering iron
-PROTIP: Take care of your soldering iron tip! Mine is a mess. Always clean with a wet sponge after use, and when using ironclad tips, DO NOT GRIND THEM DOWN!

+Hair dryer (not shown) to shrink the tubing

+Multimeter/continuity tester

Step 3: Making the Switch Body and Contact Surfaces

With the plastic stock in hand, cut a small notch on one end that's the width of the wire being used. You will probably need the pliers to pull the notch out out. The wire will be super glued in place later on.

Now cut a 1" long rectangle of copper tape that will fit on the plastic stock with just a bit folded over the sides to hold it in place. Make sure you leave about 0.25" of exposed plastic on either end of the stock. Before putting the tape in place, it would be a good idea to place a tiny drop of super glue on the plastic first, just to make sure it doesn't move.

To make the other contact, cut a piece of copper tape the same size as the first. If it has a wax paper backing, simply peel it off and re-apply it flipped over so the tape will stick to the paper. We'll work with this contact soon.

Step 4: Soldering the Wire to the Contacts

Take your sacrificial phone charger and cut however long a segment of cord you need. I suggest using the straight end (if yours has one) for the switch. Strip the insulation off the cord on both ends, and then off each wire. If your cord has more than two wires, you can snip the others off. You won't be needing them.

As a rule of thumb, tin the exposed ends of each wire. In this case though, I would not recommend twisting the strands of the switch-end wires, and if possible, fan them out just slightly. This should help make a flatter, stronger contact with the tape.

Position the cord so the end of the insulation is just at the end of the slot in the switch body. Now solder one wire to the copper tape on the body, and the other wire to the loose piece of contact tape. Make sure that both pieces of tape are lined up.

Now would be a good time to place a bead of super glue in the notch and hold the cord in place until it cures.

Step 5: Making the Contact Insulator

Next cut a rectangle of foam exactly the size of the plastic stock. Make sure to snip out the wire slot just as on the body. It is critical that the foam be the same size as the body, as it will be insulating the switch contacts until the switch is activated. If it's not just the right size, the switch might get stuck "on" once the heat-shrink tubing is applied.

 Make a small rectangular (or circular) hole in the middle of the foam so that the copper plates will make contact when pressed together. Hook up your multimeter to the other end of the cord and test for conductivity when pressed. You might need to put a bead of solder on one piece tape to help bridge the gap.

If you find that the switch needs too much force to activate, try gluing small squares of plastic (or material of your choice) to the center of the top piece of foil. This should make it easier. Again, start with a short piece and work your way up until you find something that works.

Connect it to a multimeter and hold it against, say, a screwdriver to get a feel for how much pressure is needed to turn on. Adjust it as necessary, because this is the last chance to test the switch before sealing it up for good.

Step 6: Shrinking the Tubing

With the switch tested and working, it's time to encase it in heat-shrink tubing.

Find the length and size of tubing you'll need for the switch body. It needs to be large enough that the switch isn't stuck closed before even shrinking it. Leave adequate spacing on both ends to account for shrinkage.

Use a hair dryer (or method of your choice) to shrink the tubing. I would not recommend the method I used, which involved rubbing the soldering iron over the tubing.

Once the tubing has been shrunk to its limit, the flat end can be sealed with a drop of superglue epoxy and pressure. Simply apply a drop to the edge, and capillary action should suck the glue in. Then place the flat end under a heavy book, etc. for a few minutes. Once cured, snip the excess tubing off. Make sure not to cut too close, so as to keep a good sealed end.

With the cord end of the switch tubing shrunk, slip 2-3 successively smaller <0.5" long segments of tubing down the cord. Start with the largest and finish once the tubing has created a seal around the cord. Then superglue epoxy the seams so as to ensure a watertight seal.

