Thứ Sáu, 14 tháng 12, 2018
Thứ Ba, 31 tháng 7, 2018
AMATEUR VACUUM TUBE MAKING[P4]
TUBECRAFTER: AMATEUR VACUUM TUBE MAKING
Copyright: Ron Soyland
CONNECTING UP YOUR TORCH
There will be gas and oxygen that will have to be supplied to your torch. The best way to control this is with a separate manifold. The reason for this is that you can then turn the torches on and off without touching the control valves on the torch itself. You leave the torch set to its correct operating adjustment. This saves a lot of time since most time lighting a torch is spent in getting the flame set correctly.
When using more than one torch, a means of connecting each one to the gas supply must be arranged. This is a simple manual valve manifold that allows each torch to be turned on individually or in combination. This manifold controls four torches, one set of valves for oxygen the other for gas. You can just as easily get by with a simple group of fittings with hose barbs and no valves: you don't need the valves. The torches are connected to the regulator output and you turn the torch on and off with the torch valves. And take the time hit in having to adjust the flame each time you turn on the torch.
By having separate valves to turn on and off the torch, the setting of the torch knobs doesn't have to be disturbed. This saves considerable time! You don't really need this kind of setup but the time saved makes it desireable.
A new manifold is being built that uses solonoid valves and electrical switches to turn on the torches. This will save valuable space on the glass blowing console.
OXYGEN
A set of two 5 liter per minute oxygen concentrators used to supply oxygen to the glass blowing torches.
There will be gas and oxygen that will have to be supplied to your torch. The best way to control this is with a separate manifold. The reason for this is that you can then turn the torches on and off without touching the control valves on the torch itself. You leave the torch set to its correct operating adjustment. This saves a lot of time since most time lighting a torch is spent in getting the flame set correctly.
When using more than one torch, a means of connecting each one to the gas supply must be arranged. This is a simple manual valve manifold that allows each torch to be turned on individually or in combination. This manifold controls four torches, one set of valves for oxygen the other for gas. You can just as easily get by with a simple group of fittings with hose barbs and no valves: you don't need the valves. The torches are connected to the regulator output and you turn the torch on and off with the torch valves. And take the time hit in having to adjust the flame each time you turn on the torch.
By having separate valves to turn on and off the torch, the setting of the torch knobs doesn't have to be disturbed. This saves considerable time! You don't really need this kind of setup but the time saved makes it desireable.
A new manifold is being built that uses solonoid valves and electrical switches to turn on the torches. This will save valuable space on the glass blowing console.
OXYGEN
Getting the oxygen for your torch is one of the most difficult problems to solve. Pressure tanks are heavy and have to be refilled
quite often, and have a way of waiting until you are in the middle of a critical glass operation before going empty on you.
The answer to this problem is the oxygen concentrator. This is a machine that extracts oxygen from the air and concentrates it to over 95% purity. The machine produces oxygen only while it is running so the hazard of having large quantities of oxygen stored on your premises is eliminated.
The oxygen concentrator is available in several sizes from small 3 liter per minute up to large 20 or more liter per minute machines. The cost is accordingly greater of course for larger machines. If you are going to do any long term glass blowing, an oxygen concentrator is going to be the way to go.
A new oxygen concentrator costs on the order of $1000 U.S. or more. This is not reasonable for most amateurs. The answer is a used machine. These machines are made for medical use by people that have certain types of lung disease. Thus, there are huge numbers of these machines out there and a lot of them at bargain prices since they cannot be resold for medical use.
Ebay used to be a source for the machines but the government came down on them for distributing a controlled medical device without a license. It is all political since they allow numerous other controlled medical devices to be listed!
The used machines are available from several suppliers on the web. (google oxygen concentrator, used) They range in price from $100 to around $1000 for one that is practically new.
The lifetime of the concentrator is long, about 30,000 hours. However, you don't want a machine that is approaching that end. Ask for a machine that has under 20,000 hours on it. That will cost more but you will be less likely to have a failure, plus the oxygen purity tends to drop somewhat as the machine gets towards the end of its service life.
