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Thread: How to build a hot wire foam cutter w/ pics

  1. #1
    Marine SlippyFist's Avatar
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    How to build a hot wire foam cutter w/ pics

    How to build your own Hot Wire Foam Cutter:
    Please note : all prices are in AUD currency


    An essential tool for any avid scenery building nut. A foam hot wire cutter lets you slice right through foam ( polystyrene) by using electrical current circuit, with a switch to heat a wire and carve foam with ease leaving a very smooth finish.

    These are intructions on how to make alot safer hot wire cutter using a AC/DC power pack supply rather than using current straight from a wall socket and mucking around with dangerous components and variable resistors (dimmer switches). The image shows how well it works with normal packaging foam and once my Foam-in-a-can has set I'll edit in another picture of that sliced.

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    Ok so lets begin by knowing what tools you will need for this project. If you don't have these tools try and find someone to Borrow them off of to save cash, or if you're a big spender... nice new shiny tools .

    - Powered Jigsaw
    OR if you don't have one you can pick up a Coping Saw from a hardware store for around $8-$20. This is what is going to be cutting your MDF wood. A jigsaw Is A LOT quicker and a good investment if you have spare cash.
    They start from around $40 upwards.

    - Soldering Iron and solder wire. This is a MUST HAVE tool for this project. They can be bought from a variety of places, hardware stores and electrical component stores are most common and cost anywhere between $10-$80. I bought mine from Jaycar for $14. Soldering wire starts from around $2 in small spools. This is only basic soldering and you can find plenty of basic 101 tutorials on youtube.
    - Power Drill. Again a MUST HAVE for this Project. It's used for well... you guessed it, drilling holes in your MDF.

    - Medium sand paper. about $2 from your hardware store. Just to give the frame a quick sand after its cut out.

    - Hobby Clippers. For cutting Wires. If you're reading this you most likely have one, if not around $3-$10

    - Safety Blade.
    For stripping wiring. If you're reading this you most likely have one, if not around $1-$3

    - Electrical Tape. picked up at hardware store $1-$3

    - Tape Measure. you are a wargamer... right?



    Ok so now you know what tools you need, lets get to the parts that will make up the foam cutter.


    - 6mm MDF wood. Picked Up from a hardware store or any other wood retailer. you can get a sheet size of 1200mmX600mm for around $6 from Mitre 10 (hardware store).

    - AC/DC Power supply. I have used an OUTPUT- 12V 1.5A power supply pack that came from my old mini airbrush compressor. Good ranges are from 9V-700mA to 12V-2.A and these are most commonly spared from old phone chargers, modem routers ect. Basically anything that uses an AC/DC Power supply but make sure you check the power supply against the link in the NiChrome wire section of this thread. Electronic supply stores sell variable power supply but these are $50 upwards, you can also get cheap power supplys at whatever voltage and amperage you desire on ebay, only downside is you'll be waiting at least 1-3 weeks for delivery.
    Click image for larger version. 

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    - NiChrome Wire. This is the Wire that Heats Up. It has a high heat resistance and is Most commonly used in Bar/grill heaters. You'll need atleast 50cm of 28 gauge, though i got mine in a 4M pack for $4 at Jaycar.. so i could make diff size cutters!
    - NOTE! if you're Thinking of making a different nichrome wire length to my design and/or you're using a different volt or amperage power supply you should probably check this online Nichrome wire resistance calculator out first http://www.jacobs-online.biz/nichrome/NichromeCalc.html


    - Power supply socket. you'll need to match up this to your power supply. Take your power supply into your local electrical component store and ask a staff member to match it up. these should be between $1-$3.
    Click image for larger version. 

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    - Momentary Switch switch. This is put in the curcuit for a good reason because the wire will continually keep heating up and it will melt the nichrome wire at 1400 degrees celcius. This is a bad thing lol, so this is why we have a switch.
    The difference between a momentary switch and a toggle switch is the momentary has to be pressed down for the circuit to be active, therefore a momentary switch is a much safer option. I have also bought a 1/4 inch audio socket and placed the switch in the 1/4" casing as per picture. It provides a much sturdier support for the switch. both bought at Jaycar.

    Momentary Switch - $2 purchased at Jaycar
    1/4" audio socket - $1.60 purchased at Jaycar
    Click image for larger version. 

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    -9 Cable ties. these fasten wires and components down and they need to be atleast 10cm in length.

    - 2 Metal thread bolts 25mm. All the following nuts and washers can be bought at your local hardware store for under $4 for the lot. i have used 5mm sizing for all of these in my design.
    - 2 Wingnuts.
    - 4 Metal Washers.
    - 2 Metal Nuts.


    - Insulated Copper Wire. Picked up from a hardware store or electrical component store for around 50c per metre. You'll need atleast 150cm. Personally I bought 5M of red and 5M of black wire for future projects and in case I mess up.
    Also having red and black is a good way of telling wires apart obviously.


