Quote from: akky on August 18, 2010, 04:16:16 PM
but how will you pay for it ,,,i dont have any bank account

No bank account?? Ok, just ask any of your friends/relatives with accounts.. Will transfer to them n then they can give you cash..

This is the nichron wire which i use

Just found this interesting site:

http://www.harikesh.com/FoamWing.htm

Quote from: VC on August 18, 2010, 08:55:48 PM
Just found this interesting site:

http://www.harikesh.com/FoamWing.htm

I had read that site long back and also sent PM to harikeshpk but no response..

Quote from: akky on August 18, 2010, 06:48:00 PM
This is the nichron wire which i use

Akky, pls buy me a roll of it too.. I'm desperate! I'll send you the money somehow.. Ask your friends if any of them have a account..

ok medicine man will try buy presently i am having my exams which will continue till 28...after that only i cant try..please bear with me...

No problem! I just finished my exams so I understand your pain.. Till then I'll try some other strings..

and please note the specific resistance of this wire is 3.84 ohm/meter.....the first value was wrong,
in comparison with guitar string which has more than 18 ohm/meter(approx)

Even I thought it was too low.. then I thought u might have typed meter instead of foot.. so i guess this one and the eBay one I posted are approximately the same value then.. Guitar strings have too much resistance for big cutting bows, they are fine for small one I guess.. But then they might work on a higher voltage supply.. Mine is just 12v

i use around 18 volts 2 amps...but with a regulator....but i dont preffer this hot wire cutter...anymore...

I have made my my hot wire cutter from Soldering Iron Coil.
Just bought an 35 watt soldering watt coil from your electrical shop. (I have purchased for Rs.6/- only)
Just unwind from the mica sheet. Please note that, dont use used coil as they become stiffer and the bending mark cannot be made straight.
Now some calculation :
As the coil is used with one diode in series,
Rated Current = Watt x 2 /V
and comes to about 300 mA.
Therefore, it is recomended to drive at 2/3 rd current i. e. 200mA.
Now make your Bow or tension making arrangement.
Fix the wire. Measure resistance of the desired wire.
Calculate required voltage for heating (IxR).
I found for my 14" Bow wire, 12 volt is sufficient.
As the current is low, you can use a 12-0-12 Volt 1/3 Amp with voltage doubler or tripler with 3300uF Capacotor & 1N4007 Diode as required for your cutter.
========================================================
Roughly the thumb rule is that use the multiple of 12 Volt per feet.
========================================================
The advantage for this cutter is that, as the heat per inch is very less, cutting are very accurate. Simultaniously, you can hold the wire during cutting and feel nothing but small heat (If ur sensation is very good). The disadvantage is that you can not cut very first.
========================================================
The Cuttings are be very nice and accurate.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Similarly you can use 250 Watt Heater Coil (Sometime you may not find.) The calculation will be similar but value would be different and you need 1Amp Supply.

Thanks

Could you please post your doubler or tripler circuit? Also post the pictures too

Regards,
Dileep

Akky,

Can you buy for me also.

i will send somebody to you he will collect and give you the money.

will try do so but only after my exams r over means next month

Here is the Voltage Doubler Circuit.

or rearranging,

and a voltage tripler circuit is here.


Similarly you can add more stage and get higher voltage.
Please use the voltage rating of each Capacitor well below operating peak voltage (Use 25 Volt ).

DIY Foam cutter link:

http://epp540.com/index.php?option=com_content&task=view&id=89&Itemid=43

And here is my Bow Cutter.


runs with 12 volt. PS capable to deliver 5A but use only 200mA.
Thanks

Here is my cutter.. 12v 5A transformer.. Ceiling fan regulator.. Activa/dio side stand spring for tension & guitar string tightening mechanism to adjust tension..

Medicineman, your setup is quite the same as mine. Only difference is that in your case the bow moves and the foam is stationary and in my case it is the other way around as I  plan to slice 25mm blocks into 5 mm sheets to start with. I like the guitar wire tightening mechanism, but what is the problem if we don't use a dimmer / regulator and connect the transformer directly to the mains?

If later you decide to use say a wire with lower resistance, or a short segment of wire, then the wire overheats and breaks. With the regulator I can adjust the heat to the desired level..

Hi Guys,
a simple Question.
  Can I use a variable power supply for a hot wire foam cutter ? 

come on Guys.

check this out
not mine though

http://www.submarineboat.com/hot_wire_cutter.htm

this one is way better
http://www.horrorseek.com/home/halloween/wolfstone/HalloweenTech/fotmak_MakingFoamTools.html

Dear guys

       Hotwire cutters:

     Use of Variac in the primary of a transformer is normally suitable. But I think use of Eelectronic Voltage Regulators (LM 317T) will be more economic ans very safe in handling electricity.  The mentioned IC is capable of handling1.2V to 37VDC at 5Amps.  You can vary the voltage to control the current flowing through the HOTWIRE,(ie. Temperature of the wire),for any SWG of Nichrome/Piano wire.

J A Vincent/Trichy

Thanks

Hey , Can i use Pc's UPS battery(12v) and electric guitar no 1.(thinnest) string for Hotwire thermocol cutter?