Cheap Chinese hot knife styrofoam cutting wand

Discussion in 'Lost foam casting' started by rocco, Aug 2, 2019.

  1. rocco

    rocco Silver

    This afternoon, I received a wand style hot knife foam cutter from China. I did a few small test cuts with it, on expanded polystyrene foam, it cuts too fast, the kerf is huge, it would be difficult to make accurate cuts with it but on extruded polystyrene foam, it works pretty well, I'm looking forward to doing more extensive testing to see if I can make anything usable with it. They're $5-10 on ebay without the power supply, which would be another $10 or so. Anyways here's what they look like

    [​IMG]
     
  2. Tobho Mott

    Tobho Mott Gold Banner Member

    Mine broke, so now it's just the on/off switch for my hot wire foam cutter table. Which also broke. I found it wasn't really hot enough for that, but it did work (back before I dropped something heavy on it).

    Jeff
     
  3. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Put a dimmer switch in front of your powner supply and you’ll be able to control the heat and melt/cut rate better.

    Best,
    Kelly
     
  4. rocco

    rocco Silver

    I opted not to get one of the power supplies they sell with the hot knife instead, I'm using a regulated variable voltage power supply, similar to THIS ONE , it will actually make the wand glow it I crank it up high enough. A little more experimentation with the voltage setting is warranted to see if I can get it to cut expanded polystyrene properly.

    A dimmer switch in line with the power supply may or may not work, it depends on the type of power supply you're using, if it's one of the old style supplies with a transformer inside, it'll work but, most of the newer power supplies are transformer-less with a regulated output, with that type, the output voltage remains the same regardless of input voltage.

    Anyways, like I said earlier, I'm looking forward to testing this thing out more thoroughly, time will tell if it's a tool or a toy.
     
    Last edited: Aug 3, 2019
  5. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    It doesn't even need to be DC to heat a resistance wire, but I have a box full of old transformer based wall mount power supplies I have just for that reason.

    Best,
    K
     
  6. rocco

    rocco Silver

    I know, until recently when I got that variable DC power supply, I had my homemade hot wire cutter plugged into a variac, a 20A unit, massive overkill, it worked pretty nicely although you had to be careful with the setting or it would burn out the wire in an instant.
     
  7. Tobho Mott

    Tobho Mott Gold Banner Member

    I used to just slide the top alligator clip down on the cutting wire to make it shorter and turn up the heat, orbup to cool it down (never really came up) but the broken wand I used as a switch just had on/off and would only get it so hot even over a short length of resistance wire. If I ever repair the table it's gonna become a horizontal wire cutter instead anyhow.

    Jeff
     

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