Sunday 25 September 2011
Vase Caps
Tuesday 20 September 2011
Sieves, Gauges and Grits
The commonly used designation for grits has become the gauge This is a confusing measure as it increases in number as the size of the material decreases in size. This is because the number of wires per unit increases with decreasing size and the gauge refers to the number of wires used to sieve the material.
In an attempt to indicate the actual sizes of material refered to by the gauge sizes, I have used part of a standard table of equivalents.
12 gauge is 1.7mm or .0661inch
14 gauge is 1.4mm or .0555inch
16 gauge is 1.18mm or .0469inch
18 gauge is 1mm or .0394inch
20 gauge is .85mm or .0331inch
25 gauge is .71mm or .0278inch
30 gauge is .6mm or .0234inch
35 gauge is .5mm or .0197inch
40 gauge is .425mm or .0165inch
45 gauge is .355mm or .0139inch
50 gauge is .3mm or .0117inch
60 gauge is .25mm or .0098inch
70 gauge is .212mm or .0083inch
80 gauge is .18mm or .007inch
100 gauge is .15mm or .0059inch
120 gauge is .125mm or .0049inch
140 gauge is .106mm or .0041inch
170 gauge is .09mm or .0035inch
200 gauge is .075mm or .00295inch
230 gauge is .063mm or .0025inch
270 gauge is .053mm or .0021inch
325 gauge is .045mm or .0017inch
400 gauge is .038mm or .0015inch
450 gauge is .032mm or .0012inch
500 gauge is .025mm or .001inch
635 gauge is .02mm or .0008inch
Thursday 15 September 2011
Soldering techniques
Saturday 10 September 2011
Residues
Friday 9 September 2011
Scoring Glass
Holding the Cutter
Generally, you use the cutter by moving it away from you, so you can see the cartoon lines as you score. When using a straight edge such as a cork-backed ruler to guide your cutter, you can pull the cutter toward you, or push it away as suits you. The cutter should always be held at a 90 degree angle (left to right). You can determine this by looking down the cutter to the wheel and to the cartoon line below.
It is important that the work be done from the forearm rather than the fingers or the wrist. The forearm should be held closely to the body. This reduces the freedom of movement, giving clean flowing score lines. It also reduces the actions that can lead to repetitive stress injuries. Any turning required by tight curves can be done by turning the body from the hips or shuffling around the bench with the glass at a corner. Of course, for long cuts your arm will have to extend from you body in a parallel direction with the score line.
Scoring Pressure
The second and very important element in scoring glass is the amount of pressure used. Very little pressure is required. You should hear no more than a quiet hiss on transparent glass and almost no sound on opalescent glass. However some manufacturer's transparent glass has almost no sound either. So the important element is the pressure, not the sound. Most people start with applying far too much pressure. Tests have shown that only about 2 kg of pressure is required for a clean score.
You can test the effect of this amount of pressure on a bathroom scale. Place a piece of clear glass on the scale and without touching the glass with your other hand, score it noticing how much weight is being recorded. Keep trying until you are at the 2 kg area of pressure. Try breaking the glass. Score a curve with the original amount of pressure and break the glass. Then using the same curve score the glass with the 2 kg pressure and break the glass. You will see and feel the lesser pressure provides a clean break.
Excessive pressure leads to breaks showing significant stress marks on the edge of the glass. Too little pressure has no effect on the glass, making it impossible to break along the score line. The correct pressure (ca. 2 kg.) leads to almost vertical stresses being put into the glass which assists the breaking along the score line. Too heavy pressure creates stress marks which are at increasingly large angles with the increasing pressure. This will still break cleanly on straight lines, but when working around curves the glass can follow one of the lateral stress marks away from the score line. Excessive pressure is often the cause of glass breaking away from the score line on a curve, especially a tight one.
Monday 5 September 2011
Foiling Nuggets
Wednesday 31 August 2011
Glass Stuck to Moulds
- Is the glass trapping the mould? This happens most often when the glass is draped, especially over ceramic moulds.
- Has the glass been fired high enough to fuse to the mould? If you have fired the glass to tack fusing temperatures, you may find more occasions when the glass sticks slightly or firmly to the mould.
- Is the mould trapping the glass? This can happen when slumping into a steep sided steel mould. Occasionally a steep sided ceramic mould will show the same effect.
- Has the separator been too thin or failed? If none of the previous elements apply, it may be that the separator was too thin or has been fired to tack fusing temperatures in a previous firing.
Friday 26 August 2011
Aperture Drops Finishing
For most aperture drops and for most people, it is desirable to remove the rim. To have successful drops without rims, you most often need to have access to cutting and polishing equipment.
You can use a tile saw or band saw to cut off sections of the flat rim and then a linisher to grind the edges to round, followed by polishing. This will give you a thick rim.
If you want a thin rim, you will need to cut through the drop at the top - visualise a cut at right angles to the length of the drop. Usually tile saws are too aggressive for this. If you can find a band saw with a high enough clearance, you could gently separate the rim from the drop after having reduced the size of the rim to make the use of the band saw more easy.