Rebuilding the machines is not difficult but it requires the set of parts, which will cost you as much as another used working machine. Not practical.
The torches require a relatively pure oxygen flow that varies from a fraction of a liter per minute for the mini tip, to 15 liters per minute for the large rosebud. The required pressure for the torches is 5 pounds per square inch.
The smaller most used tips use 3 to 5 liters per minute. This is a LOT of oxygen! You will find that out if you are buying oxygen in tanks! For the oxygen concentrator that is no problem of course.
Oxygen concentrators come in two main sizes, 3 liter per minute and 5 liter per minute. There are other sizes but they are rare and more expensive.
You can get by with one 5 liter unit. The largest tip will not operate at full heat but it will be acceptable for most work. The 3 liter unit is too small for working glass sizes larger than one inch.
When buying the used oxygen concentrator, explain to the dealer that you are not using it for medical purposes and do not need a certified machine, and will sign a waivier that declares that the machine will not be used for medical oxygen. This will drop the price of the machine considerably since the dealer is able to sell you a machine that has not had to be rebuilt.
The output of the oxygen concentrator is through a front panel connector. You can adapt a hose barb to this and run this to your torch or manifold. The flow setting on the oxygen concentrator is set to allow right at 5 liters per minute with the oxygen valve open. You can set it to higher than 5 liters per minute when using the large rosebud tip and get about 7 liters per minute at somewhat reduced pressure, but it will give a noticeably larger flame. This is not harmful to the oxygen concentrator.
GAS.
There are two practical gas sources for your torches. The optimum setup uses natural gas from the wall valve with an oxygen concentrator. You never have to worry about running out of gas. This is practical only if your shop has natural gas service.
Propane is the other practical solution. The small 5 gallon tanks used in barbeque pits are cheap, available everywhere, and easily exchanged or refilled at many hardware stores and propane dealers. The entire tank, a fill of propane, and a regulator costs less than $100 new. The amount of gas in a 5 gallon tank is truely amazing. You might go for half a year on one fill of the tank depending on how many times you use the largest tips.
One disadvantage of propane tanks is that you are storing a large qauntity of flammable gas in your shop. The hazard is minimal, but you must always be aware of any smell of gas.
A regulator for the tank is set to 3 to 5 pounds per square inch and connected to the manifold for your torches. It is best to use professional gas fittings for these connections, however ordinary copper tubing connections are suitable. If hose barbs are used, be sure to use clamps on each one so the hose cannot be accidently pulled loose by a child or a pet.
The answer to this problem is the oxygen concentrator. This is a machine that extracts oxygen from the air and concentrates it to over 95% purity. The machine produces oxygen only while it is running so the hazard of having large quantities of oxygen stored on your premises is eliminated.
The oxygen concentrator is available in several sizes from small 3 liter per minute up to large 20 or more liter per minute machines. The cost is accordingly greater of course for larger machines. If you are going to do any long term glass blowing, an oxygen concentrator is going to be the way to go.
A new oxygen concentrator costs on the order of $1000 U.S. or more. This is not reasonable for most amateurs. The answer is a used machine. These machines are made for medical use by people that have certain types of lung disease. Thus, there are huge numbers of these machines out there and a lot of them at bargain prices since they cannot be resold for medical use.
Ebay used to be a source for the machines but the government came down on them for distributing a controlled medical device without a license. It is all political since they allow numerous other controlled medical devices to be listed!
The used machines are available from several suppliers on the web. (google oxygen concentrator, used) They range in price from $100 to around $1000 for one that is practically new.
The lifetime of the concentrator is long, about 30,000 hours. However, you don't want a machine that is approaching that end. Ask for a machine that has under 20,000 hours on it. That will cost more but you will be less likely to have a failure, plus the oxygen purity tends to drop somewhat as the machine gets towards the end of its service life.
Rebuilding the machines is not difficult but it requires the set of parts, which will cost you as much as another used working machine. Not practical.
The torches require a relatively pure oxygen flow that varies from a fraction of a liter per minute for the mini tip, to 15 liters per minute for the large rosebud. The required pressure for the torches is 5 pounds per square inch.
