Design
- Pattern/Cartoon Tools
Pattern
Construction
Soldering
3-D Pieces
Reinforcing
Lamp Shades
Vase
Caps
Fibre
blanket Moulds for Shaped Panel Lamps
Design
of Panel Lampshades
Lamp Panel Dimensions
Lamp
Panel Lengths
If
you have determined the length of the shade and the diameters of the
top and bottom, you can determine the length of the panel by maths or
by a scale drawing.
Calculation
of length
The
maths is about right angle triangles. The dimension of the vertical
part of the right angle triangle is the height of the lampshade. The
horizontal dimension is the radius of the bottom minus the radius of
the top. The length of the angle is the square root of the sum of the
square roots of the vertical and horizontal sides.
E.g.,
a lampshade 200mm high with a 50mm vase cap and 400mm bottom width:
The
vertical of the triangle is 200mm.
The
horizontal is 400/2 = 200mm – 25mm (half the diameter of the vase
cap) = 175mm.
The
length of the panel is equal to the square root of the sum of the
squares of the sides.
In
this example, 40000+30625=70625 of which the square root is 265. So
the panel is 265mm long.
Measuring
the length
If
you don’t want to do the maths, do a scaled or full size drawing.
It only needs to be one side of the shade, but it can be the full
shade.
Draw
a vertical the height of the finished shade. Draw a horizontal line
at the top and bottom of the measured vertical.
At
the top mark off the radius of the vase cap on each side of the
vertical. At the bottom also mark the radius of the shade on each
side of the vertical.
Join
the two end points of the horizontal lines on each side of the
vertical.
Measure
this diagonal line to determine the length of the panel.
This
drawing method does have the advantage of allowing you to see the
angle of the proposed shade and adjust it if necessary.
Calculating
the top and bottom widths
When
doing custom lamp sizes is not too hard to calculate the panel sizes.
You need to remember the value for pi
(ca.
3.1417)
Start
with the bottom diameter you want. Multiply it by pi.
Divide this distance by the number of panels required for the lamp.
This gives the size of the bottom of the panel.
Worked
example
Bottom
diameter: 200mm
Top
diameter: 50mm
Panels:
8
Pi:
3.1417
Glass
thickness: 3mm
Formula
for bottom: dia. * pi
= circumference / no. of panels = width of panel
Bottom
diameter: 200*3.1417 = 628mm/8 = 79mm for the base of each panel.
Do
the same for the top, but make one more calculation. As the top has
to fit into the size of the vase cap, you need to take account of the
thickness of the glass. So, subtract twice the thickness of the glass
(the glass thickness is on both sides of the circle) from the
diameter of the vase cap and use that as the diameter for determining
the width of the top of the panel.
Worked
example
Formula
for top: dia. - glass thickness *2 * pi
= circumference / no. of panels = width of panel
Top
diameter: 50-6= 44 * 3.1417 = 138mm / 8 = 17mm
Determine
the shape of the panel
When
you have determined the widths of the top and bottom of the panel,
you are ready to draw up the shape of the panel. Set up a horizontal
line that is the calculated width of the bottom of the panel. Divide
it and draw a vertical from the centre of the line. This line should
be as long as the panel you are making. This is determined by the
method outlined in the Panel Length tip. At the top of the vertical
line draw another horizontal. Measure off one half the calculated top
distance on each side of the vertical line. Join the points on the
lower and upper horizontals to give the shape of the panel.
Design
of shaped Lampshades
Pattern/Cartoon
Tools
The
items you need to have for creating your own pattern are not
extensive or unusual. The essential ones are:
Craft
knife or razor blade
Baby/talcum
powder
Fine
pointed felt tipped pen
Highlighting
pen
Pencil
Eraser
Carbon
paper
Drawing
paper
Masking
tape
Lampshade
form
End/vase
cap
Pattern
Construction
The
first stage of the process is to prepare the design on flat paper.
The second stage is to get the design onto the prepared mould and
make adjustments to give a balanced and pleasing appearance
Trace
the pattern onto the template
Prepare
the lampshade mould by covering it in masking tape.
Take
your design elements and trace them onto the masking tape on the
form. The use of carbon paper enables you to put the design element
and trace right on top of the taped mould so that the image is
transferred onto the tape.
An
alternative method is to use a pounce wheel to perforate the design
element. The element is placed on the form and dusted along the
perforated line with a bag of dark coloured powder such as powdered
poster paint. This will leave a temporary trace on the form that can
be changed easily, but needs to be pencilled in before too much other
work smudges the shape.
Do
this tracing with each design element, flipping and rotating them
around so that you don't repeat any element exactly. Fill up major
sections of the form using this method. Drawing the main features
first and filling with the minor elements helps provide a pleasing
composition.
Fill
in background areas
Now
that the key design elements are onto the masking tape template,
create background pieces by linking your design elements. Use pencil,
since you will probably need to do corrections. Remember, avoid
creating large horizontal pieces. Larger vertical pieces are usually
better. However, try to keep all the pieces of similar size.
Correct
any pieces and number them
Once
you are satisfied with the design, go over every line with a fine
felt tip pen or other ink pen so that each is clear and distinct.
