Hello everyone,

At a recent trade show I picked up a set of "multipurpose" tools(including a jigsaw blade and 2 hacksaw blades) that will cut glass. So, lately I've been experimenting with making some glassware, mostly funnels. I suppose there's a number of things that normal glass won't work for, at least not safely, but there's also many things it will. The process by which I make the funnels is pretty basic. I saw the bottom of a liquor bottle about 1/2 deep on both sides and then I hit the part that I want to be gone a few times with a hammer at places that seem like they'll make it break right. This usually gives a pretty smooth edge. I want to make a separatory funnel and something that could be used as a buret, but I haven't been able to think of anything to use as a flow control mechanism that would stand up to nitric acid. Any suggestions? Also, the blades are tungsten-carbide gritted. Are these type of blades available at hardware stores?

Tungsten carbide is an extremely common thing to be used to tip tools. All of the drill bits at the DIY store in which I work come tungsten carbide tipped as standard.

They will not however cut glass..... although they may be hard enough to do so, the tip of the drill bits is the wrong shape, also I imagine you would need an extremely high speed drill to enable them to cut through glass?

<small>[ March 22, 2003, 07:31 PM: Message edited by: VX ]</small>

Good find photonic.

Such tools can come in quite handy. What kind of cutting power do the blades have? Could you saw a bottle in half with relative ease? I gotta try and find me some of those blades :D . Personally I've not seen anything like you mentioned in hardware stores, but maybe I'm
not looking hard enough.

I've managed to get by without actual cutting tools for glass. If your looking for another method of cutting, maybe you should try the old 'string soaked with methylated spirits' trick. It has worked almost perfectly for me.

Take some coarse string and soak it in metho. Tie the string around the item that you wish to cut. Stand the item with the neglible piece of glass, that you don't, want facing up. Take to it with a lighter and let the string take fire all the way around. Then when it's nice and hot, dump it in ice-cold water. The stress on the glass is enough to make it snap quite cleanly.

You might want to practice on a few things to get the hang of it, but after that it's very easy to get a nice clean cut.

As for finding glass to cut to bits, the only things i can think of would be jars,liquor bottles and the odd kitchen item. I can't think of anything that would act as an acid resitant separatory funnel.

Anyway, happy glass cutting :D .

you can get a large range of diamond coated tools for dremels etc. from gem supply places, including small (one CM) saw bits for cutting gem slabs and glass.
they only cost about au $7 to $40 depending on make and model.

I probably described it wrong. The saw blades are tungsten-carbide gritted. I've taken pictures of them, but does anybody have any suggestions on making the separatory funnel or buret?

<a href="http://sensorystatic.com/explosives/tungsten_carbide_normal.jpg" target="_blank">http://sensorystatic.com/explosives/tungsten_carbide_normal.jpg</a> - Normal Hacksaw blade with tungsten carbide grit

<a href="http://sensorystatic.com/explosives/tungsten_carbide_round.jpg" target="_blank">http://sensorystatic.com/explosives/tungsten_carbide_round.jpg</a> - Round hacksaw blade can be used for cutting circles

<a href="http://sensorystatic.com/explosives/cobalt_tipped_bit.jpg" target="_blank">http://sensorystatic.com/explosives/cobalt_tipped_bit.jpg</a> -
Drill Bit made out of a cobalt alloy. It will drill anything(the guy at the show drilled a rotor, a hardened file, glass, and then tried to break it)

<a href="http://sensorystatic.com/explosives/cobalt_set.jpg" target="_blank">http://sensorystatic.com/explosives/cobalt_set.jpg</a> - The whole set of above bits

If anybody could find a place to buy these, they're very useful.

I saw something on TV a while back, it was a show about how they are producing scientific equipment in poor countries by improvising, pretty much as we must do. These people were making glassware from old fluorescent light tubes. I don't know how they cut them, but it seems you can shape them really well using a torch. I guess it's because it's pretty thin glass.

The saws Photonic has look to me like tile saws - commonly available for cutting odd shapes in ceramic tiles.

I have some specialised carbide glass drills - also from my local hardware store. The trick with drilling glass is to go slowly, with light,steady pressure, using plenty of water or kerosene for cooling and lubrication.

When cutting glass by the scratch and break method, the scratch should be a hairthin, almost invisible line - if its white and dusty you are pressing too hard with the tool and you are unlikely to get a clean break.

The meths and string method sounds similar to the hot-wire method.
&gt; A fine scratch is made where the cut is required, then the scratch is applied to a red-hot nichrome wire. The heat stress should crack the glass at the scratch. This method is good for large diameter tube.

Thin tube is easily cut witha triangular file. Make a small scratch on the side of the tube (one pass only - don't saw!). Hold the tube in both hands, against your stomach, scratch facing away from you, and pull. I get a clean break every time with this method.

