What are the important elements for drilling holes in glass?

There are many aspects to drilling into glass.  This post reviews the major aspects.

Keeping Things Wet

When drilling glass it is important to keep the drill bit and glass wet always, otherwise the glass gets too hot and will break and cause the bonding of the diamonds on the bit to deteriorate. There are a variety of things you can do to achieve this:

Drill with the glass surface under water in a container.

Drill in a ring of clay, plasticine, etc., holding water. To do this, you need to make a ring about 50mm/2"  in diameter and press it around the drill site. Fill the ring with water to cool the drill site and glass. Diamond coolant is not necessary, but can extend the life of the bits.

Use a re-circulating water pump such as those made for indoor water features.

Direct the small flow of water (rapid drips) to the drilling site and catch the overflow in a separate bucket to the one in which the pump is submerged.  This extends the life of the pump and helps prevent clog ups in the water pipe.

Use a glass drill with hollow core bits and an internal water feed. This is the most expensive but it is the best equipment with which to drill holes of more than 4mm/0.158".

Drill Press

Drill presses vary from purpose-made through adaptations of industrial drill presses to hobbyist versions.  For light duty drilling that most glass workers do, a small press as set up for a dremel are suitable.

Example of a rotary tool press setup

This is an inexpensive solution to holding the dril steady while drilling.  It avoids the various contortions to stop the bit skittering across the glass when starting the hole.

Keeping the glass wet and cooling the drill bit for small pieces can be achieved by using a small temporary reservoir around the drill site to hold the water.  Alternatively, a small receptacle to submerge the glass can be used.

A plastic take-away container to hold a quantity of water

The water needs to be deep enough to cover the glass, but not so deep that it rises to the drill chuck, as that is likely to draw water into the rotary tool and short it out.  Notice also that the speed for the tool is at the minimum, because it is far too fast otherwise, and will overheat both the drill bit and the glass.

It is best to have an industrial drill press if you are doing a lot of drilling. It provides a stable drilling action and the pressure on the bit can be controlled. It is important to ensure the bit is running true without wobble. The drill press should have instructions to help correct any untrue running of the chuck. Make sure the drill bit is secured firmly. Core drill bits are easier to keep true, as they normally have a threaded fitting.

With a drill press, you can drill continually until the hole is completed, or until a white paste or dust begins to appear. This indicates the drilling is being done dry and will in a few moments heat up the glass too much. When the white paste appears, back out of the bottom of the hole a little to allow water to flush the glass out. Then continue.

Keep a firm grip on the glass being drilled.  If there is any chance of the glass spinning,  wear cut proof gloves.  Maintain the glass position, especially if you are intending to back out of the hole intermittently to allow water to the bottom of the hole. This enables you to get back into the hole without scratches.

Submerge the piece if you are drilling without a core drill bit, if possible. But if that isn’t possible, just squeeze a little puddle of water on the surface and watch it swirl around. You can see if it is pulling ground glass out of the hole by watching the circulation. Placing a plasticine or clay dam around the drill area will keep the water confined.

Don't push down any harder than you comfortably can on the lever with the tips of your fingers. Keep it steady. Listen for the sound of diamond grinding glass

White core stuck in the drill bit

If the core gets stuck in the bit, knock it out with some stiff wire or a nail. Always remove each core right after drilling. They are very difficult to remove if there is more than one stuck.

Core pushed out with 16 gauge copper wire

 When using a Dremel for drilling glass, slow it down to the minimum with the speed control. Drill presses do tend to be on the slow side for glass drilling so it takes a bit longer, but there are big advantages in other respects.

Drilling with a Flushing Head

A Typical Drill Press Set Up

A flushing head with a re-circulating pump will deliver water to the drill site through the core of the drill. These are supplied complete or as a fitting for an existing drill press. This is suitable for holes of 4 mm and larger. Smaller core drills are impractical both because the glass is easily trapped in the drill and the wall thickness of the drill makes them almost solid anyway.  An additional requirement is to have a means to direct the water to the waste bucket.