Step 7: Preparing the Scope for the Switch

Step 8: Wiring the Switch Into the Scope

With the cap drilled, strip and tin the switch wires with solder. Stick the cord through the hole and line up the wires where they will go. One end should connect to the battery terminal, and the other should connect to the scope circuit. In my case, red goes to scope, white to battery.

Before trying to solder the wire to the "finger" bit, tin a spot with solder. This makes life much easier when soldering the wire in place.

With the scope circuit end done, now it's time for the battery contact. Cut a small circle of copper tape and solder the remaining wire to the middle of the tape. Stick the tape in the center of the cap so that it will be guaranteed contact with the battery.

The only problem now is isolating the battery. If your compartment is conductive all around the battery, you will need a small strip of paper to insulate it. Cut the strip wide enough so that it can fold down over the battery and keep the "fingers" from coming in contact with it.
PRO TIP: It's easiest to place the paper in the compartment BEFORE sliding the battery in.

Lastly, put a drop or two of superglue epoxy where the cord meets the battery cap to ensure waterproofing.

Step 9: Testing the Switch

With the cap done, screw it onto the scope and turn it on. There shouldn't be any light or laser dot until you press the pressure switch. If there is, go back and make sure the "fingers" aren't touching the battery and the paper is correctly isolating it.

Step 10: Finished!

If everything is working fine, congratulations! You are now the proud owner of a tactical pressure switch. You can make one for every one of your rifle attachments and activate them without ever moving your away from the trigger. Hopefully you'll get some extra bragging rights and some increased battery life, to boot.

As an added bonus, use Velcro cable straps to attach the cord and switch to the gun body. This will keep the cord from getting snagged on anything.

Remember that to bypass the switch and use your rifle accessory normally, simply short out the switch by removing the battery isolator strip.

Please don't forget to comment and RATE!




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    28 Discussions

    Man, that's a LOT of work! If I had the tools I would do it. (thankfully airsoftmegastore sells a pressure pad laser cap for 2 bucks..) Using this for my 60th Anniversary Kalashnikov AK-47 Airsoft gun...I love airsoft...and AK-47'S.

    It's a Tippmann A-5, spray painted with five different shades of green and textured sand-colored paint. Just tape up the trigger area, charging handle, and the speed adjustment hole. Nearly everything else can be painted over.

    yea i have been wanting to start playing paintball for a while now and not sure where to start

    Don't forget about speedballl. the matches are shorter but far more intense than any woodsball match i've ever played

    Unless you're playing more than once a week for an extended period of time, it's not really worth it economically to buy your own gun (of course, it depends where you play and how much rentals cost). I did A LOT of research before settling on the A-5, but I'm happy with my purchase. Though I bought mine locally, the best way to get it (in my opinion) is through eBay as a package deal.

    If you're into the Mil-Sim look/style of play, as well as scenario/woodsball, I would highly recommend any of the three main Tippmann markers (98C, A-5, X7). They can be pricey, though, so BT sells a nice alternative which is still insanely customizable, mind you.

    Research before you buy, or you might end up sorry with your purchase. Each person might have different tastes. There's also pride in ownership, so take all gear reviews with a grain of salt.

    A nice way to seal open heat shrink ends is to put a little hot glue in there before shrinking... You can even cut a small bit of the glue off cold and place it in there. It will melt when you heat the tubing then just squeeze it closed :o)

    very nice i have been thinking about putting something like this on my shot gun

    Very cool, and waterproof no less! Haha, the third-to-last image is cracking me up (CQB anyone?). Nice marker.

    Patrick—you really ought to clean that soldering iron tip, you'll get much better performance from it. Just load it into the chuck of a drill, and then use a file or some emery cloth on it as it spins. Unless, of course, you own a lathe, in which case use that.

    7 replies

    I know what you mean. I've ground the tip down with my Dremel grinding bit, and of course, it keeps returning to this sad state. I've got a few finer tips to work with, but I figure I'll save those for working with fine electironics (i.e. adding internal bluetooth to a netbook). I've found that this tip (although pitted and battered) works quite well because the main pit holds just a bit of solder, facilitating the heat transmission to components to be soldered.

