What causes blade alignment to shift

R

Randy3000

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Jun 3, 2017
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After peening the knife together? I was making this 2 blade folder, and in dry fitting everything went together straight and smoothly. I peened it, and the little blade came off towards the center. I straighter it out and the knife works great, but I'm just curious if I'm peening wrong or if that is just the way it is sometimes?

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Is chamfer the pivot holes using a 1/64" larger bit, sanded into a slight cone. I leave half a diameter of pin sticking out, and tap all around the edges to form a head, and tap straight down to fill in the gaps. I do use a little shim cut from thin plastic from various packaging so I don't peen the knife shut, then I pull it out and peen so there is no side play. I notice that I always have gaps wherever the shim is, and I wonder if it is bending the knife scales enough to cause This? Is there a better way to prevent peening the knife shut? What am I doing wrong?
 
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How much wiggle is there in the 2 halves before peening, just with the pins installed? If you have too much clearance, it's likely you're slightly shifting the alignment when deforming the pins. If you look at your bolsters it appears the right half has shifted "up" in relation to the left.
 
kuraki said:
How much wiggle is there in the 2 halves before peening, just with the pins installed? If you have too much clearance, it's likely you're slightly shifting the alignment when deforming the pins. If you look at your bolsters it appears the right half has shifted "up" in relation to the left.
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I did not notice the shifting you mentioned, but you are right. That wasn't there before, I always check after soldering the bolsters and if it was that bad, I would of redone it. The scales fit real tight on the pins.
 
You need a slightly oversize pivot hole in the blade or the pin will swell and cause shifting and sticking, a few thousands should do.

Hoss
 
The scales may, but do the liners as well, without your spring installed? If you pinned just the two liners together, 2 pins, 3 pins, however many you're peening, could you move them around in relation to each other. If so, then there's room for things to shift as the pins deform following the path of least resistance.
 
Devin Is correct. You must give the blade pivot hole some room because when you pein the pin it grows in diameter all the way along its’ length. If too tight it has to move.

John Lloyd
 
kuraki said:
The scales may, but do the liners as well, without your spring installed? If you pinned just the two liners together, 2 pins, 3 pins, however many you're peening, could you move them around in relation to each other. If so, then there's room for things to shift as the pins deform following the path of least resistance.
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No, after soldering the bolsters I put the liners all together when sanding the profile on the handle and there was no perceptible wiggle. I would of noticed because it would of been harder to profile. Then i attach the scales and bring them to the liners, so there was plenty of time to notice loose holes, that's something I look for.
 
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DevinT said:
You need a slightly oversize pivot hole in the blade or the pin will swell and cause shifting and sticking, a few thousands should do.

Hoss
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I'll get a set of reamers and see if this will help. I've been wanting reamers anyway.
 
What about the gaps between the liners and spring? I always have gaps where my shims are. After I pull the shims out, maybe I should try pressing the handles together lightly with a clamp or vise? Is the pins swelling out what is holding the liners off from the spring? It makes sense I guess.
 
If you are swelling the pin in the blade pivot hole, you're peening entirely too hard.
 
After looking at the pic again, if the right side shifted up, it should of made the blade turn towards the left. But it isn't, it's leaning towards the right. Maybe I am peening too hard? It has to be doing some weird stuff where you can't see. Like I crushed the pin into a zigzag. The master blade ended up straight, the bolsters there aren't shifted, so maybe I didn't peen that in too hard. That makes sense too. I can see how enlarging the holes slightly can mitigate this affect, but it's better to address the root problem.

I'm going to do some experiments once I get the reamers. I'll peen the crap out of some scrap and see what happens, with and without enlarging holes.
 
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Randy3000 said:
What about the gaps between the liners and spring? I always have gaps where my shims are. After I pull the shims out, maybe I should try pressing the handles together lightly with a clamp or vise? Is the pins swelling out what is holding the liners off from the spring? It makes sense I guess.
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Your shims are too thick. I use .002 or .003" steel shim stock.
Pressing the pins is not a good idea, it will likely make things more wonky.
 
I'll look into legit shim stock. I use a small hammer like what you would use to nail a hook hanger on a wall, and i ground the head flat to a fine grit. Thanks everyone, that's enough info to get me going.

I got to travel this weekend, but when I get back I'm going to make a batch of 3 of these knives and then if I feel good I'll finally attempt another stockman. My other attempts have failed badly, but I've been reading and preparing a lot. I think if I get this last issue with the peening resolved I'll be able to muster a respectable attempt at a stockman. I want stockmans to be my main pattern.
 
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