What is the cause for off center blades on some folders?
Per Mick Strider

“The way our pivot works is this:

Our folders pivot on an “open pivot”, a shaft made of hardened 416 stainless steel that is .390”. Our pivot is designed to slide through the G10/Ti and index into the Ti on the other side. The pivot is then held captive using a bolt that threads directly into the center of the pivot shaft. The smallest part in the pivot assembly is this bolt. Its diameter measures .303”.
The second strongest pivot I have seen uses a 6-32 screw to hold the pivot shaft. A 6-32 screw has a diameter of .134”.
The Blade pivots around the shaft and between two bronze bearings that are .020” thick each. We don’t use anything but Bronze bearings because these folders are made for very hard use, and we learned a long time ago that bearings made of lesser material don’t hold up well in surf zone or dessert environments.
For our discussion, let’s use an AR as a test piece.

An AR has a pivot shaft that is .390” +0/-.001.
It has two bronze bearings that are .02”+/- .0002 thick.
Blade thickness is .190” +0/-.002
For those of you who don’t understand the measurements, +/- stands for plus or minus and represents the degree of variance we are willing to except in our parts. A measurement of .001 is one, one thousandth of an inch.

Now let’s do some math.
In order for a blade to pivot around a shaft that is .390”, the hole has to be at least .391”/.392”. Or it will not pivot, but act as a press fit part.
We ream our pivots to .3915” using a Mori Seiki NV5000 Vertical milling center. This machine is considered to be one of the most accurate made. Our holes have a variance of .3915”/.392, or one tenth of one thousandth of an inch. Give or take…
Our blade length on an AR from pivot center to tip is 4.685”

So……

We have a blade and pivot assembly. The pivot is .390 +0/-.01 let’s just say it is .389”…missed it by .001.
And our Blade has a hole that is .392”. I rounded these off because I hate math.

Okay we missed on the pivot by .001 and on the blade hole by .0005.
That is a stack of .0015 of missed tolerance at the pivot.

BUT…..we also need to add the scales. In order for the pivot to slide through the scales (sides of the knife) it has to have some clearance. We like it to be tighter than the blade, but not a press fit. So we ream them with the same reamer .3915. They are made of Ti and G10, therefore they don’t cut as cleanly as the steel, They just come out a little more tight by nature.

Let’s add that now.

So we have a stack of:
Pivot .001
Blade hole .0005
Scale side one .001
Scale side two .001

Total .0035

Or three and five tenth of a thousandth total missed tolerance.
Now lets call that blade play.

If we have roughly .0035 of blade play at the pivot, and we compound that by the length of the blade, what will our total amount of blade play be at the tip?
Sure we can pull some of that out by tightening the pivot….but then your knife will be stiff……couldn’t have that….
So what you get is a blend of taking all of those parts and making the very best knife we can.
IF it turns out that the knife functions better when the blade is not perfectly centered……then we don’t make it perfectly centered. Centered doesn’t mean good. Good means good. If the person that gets the knife isn’t happy with how the blade centering looks, they can send it in and we’ll make them happy. Even if in the end, the knife looks better than it works.

Our goal is to make you guys happy.
BUT remember, there is an ass for every seat, some people like a loose pivot, some tight.
We’ll never make EVERYONE happy on the first try.”