The smaller most used tips use 3 to 5 liters per minute. This is a LOT of oxygen! You will find that out if you are buying oxygen in tanks! For the oxygen concentrator that is no problem of course.
Oxygen concentrators come in two main sizes, 3 liter per minute and 5 liter per minute. There are other sizes but they are rare and more expensive.
You can get by with one 5 liter unit. The largest tip will not operate at full heat but it will be acceptable for most work. The 3 liter unit is too small for working glass sizes larger than one inch.
When buying the used oxygen concentrator, explain to the dealer that you are not using it for medical purposes and do not need a certified machine, and will sign a waivier that declares that the machine will not be used for medical oxygen. This will drop the price of the machine considerably since the dealer is able to sell you a machine that has not had to be rebuilt.
The output of the oxygen concentrator is through a front panel connector. You can adapt a hose barb to this and run this to your torch or manifold. The flow setting on the oxygen concentrator is set to allow right at 5 liters per minute with the oxygen valve open. You can set it to higher than 5 liters per minute when using the large rosebud tip and get about 7 liters per minute at somewhat reduced pressure, but it will give a noticeably larger flame. This is not harmful to the oxygen concentrator.
GAS.
There are two practical gas sources for your torches. The optimum setup uses natural gas from the wall valve with an oxygen concentrator. You never have to worry about running out of gas. This is practical only if your shop has natural gas service.
Propane is the other practical solution. The small 5 gallon tanks used in barbeque pits are cheap, available everywhere, and easily exchanged or refilled at many hardware stores and propane dealers. The entire tank, a fill of propane, and a regulator costs less than $100 new. The amount of gas in a 5 gallon tank is truely amazing. You might go for half a year on one fill of the tank depending on how many times you use the largest tips.
One disadvantage of propane tanks is that you are storing a large qauntity of flammable gas in your shop. The hazard is minimal, but you must always be aware of any smell of gas.
A regulator for the tank is set to 3 to 5 pounds per square inch and connected to the manifold for your torches. It is best to use professional gas fittings for these connections, however ordinary copper tubing connections are suitable. If hose barbs are used, be sure to use clamps on each one so the hose cannot be accidently pulled loose by a child or a pet.
The compressor raises the pressure from 3 ounces up to the 5 pounds. A bypass regulator is used for maintaining the pressure so the compressor runs continuously and draws only what gas is needed from the wall valve to maintain the pressure. The compressor is a small diaphragm type that has a maximum pressure of about 10 psi. A flow rate of about 5 liters per minute is all that is necessary. The colored tanks are resivours for the gas, however they are not necessary. The output of the compressor regulator can be connected directly to the manifold.
Thứ Hai, 16 tháng 7, 2018
AMATEUR VACUUM TUBE MAKING[P3]
TUBECRAFTER:
AMATEUR VACUUM TUBE MAKING
Copyright: Ron Soyland
COMMON FIXTURES USED IN TUBE MAKING
A fixture is a specialized tool. Some are used to hold glass, some to hold wires, some to position parts of a tube together. Fixtures can be used to make tubes. It is not as convenient as having a glass lathe but it can be done and is a viable alternative to having a lathe. Using fixtures is not to be considered a desirable alternative but it is possible if a lathe is not practical to make. Here we examine a set of fixtures that are needed to make basic tubes.
GLASS HOLDING
The roller stand is one of the most basic of glass holding tools. It is made of wood, metal, or plastic.
GLASS HOLDING
The roller stand is one of the most basic of glass holding tools. It is made of wood, metal, or plastic.
One of the most common tasks in glasswork is cutting off pieces of glass tubing to size. The roller stand is used to hold the tubing while the diamond saw makes the cut. Two sizes of roller stands are needed. One for small diameter tubing (1/2 inch to 1 inch) and one for large. (1 inch and up) Tubes smaller than 1/2 inch can be broken by hand.
