How to bisect a glass pipe lengthwise?

[Jake of All Trades]

Does anyone know how to split a 1-2 inch borosilicate glass tube in half lengthwise?  By this I mean along the side, making two "C" shaped troughs.  My searches online found a few "this might work" suggestions, but this stuff is kind of expensive and I'm short on time so I'm afraid I need a more sure-fire solution. 

My mom once told the tale of a glass cutter her sister made in high school for a science fair out of an old cloths iron that was supposed to have cut Coke bottles with ease.  According to my mom (my aunt is, unfortunately, deceased), it worked like a hot-wire foam cutter--neatly melting its way through the glass rather than relying on the thermal shock principles that similar-sounding devices use.  Is such a device possible, or has my dear mum fallen victim to the dreaded Altered Memory?  My aunt, though quite smart, was not terribly technical so I don't imagine this was something she invented on her own--which would lead me to believe that instructions for building such a device must be out there somewhere if it existed.  As I hinted at earlier, the only hot-wire glass cutters I could find online do not actually cut the glass, but heat it up locally so that a bit of cool water will cause a somewhat controlled crack.  Nifty, but not quite "as advertised".

So, is anyone familiar with this mythical machine?  Do you know another way to cut such a tube cleanly?

[Jake krugar]

cant you saw glass if you tape it first or somthing?

[JingleJoe]

I would say the hot wire method; Wrap a length of filament (some kind of metal that gets hot like iron) along the line you want to cut - in this case vertically up one side and down the other, then attach a big battery to the wire untill it gets hot and you should end up with a controlled break.
Hold out for another answer though, that could go wonky easily

[jringling]

I would do two deep scores along the break points and tap them with a hammer. Borosilicate glass is rather strong stuff and breaks very cleanly along score lines. If you ar working with longer stock, try breaking it along the long side first, then "trim" the ends down to the desired length.

[Zhivago]

I would suggest making two longitudinal supports for the pipe out of wood, by either carving a long V shaped groove down the length of two lengths of wood or by macking a U shaped trough from three wooden slats per support, so as the round surface of the pipe can be held steadily by clamping it between the two supports.

Then use a straight edge and a glass cutter (The little wheel thingiemajiggie) to run down each side create two opposite fractures down the length of the pipe, which will have been made easier to make central on both sides because the pipe is held solid.  To actually train a break along the fracture made by the cutters would be very tricky indeed though as you would have two breaks to train at the same time, each wanting to break in different directions...

Maybe heating the glass to make it warp under thermal expansion and hopefully crack along the weakend point perhaps?

Ps.  This is my first post on the forum hehe, hello everyone! 

[blacklines]

The suggestions thus far are probably going to cause you a lot of frustration, and very little success.  While it is often possible to cut a bottle around its circumference with a hot wire, making a long, running cut down the side of a tube, let alone two is almost sure to end in heartache.  As with scoring--in order for scoring to work cleanly you need to score the glass and break it immediately--you cant have two score lines and expect a clean break because there will be two points in the glass that are stressed differently and getting it to fracture along both of these at the same time will be quite difficult.  What I would do is look for a glass blowing shop in your area--call them and ask if they have either a diamond band saw, or a ring saw.  A band saw is preferable as it allows for less loss of material in terms of blade length.  They may be willing to show you how to use it for a small fee, or they might want to cut it for you...  Once cut you can polish the cut edges on their grit or diamond wheels.   Thats what I would do.  What is this boro for, anyhow?

justanassembler

[oldskoolpunk]

The suggestions thus far are probably going to cause you a lot of frustration, and very little success.  While it is often possible to cut a bottle around its circumference with a hot wire, making a long, running cut down the side of a tube, let alone two is almost sure to end in heartache.

True. The hot-wire trick is a good way to cut bottles and tubing. Here's a classic reference. http://pubs.acs.org/doi/abs/10.1021/ac50141a017 If I did that, I'd have a GFCI in the circuit. Here's a modern commercial version. http://www.eberbachlabtools.com/apparatus/9170.htm. For larger items, like bottles, you heat up the cut line with the hot wire cutter and then drop the glass item into a tub of water; the thermal shock will crack the glass along the desired line.

Lengthwise cuts, though, are tough. Try to buy precut materials or send the job out. There's something called "airbrasive jet cutting", where very high pressure air drives a stream of particles.  With one of those, you can cut clean slices in glass holiday ornaments. But those are hard to find.

There are companies that make custom curved glass. See http://www.curvedglass.com/. Also, auto glass shops can do larger curved pieces, and if business is slow and you're nice to them, you might be able to get something done for you.

[Inland]

Cutting glass (even tubing) is a piece of cake! We make saws with diamond coated blades that will cut glass tubing to length and/or on the bias. These same saws are also used by scale modelers with wood and (nonferrous) metal cutting blades. Straight cuts and curves, they can all be done. Our non-selling corporate site is

http://www.inlandcraft.com

and you can learn more about the saws there, as well as possibly finding a local supplier in your area.

[nathe]

is it possible to use a very lightly applied and high speed grinding bit from a dremel to cut it?

[blacklines]

is it possible to use a very lightly applied and high speed grinding bit from a dremel to cut it?

possibly--but more than likely youll end up cracking the glass or introducing stress into the glass that will cause it to break later.  the gent who suggested the inland tools was pretty spot on if you have the cash.

