Handle Scales With Hidden Pins


I did not plan a two-week pause, life circumstances just happened in a way that resulted in it. So today I will pick up where I left off last time – fixing handle scales to the tang.

After I fixed and polished the end caps I finalized the fitting of the scales. I did not fit them completely, I left them overhang the tang a bit on all sides. And because they are glued to micarta, I decided to make a hidden pins construction. I have thoroughly tested this construction for wooden scales, but I would not normally use it for bone, because bone is very rigid and fragile. However, micarta is strong both in tension and in pressure and thus it should make a good transition material.

Unfortunately, it is not possible to glue handle scales directly onto steel without using pins. Even though the glue connection is strong in tension, differences in thermal expansion, volume changes due to humidity, and/or strikes to the edge apply shearing forces to the glued joint and that can sooner or later lead to delamination. Pins going through the handle scales are at a right angle to these shearing forces and thus they reduce them very effectively.

However to fulfill this function, the pins need not go all the way through the scales and they do not need to have peened ends – and on that principle stands this construction.

For this construction, I drill the holes in the same positions where they would normally be, but I do not drill all the way through. In this specific case, I drilled all the way through the micarta and about 1 mm into the bone. I also drill additional holes.

These additional holes are for wooden dowels. A glued joint between wood/micarta/bone is much stronger than gluing to metal. In this picture, you can see six wooden pins in positions where they would be anyway if they were visible (I always choose the hole positions in a way so I can make the pins visible just in case). In addition to them, there are four 6 m wooden dowels.

For gluing, I used colored epoxy again, and I left it to cure in the warm.

Summation: wooden dowels provide a bigger surface for stronger glued connection, and metal pins prevent the creation of strong shearing forces that would lead to delamination.

When I was testing this construction, it was impossible to disassemble it without smashing it with a hammer into splinters. For wooden scales, even from stabilized wood, I still would not recommend leaving it in water for a prolonged time, but for a combination of bone & micarta, even that should not be a problem. Anything that damages this construction would damage traditional construction with peened pins too. Hidden pins do give me a larger area to embellish, which is the main reason for using bone scales – and about that, I will write next week.