            Pump (black) at the bottom and flushing head where the water enters (chrome) at the top

Avoiding Chipping

There are a number of methods to avoid chipping out the back of the glass when drilling:

Place a piece of scrap glass under your good glass to avoid break-outs on the backside. By pressing firmly but gently on the glass (not the bit) the bit will go through the upper piece of glass without major chipping the back. This can be a difficult process to keep stable when both the pieces of glass are wet.

Another method is to put duct tape under the glass to help minimise chip out.
 Although I find a smooth firm base is best - it could be wood, hard plastic, or any other thin firm material that will not dull the bit when it goes through at the end of drilling.

A further process, used in industry, is to drill from both sides to avoid chip out. Go slowly toward the bottom of the hole. When the hole is almost through, turn the glass over and drill back to front.  It is critical to centre the drilling on the back exactly with the hole on the other side. 

Sometimes the glass is curved and drilling from the back is not easy. This is when a drill press mechanism to stop the bit comes into its own. Before switching the drill on, lower it to the surface supporting the glass. You can adjust the mechanism to stop the press just as it reaches the support surface. Then place the glass under the press and the turn the drill on to begin the drilling.

Don't push hard as you come to the end. Don't push down any harder on the drill press levers than you comfortably can with the tips of your fingers throughout the process. Keep it steady. Listen for the sound of diamond grinding glass.

All these things will help to avoid chipping out the glass at the bottom of the hole.

Drilling holes with copper tube and grit

You can drill holes by using loose grit and a copper tube of the correct diameter. It can take quite a while. You will need to have a chuck big enough to take the tube, or have a means to reduce the tube diameter to the chuck size. Alternatively, use core drills that have had the diamonds worn away.  This is not a common process, now that diamond drill bits are more affordable.

Prepare the glass as for a drill press without a flushing head, so the water and grit are confined. The dam can be putty, plasticine, clay, or other mouldable material put around the area to be drilled.  The grit can be sandblast grit or other abrasive of about 100 to 200 grit.  Drill as normal.

Tools

There are a variety of tools that can be used to power glass drills.

Dremel and similar rotary motors

These are light duty high-speed drills. Those with variable speed controls are especially useful. They work best for small diameter holes. They must have the speed turned down for drilling, especially for larger holes.  These can be combined with a flexible drive shaft for lighter weight, but a drill press is much more stable.

Drill press

However, the most important thing to have when drilling glass is a drill press. Doing it by hand is very difficult and wears out diamond bits very fast. Dremel and others make drill presses for their tools, as illustrated earlier.

Drilling machines

A portable glass drilling machine 

Purpose-made glass drilling machines are important for larger holes and production work. The important thing about these is that they use hollow core drill bits, allowing the water to be fed through the drill bit directly to the glass-drilling site.

Drill bits

The other tool needed is drill bits. The recommended type depends on the size of hole to be drilled.

• Small diameter holes, up to and including 3 mm can use solid diamond-tipped bits.  A number of manufacturers make solid drill bits from 2-6 mm and some (especially lapidary suppliers) make the very small diameter bits less than 1 mm.
• Larger diameter holes are best drilled with hollow core bits, as less glass needs to be removed to achieve the hole. These can be used with a flushing head or simply by directing water to the drill bit, with a dam to hold the water around the site.
• The bits will last longer if you use a drill press. The press keeps the bit wobble to a minimum and maintains the vertical, both helping to reduce the wear on the bit.

A selection of hollow core drill bits, wire and punches to clear the drill bit of stuck cores, and dressing stones

Hollow core bits

Hollow core diamond bits are of two types:

• One -where a heating process attaches the diamond - is called sintered in Europe and a number of other countries. These are long lasting and more expensive than the alternative. They can be dressed with an aluminium oxide dressing stick to maintain their effectiveness.
• The second – where the diamond is bound to the metal with resins – is called bonded in Europe.  These are less expensive and are a good alternative for those drilling smaller quantities of holes.  Bits of this type of bonding wear more quickly and should not be "sharpened" with dressing stones.

