Off center blade on a liner lock... Need help

Hankins

Hankins

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Dec 7, 2008
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Off center blade on a liner lock... Need help
Just built my first three linerlocks this weekend... Whoa they are alot of work to get right.
Two out of three blades were not centered when closed. They all locked up tight with no sideplay using Ti liners.
What causes this and How do I prevent this in the future?
 
what kind of washers are you using at the pivot? is your pivot tight enough to stop side play in the blade?


-Xander
 
Three of the most common reasons that blades don't center on folders....

1. The pivot hole in the blade has too much "slop" in it. (doesn't fit close enough to the pivot)

2. Slight thickness difference between the back spacer and the blade + washer thickness.

3. The most common....the blade was not ground with the point dead center.

There are also a number of other issues that can occur.... one very common one is that if "guide pins" are not used in the construction, liners will often shift with each assemble, disassemble cycle. In my opinion, you cannot count on countersinking the screw holes in the liner/back spacer/liner to keep thing in place...every folder I build uses two 1/16" hardened dowels through both liners and the back spacer. These ensure that the liners and back spacer go into the exact same position/location every time.
 
Add crooked holes from a drilling on a machine that wasn't properly trammed to Eds list as an option.

And washers that are too small a diameter.
 
1/2" are plenty big, Eds suggestions are the most likely still.

If your grinds are good, and you aren't using countersunk holes to hold the knife together, you can try loosening up your screws, and pushing the side of the knife that the blade is tilting away from, forward.

Then tighten.

(Countersunk holes are self aligning, for good or bad. Try to not rely on them for alignment. I try and avoid them entirely if possible...)
 
If the flats on the blade are not flat AND parallel, the tip will be off-center. If the backspacer is not the correct thickness, the blade will be pinched, keeping it from seating on the washers. This will cause the tip to be off-center. I would check that first.
If there is slop in the fit-up, the pressure of the spring will force the blade towards the opposite liner. If you tighten the pivot up, the tip will come back towards center. The knife may no longer open, but you can see if it will center when the clamp-up is good. Then, you can take it apart and see what is causing it.

Dowel pins are helpful when making folders, as Ed pointed out.
 
Also, check to see that you do not have "ball binding", that is, there is room for the detent ball to move away from the blade before the lock bar hits the scale (or bolster) when the knife is closed.
 
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