In both cases you must grind and polish the edge of the rim to give a finished appearance. Fire polishing is not possible as the drop would collapse long before the rim was smooth.
Sunday 21 August 2011
Aperture Drops Annealing
Tuesday 16 August 2011
Aperture Drops - Stopping the Drop
Thursday 11 August 2011
Aperture Drop Observation
This kind of firing absolutely requires observation of the progress of the drop. Ideally you would set up the firing surface where you can peek at it during the firing as well as observe the bottom of the kiln or the shelf – which ever you are firing upon.
I you have to choose, then the bottom of the kiln is the most important place to have clear observation lines. Even if you do not want the drop to touch the shelf or bottom of the kiln, you will need to observe how far the drop has progressed.
Thus, planing for the placing of the supports and other elements of the drop are important. Support posts should not obscure the view of the drop, for example. The whole set up should be placed far enough back in the kiln to see the shelf/kiln bottom where the glass will touch down.
If you do not want to have the drop touch down onto a surface, you need to set up a “witness” to indicate how far the glass has fallen. This can be some pieces of fibre stacked up so that your view through the peep hole to the top visible surface of the “witness” will tell you that when the glass touches that line of vision, it has reached the desired length.
You need to patient, as the soaks can be two or more hours long for a low temperature drop.
Saturday 6 August 2011
Aperture Drop Placement
Wednesday 3 August 2011
Grinder Head Grub Screw
Monday 1 August 2011
Aperture Drops Firings
- one is to heat at a very slow but consistent rate. After the annealing point has been reached the speed can be increased.
- the second is to go a bit faster, but with soaks at three or more intervals in the heat up. After each soak the speed of advance can be increased a little. The soaks should be from 15 to 30 minutes, depending on the speed of heat up.
- aperture size
- weight of glass
- speed of advance to forming temperature
- glass used (to a lesser extent)
Friday 22 July 2011
Aperture Drop Supports
Sunday 17 July 2011
Aperture Drops – Length of Drop
glass required.
The thinning effect of the stretching can be influenced by both the temperature and material of the supporting material.
Tuesday 12 July 2011
Aperture Drops Introduction
The height of the drop from the shelf.
Material of the supporting ring or material.
Initial firing speeds
Height in kiln and relation to the distance from the heating elements.
Observation of the progress of the drop.
Arresting the drop
Annealing and cooling.
Finishing the resulting drop.
The above instalments will discuss these in turn.
Thursday 7 July 2011
Scoring Opalescent Glass
Saturday 2 July 2011
Care in the Operation of Soldering Irons
Monday 27 June 2011
Grinder Bits
Wednesday 22 June 2011
Replacing Grinder Heads
Friday 17 June 2011
Leading Nuggets
Sunday 12 June 2011
Edges for Copper Foil
You do not need to use wider foil on the edges, but I have often done so to give the edge just as much "line value" as the internal beads. However this needs to be planned from the beginning. If you simply add a wider line on the outside, many times you will compromise the integrity of the design at the sides. You need to cut the glass a fraction larger to accommodate the thicker foil. Two millimeters added to the outside edge should be enough.
Wednesday 8 June 2011
Foil not Sticking on Edge
I’m working on another irregular shaped suncatcher and I have just completed the soldering. Now I've found one small section the copper foil is not sticking. How can I fix this?
The adhesive on copper foil tape is not a permanent one. It only sticks to the glass long enough to apply the solder to the foil. The heat of soldering often degrades the adhesive so much that it no longer sticks. What holds the solder down is the solder bead. So you probably do not have a full bead on the edge. Placing a bead on the edges of pieces is difficult but you can find a method here.
You can make the edge beading a bit easier by putting thin copper wire around the edge of the piece. This strengthens the whole piece. It allows you to attach a hanger without risk of pulling the whole suncatcher apart. It also allows you to form a bead on the edge more easily.
The bead formed on the edge curves around to the front and back faces allowing the solder to hold the copper tape more firmly to the glass.
Saturday 4 June 2011
Tie Wires
The tie wires should be securely soldered to the panel at solder joints. Placing ties elsewhere leads to the tearing of the lead. The soldering of the tie wires requires more heat than simply soldering the lead joints. The tie wire needs to be heated enough to melt the solder of the joint to which it is being attached. Then an additional dot of solder needs to be added so that the wire cannot simply pull out from the joint by being only sweated to the joint.
At installation, when the panel is fully seated in its opening and fastened by nails or sprigs, pull the tie wires out at right angles right at the edge of the solder attachment before twisting the wire. Do not use any more than firm pressure. Then you are ready to cross the wires over the glazing bar. This ensures there is no excessive give in the copper tie.
Do not over tighten the tie wire twist. Only twist until snug against the bar. Then continue to twist the loose ends until you have them a satisfactory length. Cut off the twist rather than the tail ends to provide a neat finish. Then tuck the twist under or over the bar, just as you desire.