For the small diameter tubing, a simple V groove in blocks of wood or plastic are satisfactory. For larger diameters of tubing the friction of the V grooves becomes excessive so rollers are desireable. Wheels robbed off of casters work fine, or you can cut disks of plastic from a piece of bar stock. The diameter of the disks should be about 1 1/2 inches. Be sure the hole in the center for the screw is closely centered so the wheel doesn't wobble. Space the wheels apart so that a piece of 3/4 inch diameter glass will not fall through while a 2 inch piece will ride smoothly. The spacing of the blocks should be about 8 to 12 inches. Provisions for moving the far block closer can be made so that shorter pieces of tubing can be supported. This can be as simple as using double sided carpet tape to hold the block to the base. Simply replace the tape when it gets too weak to be satisfactory. Or, you can put multiple pairs of screw holes in the base and use screws to hold the movable block. The V or roller should hold the glass tube about 3 inches above the table.
For the small diameter tubing, a simple V groove in blocks of wood or plastic are satisfactory. For larger diameters of tubing the friction of the V grooves becomes excessive so rollers are desireable. Wheels robbed off of casters work fine, or you can cut disks of plastic from a piece of bar stock. The diameter of the disks should be about 1 1/2 inches. Be sure the hole in the center for the screw is closely centered so the wheel doesn't wobble. Space the wheels apart so that a piece of 3/4 inch diameter glass will not fall through while a 2 inch piece will ride smoothly. The spacing of the blocks should be about 8 to 12 inches. Provisions for moving the far block closer can be made so that shorter pieces of tubing can be supported. This can be as simple as using double sided carpet tape to hold the block to the base. Simply replace the tape when it gets too weak to be satisfactory. Or, you can put multiple pairs of screw holes in the base and use screws to hold the movable block. The V or roller should hold the glass tube about 3 inches above the table.
A simple 2 jaw chuck design that has capability of on center or off center positioning. The jaws are shown in two positions for a small diameter tube and a large one.
Above is shown a simple design for a 2 jaw chuck that is used to hold glass. The radius of the arms is made such that the V blocks are always on center. The V blocks are mounted on 1/4 inch dia. shafts protruding from the arms and are free to swivel to match the position of the glass. It can be seen that the tube can be set to be either on center or off center. This can allow centering or off-centering of the tube, a proceedure that is sometimes needed. The arms are fastened to the faceplate with screws with wing nuts to allow tightening them in place. Centering is done by hand. The jaw blocks are about 3/4 inch square with the V cut about a third the way in. They should be made of teflon because they do get hot sometimes! A chuck like this could be made entirely using hand tools.
Above is a small lathe that is made using the chuck design. This was used to successfully make tubes before the glass lathe was built. The main disadvantage is that when joining two parts one of the parts must be held by hand, demanding a steady hand!
A possible solution is to mount a clamp arm to the column that can be positioned to hold the second part.
This lathe has the ability to rotate from vertical to horizontal depending on which position is desired to work on the piece. The bearing is a large surplus bearing that is available online. The motor is gear driven to the bearing but it could just as well be friction driven since there is no force on the parts. Using this simple-to-make lathe you can successfully blow great looking spheres and other vacuum tube shapes from glass tubing.
A possible solution is to mount a clamp arm to the column that can be positioned to hold the second part.
This lathe has the ability to rotate from vertical to horizontal depending on which position is desired to work on the piece. The bearing is a large surplus bearing that is available online. The motor is gear driven to the bearing but it could just as well be friction driven since there is no force on the parts. Using this simple-to-make lathe you can successfully blow great looking spheres and other vacuum tube shapes from glass tubing.
The glass flare must be held while the pinch seal is being made. Since the entire flare will be at high temperature the holder must be able to repeatedly take the hot flame near it. Here are two designs of flare holder. The top design was a first attempt. It uses three spring loaded arms with grooved disks to hold the flare. It is very difficult to get the flare into the disks so that design was abandoned.
The lower design is much simpler. It uses a spring loaded "sissor" arrangement of two arms. The arms are U shaped with a V notch cut in the end to accept the edge of the flare. The design works great and is used for all the seal making operations. The shaft of the holder is held in the lathe chuck.
