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A Hot Knife, cuts plastic, rope opens welded plastic cases.

Manufacturers love to blisterpack, and glue shut, and weld closed all sorts of plastic things.  making it really hard for those of us whom wish to fix or modify or even recycle them!

This trick will get you up and rolling easy and cheaply slicing into plastic "like a hot knife through..... uhm plastic!"

I warn you this is pretty dangerous,  we are talking about a Exacto knife(SHARP), and a soldering iron(HOT).  there is possibility of both burns and cuts!  (and possibly burned cuts!)  Please use it with care! but if using it carefully, I think it could be safer than trying to do the same things with a sharp knife and pressure.

I first ran into mention of such a thing from a guy who rebuilt battery packs for laptops.  he would slice open the old one,  then replace the bad cells, (or all of them) and then glue it shut.

But its useful for cutting vinyl. for cutting rayon or vinyl cloth, plastic coke bottles. packaging.  It could probably also be used to carve plastic or wax ,  but i suspect the end result would be a bit globby/stringy.
 
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Step 1: Parts!

You need one cheap metal jawed Exacto Knife
and
one pencil type Soldering Iron (between 25 and 25w) Preferably one where the tip can be removed via loosening a screw on the side, (see photos)

That's it.  (might need some wire cutters, pliers, sandpaper, I didnt.)
Erchan1 month ago

Looks easy, but it's not. You have to make it strong. Because Xacto knife moves! Also you can't cut pvc, plastic etc. It's so sticky.

thats pretty cool I think I might use it for melting paracord ends
killbox (author)  Paracordaholic5 months ago
would work great for that, one mod ive done since i first made it, ive wound up dulling the blade, and even the point a little, to encourage folks to use the heat not the force to do the work.
Cool! You made the instructable like I suggested! XD

Have your tried keeping the blade clean with a brass wire sponge? Wondering how to keep it clean with all that plastic residue.

Thanks!
How many watts on the soldering iron?
killbox (author)  mattadamsnet2 years ago
The green handled one here is just 25W it would be better with a 30W, im pretty sure the one i have at home is 30W, heats up faster but has a longer barrell, makes precision slicing harder. Id say pick one with a short barrel (between the point and the handle) and one with the set screw on the side.
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