A USEFUL size for the glass sides is 15 in. x 12 in. If the frames are sloped at an angle of 30 degrees, the height at the centre is approximately. The board can be formed out of pieces of odd 6in. Flooring battened together to give the necessary width and length. The board itself should be securely cramped to the bench or to a table while the bending is done. It will be seen that we need a baseline, on which are marked off points at 1 in., 6in. And 12 in. Then from the 6in. Mark we must erect a perpendicular; the mark for the apex point comes between 10 ½ in. and 10,in. Up from the baseline.
Pegs are needed around which to bend the wire; bore holes at the marked points and insert Gauge 12 wood screws, letting the shanks stand up about ¾ in. above the base board. Then saw off the screw-heads with a hacksaw, so that they will not prevent lifting off the wires when completed. Galvanized or tinned iron wire, in Gauge 10, is suitable for the job, and no thinner gauge should be used, or the wires will not be stiff enough. Slip a piece of string around the pegs and allow 3in. For surplus; then cut off a piece of wire to the length measured by the string. The frame has an eye at the apex, through which the top wire is passed to assemble the cloche; note also, that the external ends of the frame are bent up somewhat in the form of a hook to support the glass.
Start the hook on one end by bending gently in a vice; hook this end tightly on the left-hand peg, and take the wire up to and around the apex peg at the top. Here it should make a complete turn to form the eye, and should continue down to the right-hand peg, around ‘which it is bent from the inside. Start the second hook or upturn, which can be finished off in the vice. A gentle tap with a light hammer, or a pull with a strong pair of pliers, will aid in forming the bends. Now take off the frame; the apex eye will probably need closing down with a hammer blow.
Cut ofT the surplus wire with a nacksaw; failing this tool, make a deep nick with a three-square file on two opposite sides of the wire at the point needed, when the pliers will finish the severence. (But if the file nicks are not taken deep enough the wire may be bent and damaged in trying to break it).
Bending the Top Wire
After as many pairs of the end-frames have been formed up we must deal with the top member of the assembly,. This is turned up at the ends, and formed into a loop or handle at the middle of its length. A simple jig should be formed, screwing in pegs where needed, and screwing down a disk of hardwood as the ‘former’ for the circular hoop, which is shown as having a circle of ½ in. radius. Pegs are needed wherever the wire changes direction except when the wood disk takes care of the lifting hoop. Although it would be more difficult to bend, a wire of even stouter gauge would be an advantage for this member. The handyman who is dextrous with the soldering bit could omit the central loop, which is the hardest piece of bending, and solder on a separately made loop formed from the 10-gauge wire.
Again, the eyes at the apexes of the end frames could likewise be omitted, and a separate eye soldered into the top of the bend there.
It may be possible to get glass in a size near i8in. X 12 in., but not in these actual dimensions. In such case the size of the wire frames should be modified to suit. In any case, the top and lower edges on the long sides should be protected from harm by a strip of tinplate, or, much better, sheet zinc, about an inch wide and i8in. Long, bent over to enclose the edge and stand up about ¾ in. on each side. If it is desired to save cost, the edge clips may be only about 6in. Long, and be placed one at each outer side of the sheet, where it will lie against the hooks of the end-frames.
Take one top wire and a pair of end-frames; pass the ends of the top wire through the eyes of the end-frames, and stand the assembly approximately in place on the ground. Then lay a sheet of glass with the lower edge in the hooks and leaning against the side wires; follow by inserting the opposite sheet. Adjust finally, and secure the frames to the ground with simple wooden pegs. The end-frames may be kept at the proper distance apart, at the apex, by a few turns of tinned iron binding wire, or copper wire.
Longer Pattern with Wooden Frames. Wood frames are made up to support the glass, the one illustrated representing the end-frames. Intermediate frames of similar construction should be made up as required, the footboard (A) in this case being centralized on the frame, and the uprights being furnished with a pair each of cross-pieces (B and D), one at either side of the uprights C. An intermediate is needed wherever two i8in. Lengths of glass abut. The end-frames and the intermediate ones are connected by passing a length of dowel rod, or a piece of ½ in. (nominal) gas-barrel, through holes bored in the top member (D) of all the frames to suit. These holes register, and coin-cide in all the frames.
Begin by sawing sufficient footboards (A) from a piece of sound deal or hardwood not less than full ¾ in. in thickness. A length of ½ in. barrel can be bought from a gasfitter or a builder’s merchant. It should be painted with two coats of lead or aluminium paint before use. The holes in the cross-pieces (D) must be an easy fit. If the assembly is not more than 3ft. In length a piece of wood dowel rod will serve as the central support, but gas-barrel is better. Apply two coatings of creosote to all woodwork before use. The glass can be kept in place by simple clips made of small pieces cut from zinc sheet, screwed to the woodwork with brass screws, round-head pattern. The frames can be kept steady by inserting pieces of half-inch dowel rod at each end, putting them through holes bored in the footboards so that these pegs enter the ground a few inches. Of course, all the frames must be levelled up approximately if assembly is to be stable.
Strengthening the Glass
The glasses can be framed with a strip of zinc in the passe-partout manner. Sheet zinc in Gauge 13 (approx. Gauge 22 in B.W.G.) is suitable. Cut a strip as long as the four sides of the glass, plus a little extra; the strip should be about I£ in. wide. Lay it flat on the bench and rule parallel lines to show where the flanges stand up; leave ample room for the thickness of the glass. At each point where the strip is to change direction, a vee-notch must be cut, as in passepartout work, to allow a clean junction on the flanges. The point in the strip will come in the middle of the lower edge of the glass Therefore measure from one end of the strip inwards, half the length of the long side; cut a notch at each flange; next measure for one short side (notch); the top long side (notch), the remaining short side (notch), and for the remaining half-length of the bottom side.
Start the bend for one flange by slipping the strip down a crack between two boards of the bench top, and gently bending over; complete the flanges by bending the zinc up over a thin lath, or a strip of brass, of the same thickness as the glass. Lay the strip on the bench and stand a sheet of glass over the points for the top long side. Bend upwards at the angles; take out glass and bend further inwards a little; replace glass and now bend partly over for the bottom half-lengths, just enough to get the accurate positions. Take out glass, and bend down one more half-length with glass finally in position, close-in both half-lengths. Solder on a piece of zinc, bent to the same form, over the join.