    One should never, ever sand, grind, or otherwise abrasively remove the surface of the tip of a soldering iron in an attempt to clean it.

    The inside of the tip is copper. Once the copper is exposed, the tip is ruined. Bare copper will quickly, as you say, "return to this sad state". Oxidized copper hates solder.

    Time to buy a new tip, learn to clean it properly, and try not to leave it on overnight.

    Surely there must be an instructable on cleaning and maintenance of soldering iron tips.

    Despite the poor condition of the tip, it's been working quite fine doing what I need. :)

    As I said, I have other (non-sanded) tips, but I save those for finer jobs. I just keep this one on the iron as my general-use tip.

    The most important thing is to warn others reading your instructable that sanding their soldering iron tip is not a good thing to do.

    Between r.hedgehog and your comments, I could imagine hundreds if not thousands of ruined tips because people "read it on instructables" and took sandpaper to their soldering irons in a misguided attempt to clean them.

    In all honesty, my soldering iron tip was pretty wrecked before I resorted to grinding. It's not any worse than before. In fact, it's working better than in its pre-ground state.

    I'll edit it in, though.

    Hey Patman27, I appreciate your "edit that in" as you described it. The reason being just what the SiliconeFarmer alluded to, SOME people just don't read these types of things from beginning to end like one would think, and then apply the tutorial.
    Most often they will pick-up a glimpse of what they want to know i.e. search on Google for cleaning solder tip, then go to the paragraph on sanding, grinding or using a dremel and the 6 watt bulb goes on over their head and they run out to the garage and grind their new tip down with the stone grinder because it had some solder on it...
    This is a little off-topic but explains it well,
    I belong to a fantastic site involving RC Cars, unfortunately there is a 80 - 20 mix of good and bad advice on it and even though the bad advice is "corrected" by more knowledgeable people it is done so several lines down. So kids searching power increase read: "I ran my engine really lean and gained 35% power" several lines later Joe Good Guy writes: "Hey you're going to fry your piston if you run it that lean" but all the kids seem to see is "I ran my engine really lean and gained 35% power" then 25 newbies read the same bad advice and all blow their engines and wonder why, failing to read the warning of a fried piston. I've tried to get the site owner to remove the bad advice because it causes major problems but he feels it interrupts the flow of the thread. I think your method is a decent compromise.


    That applies to ironclad tips. If the tip is bare copper, make sure it's well tinned (completely coated with solder) before you use it and add a little solder after you unplug the iron. Copper tips dissolve into the solder, so even if you keep enough solder on the tip to prevent oxidation, you eventually run out of copper. Ersin makes a "Savbit" solder that is alloyed with copper, to prolong the life of copper tips, but for fine work an ironclad tip (which you clean only with a damp sponge, while it's hot) and 63/37 solder are the way to go.

    That odd tin/lead ratio has the lowest melting point of all tin/lead alloys, and has the further advantage of having no "plastic range"; it freezes abruptly, with no slushy phase. If you can't find 63/37, 60/40 is more common.

    You can solder Aluminum, I've done it hundreds and hundreds of times. However it takes practice, patience, and did I mention patience? It is not fun and unless you have no other choice I would not recommend it.
    That said there are several tutorials on the subject found on-line the best in M.H.O. is found here
    (American Welding Society)

    You're actually never supposed to bring your heat source in contact with the heat-shrink tubing. What actually works much better than a soldering iron is a lighter. Run the flame back and forth along the tubing, and it will shrink much more quickly, with less chance of melting the tubing.

    1 reply

    I found that using the body of the heating element (instead of the tip) works quite well. Unfortunately, the only "lighter" I have on hand is a propane torch, and that just burns up the tubing. Running the iron _just_ over the tubing shrunk it rather quickly for me.