Introduction: Cut Bottles Using a Soldering Iron

In this instructable I'm going to show you how to cut a bottle with a soldering iron. I also made a video, which you can watch here: https://youtu.be/JF6M9a_bJdo

This method does take quite a bit longer than some of the others. This bottle took me about half an hour to cut. What I like about using this method is that it's been a lot more successful for me, and gives me almost complete control of where the bottle cracks. Sometimes, though, it will crack wrong, but that rarely happens.

A couple things to remember before starting: only use the tip of the soldering iron and not the thicker part. Also make sure there isn't any solder on the tip. These are some of the things I've tried that caused the bottle to crack wrong. I'm assuming it's because the heat wasn't as focused as you want it to be with this technique.

What you will need:

Step 1: Score the Bottle

We'll start with scoring the bottle with a bottle cutter. Remember to get a good score line, and only do one pass. Going over the same score line multiple times will make the cut more difficult. While making the score line you can tell when it starts to overlap when the sound changes to a crunching noise.

This score isn't ideal. There is a section that got missed because the bottle isn't perfectly round, and part of the score line strays off. But with this method of cutting, these flaws are not much of an issue.

Step 2: Start the First Pass

Choose a place to start that is away from the flaws. With a hot soldering iron, place the tip against the score line and hold it there for about 5 seconds; the exact time is not too critical. Then move the tip a bit and do the same. Continue doing this all the way around the bottle. This won't be enough to cut the bottle, but a lot of the time it will start a crack along the score line.

Step 3: Dealing With Scoring Flaws

If you happen to have stray score lines, like I did this time, just follow the line where you want the bottle cut. Also, if you have any places that didn't score, just follow the path where you want it to cut. Alhough I didn't do it this time, it helps to draw a line for the path with a marker, so that you have a visual reference to follow.

Step 4: After the First Pass

When you finish going all the way around, examine the score line and see if there are any cracks started. Sometimes they start with the first pass, and sometimes they don't. The crack will be shallow, and possibly hard to see, so try to get it to reflect. Check from above the score line, and below. If you see any cracks started, goto that spot and continue from there.

Signs to look for a starting crack vary: It could look like an obvious crack, or could look like the score line getting slightly thicker, or it could look like a reflection or glare on the inside of the glass. This time it started by looking like a reflection.

Step 5: How to Start a Crack (if One Hasn't Started Yet)

If you don't have any started, just pick a spot near your starting point. Before continuing, you'll need to get a crack started, which I'll explain how to do now.

Similar to the first pass, place the tip against the score line. This time hold it for longer, about 8-10 seconds for each position. Also, don't go all the way around the bottle, maybe about an inch or so. Sometimes you'll hear the bottle crack and sometimes you won't so check again for any signs of a crack starting then go back to where you started, and start again. Repeat this over and over, until you see signs of a crack starting.

Step 6: Growing/Guiding the Crack

If you can see the glare of the crack while you're heating it with the soldering iron, watch for it to grow. Sometimes it will fade while the crack is still starting, but that's fine. Once it does start to grow, you won't need to hold the soldering iron in the same place as long, so move it away from the crack as it grows. At this point, the crack will follow the soldering iron. If you do happen to have any places where there is no score line, keep following the path you want the crack to go and it will follow the soldering iron.

Step 7: Finishing the Crack and Separating the Bottle

When you get close to the start of the crack, sometimes you will see the two ends meet, but sometimes it will seem like they don't want to meet. If at this point the crack stops growing, the cut may be complete. Try separating the top of the bottle, but don't force it apart. If the cut is complete, it will separate easily. But if it feels like it doesn't want to separate, try heating the crack a bit more. Usually just heating the last bit helps, but sometimes you need to heat random parts of the crack. Just remember to not force it to separate, because that could cause it to crack randomly.

Step 8: What Next?

Now that the bottle is successfully cut, it's ready to be sanded and polished. That needs to be done because right now it's basically a broken piece of glass, and can easily cut somebody. You can go here to see my instructable for that: Polishing-Bottle-After-Cutting

To learn how I made my jig, check out my instructable for that: Make-a-Bottle-Cutting-Jig-Teardown

If you want to see the video version of this instructable, you can watch it here: https://youtu.be/JF6M9a_bJdo

Comments

author
Razanur (author)2017-03-16

This method looks nice, but very slow.

Has anyone tried running a wire along the score path and heating it (running electricity through it)?

author
johneby (author)Razanur2017-03-16

This works nicely using a heavy gauge nichrome wire attached to upright insulating posts. Make connections at the top of the posts to the output of a very low voltage output high current transformer, with a good sized variac supplying the primary. You can let the wire sag to form a cradle to extend the contact around the periphery of the glass.

author
Razanur (author)johneby2017-03-18

I'm not sure if I understood this correctly. You would hang a wire across the glass, then heat it and let is sag onto the bottle? But then you still need to carefully turn it, right? Seems kinda hard to me to keep everything aligned. Why not put a loop around it and then heat it? The wire should extend when heated, so no worries about "squeezing" the bottle to splinters...

author
hotamale35 (author)Razanur2017-03-26

I believe he was thinking of having the wire hanging in a between 2 points in a " quasi "U" shape and resting bottle in that "U" to do the cutting.... I believe

author
Razanur (author)hotamale352017-03-27

Ah, thanks, yeah, that makes more sense :D

author
charliewinters (author)Razanur2017-03-24

Doesn't necessarily need to be a wire. It could be a plate.