A diamond core drill breaks out much less glass at the bottom of the hole than a solid drill bit.  So they are quicker and have a lower risk of creating failures.  Buying better (more expensive) bits is worthwhile as they work much better and last much longer than the cheaper ones.

Water pump and reservoirs

A further tool that is useful to have is a pump. This can be a small fountain pump with a valve to regulate the flow, and a flexible spout to aim the water on the drilling site.  A bucket is required to act as the catch basin for the water that comes off the drill and and another as the reservoir for the pump.

Drilling glass without a drill press

It is best to have a drill press for drilling holes in glass, but there are ways of doing it with a hand drill.  Make a ring of modelling clay, plasticine, putty or other mouldable material about 5cm/2" in diameter and press it around the drill site. Fill the ring with water and a little diamond coolant if you like. The liquid will cool the drill site and surrounding glass as well lubricate the drill bit.  Adding diamond coolant to your water can extend the life of the bits. 

Use a paint pen to mark the spot where the hole is to be. Without a drill press, starting at an angle with a slow drill speed will stop the bit from sliding around as you establish the drilling point. As the glass surface is roughened, bring the drill to vertical. Move the drill up and down a little as you drill to allow the water into the hole. If you are using a solid or spade drill, a little oscillation keeps the bit from jamming in the hole.  This process is suitable for solid drill bits.  Do not do this with a core drill, as it may damage the edge of the bit and wears diamonds further up the bit.

Drilling speeds for diamond bits in glass

Every diameter drill bit has an optimum drill speed. The smaller they are the faster the speed. Drill presses do tend to be on the slow side for glass drilling, but often have ways of altering the speed. So they take a bit longer, but there are big advantages in other respects, mainly less wear on the bits and fewer break outs.

Diameter -- Speed

3-4 mm -- 6000 rpm

5-8 mm -- 4500 rpm

9-12 mm -- 3000 rpm

13-16 mm -- 2500 rpm

17-25 mm -- 2000 rpm

26-28 mm -- 1800 rpm

29-44 mm 1500 rpm

45-64 mm -- 1200 rpm

65-89 mm -- 900 rpm

90-120 mm -- 800 rpm

[Based on CR Lawrence and Amazing Glazing recommendations]

As you can see the larger the diameter, the slower the speed. This is because you are attempting to keep the speed of the diamonds moving against the glass at approximately the same speed, regardless of the diameter. If you did not slow the speed as the diameter went up, the speed of the diamonds across the glass would increase, leading to overheating of the bit and reduction in its life.

Hole Placement

The general rule on drilling holes in glass is that the edge of the hole should be further away from the edge than the thickness of the glass. This means that the edge of the hole on a 6 mm thick piece of glass must be more than 6 mm from the edge of the glass.

The calculations are simple arithmetic. You calculate the centre point of the hole by adding the radius of the hole to the thickness of the glass plus at least 1 mm. For example, to drill a 10 mm hole in 6 mm glass, you add 5 mm (radius of hole) to 6 mm (thickness of the glass) plus 1 mm = 12 mm as the minimum distance from the edge of the glass to the centre of the hole.  For methods of centring the drill see here.  Remember this is the minimum distance. For safety and durability in architectural or heavy circumstances, an additional margin must be added.

What Soldering Bit Size do I Need?

“What size of tip should I get for copper foil?”

The size of the tip is less important than the amount of solder applied. I can use my 200 watt iron with a 12mm tip in copper foiling. The iron power and large bit mean that there are no cool times to slow the progress of making the bead. I admit the 12mm bit is over large, but a 6 or 8mm bit will work well.

Do not go for very small bits intended for electronic soldering, because they cannot hold the heat as long as bigger ones, nor as long as is needed to run a long bead of solder. 

The amount of power and tip size are relevant to temperature recovery time. The soldering tip is the heat sink of the iron. With certain limits, the larger the tip is, the fewer times the iron has to heat back up to the appropriate temperature. The greater power also helps maintain the temperature with fewer drops below the right temperature.