    OK! now we've gotten that all out of the way I'll start explaining how to build this awesome tool!


    First Off Make sure you are working in a well ventilated and safe environment... safety first!


    Step 1

    This is the measurements of the frame in this picture below. They are all right angles so its easy to draw up with a pencil and ruler.
    If you look at the handles I've added in grooves for my fingers, you can choose to do this or not, up to you.

    Click image for larger version. 

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    So once you've drawn your lines onto the MDF its time to start cuttting!

    Step 2
    Carefully cut the frame out with either a jigsaw or coping saw and then just give it a quick sanding. you should only be sanding for 3-5 mins at most.

    Step 3
    Now its all nice and sanded its time to whip out your power drill. Remember to drill the same size as your bolts.
    As you can see from the picture below these are the locations you need to drill.
    Click image for larger version. 

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    Step 4
    Time to cut some insulated wire!
    you'll need to cut a piece of black wire aprox 120 cm and strip and expose the copper wire one end 30mm and the other only 5mm. this piece is going from the far bolt hole to the power socket at the bottom of the handle.
    you then need a 6cm red wire to go from the power socket to the switch located at the top of the handle. you can have this in two pieces of 3c each if you want and solder them together at the end.
    and finally another red wire 20cm long going from the switch to the bolt hole at the top of the handle. strip and expose the end near that bolt hole 30mm.
    Heres the wiring and positioning diagram. the blue lines are for the cable ties.


    Step 5

    Now its time to solder on the wires connecting to the power plug terminals and wires to the switch terminals. if you don't know how to solder, you tube can teach you in about 5 mins, its really easy.
    once all the soldering is done get two cable ties and position the newly connected switch and power plug and cable tie them like in the picture in step 6.


    Step 6
    Now tie down the long black wire going right around the frame with cable ties.
    After you've done that the whole device should look like this.


    Click image for larger version. 

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    Step 7
    now twist the 30mm exposed wires in your fingers to make them look sort of like those raspberry twist lollies.
    Then take a bolt and wrap the exposed twisted wire around the bottom of the thread near the head of the bolt. do this for both bolts and wires. drop a washer over that and insert like shown below. the bolt head should be on the oposite side of the frame than the switch and power socket.


    Step 8
    First off drop a washer over both the bare bolts sticking up.
    Time to cut the Nichrome wire, if you've followed my instructions and scale then you'll need 52cm of it.
    Start wrapping the nichrome wire around both the bolts near the washers. Wrap them
    CLOCKWISE.
    This is so when you screw on the wingnuts it tightens the Nichrome wire.

    Click image for larger version. 

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    Now screw on the wingnuts and tighten it but don't go overboard. Remember you're cutting foam with a searing hot wire, you dont want it to snap and hit you in the eye.

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    Step 9
    If you're unsure, Double check your switch and socket solder joins and reapply the cable ties.
    Wrap the handle up in electrical tape for protection......


    !!!AND YOU'VE FINISHED!!!


    Instructions of use : Never have the switch pressed down for more than 40 seconds. Give it 10-30 seconds to cool down.
    Do not try and burn things other than foam with it, thats just dumb. The nichrome wire may snap and cause serious harm.
    Use well ventilated areas and protective masks. you're creating fumes when in use whether you can see them or not.
    WARNING : MAY CAUSE BURNS. ALWAYS WEAR PROTECTIVE GLOVES AND CLOTHING.









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    Last edited by SlippyFist; 26-05-2012 at 22:23.

  2. #2
    Chapter Master Erazmus_M_Wattle's Avatar
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    That's an awesome bit of work there. Thanks for showing how that's done. Sadly I won't be making one because I'd just end up electrocuting myself.

  3. #3

    Re: How to build a hot wire foam cutter w/ pics

    That's a great tutorial! I might give it a go when my wife's out of the house (otherwise, she'd just worry...).

    R.

  4. #4
    Marine SlippyFist's Avatar
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    Re: How to build a hot wire foam cutter w/ pics

    thanks guys! if you have any questions feel free to ask and i'll do my best to answer!

  5. #5

    Re: How to build a hot wire foam cutter w/ pics

    This is an awesome tutorial! I can see you have put alot of work into it. Well done

  6. #6
    Chapter Master chromedog's Avatar
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    Re: How to build a hot wire foam cutter w/ pics

    Awesome tutorial and pretty much how I made my own cutter (except mine is an emplaced one clamped to my bench).
    Down to the use of a spare AC/DC plugpack adaptor.

    Nice work. It's handy when I have a Jaycar store a 5 minute walk away from my house.
    Sent from my Nokia Lumia800 using my microwave as a proxy server.

    That is not dead which can eternal lie
    And yet, with strange aeons, even death may die.

    I am the guy who thought the LoTR movies were crap and liked Judge Dredd.

  7. #7

    Re: How to build a hot wire foam cutter w/ pics

    Very nice one!
    In order to help fellow friends check this cheap and effective homemade model of hot wire foam cutter I have found searching.

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