pin size revisited

[beresman]

I posted previously about re-assembling a knife where the blade pivot holes were significantly larger than the bolster holes. I considered what was said and did my best to follow what was suggested.

To re-cap: the holes in the blade are 0.093" diameter; the bolster holes are about 0.082" and the pin material I used is about 0.081". I assembled pins at both ends of the knife, filed the material so that only about 0.020" excess remained proud of the bolster on either side, and very gently peened the material into place. Nonetheless, you can see what happened in the following photos. The pin seems to have bent internally, where there was plenty of excess room to allow it to do so, and the bolsters are mis-aligned.

How do I avoid this if I am assembling parts in this way?

Brent

[Mess1ah1]

12 one thousandths is a big difference. Assuming you can assemble outwards, personally, and only because I have the tools to do it, I’d have made a custom pin, small on both ends and fat in the middle. Slip the middle parts onto the bigger part of the pin and then attach the outer parts, peen. That would alleviate your issue here.

[ea42]

Brent how big is the hole in that center scale? You might not want to be quite so gentle with your peening. You want to get a decent head on the pin quickly before it has any time to get wonky or spread in the center. you can also squeeze the knife together as you peen. If you're worried about over tightening use a thin shim between one of the blades and the liner, maybe roughly .003 or .004, and pull it out once you're done peening. If after you do that there's a bit of wobble in the blade just tap the pin a bit until the wobble disappears. The important thing is that your pin and your bolster/liner holes are very close. You don't want a lot of wiggle room in there. The tighter it is the faster it closes up.

You can fix what you have there by resting the backspring side of the lower bolster on your stiddy at a bit of and angle and giving the high side bolster a whack to bring them even. You'll likely then have to peen your pin a bit more to close everything up. If you open a blade halfway and sight down into the well towards the tang you can see if the tang is parallel with the liners. I hope that all makes sense. It's a lot easier to do it than explain it lol! What you have there isn't uncommon, and I don't think it has anything to do with you blade hole size, especially if that center scale hole is small. I regularly put knives together where the bolster hole and pin is .093 and the blade tang hole is .104 to .106 with no problems.

Eric

[herbva]

The blade hole size has nothing to do with that problem. I can't tell for sure from you pictures, but it looks like that pivot pin might be bent. Did you have everything together nice and tight before you started peening? How did you peen it? Did you alternate from side to side and go around in a circle with your hammer as you were peening? What did you use for pin material? Also, as another afterthought, I usually put the knife together using drill bits just as a test (or finishing nails of the right size work too) to make sure there aren't any other problems or issues before I assemble it with the pin stock I am going to use.