The lower design is much simpler. It uses a spring loaded "sissor" arrangement of two arms. The arms are U shaped with a V notch cut in the end to accept the edge of the flare. The design works great and is used for all the seal making operations. The shaft of the holder is held in the lathe chuck.
Above are shown two models of wire holders. The shaft on each is 1 inch in diameter for size reference. The top holder has a spring loaded clamp. To make one, a paper clamp available at most office supply stores would work fine. Get a small one since the total width doesn't need to be wider than about a half inch. The lower model has a swivel joint inside the shaft. This allows the wires to be centered more easily in the lathe. The clamp is a piece of spring steel that clamps down on the wires using the thumb nut.
Putting slight pressure inside a glass item while hot is done to expand the glass. To do this, a blow hose is used. A rotary joint makes the hose useable with the lathe. To make a rotary joint, get a 1/4 by 1/2 shielded ball bearing. Make a tube and a cup like the drawing. The bearing can be glued in place with super glue. Be sure not to slop glue into the bearing itself. The free end of the bearing tube is pushed into a rubber stopper (get on ebay) that plugs into the glass tube end.
Tube can be held vertical or the head can be rotated horizontal
Above is a small fixture that is used to assemble a tube. The rods slide horizontally to position the parts and hold them in place while the glass is sealed. To get to all sides, the entire fixture is simply laid over on its side. This fixture has one side with a gear driven slide but that is not necessary if you can't find a drive unit like that. Simply make both sides slide through a block like the left hand one. The rods are made according to the type of tube being made, and may have wire slots like these, or carbon holders, or cup holders with set screws. This can take the place of a glass lathe for assembly and is used even now to make tubes.
AMATEUR VACUUM TUBE MAKING[P2]
TUBECRAFTER:
AMATEUR VACUUM TUBE MAKING
Copyright Ron Soyland
DIFFUSION PUMPS USED IN TUBE MAKING
To get the high vacuum for the vacuum tube the diffusion pump is used in combination with the mechanical pump. The diffusion pump will only operate at very low pressures around 100 microns or lower. A few specially designed diffusion pumps will operate at pressures up to about 1 torr, but these are hard to find. They do come on ebay quite regularly though.
There are two basic kinds of diffusion pumps. These are the water cooled and the air cooled. We will examine the characteristics of both. Either type is suitable for tube making but not having to fool with water connections is quite convenient!
WHAT SIZE OF PUMP DO YOU NEED?
Diffusion pumps come in all sizes from less than an inch inlet diameter to huge monsters over six feet across used for space simulation chamber evacuation. The size of pump needed for tube making is determined mostly by what the vacuum system will ultimately be used for. If it is strictly for tube making and will not be connected to a larger chamber such as a large bell jar, then a very small pump will do fine. There are several models of pump that are 1 inch inlet diameter that come on ebay occasionally. These are almost all water cooled, but can be modified easily to be air cooled.
If you are going to use a larger chamber on your system, you will need a pump accordingly larger. A rule of thumb is to have the pump inlet diameter approximately 1/4 the diameter of the chamber, or greater. Thus, for a 12 inch diameter bell jar, you would use a 4 inch diffusion pump or larger. The time required to reach a given vacuum will be determined by this ratio.
The best pump size for the tube making system is a 3 inch air cooled type. These are available by many manufacturers and are available used on ebay for a hundred dollars or so. The three inch size is large enough to give excellent pumping speed and yet it is not so large as to be difficult to mount and get valves for.
There are two basic kinds of diffusion pumps. These are the water cooled and the air cooled. We will examine the characteristics of both. Either type is suitable for tube making but not having to fool with water connections is quite convenient!
WHAT SIZE OF PUMP DO YOU NEED?
Diffusion pumps come in all sizes from less than an inch inlet diameter to huge monsters over six feet across used for space simulation chamber evacuation. The size of pump needed for tube making is determined mostly by what the vacuum system will ultimately be used for. If it is strictly for tube making and will not be connected to a larger chamber such as a large bell jar, then a very small pump will do fine. There are several models of pump that are 1 inch inlet diameter that come on ebay occasionally. These are almost all water cooled, but can be modified easily to be air cooled.
