<<Preparing the Boom Clamps>>

The steel front boom tube is attached to the chassis by a pair of identical carbon-fibre mouldings, the boom clamps This section covers the preparation of these mouldings. This does not need a lot of work: predrilled holes in the moulding simply need to be enlarged, and two lengths of 8mm stainless steel studding are then epoxied in, along with a pair of thin nuts.

The pieces of studding should be 125mm long, although if you make them longer, you could trim them to length afterwards. The nuts that are bonded in are 4mm thick (about half the thickness of a standard 8mm nut)

The holes for the studs are predrilled in the mouldings, but you need to enlarge them from 6mm to 8mm. The best tool for this is an abrasive rod - also used on the rear arm . It may look like a quarter-inch round file in the photo but in fact the surface is coated with carborundum or something similar. I have two of these in my workshop, both bought from cheapo tool suppliers when I had absent-mindedly locked my trike without having my keys with me. They cut carbon composite fairly quickly (although you need patience to cut hardened steel). An ordinary file won't last long on carbon fibre.

When you enlarge the holes for the studding, cut down squarely to the inside of the corner, allowing the studding to nestle snugly in position. Try not to make the holes larger than necessary. Place each moulding on a flat surface to check that the studding can pass through squarely. You can measure the height, at each side, of the studding above the surface with something like a flat file, as in the picture.

The next thing to do is to abrade the surface of the mouldings where you want epoxy to adhere. Use emery paper to do this. There will be release agent remaining on the surface from the moulding process. You want to remove this, and the surface shine, to encourage adhesion. You need to do this inside the mouldings, and outside on the area underneath the nuts.

Now you can bond in the studding with epoxy. Protect the moulding with sticky tape where you do not want epoxy to adhere. Proper masking tape is best as ordinary tape may leave a hard-to-remove deposit on surfaces. Apply epoxy to the insides of the nuts and along the length of the studding. Rest each boom clamp on a flat surface during the curing process so you can check that the studding is the same height on both sides. Epoxy likes to be warm while it sets.

<<Overview BUILDING THE GNAT The Rear Arm>>