Vase Cap Fitting

“Can anyone offer me any tips for fitting the brass caps onto lampshades?””

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.

A general discussion of panel lamp dimensions

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.

Another another method of attaching vase caps will be given soon.

Tinning vase caps

Reinforcing Panel 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 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.

Also look at the ways of reinforcing the bottom edges of lamp shades

Attaching a Spider to a Lamp

To get the maximum support from the spider, bend the legs to fit the shape of the lamp. Then clean the spider assembly well with steel wool, or if particularly dirty with fine sandpaper, until it is bright again.

Apply flux and run a film of solder onto the legs where they will be in contact with the lamp. This will give you an indication of the amount of heat required to solder the legs to the lamp. It will also make it easier to fix the legs to the lamp once the appropriate temperature has been achieved in the legs.

You need to use the full power of your soldering iron, as the brass soaks up a lot of heat. If your iron is small you may need to change to one with higher wattage for this work.

As the heat is transferred quickly to all parts of the spider, wear gloves or hold with pliers while soldering.

Tinning brass vase caps

Tinning brass vase caps can help in obtaining a secure joint without long dwells at each joint, that risk overheating 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.

Lampshade Pattern/Cartoon Tools

Lampshade patterns –tools for custom-made patterns.

The items you need to have for creating your own pattern are not extensive or unusual.

• Craft knife or razor blade
• Baby/talcum powder
• Fine pointed felt tipped pen (Sharpie)
• Highlighting pen
• Pencil
• Eraser
• Carbon paper
• Drawing paper
  Masking tape
• Lampshade form
• End/vase cap
  

Further design process information is here and here

Lamp Panel Dimensions

Lengths of Panels

Lampshade Pattern Construction, 3

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 and throw it away.

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 the 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 do not tear or cause to pull away the underlying masking tape 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.

Cut out one copy and reapply it back to the form
One copy is fastened back onto the form so that you know where to put your glass pieces.

Cut out the other copy and paste it onto your glass
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

Lampshade Pattern Construction, 2

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
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 feature first and filling with the minor elements helps provide a pleasing composition.

Fill in blank 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

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 length of the shade.
• At the top draw the radius of the vase cap on each side of the vertical.
• At the bottom draw 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 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.

Lamp Panel Dimensions

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 (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.

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 the thickness of the glass time 2 (the glass thickness is on both sides of the circle). Do the calculation as for the lower edge of the panel, and then subtract the thickness of the glass from that width. For most glass this will be 3mm.

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

Formula for top: dia. - glass thickness *2 * pi = circumference / no. of panels = uncorrected width – thickness of glass =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 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.