If you are going to use a larger chamber on your system, you will need a pump accordingly larger. A rule of thumb is to have the pump inlet diameter approximately 1/4 the diameter of the chamber, or greater. Thus, for a 12 inch diameter bell jar, you would use a 4 inch diffusion pump or larger. The time required to reach a given vacuum will be determined by this ratio.
The best pump size for the tube making system is a 3 inch air cooled type. These are available by many manufacturers and are available used on ebay for a hundred dollars or so. The three inch size is large enough to give excellent pumping speed and yet it is not so large as to be difficult to mount and get valves for.
The photo above is of a small water cooled diffusion pump. This pump is a 2.5 inch size and operates off of 120 volt power. The pump needs a constant flow of water through it for cooling. Small pumps like this cannot be easily converted to air cooled. If you have water and a drain available in your shop, these pumps will do just fine. Water cooled pumps are somewhat smaller physically than air cooled pumps because of the greater efficiency of water cooling. The vacuum attained by the pump is in the low 10 -6 torr range, which is excellent for vacuum tube operation. The small size of the inlet makes it lower cost to find a suitable high vacuum valve for it. The main disadvantage of the pump is the water cooling.
Here we have a 3 inch Varian air cooled diffusion pump. Note that the length of the pump is considerably greater in proportion to the pump diameter. The pump requires a constant airflow over the finned part. This is usually provided by a shrouded muffin fan or even a small squirrel cage blower. The three inch size is still small enough to find a reasonably prices vacuum valve for the inlet. The price of valves, even used, begins to escalate rapidly as the size increases, especially over 4 inches diameter. The tall size of the pump indicates an efficient pump design that provides a greater outlet pressure tolerance than a shorter pump. This pump will operate with an outlet pressure up to about 250 microns, which is easily achieved with most mechanical pumps.
This is a small air cooled diffusion pump from an Alcatel leak detector. Note the blower shroud on the body. The muffin fan is mounted on the right hand side. The inlet of the pump has a blank off plate with an elbow pipe joined to it. The pump itself is about 11 inches tall, noticeable shorter than the Varian pump. The penalty for this shorter size is the reqirement for a lower outlet pressure to keep the pump operating. This pump stalls at outlet pressures above about 75 microns. This pressure is still quite easy for modern two stage mechanical pumps to maintain so it is not a serious disadvantage. The advantage of the small size and air cooling is easily worth the small loss in pumping speed due to the lower stall pressure. It is an ideal pump for tube making. The pump will achieve a vacuum of below 10 -5 torr.
Each of the pumps above is suitable for tube making systems. The water cooled pump makes the smallest system however cooling water is necessary. The taller Varian pump is commonly available on ebay for a hundred dollars or so but is tall, almost 16 inches, which makes it somewhat clumsy to mount unless you make a floor mounted console. The small Alcatel pump is ideal in size and performance but is harder to find.
These pumps operate on Corning DC 704 silicone diffusion pump fluid. Using this fluid, the vacuum achieved by any of the pumps will be completely suitable for tube making. The use of expensive and critical fluids such as Octoil should not be considered.
Octoil is an obsolete fluid that was originally specified for each of the pumps above. The DC 704 was formulated to directly replace the Octoil and not have the critical problems Octoil has. Octoil is flamable and is far above its flash point when operating at normal temperatures in the diffusion pump. If the system accidently or from operator error is opened to air while the Octoil is at operating temperature, it instantly bursts into flame inside the pump. This can even cause an explosion.
Each of the pumps above is suitable for tube making systems. The water cooled pump makes the smallest system however cooling water is necessary. The taller Varian pump is commonly available on ebay for a hundred dollars or so but is tall, almost 16 inches, which makes it somewhat clumsy to mount unless you make a floor mounted console. The small Alcatel pump is ideal in size and performance but is harder to find.
These pumps operate on Corning DC 704 silicone diffusion pump fluid. Using this fluid, the vacuum achieved by any of the pumps will be completely suitable for tube making. The use of expensive and critical fluids such as Octoil should not be considered.
