Making a tool for polystyrene sculpting

[Android 21]

Hi,

Im making a tool for polystyrene sculpting using nicrom wire and 2 batteries, however the heat is take by the cooper wires and go to the batteries which is not recommended and also not energy efficient. Any idea?

 

[.Scott]

From what I gather, you are going from battery to copper wire to nicrom wire to copper wire to battery.
So what you need to do is make handles for yourself. Make the copper wire longer and wrap each one around a pencil before it is attached to the nicrom.
The extra windings will allow some of that heat to radiate. Also, make sure that the copper wire is not super thin.

 

[Borek]

Switching to thick copper wires would be my first step as well. My bet is that the problem is not with the copper wire conducting heat, but with copper wire heating up (sure, it has a lower resistance, but it still heats up with I²).

 

[berkeman]

Welcome to the PF.

Hi,

Im making a tool for polystyrene sculpting using nicrom wire and 2 batteries, however the heat is take by the cooper wires and go to the batteries which is not recommended and also not energy efficient. Any idea?

Where did you get the plans for the tool? What size batteries are you using? What is your target wire current and temperature?

It looks like other similar cutting tools are not battery-powered. Would you consider using a wall transformer power supply instead of batteries? How long do you expect the batteries to last?

https://www.amazon.com/dp/B00O0XY9D2/?tag=pfamazon01-20

 

[jim hardy]

A secondhand soldering gun would be a good source of low voltage high amperage AC
and it's safe.

around five bucks in junkshops here..

 

[Android 21]

From what I gather, you are going from battery to copper wire to nicrom wire to copper wire to battery.
So what you need to do is make handles for yourself. Make the copper wire longer and wrap each one around a pencil before it is attached to the nicrom.
The extra windings will allow some of that heat to radiate. Also, make sure that the copper wire is not super thin.

Yes doing like that, will try that with the wood!

Welcome to the PF.

Where did you get the plans for the tool? What size batteries are you using? What is your target wire current and temperature?

It looks like other similar cutting tools are not battery-powered. Would you consider using a wall transformer power supply instead of batteries? How long do you expect the batteries to last?

https://www.amazon.com/dp/B00O0XY9D2/?tag=pfamazon01-20

View attachment 239177

Thanks :)

No plans, :ust connected them to try first. Batteries AA rechargeable.

 

[Android 21]

Switching to thick copper wires would be my first step as well. My bet is that the problem is not with the copper wire conducting heat, but with copper wire heating up (sure, it has a lower resistance, but it still heats up with I²).

Yes the copper wires where very thin and close to the nicrom.

A secondhand soldering gun would be a good source of low voltage high amperage AC
and it's safe.

View attachment 239187

around five bucks in junkshops here..

Yes but the idea is make my own one :)

 

[jim hardy]

Yes but the idea is make my own one :)

Where do you start? With iron and copper ore, or with a surplus transformer ?

Doesn't matter in the long run, just have fun and learn a lot.
We learn by doing.
You're already learning about the relation between heating of wire and its cross sectional area..

old jim

 

[Borek]

Batteries AA rechargeable.

They won't have enough juice for any serious work. If you really want to go battery way, go for LiPos. The one I happen to have on my desk right now is 12 V and 2.2 Ah, that's something like a dozen AAs (more or less, depending on capacity).

 

[Android 21]

Where do you start? With iron and copper ore, or with a surplus transformer ?

Doesn't matter in the long run, just have fun and learn a lot.
We learn by doing.
You're already learning about the relation between heating of wire and its cross sectional area..

old jim

Just nicrom and cooper.

They won't have enough juice for any serious work. If you really want to go battery way, go for LiPos. The one I happen to have on my desk right now is 12 V and 2.2 Ah, that's something like a dozen AAs (more or less, depending on capacity).

With 30 minutes is enough, and good for batteries for discharge (is better to use them a lot) here I don't have the exact nicrom diameter, later will post it.

 

[berkeman]

With 30 minutes is enough

With AA batteries, you will only get a few minutes, not 30. Ballpark 30W power delivered to your heating element from 3V (2xAA batteries) takes 10 Amps. That's well above what AA batteries are sized for:

https://www.powerstream.com/AA-tests.htm
https://www.powerstream.com/z/AA-1amp.png

 

[berkeman]

That's well above what AA batteries are sized for:

Instead, for your hobby use, I'd recommend using a sealed lead-acid battery like the one below. It has good power and energy capability, and is pretty vanilla to recharge (buy a commercial recharger for it). You can still start a fire with this size battery if you are not careful or make a mistake (please do not ask me how I know this), but overall it is a good building block for your hobby projects like your electric cutter/sculpting tool, IMO.

https://www.batteriesplus.com/content/images/product/large/813987.jpg