Iyer sir ibuilt foam cutter with nicrome wire of 0.5 mm and use 3 to 12 volt dc transfermor as a powersupply but my wire dont heat more i use 90cm wire so ehat can i do to more heat 90 cm is to big?

@gaurang.1972
Your transformer may be too weak.
See the label. How many volts and amps mentioned for output?

You may have to reduce the length. Shorten it little by little while testing with a piece of thermocol.
Be careful not to burn your hand, as you cant see how hot it is.

Do you have a wattmeter?

Iyer sir it is 12 volts and 2 amp and sir ihave only multi meter no wattmeter

@gaurang.1972
Sorry for the delay. Was looking up nichrome data.
The wire i am using (60cm) needs about 2.4 amps at 12v.

Your wire (if it is 0.5mm) should have resistance of about 4.8 ohms for 90cm length.
About 2.5amps is required to heat it enough.
So a 12v supply should be enough, provided it has the capability to supply 2.5amps.

I suspect that your transformer is too weak for this. With a 2amp rating it may actually be capable of only 1.5amps or so. This cannot heat it enough.

Even reducing the length may not work, as this will reduce the resistance, and so it will try to draw more current, loading your transformer even more.

I think a larger transformer of say 5amp rating may be required.

Alternatively, like me, you can use a 3s lipo of say 2200mah, that can easily provide 2.5amps at 12v.

Thanks iyer sir i will try because i am going to build wing of guppy

I think my warning about use of LiPo batteries for a foam cutter is quite a bit late.

Yet, I feel it is relevant.

If you use an ESC as part of the wiring, it adds some measure of battery protection. However, in case of an accidental short circuit (Crocodile clips promote this) the ESC and battery are both at risk.

If you do not use (should I say misuse?) the ESC for this, the risk is of the battery getting over-discharged. If the voltage of any cell drops below 3.2 V, the battery is useless and possible dangerous.

Instead of LiPo, I would use an old car battery or even better, an old motorcycle battery (or two if 6 V). With some home-made fuse protection, this is cheap and safe.

Most battery dealers will sell an old battery for you at little more than the rebate they paid for, when they got in exchange when selling a replacement battery to a customer. Just check or get them to check that each cell is not totally gone.

Regards