Episode: 2147
Title: HPR2147: Glass cutting bottles
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2147/hpr2147.mp3
Transcribed: 2025-10-18 14:54:49

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This is HPR episode 2,147 entitled Glass Cutting Bottles.
It is hosted by Opera Nero R and is about 14 minutes long.
The summer is, you may have seen Mars is made from bottles and wondered how they cut the glass.
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Okay, this is Operator or Armacurty.com. My name is Robert McCurdy.
I'm going to be doing my most preferred method of cutting glass bottles.
So you look around and there's the whole, like, tie a string around the thing with, like, rubbing alcohol on it and then set it on fire.
Please don't do that. That's not, it doesn't work at all for me.
I've tried the dunking method where you kind of heat, you score it and then you throw it in water and you kind of heat it.
Now, then there's also the method of cold water, hot water, hot water after you've scored it.
I think the most important thing about this whole process is one is the glass itself.
The bottle itself needs to be a certain kind of quality or more or less determines how it's going to crack or, or, or, or come apart.
And then the second part is really mainly your kind of what?
What more or less? And the third kind of most important is how you score it.
So there's these glass bottle colors. This one's called green, something or other.
You want to make sure everything's all short up and tight.
And it's kind of a night. Everything's at a 90 degree angle before you start scoring.
So I've got a big wide bottle here. You don't want to score it on a bend also.
It makes it really difficult to do that.
I try to make a little high ball glasses. Those are, those are pretty popular.
And really, if you really, really want, if you have a favorite type of bottle,
and you really want it to go successful, I would suggest practicing on three or four cheap wine bottles first.
And then once you kind of get the process kind of okay, you at least want to get one or two good ones.
Then start get your three, three that you're going to one out of three that's going to go over easily easily,
without having to do much sanding. So the idea there is, you know, I've got two nice grey goose little pint bottles
that are really cool looking small tall glasses.
And I done a couple of those, but really your best bet is if you want this to go easily
and you don't want it to be a big pain to have to sand everything down,
just buy three of whatever it is, bottles, and then go from there.
Because having to sand down, even just, you know, even having to sand down like in, you know, an eighth of an inch
is just, just ridiculous.
So I get my kid here, my two year old, and he's got his thinking out design.
So whenever you're working with stuff, little bits of glass are going to flake out when you take the blowtorch to it.
So that's my preferred method is doing a blowtorch.
You want to grease up the bearings, or the cutter piece, the little rolly part.
So I put WD40 on it, you can use like, you know, like a regular oil, or, I think really anything,
as long as it's not going to make a mess of the mess.
So I make sure the roller is nice, and this one's got like eight different blades on it.
So I'll rotate it out every once in a while, I'm not sure what the mess is on it.
But the important part is getting it all short up and everything at a 90 degree angle,
and get yourself comfortable right before you score.
You want to be in a very comfortable spot, where it's not going to bother you to have to move or shuffle around.
And when you press down hard, you don't want to press down too hard, because you're going to flex it,
and then that's going to change your score line.
So you mainly want to push the blade, as close as you can to the blade, push the blade up against the bottle.
But don't use too much force to where you're bending everything, and then you're changing the score line.
So you essentially kind of want to do a first-built pass around while you're dotted on there,
and just see how it feels to score it, and just let it lightly roll around.
And this does two things.
Once you do it lightly rolled around, it kind of goes through and you kind of outer,
outer, outer, maybe you've got it on a sticker or something like that.
You can kind of cut through the sticker first, that works pretty good.
But really, it's just to get a feel for how hard you're going to have to push, and how hard.
Now this one I'm doing really tall glass, so I don't have a lot of play,
and I'm not in a comfortable spot to actually perform this.
So I feel like I might put it in the vice grip to get it to hold tightly,
and so I'm not like wrenching it around, and I'm not feeling comfortable by myself.
But there's not an easy way to get it in the vice grip, so.
All right, so we're going to do here.
I'm just going to do one glass, score one glass, because that's not exactly very fun.
So you'll hear that crack, you want to hear that crack in the sound.
And some people say more and it's going more than once, blah, blah, blah.
I've always heard it once you score it once you're done.
You know, it's all the way around, you'll hear the sound.
It'll just start crunching.
So it's really, I've heard, I've seen two different methods where they just keep scoring it.
From what I understand once you score it, you're done.
If you do it incorrectly, or you do it uneven, or whatever, you're done.
From there, you can just try to sand it down.
Now I've seen some plates that you can buy, big metal plates, and you get some kind of sand.
And you can sand the glass down using a real setup instead of just sandpaper.
I've got like some 60 grit and 120 grit that I'll use on that portion.
So I'm going to pause it for a second and pick this back up once I'm ready for the next step.
All right, so I've got the little blow towards here.
I'm going to actually use it to sweat pipe.
You can actually take sugar and put it on a banana.
And make you some crème brulee banana type of sink.
The same kind of stuff to people use to make crème brulee, except it's a giant tank instead of a small tank.
So the amount of heat I put on here is just enough to keep it going.
Just enough to keep it from blowing out.
Maybe a little bit more if you're inpatient, or you got some thick glass, you're going to have to run into.