author
Razanur (author)Razanur2017-03-18

Can you maybe show us a video of your method?

author
How Do You - DIY (author)johneby2017-03-16

I'm glad you mentioned this, it's actually something I've been thinking about trying. I just haven't done the research yet to build it. I was thinking about having a tight wire, kind of like the Styrofoam cutters use, but having a sagging wire seems safer. I appreciate the input!

author
Razanur (author)How Do You - DIY2017-03-18

I was also thinking of a rig as I use it for Styrofoam cutting (usually connect it to an old car battery :D)

author
callhow (author)2017-03-19

Maybe you could make a "jig/rig" to hold the soldering iron tip - against the scoring line, and simply rotate bottle - while adjusting "in" soldering iron tip ?

author
mabrady834 (author)2017-03-17

Can you cut the side out of a bottle instead of just the top or bottom? I have seen bottles that lay on their sides with slices cut off of them and flowers planted in them. Wonder if this method would work?

author

I've seen some bottles cut like that too, I think the ones I saw were cut with a diamond saw. I haven't tried a side cut yet, but I am planning an instructable for unusual cuts. I'll experiment and see if I can get a side cut to work. But based on my past experiments, I think it will! :-)

author
AOTN2000 (author)2017-03-17

Good info, I will try it, and cool jig too. Thanks.

author
billdeserthills (author)2017-03-16

My science teacher Mr Heard used to tie a cotton string where he wanted the cut and soaked the string in lighter fluid and light it on fire. The heat would score the bottle and a few taps would separate the two pieces. He would use sandpaper on any rough spots

author
dave_in_delaware (author)2017-03-16

I can recall a "home science project" book I checked out from the library maybe 20 years ago that had a glass cutting project. You scored the bottle with a glass cutter, then used the "nichrome" wire from a toaster (plugged in to heat the wire) to cut it. I never tried it, but I'd imagine it would be pretty fast. I've never thought of this method (soldering iron). You must have tons of patience to do it this way.

author
saxondale (author)2017-03-16

Looks interesting, thanks for sharing. I remember seeing this done on a TV documentary by a guy making a living from it in Brazil. He was turning large jars he recovered from land fill into salad bowls and he used an old record turntable to turn the jars with a small flame mounted at the side to heat the glass, which he then dunked in a bowl of cold water.

author
Yonatan24 (author)2017-03-16

How about a soldering gun? Could be better...

author

I don't have a soldering gun to try it with, but I would imagine that it should work. If you try it, let us know!

author
caruncles (author)2017-03-16

I appreciate the idea but I'm afraid I don't have that much patience. I remember when we were kids, and didn't have a glass cutter, we would soak twine in some kind of fuel then wrap it around the bottle where we wanted the cut, then light it. It wasn't always perfect, but It worked most of the time.

author

I know what you mean, this definitely need patience. It gets frustrating at times because of how long it takes.

author
fixmystuff (author)2017-03-16

Great instructable! I am to try this and "patience is a virtue". Thanks for sharing your method.

author
Aplus1 (author)2017-03-16

Cheaters, the boat goes in without breaking the bottle!

author
wingpilot96 (author)2017-03-16

Exactly the same way I did it in the 70's also..really quite foolproof!

author
StuartB44 (author)2017-03-16

I used to do it in the late 70's. Score the bottle, heat the score over a
candle, then run an ice cube around it.

With one of these.:

https://www.youtube.com/watch?v=BjYVk9cz_aE

Never tried it with a soldering
iron. Might have a go, although it does take a lot longer.

author
Craftcorner (author)2017-03-16

Too time taking consuming...Prefer hot water and cold method

author
YS Creations (author)2017-03-15

A mate & I spent days playing around with various types of bottles & attempting to cut them. We were particularly interested in the 1L glass coca-cola bottles we were getting at the time. They had a thick glass, however it was inconsistent in its thickness around the circumference of the bottle. The best method we found was to have the jig (like you've got), rotate the bottle whilst applying heat to it with a butane blowtorch (just using the tip of the flame). Then we scored the line on the pre-heated bottle. Then we would apply more heat whilst rotating the bottle evenly & it would just pop off itself. Worked even better on the brown glass beer bottles we tried.

author
dan3008 (author)2017-03-14

it can really speed things up if you have a bucket of ice water (or just cold water) too. Heat the bottle with the iron, like this, then dunk it. Dry and repeat

author
How Do You - DIY (author)dan30082017-03-14

When I was experimenting with this, I tried a few ways of applying cold, but kept getting inconsistent results. I haven't tried a bucket of water/ice water, maybe that's just what's needed! Just applying heat takes forever. Thanks for the advice!

author
dan3008 (author)How Do You - DIY2017-03-15

Ah, I've been cutting bottles like that for years. I also tend to use a tealight for the heat source. but I can see a sonldering iron being easyer

author
gm280 (author)2017-03-14

Interesting concept. I see folks cutting bottles and often wondered how it was done. Thanks for the project post.

author
DIY Hacks and How Tos (author)2017-03-14

Cool! I am going to have to try this. You've got my vote.

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