Folder bearing question

gudspelr

Well-Known Member
I’m considering using caged bearings on my next liner lock and it’ll be a first for me. I’ve seen where guys will recess both the liners as well as the blade for the bearings. I’m curious for anyone’s opinion on how they do it and why.

Specifically, how big of a gap between the blade and liner do you go for when the blade is installed? I believe the bronze washers I’ve used are .010 thick-do you use the same clearance with bearings and mill the pocket to leave .010 of your bearings proud? I was also thinking of just milling a pocket in the liner material and not in the blade as well. What is the minimum thickness of liner or blade you like to ensure is left? (For the sake of round numbers, say you are using .080 liners and the bearings are .060 thick. You want .010 left for the blade to ride on, milling .050 out of the .080 liner. Is .030 left “enough”? How thin is too thin?)

Thanks for anyone that is willing to share their experience.

Jeremy
 

EdCaffreyMS

"The Montana Bladesmith"
Personally, I only recess liner/scales, unless it's a special situation. The "recess" is actually called "counterboring", and it's done with a counterbore sized for the diameter of the bearings you're using, and a pilot that equals the size of the pivot hole.

Using bearing requires a little different thinking then washers. With washer there is no "wear in"..... but with bearings, especially in titanium, they will "wear in" or in other words, the bearing will "cut" a race or track in the Ti....usually a couple thousandths. The way you figure the depth of the counterbore is by taking the individual bearing diameter of the bearings you use, for example the caged bearings i use have individual "balls" of .0625" (1/16"). To achieve .010" clearance on each side of the blade, I want to leave .012" of the bearing sticking up/out on each side....so I counterbore the liners/scales to.050". Then, after "break in", and the bearings "cutting the race" to approx. .002", so that leaves me .010" clearance in the finished folder.

When it comes to how much "web" you can leave and still be safe. I personally would not leave less then .030", but have seen many makers get away with .025"...... I tend to err on the side of caution when it comes to thing like that, simply because the worst thing in my mind is for a knife to be returned due to a failure.
 
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gudspelr

Well-Known Member
Thanks so much, Ed-I really appreciate it. There’s a lot to think about and consider with folders and every little change affects several other things....so not having to just make a guess and go for it is huge for me. And I’m with you-I don’t feel like tempting fate with leaving too little web in the liners. Would definitely suck to have that fail.

Jeremy
 

BrandantR

Well-Known Member
The knives I make are thin, gentleman's style knives where my blades are usually 0.1" and liners are 0.050". I use 0.625" caged bearings like Ed described. Because the liners and blade are so thin, I'm forced to counterbore both the liners and the blade. I leave a little wider clearance of 0.020" between the blade and liner which gives me more clearance for the detent ball height for a stronger lock up and it's easier to clean out (compressed air) the slightly wider gap if pocket lint or other debris accumulate in the bearings.

Every maker does things a little different, but this is what works for me and my designs.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
With bearings, I usually shoot for around .023" gap which matches about how much proud the detente ball is. For a liner lock, that means you have to relieve the scale a bit. (Frame locks are easier btw) I am working on one (with bearings) that is around .015" gap and preventing blade rub is a bit challenging. Bearings can be "run in" as Ed describes. I use .010" hardened stainless washers as a bearing surface against Ti. On thin liners and blade a washer set up is going to be better for a number of reasons.

When milling both the blade and liners, consider leaving as much pivot surface as possible on the pivot, ie, minimal relief on the blade. The less surface you have on your blade/pivot, the more the blade will flex side to side.

As for folder parts, I will put our assortment, in-stock, quality and pricing up against any ones.


I’m considering using caged bearings on my next liner lock and it’ll be a first for me. I’ve seen where guys will recess both the liners as well as the blade for the bearings. I’m curious for anyone’s opinion on how they do it and why.

Specifically, how big of a gap between the blade and liner do you go for when the blade is installed? I believe the bronze washers I’ve used are .010 thick-do you use the same clearance with bearings and mill the pocket to leave .010 of your bearings proud? I was also thinking of just milling a pocket in the liner material and not in the blade as well. What is the minimum thickness of liner or blade you like to ensure is left? (For the sake of round numbers, say you are using .080 liners and the bearings are .060 thick. You want .010 left for the blade to ride on, milling .050 out of the .080 liner. Is .030 left “enough”? How thin is too thin?)

Thanks for anyone that is willing to share their experience.

Jeremy
 

gudspelr

Well-Known Member
Thanks for the information. Could you expand on the blade rub comment with .015 clearance? Do you get issues with the side of the blade rubbing on the inside of the liners?

Jeremy

With bearings, I usually shoot for around .023" gap which matches about how much proud the detente ball is. For a liner lock, that means you have to relieve the scale a bit. (Frame locks are easier btw) I am working on one (with bearings) that is around .015" gap and preventing blade rub is a bit challenging. Bearings can be "run in" as Ed describes. I use .010" hardened stainless washers as a bearing surface against Ti. On thin liners and blade a washer set up is going to be better for a number of reasons.

When milling both the blade and liners, consider leaving as much pivot surface as possible on the pivot, ie, minimal relief on the blade. The less surface you have on your blade/pivot, the more the blade will flex side to side.

As for folder parts, I will put our assortment, in-stock, quality and pricing up against any ones.
 

BossDog

KnifeDogs.com & USAknifemaker.com Owner
Staff member
Yes.
The stronger the lock bar is "bent", the more you will fight the blade being off center.
The looser your parts are tolerance wise, the more you will fight it being off center.
With a wider gap, you have more room to work with and it isn't as obvious.
This is for a liner/frame lock of course. A lock back doesn't have this nonsense but has a whole new set of nonsense issues to deal with.


Thanks for the information. Could you expand on the blade rub comment with .015 clearance? Do you get issues with the side of the blade rubbing on the inside of the liners?
 
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