Note that rheostats do not control the temperature, they control the amount of power reaching the iron, making the recovery time longer. 

General information on soldering irons.

Narrow Grozing Pliers - Use?

 

Top pliers are used but undamaged.  The bottom pliers have rounded tips and will not grasp thin pieces of glass anymore.

Narrow grozing pliers are very useful in many circumstances, but their use is different from the standard 10mm grozing pliers.

Use narrow pliers to grasp small pieces and pull away from score. A firm but not hard grasp of the glass is required to pull the small pieces off. The square tips are important to the function of the pliers. If the tips are rounded, it is not possible to grasp the small pieces of glass to pull them away from the scored part without slipping off.

Squeezing hard crushes the glass and wears away the jaws quickly, which rounds the ends of the pliers, making them unsuitable for their intended purpose.

They are not meant for grozing. And in any case grozing is done with the serrations further away from the tip of grozing pliers. Misuse of the narrow pliers causes rapid wear and greatly reduces the useful life of the tool.

Possibility of Stopping Chipping Glass while Sawing?

Frequently there are chips on the bottom surface or breakouts at the end of cuts while sawing glass. There are several methods to reduce these effects.

Saw blade depth

The blade on an adjustable depth overhead saw should be set to just below the saw table depth. This reduces the break outs on the bottom surface. It helps to make the angle at which the saw blade meets the glass more acute, helping to reduce the chipping of the surface.

Of course, on an adjustable overhead saw blade could be set to just mark the surface to reduce chipping on the top. Then the table drawn back to adjust the blade to the full cutting depth. However, that is a lot of adjustment to reduce minor chipping that will be remedied in further cold work or fire polishing.

For saws that do not have adjustable depth, bottom surface chipping can be reduced by placing sacrificial glass below the main piece. This raises the main glass and creates a more acute angle between the glass and the blade, also reducing chipping on the upper surface.

Ends of Cuts

Break outs often occur at the ends of the cuts. Placement of a sacrificial piece of glass vertically at the exit of the cut helps to give a clean cut at the end. This will apply whether using a fixed or adjustable saw blade.

Of course, the two can be combined:

Diagnosis of Cutting

If your scoring and breaking of your glass is not going well, you need to diagnose the reasons.  There are always a lot of suggestions that warming the glass will solve the problem. Yes, warming glass may help. A discussion of the effect is here. But it will not overcome any faults in the basic skills of scoring.

A lot of images, shown on the internet, of straight line scores failing to break along the score, indicate some possible elements in scoring that lead to these unwanted break-outs. 

One possibility is you are using too much pressure. A discussion of the amount of pressure required is here.  You should be scoring to the pressure required, rather than any sound that may come from scoring.  This is emphasised when cutting opalescent glass.  The correct scoring pressure makes almost no sound or only a gentle rumble as it cutter moves over the undulations of the glass.  The most frequent reason for more difficulty in breaking opalescent glass is excessive pressure while attempting to get the same sound as from transparent glass.  There are even a few transparent glasses that make little or no sound when being scored with the correct pressure.

Another common problem in scoring is keeping an even pressure throughout the score.  It can be difficult to keep the pressure even on complicated cuts.  When the cartoon has multiple curves or deep concave lines, it can be difficult to keep the pressure even as you move your body around to follow the line.  One piece of advice I received early on in my learning was to rehearse the score allowing the cutter wheel to move along the score line with virtually no pressure.  This shows how the piece of glass needs to be oriented to ease your movement around the glass to make the score.

Slowing the cutting speed can help to keep the pressure evenly distributed along the score.  Straight lines are often scored quickly.  But, even on straight lines, slowing the speed can make the pressure more even throughout the score.  It can also avoid variable speed during the scoring, which leads to different forces being placed on the glass.  The pressure may be consistent, but the effective pressure is greater when slow than when fast scoring is used.  If the speed is variable, the effective pressure differs along the score line.

