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

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: https://youtu.be/Ny8OXoux-U4

Here is what you will need:

Step 1: Prepping for the Cut

Picture of 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

Picture of 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

Picture of 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

Picture of 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

Picture of 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!

Picture of 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

Picture of 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.

Comments

mpulliam1 (author)2017-11-29

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!

Faith Grady (author)2017-11-28

How can i and what would be the easiest way to make a hole in the bottom of a bottle not a bigg one a ssmall hole.. would love to here , one of the things that i make require that and for now. I am using just a drill but am looking for a easier way

LynnW5 made it! (author)Faith Grady2017-11-29

I use a diamond studded bit from my small bit kit. but here is a link for a kit.

https://www.amazon.com/BLENDX-Diamond-Drill-Bits-E...

I use them in a drill press, as well as a hand drill.

TC25 (author)Faith Grady2017-11-29

When you say small hole, what size exactly is the hole you're trying to bore? If it's very small, like no more than a 1/16", you can use industrial carbide micro bits that harbor freight sells in a small set. These bits are used in cnc machines drilling electronic parts and component pcb but shank small enough for drills. They're multi fluted, mill type solid carbide, not the regular two flute twist type bits.
I've used them one time to drill a drinking glass close to the lip as a prank.
If you can, drill underwater, submerge the item just below the water so only the bit gets wet. Vibration is what breaks glass but try cutting 1/8" thick glass plate underwater with regular scissors and you can cut even slight curve with it just like cutting cardboard and no breaking.

itsmescotty (author)Faith Grady2017-11-28

no easy way, sigh. You can find many sizes of diamond core drill bits on eBay. Use a bit of modeling clay to make a water dam around the area you want to drill and fill with water. Variable speed 'Dremel' works best. Takes a while tho. Water is for keeping the bit cool.

RonGarza (author)2017-11-28

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.

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.

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.

Zaacharia (author)2017-11-28

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.

Can't wait to hear how that works out!

TheonlyMikGyver (author)2017-11-28

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.

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?

Peter Angel (author)2017-11-28

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

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.

sbhans (author)2017-11-28

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.

How Do You - DIY (author)sbhans2017-11-28

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.

itsmescotty (author)2017-11-28

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.

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.

Builders Shed (author)2017-11-24

So cool! Never thought you could use a soldering iron to cut glass!

Rhumour (author)Builders Shed2017-11-28

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.

How Do You - DIY (author)Rhumour2017-11-28

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.

OneBirdieMa (author)2017-11-28

Thank you for this 'ible. This re-piques my interest. I have glass bottles I've wanted to take the tops off of, but have had no luck with the techniques I've tried. This, however, gives me an idea: a solderlng iron I can handle! And, to answer someone's question (below) I can think of one or two uses for a bottle with one or more holes in the side -- a dried flower arrangement that isn't suited to being only vertical, for instance. Or even a flower arrangement (not necessarily dried) that occupies the hole but uses the bottle like a part of the arrangement. (Sorry, I'm not making myself really clear on that last one.) I'm sure there are other uses -- I can think of a couple more that are completely absurd . . . . oh, here's one already in the marketplace (as it were): have you seen the winebottle trees purportedly from southern tradition? Put a hole in the side of the bottle and hang it from that and there's a whole new (NON TRADITIONAL!!!) version . .

It was the same for me with all the other techniques. I always felt like I was missing a step or doing something wrong. Glad I found this technique!

mebewalt (author)2017-11-28

When cutting a sharp angle, do you think that drilling a small hole at each corner would help to stop cracks from forming beyond the desired path? Maybe even along curves?

That's a good question! I think it might, but you may have to take a bit of a different approach. But it's definitely worth trying!

sgbotsford (author)2017-11-28

Very cool. Any particular tip or wattage of soldering iron?

Tip on doing photos of glass:

A: Use a solid background colour that is dark, but not black. A dark coloured towel works well. In your pix, the graph paper background is confusing.

B: Use coloured glass if you can. Green or brown is fine.

C: Multiple light sources. One should be somewhat diffuse. A flood light works well. The other should be a point source. A clear tungsten bulb works, as does a CREE unfrosted LED light.

***

Putting a duck tape handle on the glass that is going to be removed makes it easier to deal with if it falls into the bottle.

thehoss (author)sgbotsford2017-11-28

My questions and comments exactly. I find cutting a bottle this way very interesting but the photos are somewhat confusing. Also wattage, bottle color, etc. Great concept though.

How Do You - DIY (author)thehoss2017-11-28

I agree on the photos, definitely need improvement. As far as the other questions, I've done this will clear, brown, green, and blue bottles. I'm assuming that any color will work. And as for the wattage of the soldering iron, in my other instructables I used a 30 Watt, but in this one I used a 15 Watt. Oddly, this one seems to work better even though it's a lower wattage. I think the tip may be the reason.

davea0511 (author)2017-11-28

If you renamed it cut a hole in a *glass* bottle I think your views would Skyrocket. This is really cool.

Awesome idea, thanks for the tip!

TammyT5 (author)2017-11-28

Love the info., but what do you do with them once you've made the cuts/holes?

How Do You - DIY (author)TammyT52017-11-28

I don't to anything with these cuts personally, but I know that some people have ideas. I've had people ask me if some of these things were possible, so I tried them out, and decided to share the info :-)

Mousepotato01 (author)2017-11-28

Try scoring the glass with a diamond cutting wheel on a dremel tool you will have almost perfect results if you do not try to cut the entire glass completely threw. They have special wheels coated with diamonds for cutting glass and ceramics. Also you can use a mini torch to heat the glass to cause the thermal fracture along the score mark. Use a mini torch one that has a pin point flame just be careful some of the bottle will shatter completely and may cause serious cuts into the flesh of your hands not to mention a serious burn from the glass if it was heated to greatly because of the shape of the bottle and all the stress they have been under in all the processing that has been done to them with heating cooling and internal pressures.

There is also the option to use a drill and drill holes into the four corners to prevent wondering thermal fractures at the corners.

Those are helpful tips. Thanks for the feedback!

dimjimc (author)2017-11-28

Wow, Awesome. Thanks for a great vid.

Wrrr 10-G (author)2017-11-27

This is very interesting... thanx for sharing!

deluges (author)2017-11-26

I knew the old "string and lighter fluid" trick but this is good to know.. Thanks for sharing!

MillennialDIYer (author)2017-11-24

What's the detailed theory behind how this is cracking the glass? Is expanding the glass in front of the crack via heating what "pulls" it along, or is there something else happening?

That's a good question. I'm not exactly sure, but that is what I was thinking. Heating a small section of the glass to expand it. The expanding glass pushing the surrounding glass away from the heated center. With a crack nearby being the weak point, and the glass expanding somewhat equally on either side of the crack, the expanding glass splitting the crack toward the heated center. Don't know if that makes sense? Also not sure if that's what is happening.

It's nice to see that you've thought about it too and think that there may be more to it than it seems. It's easy to think "the heats doing it" and not give it more thought.

gm280 (author)2017-11-25

Interesting concept. Nice...

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