Ever wonder how the old time pocket knife makers used to inlay the fancy little nickel shields into the knife handles? They used the simplest of tools but the only one I know which will drill a hole of any shape - this tool was a 'two legged parser' (or 'parsey' in our local dialect). It is made from a length of round spring steel which is folded in half and has the fold welded into a point (see the pictures below). The ends are then made level and are forged out flat so that, as you look at the 'vee' you see the flat faces. These flat ends are then filed so that the inner edges are untouched but the outer edges have a step filed into them of a certain depth which I'll describe later. The ends of the legs and the outer edges below the step are then filed to sharp knife edges. To complete the tool, the legs are sprung apart and hardened and tempered and a wooden bobbin is pushed onto the folded part. To use this tool, a steel template is first made with a hole cut in it of the exact size and shape required and it is hardened. The step I mentioned on the ends of the parser's legs needs to be the depth of the inlay or hole required plus the thickness of this template. To inlay a shield into a knife handle, the blank 'scale' (handle side piece) and the template would be fixed vertically in a vice and the worker would strap an oval steel 'breastplate' around his midriff. The pointed end of the parser would be placed in a dimple in the centre of the breastplate with the 'prongs' or legs squeezed together within the hole in the template and the cord of a bow would be wrapped once around the wooden bobbin (the bow was traditionally made of an old wooden umbrella handle with a twisted leather thong as the cord). With just a few rotations backwards and forwards the hole would magically appear exactly the same shape and size as the template. The nickel shields were punched out of sheet and were used just as they came from the punch - so, they were slightly domed and had a sharp edge. They were placed in the hole dome uppermost and, by giving them a quick nip in a press, they were flattened and, at the same time, the sharp edges bit into the bottom sides of the hole so fixing them firmly in place - no glue, rivets or whatever. Here are some pictures of the tools.....
This group shows three different sized parsers along with the bow (or Fiddlestick as it was often known), breastplate and samples of the templates, shields, and ivory scale with the shield hole cut and a rosewood scale with the shield in place.
A couple of the parsers close up.
The Fiddlestick or bow. This is made from the handle of a wooden umbrella or parasol and a length of twisted leather thong. At the right hand side you can see how the wood has been worn away by the thumb and finger of the worker who used it for many years.
A selection of steel templates along with the nickel shields. To the right is an ivory scale with the recess for a shield cut into it while to the left is a rosewood scale with the shield set in place.
These tools are generally only found in museums now but they are still the easiest way to cut odd shaped recesses and are very simple to make and maintain. It is a shame when simple but very effective devices like these pass out of use, only to be replaced by machines costing a great deal of money but which have limitations which these tools do not. For example, to do this job now you could use a CNC milling machine, however, such a machine uses rotary tools and so it wouldn't be possible to cut the recess with sharp corners as at the top of these shields. If the material were metal, you could consider spark erosion which would give the sharp corners but it isn't - the scales of pocket knives are usually wood, bone, ivory, pearl or plastic. All the knifemakers I knew could fit a shield to a knife handle in a matter of seconds - probably less time than it would take to secure the work in place on a modern machine - and they call that progress!!!
If you decide to make and use one of these tools I would be interested to know......