One of these days I'm going to make a video on how I do bolsters. Until then, here's my process. First, all my bolsters have at least two pins, sometimes three. I cut my bolster material to rough size and flatten the undersides with a quick touch on the disc and then a few strokes on 400 grit on a lapping plate. Once the bottoms are lapped flat, I square the back edge on the disc. Now I am ready to drill one of the bolsters; I clamp it to the blade with a pair of vise-grips I have modified to remove the teeth. I am careful not to clamp too close to the back edge because I don't want the vise-grips to deform that finished face. I now use the blade as my drill guide on the drill press and put the pin holes in the first bolster.
Once I have the holes drilled in the first bolster, I unclamp it and re-lap the underside lightly to remove any burr from drilling. Now I take the undrilled bolster and mate it up with the drilled one so the lapped surfaces are together and the squared ends are at the same side. I place them on the surface plate with the squared end down flat on the plate and then clamp them together with my vise-grip. Now, my drilled bolster is the drill guide for the undrilled one. I drill the holes.
Now that I have the holes in the bolsters with the back faces aligned, I do the front edge. Keeping the bolsters in the same orientation as the last operation, I place a couple twist drills in the pin holes as alignment dowels and reposition the vise-grips as necessary to be able to hold them while grinding on the front faces of the bolsters. Alignment is critical when you move the vise-grips, if you change the alignment, use the surface plate to fix it and then clamp the bolsters. I contour the front faces together on the rotary platen starting with 50 grit and progressing through 600. When I come off the rotary platen, I clean up further on a medium and then a fine scotch-brite wheel before polishing out with green compound on the buffer.
Separate the bolsters. Now that the front, back, and bottoms of the bolsters are finished, the holes get reamed with a taper pin reamer by hand. I hold my reamer in a large pin vise and ream only about 3/4 of the way through the holes. If you blow out the bottom of the holes with the reamer, you will lose your alignment when peening.
Next step is to measure the thickness of the bolsters plus the blade to determine pin length. I add the diameter of the pin stock to my measurement to determine how long to make my pins; for example, if my bolsters/blade thickness is 1.000" and I'm using 3/32" pin stock, I will cut my pins to approximately 1.093". I like to put a small bevel on the ends of the pins after cutting them just to make sure they go into the holes easily and prevent premature mushrooming as I peen them. Next I do one more brief lap of the bottom of the bolsters, clean everything up and assemble using my vise-grip to hold it all together. Again, be careful of that back edge during clamping and peening; you don't want to have to fix a ding.
I peen the bolsters down very tight before I remove the vise-grip and I'm always checking to make sure that no gaps form between the bolsters and the blade. If you start to get a gap, you can usually reposition the vise-grip to close it and keep peening. Once I'm confident that everything is tight, I'll remove the vise-grip and peen down a bit tighter. For me, the vise-grip is always just a little bit in the way while I'm peening so I want to get some good smacks after I remove it.
That's pretty much it! From there, I attach my scales. Once the epoxy has set on the scales, I profile the scales and bolsters down to the tang and then start contouring.
Hope this helps.
Bob
