Question for Slipjoint makers

J

John L

Joined
Oct 28, 2004
Messages
1,330
Lately I have been having a problem achieving centered blades between liners when in the closed position. I have checked drill press and in a 4" radius of revolving pc of wire I have less than .001 variance from side to side to top of table. I drill and then ream 2 thous over pin size(3/32). There is no binding on pin. I recently decided to try 3/16 bushing and have lapped to .0015 over blade thickness abnd followed the Bose bushign tutorial. No help although the action has improved...smoother, etc. Everything, in my opinion, is good on knife other than centering problem. When peining I shim equally on both sides and then pull shims....not centered. Ugh..... What else could it be. I have sharp bit, reamers, etc. Just very aggravating to spend hrs and then have these problems. The knives are not always canted to one side or the other.... Ugh. At times I even leave blade a little thick at point and then grind a bit more on one side to even up..but this should not have to happen..should it? Any help here is really appreciated. Thanks in advance.
John Lloyd
 
I have noticed alot of the time it is the liner that is the problem if you take too much off of one when sanding it it will put the blade off to one side or the other even if your usning a flat suface plate. Make sure its flat before you drill the holes. When you fit your scales, if you fit them too tightly it will bow the liner a bit and this will make the blade to fall to the side when you peen the pins. I also peen the blade pin first just to make sure it lines up good.
 
John,

I construct my knives with bushings as well. The problem comes when the pile, (liners, spring, and blade) become skewed which then makes the pivot hole and spring holes not perpendicular to the liners. Do you use a clamp or a pair of vice grips to hold your pile together as you peen? This will help. My advice also is to start with your pivot pin then, before spinning or peening your end pin and center pin, open and close the blade to see where the tip lies. If not centered, I will place my knife in a soft jawed machine vice in a skewed (corner to corner) position and shift the liners accordingly. When centered then I place my vice grips near the end pin and spin or peen. I check again for centering and then spin or peen the center pin. I know first-hand how frustrating this can be. Nearly every knife I put together needs tweeked in one way or another. There are some adjustment techniques that can be used after assembly. However, they are more difficult to explain without pictures. If you have more questions, pm me and we will talk. Hope this helps.
 
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I'm working on slip joints now and this has not hit me yet, but it's one of the problems I'm expecting. I'm wondering if it's a stacking of tolerances? What I mean if your drill table is off a hair when you drill the blade then you drill the pivot hole in the liners then you drill the middle pin ect if each one is off a hair (.001" on blade .001" on one liner, .001" on the other liner and your are sitting at .003") it adds up. I've seen where guys stack the pieces all together then ream them all at onnce making all the holes parrallel with each other and perpindicular to the knife. I wonder if this would help the problem you are having? It was going to be my first step at fixing the problem if I ran into it.
 
I'd be inclined to think your drill table is off!!i know you've checked it,but you may want to try with a test dial indicator.i had similar issues using drill presses.i could tram them over and over,but upon tightening/clamping parts ect the table would be out of tram pretty fast.i eventually got fed up and baught a mill/drill.one of my best investments for folder work!
 
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