A fourth thing that may be happening on straight lines is that the cutter wheel is at an oblique angle to the direction of the score.  This will often be heard as a scratching sound as you move along the score line.  This can be overcome by a gentle pressure against the straight edge you are using to align your score.  Of course, the straight edge needs to be held firmly to avoid having it move.  Allowing the head of the cutter to have a little freedom of movement also helps keep it parallel to the straight edge.

All this is merely speculation about your scoring practice.

You need to get someone to observe you scoring.  They do not need to be experts, nor other glass artists.  They just need to be observant. Tell them what you are looking for in each of the four elements of scoring and have them observe only one thing at a time.

First get scales that you can zero when you have a small piece of glass on it. Score without touching the glass. Have the observer tell you if the pressure was consistent throughout the score, and if you are in USA, whether the pressure was above 7 pounds or below 4 pounds. (For the rest of the world 3kg to 1.8kg). Practice until you can score consistently at about 2.2kg (ca. 5 pounds).

Second, have the observer stand a little distance from you. Score toward the observer. They need to observe whether your cutter is perpendicular to the glass while scoring and if there is any variation.

Next, they need to tell you if your head was directly above the cutter all the way through the score. They will be able to see whether your eye is directly above the cutter

Is your body behind the cutter, or do you use your arm to direct the cutter?  The observer will be able to tell that when you are scoring curves. The most consistent speed and pressure is delivered when the cutter is steered from your torso, rather than your arm and wrist.  It slows the scoring action, gives smoother curves, and more even pressure.

The last element, you can do yourself.  Once you are doing all the things above, you will be able to hear any scratching noise, rather than the gentle creaking noise of an even score with adequate pressure.  If the scratching noise is intermittent or only at one point, the likelihood is that you are twisting the cutter head, so the wheel is not in line with the score line.

Adjusting Cut Runners

There are a number of types of cut running pliers.  These photos show some of them. 

The apparently most popular is this:

Cushions

It is frequently difficult to find replacements for the plastic cushions that come with a new pair of cut runners.  People resort to a number of means to provide a substitute.  Some wrap electrical tape around the jaws, others use fabric bandages (Elastoplast/band aids).  I have even used the liquid plastic that is designed for coating tool handles.

However, if you adjust the cut runners appropriately, you can use them to run your scores even without cushions.  The purpose of these cushions is only to compensate for too much pressure in running the score.

Use without covers

You can run the score without cushions by using the adjustment screw on the top jaw of the tool. Yes, it does tell you which is the top jaw without having to check the end of the runners, but it has a more important use.  It is not just a pretty cool way to tell which is up. 

Its purpose is to adjust the width of the opening so that it provides the appropriate amount of bending force no matter how much pressure you exert at the handles.  If you are running scores in three-millimetre glass, set the jaws to that width by turning the screw until the jaws are that width apart.

Place the jaws in line with the score, aligning the mark on the top jaw with the score line and squeeze the pliers.  As you squeeze, the curved jaws provide enough bending force to run the score without over stressing the glass.  It is the adjustment screw that limits the over-stressing of the glass during the running of the score. Yes, you may not be able to run the whole length of the score this way, but you can repeat from the other end and that is usually enough to complete the running of the score.

You can continue to use cushions of various sorts with this adjustment for thickness, but I found that these were not necessary when the runners were properly adjusted.  In fact, I found that soft cushioning made more difficulties than using them with the bare metal.  I discovered this during the period of using the liquid plastic coating as used for tool handles.  I dipped the jaws multiple times to give a cushioning effect and it worked fine.  The cut runners continued to work even after the coating had worn off.  It was then that I realised I could control the running pressure more directly than by having a cushion between the glass and the jaws.

Setting the spacing

An easy way to set the correct opening of the jaws is to test against the glass you are about to score and break.  Place one side of the jaws against the edge of the glass. Slide that corner just a few millimetres over the glass.  Turn the set screw on the top of the jaws anticlockwise until they are fitting the glass snugly.  Back off a half turn (clockwise) so the jaws move easily along the edge.  This is now set to run the score on this glass. 