Number each piece and mark colour and glass textures as necessary.
Based
on work by Christie A. Wood, Art Glass Ensembles
Templates
Cut
the finished template into sections (if you are using a 360 degree
form)
The
masking tape template will need to be cut off the curved form and
laid out flat. This is easier to do if you can logically separate the
template into smaller sections. To do this you need to find lines
running almost vertically from the top to bottom of the template.
Mark these separation lines in a different colour. Also label each
section.
Remove
the template(s) from the form and press it out flat
Take
a craft knife or razor blade and trim away excess masking tape from
the end cap mark. Do the same for the bottom edge. Carefully remove
the excess.
Prepare
a section of your work surface by sprinkling some talcum powder on
it, and onto your hands as well. This will help keep the sticky side
of the masking tape from sticking where you don't want it later.
Using
a craft knife, slice through the middle of each separation line that
you marked in a special colour. Try to stay in the exact middle of
the line. Be careful that you don’t tear the underlying masking
tape, or pull it away as you cut through the line. Do this with each
separation line.
Starting
with the top edge, use the craft knife to gently pull the masking
tape template off the form. If the masking tape starts to separate,
stop and repair it. As each section is taken off the form, put it
sticky side down into the talcum powder and press it flat. Do this
for each section.
Scan/copy
the template(s)
At
this stage you can scan each section into Glass Eye or other image
software. This allows you to:
select
and change colour/glass choices very easily
print
out or email colour proofs to the client
keep
them in an electronic form for future reference or manipulation
You
don't have to scan your pattern, but you do need to make at least two
copies of the pattern.
One
copy is fastened back onto the form so that you know where to put
your glass pieces.
The
other copy is cut out using pattern shears (the three-bladed
scissors) and glued onto the glass for cutting.
Based
on work by Christie A. Wood, Art Glass Ensembles
Soldering
3-D pieces
When
soldering 3-D pieces together, first tack the panels together with a
single tack at each end. If it later turns out that there is an
alignment problem, it is much easier to dis-assemble a few tacks,
with a piece of paper inserted into the space between the pieces of
glass and moved up into the molten solder while your iron is at the
tack joint. The paper will strong enough to move through the solder,
separating the two piece of glass.
Once
your 3-D piece is tacked together and looks OK, turn the piece over
on its side, and, using 50/50 or 40/60 solder, fill in the inner
seams, moving the piece around. Be careful to support the piece with
boxes or blocks and by holding it at the top part above where you are
soldering, to prevent the piece collapsing.
Once
the inside of the piece - say a panel lamp - has been soldered
smoothly with the solder with a higher lead content, turn the lamp
over and prepare to do the outside. Arrange boxes or similar supports
to prop the lamp upon, and orient it make a level joint to solder.
Using the 50/50 or 40/60 solder again, fill in the seam. It doesn't
have to be perfect, at first. Do all of the seam filling first, to
ensure the stability of the piece. Then go back with 60/40 – the
higher tin content - solder and, again making sure the lamp seams are
level, finish by smoothly soldering each seam.
Reinforcing Lamp Shades
When
constructing large or heavy lamp shades, reinforcement needs to be an
integral consideration in the construction. With panel lamps the
reinforcement is relatively simple – it can be along the seam
lines. In fact, if you do not bevel your glass at the panel edges, it
can be in the upper seam lines, as the solder filling the open joint
will cover the wire. If the panels are bevelled, the wire can just go
on the inside along the joint.
The
wire should end at the edge of the bottom of the skirt so that it
does not extend beyond, but will still be in contact with the edge
reinforcement. The upper wire should extend beyond the top of the
shade, so that it can be soldered to the vase cap. If there is not
one, the wire should be dealt with as for the bottom, and there
should be edge reinforcing.
The
wire that is easiest to use is single strand copper or brass. It
should be of a size to fit at the bottom of the “V” of each
joining panel.
The
bottom edge of a lampshade can be reinforced in various ways
depending on the shape.
If
the bottom edge is straight or only slightly undulating, brass “U”
channel or other hard metals can be used.
Where
the edges have points or acute angles on the edge, you need to use
copper or brass wire. Again, single strand wire is better than
twisted. It needs to be thin enough to conform to all the angles of
the edge.
Choose
a starting point. The best is where a reinforcing wire comes to the
edge. Also you can begin at the base of an internally facing angle,
so there is no opportunity for a wire end to stick out.
Tack
solder or sweat the wire to the bottom edge of the panel where you
decided to start. Then bend the wire to conform to the angles and
curves of a portion of the lamp. If it is a panel lamp, bending the
wire to conform to the edge of one panel at a time should be enough.
Tack or sweat the wire to the panel at the bottom of each inward
facing angle, as it is more difficult to keep the wire down in those
areas than on outward facing angles. Once you have tacked the wire
all around the panel, you will come to the start where you need to
make sure you do not un-solder the beginning of the wire while trying
to fix the end. It can be a help to overlap the end of the wire
along the beginning. Alternatively, you can take the end up along
the vertical reinforcing wire and fix it there.
