Hi all,
Can someone tell me how I should go about cutting and smoothing the edges of glass tubing with a diameter of 7mm, simply and safely? It's not something I've ever had to do before.
Thanks
Glass tubing
Re: Glass tubing
You can buy a glass cutter which scores around the eadge of the glass and you just gently snap it. You can also score the tube with a very fine file.
The ends can be heated and the pressed on a heat proof mat to flatten or round off, of a fine file will also smooth of the ruff bits.
Dont forget safety glasses and I where cotton gloves when working with glass.
The ends can be heated and the pressed on a heat proof mat to flatten or round off, of a fine file will also smooth of the ruff bits.
Dont forget safety glasses and I where cotton gloves when working with glass.
Re: Glass tubing
I always wrap my glass tubing in a tea towel when i snap it after scouring with the glass cutter. Guess I'm just chicken. 
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cactus155
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Re: Glass tubing
2.16 Cut glass tubing
Break and bend glass tubing
1. One way to cut glass tubing is to score the surface with one forward stroke of a three cornered file. Make the score mark at right angles to the centre line of the tube so that the tube will snap squarely across. To snap the tube, place it on the bench top with matchsticks or toothpick directly beneath the upward facing score mark. Then, holding one end securely, press down on the other end and the snap will be immediate. Another method frequently used is to scratch the glass tubing with a quick smooth file stroke, then hold the scratched tubing firmly in both hands with one's thumbs pointing towards each other, but on opposite sides of the scratch, and snapping the glass tubing away from one's body. Fire polish the cut ends.
2. The method of cutting a glass tube depends on its diameter. Different methods are used to cut glass tubes of different diameters. Place the tube flat on the table. Measure the required length. Hold the tube firmly and draw a triangular file across it a couple of times so that a scratch is made. Do not saw back and forth. One or two firm cuts are usually sufficient. Take the tube in both hands, one each side of the scratch. Keep your thumbs as close as possible to the scratch. Press gently with your thumbs and pull with the fingers. The two pieces of tubing should separate. Brute strength is not needed. If the tube does not break easily, make the file scratch a little deeper and longer. Fire polish the cut ends
Light the burner, and open the air hole. This gives a hot blue flame. Warm one end of the tubing by passing it through the flame a few times. When the tubing is warm, rotate the end of the tube in the flame until the glass begins to turn yellow and melt a little. Keep rotating the tube until the rough edges become smooth. Do not heat too much and do not stop rotating. Place the hot glass on a gauze mat to cool. The end is now fire polished. When the tube is cool, fire polish the other cut end. Again allow to cool.
3. Place the tube flat on the table. Measure the required length. Hold the tube firmly and draw a triangular file across it a couple of times so that it makes a scratch. Do not saw back and forth. One or two firm cuts are usually sufficient. Take the tube in both hands, one each side of the scratch. Keep your thumbs as close as possible to the scratch. Press gently with your thumbs and pull with the fingers. The two pieces of tubing should separate. Do not use brute strength. If the tube does not break easily, make the file scratch a little deeper and longer.
4. Fire polish the cut ends.
Light the burner, and open the air hole. This gives a hot blue flame. Warm one end of the tubing by passing it through the flame a few times. When the tubing is warm, rotate the end of the tube in the flame until the glass begins to turn yellow and melt a little. Keep rotating the tube until the rough edges become smooth. Do not heat too much and do not stop rotating. Place the hot glass on a gauze mat to cool. The end is now fire polished. When the tube is cool, fire polish the other cut end. Again allow to cool. Put all broken glass in a special labelled container, not in the waste paper basket.
5. Seal the end of a thin glass tube
Place the glass tube at the top of the hot blue flame of the Bunsen burner because the flame is the hottest there and rotate the tube to heat it uniformly. Note that the part being heated is some part at the middle of the glass tube not its end. When the part being heated becomes hot and soft, clamp the two ends of the tube and pull the tube outwards so that the part being heated becomes thin into capillary. If go on pulling, the thinnest part will fall down thus the original tube will become into two tubes and their ends have been sealed or have became very thin. Place one end of the tube at the top of the hot blue flame of the Bunsen burner and rotate it during heating it until the end is sealed completely and it becomes very smooth. Leave the tube off the flame and blow the inside of its open end while it is hot to make the end sealed smoother. Stress relief the sealed end by gently heating but do not soften the glass.
6. Seal the end of a thick glass tube
Place one end of the glass tube at the top of the hot blue flame of the Bunsen burner because the flame is the hottest there and rotate the tube to heat it uniformly. When the end is soft, lower the cool end so that the heated end is at the top. Keep rotating and heating until the glass at the end heated becomes soft and flows into the tube so that the end is sealed completely.
This is not my work, but something that the University of Queensland had on a website of school science lessons, which said it was free to download for educational purposes, and that is what this is. Steps 5 and 6 are not relevent for just cutting glass tubing, however I thought it best to include all the information
Break and bend glass tubing
1. One way to cut glass tubing is to score the surface with one forward stroke of a three cornered file. Make the score mark at right angles to the centre line of the tube so that the tube will snap squarely across. To snap the tube, place it on the bench top with matchsticks or toothpick directly beneath the upward facing score mark. Then, holding one end securely, press down on the other end and the snap will be immediate. Another method frequently used is to scratch the glass tubing with a quick smooth file stroke, then hold the scratched tubing firmly in both hands with one's thumbs pointing towards each other, but on opposite sides of the scratch, and snapping the glass tubing away from one's body. Fire polish the cut ends.