Open the jaws and place the centre mark in line with the score.  Close them gently and you can observe the arc of the jaws above the score line. Squeeze the handles and the score will run along the line away from the cut runners.  As you have adjusted the opening, no matter how hard you squeeze the cut runners, you cannot add more pressure.  This means you avoid crushing the glass.

The principles

The curve of the jaws is designed to provide the bending force required to run the score.  The radius of the curve has been designed to provide the correct bending pressure for differing sizes of glass.  The most common ones are useful for glass up to, but not including, 6mm glass.  The screw adjustment provides compensation for differing thicknesses of glass.  Setting the width of the gap to match the thickness of the glass prevents the application of too much pressure.

Thicker glass

For thicker glass you need cut runners with wider jaws.  These usually are fitted with three points to apply the breaking pressure - one under the score and one each side of the score on the top.  Again, these are adjusted to be just less than snug to the glass before applying the pressure.

One example of  cut runners for thick glass.  There are a variety of others.

Polishing Edges by Hand

 This post is about hand polishing edges, although the most common method seems to be a fire polish.  But the other, less considered, method is to polish by hand. 

Advantages of cold working

• Hand polishing edges does not need to take long, as the area to be polished is very small in relation to the whole piece.
• The effort of manual polishing is rewarded by kiln time saved for additional pieces that can be produced while refining the edges of the current piece.
• There is much less risk of anything going wrong in hand work than in re-firing the piece.

Equipment

Handheld smoothing pads and water are all that is required. 

The pads are normally diamond ones and should start with 60 grit, if a lot of glass needs to be removed, but 100 grit will be good to start with for smoothing a ground edge.  Then double the grit number (which is a halving of the particle size) to remove the coarser scratches and finally a 400 grit.

Then move to a 220 grit resin smoothing hand block.   These hand pads with diamonds encased in resin, are similar to this from HIS Glassworks.  

Credit: HIS Glassworks

They give the edge a satin finish, and that may be enough to be so pleased with the appearance that you do not need to do any further work.

In all these stages you need to have the surface damp.  When a white paste appears around the grinding area, it indicates that more water is needed.

If you want to go further toward an optical finish, you can use a cerium impregnated hand pad such as this. 

Credit: HIS Glassworks

For cerium impregnated pads you need less water than previously, to be able to generate the heat required to cause the chemical reaction between the cerium and glass.

You, of course, can use machines such as a handheld rotary tool.  You can get small diamond and cerium pads for these from many suppliers such as HIS Glassworks or Eternal Tools.  You will need to turn the speed down to almost the minimum to do the work needed without generating too much heat, or spraying water all over the workspace.  Most importantly you need eye and breathing protection against glass particles and dust when using rotary tools with no guards on them.

 

 

Soldering Iron Maintenance

“How do I maintain my soldering iron?  I see so many different methods online that I find it confusing.”

Regular cleaning

There at least two reasons for regular cleaning of the solder bit.

The first is to avoid the build-up of carbon and other contaminants which impedes the transfer of heat from the soldering bit to the solder and surfaces to be joined.

Many soldering stations come with a sponge which, when wet, is used to quickly swipe the iron's tip clean. A small amount of fresh solder is usually then applied to the clean tip in a process called tinning.

The second is to maintain the soldering bit in good condition.

The copper that forms the heat-conducting bulk of the soldering iron's tip will dissolve into the molten solder, slowly eroding the tip if it is not properly cleaned. As a result of this, most soldering iron tips are plated to resist wearing down under use. To avoid damaging the plating, abrasives such as sand paper or wire brushes should not be used to clean them. Tips without this plating or where the plating has been broken-through may need to be periodically sanded or filed to keep them smooth.

To avoid using abrasives, cleaning with sal ammoniac is recommended. This comes in a block. You rub the hot soldering iron bit on the surface. As the surface becomes hot, it begins the cleaning process, noted by the smoke rising from the block. When the block under the bit becomes clear, the bit will be clean and can be tinned as above. If this is done at the end of each session of soldering, the bit will last longer and will be ready for soldering immediately when you next need to use it.

