Cut a Hole in a Glass Bottle (Using a Soldering Iron)





Introduction: Cut a Hole in a Glass Bottle (Using a Soldering Iron)

About: Creating DIY projects

In this instructable I'm going to show you how to cut custom shaped holes into a bottle, using the same cutting method I use in my other instructables. I'm also going to discuss some things to take into consideration when you're planning your design.

I also made a video, which you can watch here:

Here is what you will need:

Step 1: Prepping for the Cut

When planning your shape it's helpful if part of it follows the curve of the bottle, because then you can use a bottle cutting jig to score the bottle easier. It's also easier to start the crack around the curve of the bottle rather than a flat edge of the bottle.

Step 2: Starting the Crack

To start the crack hold the tip of the soldering iron in one spot for a few seconds, then move it a bit. If the crack hasn't started after a couple inches, stop and heat the score line in the opposite direction. Continue that process, heating each spot slightly longer each time, until the crack starts. Once it does, continue moving the soldering iron in that direction, the crack should follow the tip of the soldering iron as you move it. If it stops moving, try heating the opposite end of the crack. It's helpful to switch things up a bit.

Step 3: Turning the Crack

When you get to the corner, move the soldering iron to follow the path you want the crack to go. If it's not too much of an angle, the crack will follow the tip without much trouble. The same goes for any curves you want the crack to follow. But one thing to be careful of when making sharp turns is a random crack forming. Trying to go around a tight angle or tight curve doesn't always go as planned. Because of that, this method isn't a good idea for small holes.

Step 4: Issue With Corners

Sometimes after you've gone around a corner just fine, a crack will form on it's own at the corner and go away from it. This seems to be from the stresses of heating the bottle, and the corner being the weak point.

Step 5: Finishing the Crack

When you finally do get both ends of the crack close to each other, they usually seem to stop moving completely when they are about 1/8 inch apart from each other. If this is the case, try separating the pieces. If you're cutting a hole, keep in mind that the edges of the crack will be jagged, and this makes it hard to separate the pieces because they are still a bit interlocked. You'll definitely need to tap it loose from the inside of the bottle.

Step 6: All Done!

As you can see, I could have done better following the line I drew on the one side, but other than that this piece came out just fine.

Step 7: Other Cuts I've Made With This Method

I've also used this same method to split a bottle in half length wise, mostly. I was unable to drag the crack into the base of the bottle so I dragged the crack around the base. I also did the same thing to cut a slice off the side of a bottle.

And here is another bottle where I cut a rectangular window out of the bottle. But as you can see, two of the corners have that same crack coming off of them. I've noticed that this happens sometimes with corners, but with most curves this isn't an issue unless it's a tight curve.



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Hi How Do You - DIY,

my soldering iron's
temperature --446°F (230°C)
watts -----------30

I tried to put a
small square sized hole on a
empty mayonaisse jar(bottle)

I placed the tip of the soldering iron
30 seconds each space about 20°angle.
Then I move the tip a bit (1 mm)
at a time.

However, I was unsuccessful in
making any score marks
Therefore, I cannot make the bottle to crack

How long does it take to do it?

I sincerely want to make this work.
Please tell me what did I do wrong

Many thanks & look forward for your advice :)

Very nice project and great video. Have you done anything with sanding? Harbor Freight sells these cheap ($10USD) Dremel kits. I wonder if scoring the path first would keep the cracks in the trough.

4 replies

I've never tried scoring a path that way. I do have a Dremel, but I've been afraid of breathing in glass dust, even with a dust mask. I do know there are safe ways to do it though.

When working with really fine powder (I was using different grades of sieves on bags of glass) and repurposed an old CPAP to protect my lungs.

Every day we learn something new, CPAP stands for Continuous Positive Airway Pressure, a "snorkel-like" mask that isolates the user from a hostile environment (the ESC keys doesn't work, I tried it LOL) Thanks, Zaacharia, and good idea too.

I found a cone shaped metal bit for my 12V "Dremel" (Drill Master, 16000 RPM rated), but I did a horrible job attempting to create a path. The bit did etch the glass and it does feel lower in spots. I had a thin stream of water running down the side of the glass jar to avoid any minute glass dust. After drying the jar, I applied the heated 30 watt soldering iron to the etched path but nothing happened. The jar is thick (1/8"?). Applying the iron anywhere else does not crack the glass there either.

When cracks like that appear in the corner, is that piece unusable as a project now? Too high of risk of failure? Can the crack be glued, like they do to windshields or does that start costing too much? Can you cut that crack out somehow? I'm curious about glass and have a large collection of bottles that someday I plan on working on. Thanks for your time!

Way kool! I cast glass and there are some bottles with colors I really want to use. What I have done is score around the bottom then across the bottom (like cutting a pie) then drop a piece of rebar through the top of the bottle and knocked out the bottom. Cutting the bottle into strips just never went well - I think this will solve that problem. I will post if/when I get a chance to try it.

1 reply

You’re right on what’s going on with the heat causing internal stress and “running” with your score line. Question about your corners. I’m surprised you don’t get more stray cracks when you turn a 90* corner but have you tried using a cool, damp cloth close on the “outside” of the turn? I don’t know if it would make a difference since the crack is stress related but I’d be really curious to know if it helped.

1 reply

That's a good idea, I haven't tried it. The stray crack on the 90* corners don't show up until later, as more of the bottle heats. Maybe this would help?

Could use this method to cut thick, flat glass? (score with a glass cutter then crack with soldering iron?)

1 reply

I don't think it would be very successful with that. Using a soldering iron on a flat surface is possible, but a bit more likely to crack randomly. Also, the thicker the glass, the harder this method is.

For Step 1: Did you score the entire outline of the cut shape or just the part with the jig? This was not clear to me.

1 reply

I only scored the part with the jig. The rest of the shape was not scored at all. With this technique, a score line is only needed to start the crack. And another side note, you can also pull the crack away from a score line, if you need to.

question: you mention scoring a line (perpendicular to the longitude of the bottle) with a bottle cutter, couldn't you freehand the entire shape with diamond stylus? I ask because I can't find mine to try it and say whether or not it works.

1 reply

Yes, you can definitely score a shape freehand. I've never tried a diamond stylus, but I don't see any reason it would be a problem.

A word about the using heat to fracture glass - it will work on moulded glass with a reasonable degree of predictability - but if you are thinking of trying this on sheet glass (typical float glass) it could go horribly wrong, better to stick with traditional glass cutting techniques.

I'm glad you mentioned that. It's important to know there's a difference, and that different techniques are needed for different types of glass.