Photonic, you might be able to use aluminium or stainless for your flow control - I've seen both listed as possible materials for nitric acid containers (including RFNA!)

<small>[ March 23, 2003, 04:13 PM: Message edited by: Tuatara ]</small>

cutting fluorescent tubes:make a scratch on it and then with hot soldering iron.
end pieces can be filled and used as el.ignitors.

How much mercury do those fluerescent lamps have? And how can one remove the inner coating, with HCl?

The amount of mercury (20 mg) in fluorescent tubes is roughly 0.01% by weight of the tube/lamp. <a href="http://www.environment-agency.gov.uk/commondata/105385/swen047.pdf?lang=_e" target="_blank">http://www.environment-agency.gov.uk/commondata/105385/swen047.pdf?lang=_e</a>

The inner coating is easily removed with a wad of cotton (or a piece of cloth) and a spike. It's much easier to remove it if wet.

<small>[ March 27, 2003, 01:25 PM: Message edited by: a_bab ]</small>

It looks like the rim of your mom's most expensive wine glass.
Looks like, but is just as sharp as a razor, obviously. Touch up with fine grit wet or dry paper.

Jars or bottles can also be cleanly broken by filling with water to the desired level, then heat with a pencil torch at this line.

A break will result, due to the difference in expansion.

You can use a specific glass bit to drill glass no problem. It's a heart shaped blade on the end, and you need a dam around it to hold grease or some sort of heat removal lube. It will shatter as you come through the backside if you press too hard. Use a low speed and a fair bit of pressure.

As for the carbide tipped drill bits, they are now becoming available over here for things other than masonry bits. They are hellish expensive, though, and easily broken, despite the claims, when you are drilling anything composite, as when anything grabs it rips the head off! They are also really, really blunt compared to a normal HSS bit, and you will find the cut is really poorly finished. They do get through, though.

I've been told you can re-sharpen your masonary bits into steel bits if you get a resharpener.

As for making the glassware, soda glass can be heated and worked in nothing more than an alcohol flame, at the low end, whilst Pyrex needs silly heats. Start out using soda glass before trying the hard stuff.

A diamond file is great for taking off sharp edges, or putting them on, depending what you want. You can get them dead cheap now, and they last forever.

Any one know where I could get a small glass tube that could span the distance of the top of 2 coke bottles. I was thinking I could cap both of the bottles with teflon tape and then put a cap over them then drill holes in the bottles and connect them with a small glass tube angled down. I would also make the tube fit snug with teflon tape. This all in the sake of making some nitric acid with the lack of a retort.

A local petrochemical testing store, (They cater to the geological oil-field testers) They keep most of it in their show room. 500ml Pyrex Erlenmeyer’s are 10 bucks each, number 7 rubber stoppers are 1.70 each, and glass tube is 2.00 for 4 feet, rubber house is less then a buck a foot. They even have used lab-ware for sale. A place like this can get most of your chemical as well.

Donman, you'll not be making nitric acid in plastic soda bottles. :eek:

LOL, I was talking about glass bottles! Why would I want a glass tube if I was going to be using plastic soda bottles. You know like the classic coke bottles.:D

You may want to look at this for improvised nitric acid production. 'http://www.geocities.com/brainfevert/hno3.html'

I have seen that synth method before, and my only problem with it is what plastic to use on the top. I don't think I can find any teflon saran wrap stuff that will withstand close to pure HNO3.

Aren�t most plastics wraps LDPE and HDPE?

HDPE would be the most likely 'kitchen plastic' to withstand nitric IMO, it is used to store sulfuric.

How about aluminium foil, when aluminium is of high enough purity sulfuric nor nitric would corrode it, hence brainfeaver using it for a support stand for his beaker.

Replace beakers with glass jars and you have a 100% improvised nitric acid distillation and production set up.

Well, I would have to make a coating of oxide on the foil before starting the reaction (easily done by electrolysis).... Do you think that the plastic wrap would really stand up to nitric acid. Every other post I have read here says that nitric acid eats through most plastics.

Zip-lock bags work fine, just cut them up and put them on your jar. Here is a picture of the method that I use. The weight pushes the 1/4" rod down and it gives it a better cone shape, and the NA production goes a lot faster.

This IS Brainfever's method, just a little modded up. (And yes, that is crappy Bomex)

http://stupid939.tripod.com/nitricacid/

Another way to practice melting and joining pieces of glass is to buy some tubing or cheap borosilicate test tubes and practice melting them together with a blow torch or something similar.

I also have Granddad's Wonderful Book of Chemistry (99MB) which has a whole section on glass blowing, forming, joining, etc. If anyone is interested, I could cut that section out of the pdf and upload it to rapidshare.

To speed up your method add some ice water on top of you zip lock bag. It will make the fumes condense faster.