But the more patience you have, the better.
So what I'll do is I'll place the torch, obviously Amy away from me.
Then I'll take a piece of paper so I can easily slide.
The slide the glass around.
And I'll just take your time.
This is actually a better luck and colder weather.
Believe it or not, it makes sense because it's that transaction from going from hot to cold to hot to cold is what makes the weekends the bond where the score line is.
And what I'll do is I'll let it get hot.
You know, spin it around for a while, let it get hot to the touch.
And I won't really put a much heat on it until I blow in it a little bit.
So I'll let it roll around for maybe 20 seconds or so.
Let it get hot.
And once you start hearing that cracking, you're kind of done.
What I'll do is if I hear the cracking, I'll start blowing on it.
And they go from there.
So it's kind of hot to the touch.
Now this is a thicker bottle, so it's going to take quite a bit more.
I'll blow inside to kind of get some of that air, that hot air out of the away from the away from the glass.
But I spin it around pretty quickly.
I mean, I haven't found it.
Like again, it's more of a luck thing slash quality of glass thing.
I can already hear it.
You probably won't be able to hear it until I get to the last stage.
But I can already hear it cracking, so right now it's actually scoring.
Look at that.
Yep, it's done.
So essentially what you can do is once it, oh, I actually lost my mind.
Once it starts scoring or sputtering, you can give it a little bit more heat.
And then blow on it.
You can try and kind of pull it apart.
I really don't know what the best method is.
I think again, once you've scored it, and then once it starts cracking, you're on a path of just hoping for the best, right?
I've found the more patience you have, the better off, the better luck you have in most cases.
With the wiring glasses, it's really just crappy bonds.
Now you can see the seam on the glass going off the middle of the bottle.
You'll really notice it when you have to actually, when you're done with the scoring, and you'll see the score.
You'll see where the glass was melted together.
And you just see this ugly steam going down the middle of it.
So it'll be uneven glass.
Yep, we're done.
So we got about all the way around perfect, except we have a dent going in towards the glass.
And it goes down about an eighth of an inch.
Essentially, this is not a perfect cut.
So we would probably just, on this one, we probably just can it, or just follow it down and have that natural dip in the glass.
Which is fine. I mean, it's not going to be perfect.
But generally, if it's not a big, huge jagged edge, you can kind of just have it a give away for that one.
So normally, I'll do those with kind of a give away.
Now, I'll move to the kind of sanding portion.
I've tried a diamond sander for a dremel tool that's way too harsh.
It gets hot and then starts flacking the glass around all of the place.
And you just have glass shards going everywhere.
We've got some, Jesus, this is 60 grit.
The 60 grit, if you're going to work on it hard, obviously.
But the 60 grit is just going to make it really, really coarse.
You're going to have these big coarse things in the glass.
If you can avoid the 60 grit, use something like a much, much, much smaller, but not too small.
Like, here's an 80 that wouldn't be too bad.
I think even the 60 is going to be too much for the, so the 220 is your finishing or like the 320 is going to be your finishing.
That's just to give you that smoothness on the edge of the glass.
And again, it's really a user preference.
If you decide that, you know, you want a super smooth and you want that rounded edges,
you're going to want to do it like that way.
Now, what seems to be a good way to get at it pretty easily is if you tape,
put masking tape on the surface and kind of tape the sandering, the, the glass down.
And you can kind of rotate it around in a circle.
I don't know, I'm making pretty ridiculous noises right now.
But you can kind of rotate it around in a circle until you get kind of a flat surface all the way around,
minus the little dip here in the, in the glass that I just did.
And once you spin that around and you get a nice flat surface, then you can start finishing off with,
with something like the, the 220.
And I can say, you know, as far as using a hitting it with a dremel, you can hit it with a dremel.
You just have to be very careful about heating the glass.
Once you start heating that glass, chunks of glass will come off.
And then you're just doing a lot worse than you were before.
So you might be able to have some kind of special glass.
There might be some kind of special glass dremel tool you could buy.
But from what it sounds like, mathematically speaking, once you hit the dremel on it,
it's, it's going to get hot, right?
So unless there's some kind of special tool, dremel tool that somehow gets rid of heat and friction,
the church is impossible.
So it's probably going to be a manual process.
And again, just, just spinning that thing around and getting it the best.
All the other methods I've looked at, all the other methods I've tried are either really take a really long time.
The hot cold method, after you've scored it, it actually works.
You know, you get a hot cup of tea or a hot, hot thing of tea and then just cold water and you alter any back and forth.
That worked, but it worked just about as good as a torch method and the blow torch method takes a lot less time.
And you don't have to sit there and wait forever.
So I hope someone helped this out.
You can also make some weird tea light things.
There's all kinds of different things you can do with once you've cut glass or you have the glass cutter for the bottle glass cutter.
You can do all kinds of fun stuff.
But I just try to make cute little high bottle glasses and gray goose bottles and nice, nice looking glasses.
I'll give away sometimes the little wine sets of similar looking wine glasses.
So I'll have a bunch of green ones, so I'll have like four in a set or something.
But anyways, we'll see how this goes.
Appreciate it. Thanks.
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