Octoil is an obsolete fluid that was originally specified for each of the pumps above. The DC 704 was formulated to directly replace the Octoil and not have the critical problems Octoil has. Octoil is flamable and is far above its flash point when operating at normal temperatures in the diffusion pump. If the system accidently or from operator error is opened to air while the Octoil is at operating temperature, it instantly bursts into flame inside the pump. This can even cause an explosion.
This is a stack from a 3 inch diffusion pump that was using octoil when a gasket failure caused the inlet to be opened to air while the diffusion pump was operating. It took about an hour for this mess to happen, before the break in the system was noticed and shut down. The caked on material has the consistency of epoxy glue! It had to be chipped painstakedly off and the stack sanded to get it clean. Amazingly, the inside of the stack where clear octoil was present with no oxygen there was no burned oil. It was completely clean!
Chủ Nhật, 15 tháng 7, 2018
AMATEUR VACUUM TUBE MAKING [ P1]
TUBECRAFTER:
AMATEUR VACUUM TUBE MAKING
Copyright Ron Soyland
BASIC EQUIPMENT USED IN TUBEMAKING
To make tubes you must have certain equipment, and you will have certain equipment that would be nice to have but is not absolutely necessary. This is only a list of equipment, an overview. Full descriptions of each piece are given in other sections of this site.
GLASSBLOWING:
To work glass there are certain items that must be on hand and others that you might be able to do without. Here is a list of typical glassblowing tools and if you need them or can do without.
.
VACUUM PUMPING: The degree of vacuum necessary for tubes is such that a vacuum SYSTEM is required.
The two types of pumps are manditory.
The inlet valve lets you open the system to air without shutting off the diffusion pump. This is not strictly necessary but saves considerable time when changing out tubes. The outlet valve is necessary to isolate the diffusion pump while roughing down the vacuum tube from atmospheric pressure. Without this valve, you would have to cool off the diffusion pump while you did the roughdown. Very time consuming. The vacuum system is described in detail in the section MAKING THE VACUUM in this website.
PINCHER WELDER: The main way electrodes in the tube are interconnected is via resistance welding. A hand held pincher with electrical contacts is used to clamp the two parts to be welded. A brief burst of electric current is passed to make the weld. This is an essential piece of equipment and will be necessary to have.
GLASS LATHE: Of all the equipment used in tube making, the torches and glass lathe are the most used. However, it is possible to get by without a glass lathe. It will take a LOT more experience at glassblowing technique. You can make up fixtures of wood and sheet metal to handle a lot of the setups, but it will be quite difficult to hold the parts of the tube in exact relation, sometimes as close as 1/2 millimeter spacing, while doing the seals. Unfortunately, the glass lathe is the most expensive tool in glasswork. If you plan to make a continuing practice of tubemaking, you should plan to have a glass lathe. If you are only going to make a few tubes and go on to something else, simply make tubes that can be made without a glass lathe. Several are described in detail on this site.
BAKEOUT OVEN: When pumping the tube to develop the vacuum, the air trapped in the glass and elements must be driven completely out to keep it from seeping out over time after the tube has been sealed off, thus ruining the vacuum. To drive the air out the tube is heated to 1000 deg. F while the tube is being pumped. This requires a small oven that can be placed around the tube while it is on the vacuum system. If you are making tubes that are expected to last longer than a day or two after being sealed off, the bakeout is absolutely necessary.
GETTER FLASHER: The getter is absolutely necessary if you expect the tube to remain good for longer than a few weeks. The getter is a small element containing a reactive metal such as barium. The getter metal is heated to evaporate it onto the inside surface of the tube envelope. This must be done while the tube is under high vacuum, so the heating must be done through the glass. This is done with an induction heater connected to a suitable coil that is held over the tube adjacent to the getter element. The getter flasher is available for around $400 U.S. or you can build one with parts from ebay for much less.
TUBE TESTER: This is not your standard tube tester like is used to test TV tubes. This is a metered power supply that allows you to adjust the various voltages applied to the new tube while watching the results on meters. This tester is not available commercially and would have to be homebuilt. You could get by without the tube tester by using portable bench power supplies and a V.O.M. to read the tube current. This would be quite inconvenient.