I would also like to see that book. Where can you get that glass?

There was ice on the top, but it melted after awhile. I just took a picture when the ice wasn't refreshed.

Here is the link to the PDF:

http://rapidshare.com/files/7086309/Glass_Blowing.pdf

The file is 18.3 MB, so it may take awhile, but I just cut it out of the original PDF. If you already have "Granddad's Wonderful Book of Chemistry" just look towards the end, and there is a section on it.

I paid about $25 US for 1000 10x75mm Borosilicate test tubes on eBay, and I use them in my dreams for blasting caps and practicing joining. Blowtorches don't work all that well, because they don't distribute the heat very efficiently. I would try a alcohol burner.

I haven't bought any glass tubing, but you can get it all over the internet, or you can call up a toy/science store. I called around for nitric acid, and when I went to get it, they had lots of tubing and general lab equipment.

Have a look at the mini diamond saw blades this fellow has for sale, there are many other usefull things for making your own glassware here too.

http://stores.ebay.com.au/Gemcuts-Diamond-Lapidary-Products

I don't know this ebayer nor have anything to do with the products other than I bought a few of those blades a while ago. They work well for cutting glass.

Another source of glass...this one high-quality...

TV picture-tubes are made out of a fairly high-quality glass....borosilicate I'm almost positive....and the 'neck' of the tubes are a useful size/diameter and long enough to be useful.

If you have any old junk oscilloscopes around to be scrapped out; those CRT's generally have much larger diameter necks; perhaps good for large graduated cylinders, or outer-jackets of condensers?

Also, all CRT's are chock full of lovely metals...like nickel...molybdenum...tungsten...etc.; and they are super high-grade....very pure, very 'clean' metals.

TV image tubes are made of leaded glass, which has a more useful index of refraction, as well as eliminating the X-rays generated by the electron gun impinging on the shadow mask/screen. Lead glass is neither as tolerant of rapid temperature shifts nor as chemical resistant as borosilicate. It's a little tougher, but scratches easier and melts at a much lower temperature.

As far as getting borosilicate to practice glassblowing with, most major cities have at least one store that serves the art-glass trade. These places are quite used to having a few scraggly or questionable people a day drop in and buy small quantities of boro tubing. These would be pipemakers. You might benefit from taking a few beadmaking or lampworking courses, though these are not cheap, the techniques you'll learn, as well as the access to real lampworker's torches would probably more than compensate.

On the other hand, if you just need a glass funnel, you might check out some of the trendy-type cook supply stores, as most of them stock pyrex parts of any imaginable variety.

As an aside, cut up CRT screens are known in the lapidary and gem-cutting trade as 'TV stone', and they are indeed a good source of cheap, high quality crystal.

Yes, most big-cities have such a place. However, not all of us live in, or even near, a "big city". The suggestion was for a ready source of material which could be found virtually anywhere; i.e. in line with the "Home Made" nature of the thread; and the point was to mention a material which would be higher in both quality and precision than the usual grocery-store glass bottle or jar.

While I don't dispute your characterization of the glass as "leaded", I was pretty sure I'd read that CRT necks were borosilicate. So I dug through my high-vacuum library a bit last night...


From the RCA in-house tube design handbook for their engineers, "Electron Tube Design", 1940 ed....

"In the hard-glass group, we have the lead-borosilicate glass No.772 (702P), and the boro-silicate glasses 774 (726MX) and No.704 (705BA). The lead-borosilicate glass has the trade name "Nonex" and is used for tube-stems where tungsten lead-wires are sealed into the glass stem press. It is also used for bulbs. The borosilicate glass 774 (726MX) is a chemical-resistant glass and has the trade name "Pyrex". It is used for transmitting and >>cathode-ray tube<< bulbs."


From the same in-house handbook, but an updated edition, "Electron Tube Design", 1962 ed.

"The requirements for the bulb of a color tube; over and above those normally considered for a black-and-white bulb, are:

1...
2...
3...
4. Use of a hard glass to minimize bulb-distortion during thermal processing"

-----------

In those internal handbooks, the word 'hard' meant any borosilicate-based glass; including the leaded-borosilicates; e.g. Nonex, et al.

I guess my point is that "leaded glass" does not necessarily mean NOT borosilicate. There are many grades of leaded borosilicates; so a certain glass could as easily be called a "lead" glass as it could be called a "borosilicate" glass.

The leaded boro's have much higher electrical-resistance while hot; which is why they're selected for high-voltage tubes. They are still fairly chem-resistant (compared to soda-lime bottle glass), but it is true that they're not as chem-resistant as 7740 Pyrex.

Since the newest of the above refs is from 1962, it's entirely possible that more modern CRT's are all soft glasses now; I don't know for sure.

I do know that the neck of a CRT is better quality glass, and more precisely made, than a soy-sauce bottle though... :D