[nathe]

possibly--but more than likely youll end up cracking the glass or introducing stress into the glass that will cause it to break later.  the gent who suggested the inland tools was pretty spot on if you have the cash.

:/ i see.

ah well, i can always try and see, i have an old piece of glass from an old broken record player i can use

[Random Number]

I would say the hot wire method; Wrap a length of filament (some kind of metal that gets hot like iron) along the line you want to cut - in this case vertically up one side and down the other, then attach a big battery to the wire untill it gets hot and you should end up with a controlled break.
Hold out for another answer though, that could go wonky easily

The filament you want to use would be nichrome wire, most likely. iron wire, steel wire, and most normal wires will just make your power supply short out or kill your battery, at best. (at worst, your battery, depending on the type, will explode. Yay thermal damage.) Nichrome wire has a high enough resistance and enough strength to do the job. it will take forever to do it correctly, though.

If you don't have the cash to get blades to bisect the tube or have someone do it for you, it would be much easier to get two tubes (if you have them), and cut them both in half. One side would be sacrificial, basically whichever side broke first during cutting/grinding. You could try scoring or hotwire cutting, scoring will be tough on curved glass since you won't have a decent lever arm to snap the glass, and wire cutting takes a loong time. I'd try a diamond wheel for a dremel, that's probably the cheapest solution. cutting the straight part won't be too terribly hard, but the curve will be tricky. Diamond dremel wheels are cheap, maybe 10 bucks or so, and should do the trick.

[Adan Shepard]

I think Inland has the right idea. If you can make a guide you could use a dremmel with a diamond coated cutter. A scribe line can be made and a piece of doweling or other wooden tapper. You should be able to lightly tap the part and it will crack/split along the scribe lines. Be patient when tapping though, and don't let the part get hot while scribing. It might crack in an undesired direction.  Oh and be sure to wear a dust mask and goggles when using the diamond cutter, powdered glass is nasty to breath or in your eyes. If you can get a friend to drizzle water on it while cutting that will help control the dust and keep the grinding heat to a minimum. Good luck

Adan

[aquafortis]

I haven't done this but my first try would be with a diamond-blade tile cutting saw. These look like a little table saw with a wet-cutting diamond blade. They work great on ceramics.

Always cut wet or you'll generate glass dust, get silicosis, and that will be the end of you. And you'll ruin your blade.

You may be able to hire one for a couple of days.

I think melting it will be a nonsense, borosilicate glass melts at far too high a temperature for this to be useful and it would almost certainly fuse behind the wire even if it did make any headway. I would suggest that the wire method mentioned above was either diamond-wire cutting or slurry wire cutting. Both are essentially abrasive processes, with DWC relying on embedded diamond particles in the wire, and SWC relying on a carborundum sludge being fed into the kerf.

hope this helps, remember if you want to re-form the tube into a percedt cylinder you'll need to cut two perfect semicircles to allow for kerf width.

[blacklines]

I haven't done this but my first try would be with a diamond-blade tile cutting saw. These look like a little table saw with a wet-cutting diamond blade. They work great on ceramics.

Always cut wet or you'll generate glass dust, get silicosis, and that will be the end of you. And you'll ruin your blade.

You may be able to hire one for a couple of days.

I think melting it will be a nonsense, borosilicate glass melts at far too high a temperature for this to be useful and it would almost certainly fuse behind the wire even if it did make any headway. I would suggest that the wire method mentioned above was either diamond-wire cutting or slurry wire cutting. Both are essentially abrasive processes, with DWC relying on embedded diamond particles in the wire, and SWC relying on a carborundum sludge being fed into the kerf.

hope this helps, remember if you want to re-form the tube into a percedt cylinder you'll need to cut two perfect semicircles to allow for kerf width.

The wire method mentioned above is an adaptation of a technique used by hobbyists to cut the tops off of bottles...  it has also been used in industry in places where low-tech, low cost finishing solutions were needed (cheap glass factories in india and mexico) it does not involve any kind of abrasive and instead relies on the heat to setup a line of stress in the otherwise annealled glass.  Once this is done, it can be broken on this line with a fair degree of reliability... 

[Dr cornelius quack]

While I know this takes all the fun out of the thing, I'd be inclined to enlist the services of a friendly scientific glassblower.

The chaps who made up all the "specials" in the lab I used to work in were looked on as some sort of magicians by the rest of us mere mortals.

Does it have to be Borosilicate tube? The other stuff is probably cheaper.
In fact does it have to be glass at all? You can get clear acrylic tube in a range of sizes

The only other suggestion I can come up with is to use some kind of former and heat up a flat sheet to "drape mould" to the required shape.

Make sure to keep the heat even over the whole piece while you try anything as thermal shock can cause the thing to crack in uncontrolled ways.

A leather apron, gauntlets and a full face shield would seem to be indicated.

Good luck.

Dr. Q.

[Phineas Lamar Alexander]

How long is the tube you intend to cut?

If you wish to bisect it along the length you will need to secure the wire to the tube in some fashion to prevent it slipping out of place as it heats up.

I would suggest using a triangular file to cut two v's on the ends that will hold the wire in place and wrap the tube and wire in something similar to a NOMEX material tape then proceed with the heat and cold water cracking method.