Third pin location?

I'm going to experiment with making scales. Of course, I'm not really expecting a great set right off. I'll just be getting my bearings.

But any way, it' making me a bit curious about third pins. Is there a specific or recommended location for them, and how wide are they typically made?

Third pins are typically a strengthener and stiffener for the scales. They are not usually a blade rest, although they could be. Location should be midpoint of the scales vertically (for aesthetic reasons) and between the pivot and the rear of the blade. It needs to be far enough forward to clear the tang when opened, and far enough back to not interfere with the blade when closed. An easy way to determine pin location is to take the drawing of the scale (I always draw out the scale on paper before making it out of wood) and use an engineers compass to draw a circle....that'll show me the alignment and relative positions of the various parts. You can spot a design flaw easily that way. As far a width, if I understand you correctly, it only needs to be wide enough to assure clear blade movement, without pinching the shank (which will usually force it up and out of the handle), and not so so thick as to bow the scales extremely, which will force a bind at the pivot, often breaking the scale at that point.

Hope this helped