Now
you can begin to run a bead along the bottom edge of the panel to
cover the wire. Make sure the wire and foil are both fluxed all along
their length. Then orient the soldering surface is horizontal as you
apply the solder. Move the shade frequently to keep the area to be
soldered horizontal to avoid the liquid solder running into uneven
lumps.
Vase
Caps
Attaching
the vase cap securely is important as often the whole lampshade hangs
from the attachment points between the cap and the solder seams of
the shade.
Once
you have assembled the shade and tack soldered it together, perch the
vase cap on the top covering the opening and apply solder so it joins
the vase cap with the solder seams. It is a good practice to turn the
lampshade over and apply solder from the seam to the inside of the
vase cap. A good strong joint at each seam will be perfectly strong
enough to hold the shade in position for many years.
Vase
Cap Fitting
There
are at least three ways to get the right vase cap size.
Make
up your shade in a cardboard mock-up. Use 3mm thick card or foam
board to represent the glass, as the thickness of the glass is
important in determining which vase cap is the correct size. Try your
vase cap against the cardboard model, then if you need, alter the
pattern so the glass pieces meet at just the right place to make the
lip of the vase cap fit just over the top of the glass. You can do
this by either shortening or lengthening the pattern a little at the
top edge.
The
second also involves making a cardboard mock up. After making this
maquette, choose a vase cap that overlaps the top opening, covering
all the edges.
The
third option is to use two vase caps, one above and one below the
opening to clamp them together trapping the edges of glass between
them. Use a furling and lock nuts with no solder at all to hold the
lampshade together.
Tinning
brass vase caps
Tinning
brass vase caps can help in obtaining a secure joint without long
dwells at each joint, risking the overheating of the glass.
Heat
your vase cap with a torch of one kind or another. You can heat until
it becomes a dull red. The quickly brush or rub (with a cloth) flux
onto the inside and outside of the rim of the vase cap. Apply a
little solder to the fluxed area while everything is still hot. This
will tin all the areas where the flux was placed.
This
method gives a strong solder to solder joint that requires much less
time when soldering the cap to the rest of the lamp shade.
Tinning
Brass
Brass
transmits heat much more quickly than lead, so a considerable length
or the whole of the piece, e.g., a vase cap needs to be heated to
avoid the cap acting as a heat sink and so not allowing even tinning
of the object.
When
tinning any brass pieces, like a lamp cap, rub it with fine grade
steel wool (often labeled 000) until bright, then wash the residue
off and dry. Apply flux with a fresh flux brush, and hold the piece
with a pair of pliers. Brass transmits heat much faster than
lead or solder, so this is a precaution against getting burnt.
At
this point you can heat the brass or vase cap with a low heat blow
torch to warm the whole piece. When warm, turn off the blow torch and
begin applying the solder with the soldering iron. Touch the
piece with your hot soldering iron, pause and then start moving the
iron slowly and smoothly over where you have applied the flux,
applying a little solder all the time.
Alternatively
you can work without the blow torch. Apply a bit of solder to the tip
of the iron. Touch the piece with your hot soldering iron, let the
piece heat up a little, and then start moving the iron slowly and
smoothly over where you have applied the flux.
When
the whole piece has been covered, wash it, dry, and then inspect for
any missed spots or unsightly solder blobs. Apply a little bit more
flux and touch with your soldering iron. If you are doing a lot of
this kind of work, an 800 degree iron tip will speed up your work.
Fibre
blanket moulds
It
is possible to make moulds from fibre blanket which will last for a
number of firings if handled carefully.
Pre-wetted
fibre blanket is available - Moist Pack is one brand name.
Or
you can make the mould yourself from fibre blanket and hardener. You
need:
-
ceramic fibre blanket. It should be 3 mm or thicker, but 25 mm needs
to be compressed when wet. It is possible to use two layers of 3 mm
fibre blanket, but they do not stick together well unless thoroughly
wetted.
-
colloidal silica - often is called mould hardener. Paint this onto
the fibre blanket liberally, both sides if possible.
Process
You
must protect the master with cling film, Vaseline, or other
waterproof separator. Be sure about whether you want a draping or
slumping mould, as the inside needs to be smoothest for a slumping
mould and the outside smoothest for a draping mould.
Press
the wet fibre blanket to the master. Then let it dry for a couple of
days to become stiff enough to remove from the master. Let the
negative dry for another period.
If
you are short of time, you can dry it in the kiln at about 200C. Once
dry, you can then fire to a minimum of 760C to harden the mould. The
point is to get the glass which has been in suspension to soften and
stick together. Upon cooling the mould will be hard, as it is held
together by the glass structure within the fibre blanket.
Then
sand to smooth. Wear a dust mask during this process and do it out
doors if possible. Otherwise a well-ventilated room is necessary. If
unhardened blanket is exposed during the sanding process, soak in the
colloidal silica and dry and fire again. Alternatively you can make
a paste of the sanded material and the hardener and apply it to the
mould before firing it again
Before
use, the mould needs to be kiln washed, or have alumina hydrate
powder sprinkled over mould, otherwise glass will stick to mould.
With
delicate treatment, the mould can be reused many times.
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| Example of a lamp panel mould from fibre blanket |