VARIOUS HAND TOOLS: There are various hand tools that are used in the working of glass, such as carbon prods, carbon flats, pinchers, wire holders, etc. These are necessary and very easy to make yourself. All the tools you would need to do the tube glasswork would be easily made up for under a hundred dollars, so these tools are not a problem to get.
GLASSBLOWING:
To work glass there are certain items that must be on hand and others that you might be able to do without. Here is a list of typical glassblowing tools and if you need them or can do without.
- NEEDLE POINT FLAME TORCH
- 1/4 INCH FLAME TORCH
- 5/8 INCH "ROSEBUD" TORCH
- CROSSFIRE TORCH
.
VACUUM PUMPING: The degree of vacuum necessary for tubes is such that a vacuum SYSTEM is required.
- TWO STAGE ROTARY VANE MECHANICAL PUMP
- 3 STAGE AIR COOLED DIFFUSION PUMP
- HIGH VACUUM VALVE TO FIT INLET OF DIFFUSION PUMP
- HIGH VACUUM VALVE TO FIT OUTLET OF DIFFUSION PUMP
The two types of pumps are manditory.
The inlet valve lets you open the system to air without shutting off the diffusion pump. This is not strictly necessary but saves considerable time when changing out tubes. The outlet valve is necessary to isolate the diffusion pump while roughing down the vacuum tube from atmospheric pressure. Without this valve, you would have to cool off the diffusion pump while you did the roughdown. Very time consuming. The vacuum system is described in detail in the section MAKING THE VACUUM in this website.
PINCHER WELDER: The main way electrodes in the tube are interconnected is via resistance welding. A hand held pincher with electrical contacts is used to clamp the two parts to be welded. A brief burst of electric current is passed to make the weld. This is an essential piece of equipment and will be necessary to have.
GLASS LATHE: Of all the equipment used in tube making, the torches and glass lathe are the most used. However, it is possible to get by without a glass lathe. It will take a LOT more experience at glassblowing technique. You can make up fixtures of wood and sheet metal to handle a lot of the setups, but it will be quite difficult to hold the parts of the tube in exact relation, sometimes as close as 1/2 millimeter spacing, while doing the seals. Unfortunately, the glass lathe is the most expensive tool in glasswork. If you plan to make a continuing practice of tubemaking, you should plan to have a glass lathe. If you are only going to make a few tubes and go on to something else, simply make tubes that can be made without a glass lathe. Several are described in detail on this site.
BAKEOUT OVEN: When pumping the tube to develop the vacuum, the air trapped in the glass and elements must be driven completely out to keep it from seeping out over time after the tube has been sealed off, thus ruining the vacuum. To drive the air out the tube is heated to 1000 deg. F while the tube is being pumped. This requires a small oven that can be placed around the tube while it is on the vacuum system. If you are making tubes that are expected to last longer than a day or two after being sealed off, the bakeout is absolutely necessary.
GETTER FLASHER: The getter is absolutely necessary if you expect the tube to remain good for longer than a few weeks. The getter is a small element containing a reactive metal such as barium. The getter metal is heated to evaporate it onto the inside surface of the tube envelope. This must be done while the tube is under high vacuum, so the heating must be done through the glass. This is done with an induction heater connected to a suitable coil that is held over the tube adjacent to the getter element. The getter flasher is available for around $400 U.S. or you can build one with parts from ebay for much less.
TUBE TESTER: This is not your standard tube tester like is used to test TV tubes. This is a metered power supply that allows you to adjust the various voltages applied to the new tube while watching the results on meters. This tester is not available commercially and would have to be homebuilt. You could get by without the tube tester by using portable bench power supplies and a V.O.M. to read the tube current. This would be quite inconvenient.
VARIOUS HAND TOOLS: There are various hand tools that are used in the working of glass, such as carbon prods, carbon flats, pinchers, wire holders, etc. These are necessary and very easy to make yourself. All the tools you would need to do the tube glasswork would be easily made up for under a hundred dollars, so these tools are not a problem to get.
Thứ Sáu, 13 tháng 11, 2015
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