String Task

[CookiePie1]

Hey guys, I'm currently passing current directly from a 9V battery through a ~2cm length of 38 AWG nichrome (pretty darn thin). The way my machine is built is that the current stops immediately after the string is broken, so the wire only glows red hot for a fraction of a second.

However, I would like to make some changes to my machine that would essentially keep the current running through the (glowing) wire for a good while (~1 minute). Would my wire potentially burn out and break? Will safety be an issue? Should I add a resistor?

For whether or not the wire will break, I believe testing it is the best answer (unless you have limited amounts). Same answer for the resistor question.
As to whether or not safety is an issue, if the wore is only glowing, and not near anything flammable, I do not see why it is a safety issue. In VA at least, I asked the ES if it would be (I have a kill switch to turn off the nichrome), and they said that they have no problem with it glowing for the duration of my run, and if i really wanted to, I could turn it off without counting it as a touch if the kill switch did not work.
While this is obviously only the VA ES's perspective, I cant imagine that many others will think a glowing nichrome wire is a big deal... after all they did use to have actual matches and flames in mission possible.

Thanks for the suggestions! My main concern though is that the battery may not be able to withstand a long nichrome action duration for more than a few trials. Would it cause the battery to overheat and possibly blow up? Don't want to test that one for obvious reasons....

With our nichrome wire, the batteries will heat up a lot. I think your biggest concern should be that you're basically killing your batteries, and we went through a ton of batteries with ours.

[PM2017]

Hey guys, I'm currently passing current directly from a 9V battery through a ~2cm length of 38 AWG nichrome (pretty darn thin). The way my machine is built is that the current stops immediately after the string is broken, so the wire only glows red hot for a fraction of a second.

However, I would like to make some changes to my machine that would essentially keep the current running through the (glowing) wire for a good while (~1 minute). Would my wire potentially burn out and break? Will safety be an issue? Should I add a resistor?

For whether or not the wire will break, I believe testing it is the best answer (unless you have limited amounts). Same answer for the resistor question.
As to whether or not safety is an issue, if the wore is only glowing, and not near anything flammable, I do not see why it is a safety issue. In VA at least, I asked the ES if it would be (I have a kill switch to turn off the nichrome), and they said that they have no problem with it glowing for the duration of my run, and if i really wanted to, I could turn it off without counting it as a touch if the kill switch did not work.
While this is obviously only the VA ES's perspective, I cant imagine that many others will think a glowing nichrome wire is a big deal... after all they did use to have actual matches and flames in mission possible.

Thanks for the suggestions! My main concern though is that the battery may not be able to withstand a long nichrome action duration for more than a few trials. Would it cause the battery to overheat and possibly blow up? Don't want to test that one for obvious reasons....

You should probably make it turn off immediately after it burns the string.

[Shr3D]

Um I have 38 AWG nichrome... is this too small? It breaks if it’s not looped 2-8 times... and is sometimes hard to handle... what AWG nichrome would you suggest so that the wire glows but doesn’t break? Any help would be appreciated.

[CookiePie1]

Um I have 38 AWG nichrome... is this too small? It breaks if it’s not looped 2-8 times... and is sometimes hard to handle... what AWG nichrome would you suggest so that the wire glows but doesn’t break? Any help would be appreciated.

The wire doesn't need to necessarily glow in order to break a fishing line - ours has never become red hot and works reliably. I'm not sure what guage we use but we only use 2 AA batteries.

[TheSquaad]

Um I have 38 AWG nichrome... is this too small? It breaks if it’s not looped 2-8 times... and is sometimes hard to handle... what AWG nichrome would you suggest so that the wire glows but doesn’t break? Any help would be appreciated.

Why do you need the wire to glow? Our nichrome can cut standard fishing line without ever getting that hot

[jinhusong]

Um I have 38 AWG nichrome... is this too small? It breaks if it’s not looped 2-8 times... and is sometimes hard to handle... what AWG nichrome would you suggest so that the wire glows but doesn’t break? Any help would be appreciated.

Why do you need the wire to glow? Our nichrome can cut standard fishing line without ever getting that hot

Search internet. There are some places that you can input voltage, expected temperature, it will calculate the resistance for you. Then you can use multimeter to find out how long of your wire will get to that ohm.