Turn off the Iron

The most important element in the deterioration of soldering iron bits is long idle times. This is where you leave the iron on, and not in use, for a long time.

Have everything ready when you start soldering, so the iron will be used continuously, and will not sit there building up heat, while you get ready to use it again. An idle iron without internal temperature control will keep heating to its maximum capacity and, without anything to transfer the heat to, it will start burning off the tinning after a short while. If you will not be using the iron for a while turn it off until you are ready again.

Tinning

If a bit has not been properly tinned, solder will not wet to it. Without solder on the bit heat transfer from the bit to the work surface may become extremely difficult and time consuming, or even impossible.

You will understand that proper wiping and continuous wetting is important and a lot easier than continually having to clean and re-tin the bit, especially at the risk of damage to the plated surface because of accidentally scratching, or over abrading it.

When you notice that an iron is not performing as well as it did when it was new you will find that poor thermal transfer from the soldering bit to the work is usually the cause. Improper care and maintenance and the lack of a periodic cleaning of the bit can cause a layer of oxides to form, which will inhibit the transfer of heat through the bit.

These factors are reasons why keeping a film of solder on the bit (tinning) is important in maintaining the long life of the soldering bit.

Courtesy of American Beauty Tools

Cleaning the whole Bit.

Each soldering bit has a shank which fits into a heating collar of one kind or another.  The bit should be removed at periodic intervals and the build-up of oxides should be cleaned from the shank.  The oxides inhibit the transfer of heat from the elements to the soldering bit.  This cleaning work, of course should be done when the iron is cool.  You can use fine abrasives on the shank to remove the oxides.  You can also make a tube of fine sand paper to clean the inside of the heating collar.  This should not be done on ceramic heated soldering irons such as the Hakko.

Wattage

Another element in the maintenance of soldering irons is to have an iron of high enough wattage to readily melt the solder and be able to reheat fast enough to maintain the necessary melting temperature. An iron with enough power will reduce the strain on the heating element of the iron and the strain on the user while waiting for the iron to catch up.

For example, an 80-watt iron is sufficient to solder with, but it will continue to get hotter, as it has no temperature control, becoming too hot for stained glass soldering, and often causing breaks in the glass. An iron of this type is often used with a rheostat in order to prevent overheating while it is idling. However, this  reduces the power to the iron and so increases the time needed to recover sufficient heat to continue soldering.  Also, a rheostat only slows the heat up, it does not limit it, so eventually the iron will still become too hot if left to idle.

Most temperature-controlled irons seem to be produced in 100 watts or higher. These irons attempt to maintain a constant temperature. Their ability to do so depends on the wattage and the amount of heat drained from the bit during soldering. The temperature-controlled irons are normally supplied with a 700°F bit (identified by the number 7 stamped on the internal end of the bit) and is sufficient to melt solder without long recovery times. You can obtain bits of different temperature ratings, commonly 800°F and 600°F. The 800°F bit is particularly useful when doing a lot of copper foil soldering, because it recovers to a higher temperature, allowing much more continuous soldering action.

An increasingly popular soldering iron has a ceramic heating element, requiring less time to recover heat, and with a lower wattage.  Most of these have a temperature dial for setting the soldering temperature, and most find 410C suitable for copper foil work, although 380C may be enough for leaded glass soldering.

You can also get several sizes of tips for different detail of work.  Upon first sight a fine tip would be useful for fine copper foil work.

But fine tips loose heat quickly, requiring the user to wait while the tip regains the required heat.  A 6mm to 8mm wide bit is useful to maintain the heat during the running of a long bead.  Of course, the bit is wider than the bead being run, but the solder has enough surface tension, while molten, to draw up into a bead on the copper foil without spreading – unless too much solder is being applied. Really big bits of 12mm or larger are not practical – long initial heat up times, and too much area is covered, even though there is enough heat stored for really long solder beads.

Revised3.1.25