Defusing the fuse issue
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Well, the use of fuse ignition in the Build a $5 Heli-Rocket article from MAKE Volume 25 (also on Make: Projects), has caused quite a dust-up in the model rocket community. Use of fuses (as opposed to an electronic ignition system) is a no-no under NAR rules. So, don’t use fuses if you want to be safe and rules-abiding. Building a simple ignition system is easy (a great beginner electronics/soldering project) and if you want to keep it all seriously DIY, you can even roll your own igniters. In this Make: Projects piece we ran during Maker Hobbies month, Stefan Jones shows you how to make your own model rocket igniters out of lengths of nichrome wire and hobby lacquer.


Make: Projects: Model Rocket Igniters

More:
Top 10: Model rocketry posts

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MAKE Volume 25: Arduino Revolution
Give your gadgets a brain! Previously out of reach for the do-it-yourselfer, the tiny computers called microcontrollers are now so cheap and easy to use that anyone can make their stuff smart. With a microcontroller, your gadget can sense the environment, talk to the internet or other hardware, and make things happen in the real world by controlling motors, lights, or any electronic device.

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10 thoughts on “Defusing the fuse issue

  1. I don’t remember WHICH forum I came across this idea, but I love it:

    You know those chunky 12v batteries used to power cordless screwdrivers, drills, lamps, and so on?

    Some folks are using them as the power source for a portable but highly capable electric launch systems.

    If you’re going to use nichrome igniters, or want to try out clustered motor launches, you pretty much have to have a 12v launch system. In the past this meant charging and lugging around a car battery or motorcycle battery. These tool batteries are compact and cheap enough that you could buy a few spares, charge them all, and run a club launch panel off of them for a day’s launch.

    Tool batteries have flat copper contacts on either side of a keyed plastic lug that fits into the base of the tool. Unfortunately, these don’t appear to be standard from brand to brand.

    Depending on the design, you could either hook a sturdy, clean battery clip around the edge of a contact, or build a sleeve that fits over the lug.

    The rest of the circuit is dead simple. Push-button switch to launch, some kind of removeable key switch, and a continuity check lamp. (Either a 12v bulb, or a resistor and an LED.) A well-stocked automobile parts store can supply everything you need.

    I’d love to see some Make Projects to follow the above through.

  2. I went nuts designing a launch system with a big covered toggle, key, and a huge red button. I probably spent $100 on parts, total overkill, but my niece and nephew sure got a kick out of it.

    Using a shorted phono plug and socket makes a good key, I used a 1/4″ plug from an electric guitar cable.

    I usually used a 6-D cell pack, but also drill batteries as well.

    -RG

  3. A long-ago Centuri rocket set, made for cub scout launches, had a plan for an ultra-cheap launcher. They had a nifty idea for the safety key: The plug and receptacle of an extension cord. The lead into the plug is cut about an inch from the base. After stripping off a 1/2″ or so of insulation from each line, the wires are wrapped together.

    The receptacle is wired into the launch panel’s circuitry, such that when the key is inserted the circuit through the continuity light is complete.

    The rest of the extension cord is used as the launch leads, of course!

  4. use a fuse if you want to use a fuse.

    since when do makers care about rules and safety?

    insert something under your skin.

    jailbreak a device you own.

    copy some mp3s and give to a friend.

    light a fuse.

    cross a stream in the name of exploration.

    berate me.

    grow a pair.

    1. the reason they warn you is because you could get arrested.

      in most states you are permitted to transport rocket motors and igniters together. The reason you can do this is because the NAR lobbies to keep it legal.

      as soon as you use them in a non intended use(fuses) you are in possesion of explosives which can be a felony if you have enough mass of motors.

      you should never keep fuses or matches or any ignition source near your motors cause they can cause some serious damage.

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Gareth Branwyn is a freelance writer and the former Editorial Director of Maker Media. He is the author or editor of over a dozen books on technology, DIY, and geek culture. He is currently a contributor to Boing Boing, Wink Books, and Wink Fun. And he has a new best-of writing collection and “lazy man’s memoir,” called Borg Like Me.

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