2. The method of cutting a glass tube depends on its diameter. Different methods are used to cut glass tubes of different diameters. Place the tube flat on the table. Measure the required length. Hold the tube firmly and draw a triangular file across it a couple of times so that a scratch is made. Do not saw back and forth. One or two firm cuts are usually sufficient. Take the tube in both hands, one each side of the scratch. Keep your thumbs as close as possible to the scratch. Press gently with your thumbs and pull with the fingers. The two pieces of tubing should separate. Brute strength is not needed. If the tube does not break easily, make the file scratch a little deeper and longer. Fire polish the cut ends
Light the burner, and open the air hole. This gives a hot blue flame. Warm one end of the tubing by passing it through the flame a few times. When the tubing is warm, rotate the end of the tube in the flame until the glass begins to turn yellow and melt a little. Keep rotating the tube until the rough edges become smooth. Do not heat too much and do not stop rotating. Place the hot glass on a gauze mat to cool. The end is now fire polished. When the tube is cool, fire polish the other cut end. Again allow to cool.
3. Place the tube flat on the table. Measure the required length. Hold the tube firmly and draw a triangular file across it a couple of times so that it makes a scratch. Do not saw back and forth. One or two firm cuts are usually sufficient. Take the tube in both hands, one each side of the scratch. Keep your thumbs as close as possible to the scratch. Press gently with your thumbs and pull with the fingers. The two pieces of tubing should separate. Do not use brute strength. If the tube does not break easily, make the file scratch a little deeper and longer.
4. Fire polish the cut ends.
Light the burner, and open the air hole. This gives a hot blue flame. Warm one end of the tubing by passing it through the flame a few times. When the tubing is warm, rotate the end of the tube in the flame until the glass begins to turn yellow and melt a little. Keep rotating the tube until the rough edges become smooth. Do not heat too much and do not stop rotating. Place the hot glass on a gauze mat to cool. The end is now fire polished. When the tube is cool, fire polish the other cut end. Again allow to cool. Put all broken glass in a special labelled container, not in the waste paper basket.
5. Seal the end of a thin glass tube
Place the glass tube at the top of the hot blue flame of the Bunsen burner because the flame is the hottest there and rotate the tube to heat it uniformly. Note that the part being heated is some part at the middle of the glass tube not its end. When the part being heated becomes hot and soft, clamp the two ends of the tube and pull the tube outwards so that the part being heated becomes thin into capillary. If go on pulling, the thinnest part will fall down thus the original tube will become into two tubes and their ends have been sealed or have became very thin. Place one end of the tube at the top of the hot blue flame of the Bunsen burner and rotate it during heating it until the end is sealed completely and it becomes very smooth. Leave the tube off the flame and blow the inside of its open end while it is hot to make the end sealed smoother. Stress relief the sealed end by gently heating but do not soften the glass.
6. Seal the end of a thick glass tube
Place one end of the glass tube at the top of the hot blue flame of the Bunsen burner because the flame is the hottest there and rotate the tube to heat it uniformly. When the end is soft, lower the cool end so that the heated end is at the top. Keep rotating and heating until the glass at the end heated becomes soft and flows into the tube so that the end is sealed completely.
This is not my work, but something that the University of Queensland had on a website of school science lessons, which said it was free to download for educational purposes, and that is what this is. Steps 5 and 6 are not relevent for just cutting glass tubing, however I thought it best to include all the information
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Lyn
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Re: Glass tubing
No-one has mentioned a specific type of bunsen to be used for glasswork. I have several old style bunsens called "batwing bunsens" which give a very low hot blue flame for heating glass. They do not have a collar to regulate air intake. The top has a 2cm metal grid with fine holes. These bunsens work really well. I'm not too sure if they are replaceable though. What style of bunsen do others use for their glasswork.
Lyn.
PS. I have to keep these away from students and teachers so I don't have any melted offerings sent back to me.
Lyn.
PS. I have to keep these away from students and teachers so I don't have any melted offerings sent back to me.
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shanedavis1
- Posts: 4
- Joined: 17 Jan 2008, 12:47
- State/Location: NSW
Re: Glass tubing
I use one of those 'batwing' bunsens also and I indeed do find it and excellent tool as I've attempted to use the normal type bunsen that's in the labs and thay are to fine and intense.
Shane
Shane
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Labbie
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Re: Glass tubing
We have the bat wings also, We put them onto our normal bunsens, I just keep the bat wings locked away, they just pull off when it has cooled down. No other way to do glass.
Regards Labbie
Lab Manager/Lab Tech, mind reading etc etc
Now retired
Lab Manager/Lab Tech, mind reading etc etc
Now retired
Re: Glass tubing
The burner with the 2cm grid of fine holes is a meker burner. Don't let it out of your sight, you won't get it back! 
Great for melting glass. Use a batswing bunsen for bending glass, as it heats a 4 or 5 cm length of tubing evenly with rotation, making lovely even bends.
Great for melting glass. Use a batswing bunsen for bending glass, as it heats a 4 or 5 cm length of tubing evenly with rotation, making lovely even bends.