Folder blade / liner clearance..What is acceptable to you?

[J S Machine]

I started using bearings in my folders a few years ago, and I really like the smooth performance. However, a problem I have fought with constantly is the blade gap between the blade itself and the handle sides.

I use some bearings which are some of the smallest available. They have a .125" hole in the carrier and the balls themselves are .0625". My problem is that I cannot figure out what the best way is to recess and get the gap between the blade and handles on each side I want.

Here is an example of three options that I have tried.

In these examples, the blade is green, pivot is red, liners are yellow, bolsters are light blue, and the bearings are pink.

The first option (Option A) is what I encountered the first time I assembled one without any recesses. I essentially had a 1/16" gap on either side of the blade. This just looked way too big to me, so I started to work on getting some recesses in to help close the gap. Once I went as far as I could go on the liners (Option B) where I still felt comfortable with the amount of material there, it still wasn't enough. My liners were thin on that particular knife so there wasn't much to work with.

Since I had no other option at that point, I moved to the blade and recessed it (Option C). A major pain too..because I had to use carbide since it was already hard. I ended up with a combination of both Option B and C to close the gap.

I was just wondering how you guys close this gap?

I'm fixing to do another couple of folders with bearings, and I want to review all the possible options first.

I like the idea of option B above, but the way I am thinking, the liners will be completely cut out and the bearing will actually ride on the bolster surface. I'm not sure how to make this work other than to be absolutely sure that the bolsters are securely attached to the liners..maybe with screws from the backside of the liners so they are not seen?

Just a big headache. I like bearings, but I don't like how it makes me do a bunch of extra work to make the knife clearances look right.

On a related note - How about the long term affects of those ball bearings on Ti? Will it eventually wear a groove and compromise the pivot? What about damascus blades? Do you ever allow a ball bearing to roll on the surface of Damascus? I would think the blade would produce a gritty feeling when opened and closed, because of the alternating metal types and hardness of each.

Maybe Teflon or bronze friction washers are not so bad after all. Lol

 

[Self Made Knives]

I'm still a newbie, so take it how you want, but I believe the best method is to use a hardened steel washer as a bearing race on the Ti side, which means the bore is even deeper. I'd say a normal blade is fine by itself, but damascus, I don't know?. I think the Ti is too soft for bearings to ride on directly. And, I agree with a big space around the blade looking bad, I'm working on my first folder now and I used 0.015 washers. That gap looks huge to me!

 

[tomwatson]

On damascus blade with ball bearings, you leave a polished area for bearings to run. I run bearings against Ti all day long, no problem. So does a lot of makers.

 

[tomwatson]

I use bearings that are .062 and I counterbore .042 into Ti liner for pivot bearings. This gives .020 clearance between blade and liner.

 

[EdCaffreyMS]

I do the same as Tom....with the exception that my counterbore is .050". Unless you're using a thrust washer (hardened washer that lays in the bottom of the counterbor), you can count on the bearings cutting a "race" in both the blade and the liners/scales, usually .001-.002" deep....which means I generally end up with approx. .010" gap.

Everything we do in knifemaking is a "give-n-take".....in the case of using bearings, it often forces you to design the given folder to utilize bearings.....meaning that you either use materials that allow for the counterbore and/or the thrust washers. In my case I tend to use them mostly on "frame lock" designs, utilizing .155" Ti as scale material. I find that trying to use bearings in a folder with liners means the scales must be what I consder overly thick, making the knife look and feel clunky.

Personally, I don't like any of the options pictured, all of them leave far too much blade gap. I've tried all of those variants in the past, and was jeered down about it. It took me a while to figure out what to do, and how to do it, but once you "get it right", it's kinda like "Duh! Wish I would have done that to start with." (At least that's how it was for me)

 

[KenH]

Not to hi-jack the thread - how well do bearings work with slipjoints or lockback folders using a peened pin for pivot rather than a screw type pivot?

Thanks to all for any guidance,

Ken H>

 

[J S Machine]

I do the same as Tom....with the exception that my counterbore is .050". Unless you're using a thrust washer (hardened washer that lays in the bottom of the counterbor), you can count on the bearings cutting a "race" in both the blade and the liners/scales, usually .001-.002" deep....which means I generally end up with approx. .010" gap.

This would not be too bad. Problem is, my Ti liner material is only .048". If I cut down to .042", that only leaves my a hair's thickness of material there, and that makes me uncomfortable. When I did the framelock, it was not a problem for that side's counterbore, because the material was around .125" or so.

Everything we do in knifemaking is a "give-n-take".....in the case of using bearings, it often forces you to design the given folder to utilize bearings.....meaning that you either use materials that allow for the counterbore and/or the thrust washers. In my case I tend to use them mostly on "frame lock" designs, utilizing .155" Ti as scale material. I find that trying to use bearings in a folder with liners means the scales must be what I consder overly thick, making the knife look and feel clunky.

I agree with this. Often the design changes start to mess with the look and feel of the knife; neither of which I am crazy about.

Personally, I don't like any of the options pictured, all of them leave far too much blade gap. I've tried all of those variants in the past, and was jeered down about it. It took me a while to figure out what to do, and how to do it, but once you "get it right", it's kinda like "Duh! Wish I would have done that to start with." (At least that's how it was for me)

I guess I could use bronze or Teflon washers. This particular design I am working on was originally supposed to be without a thumbstud and only the flipper "drop" which protrudes on the top of the handle though. I guess it is possible to make it smooth enough for flipper type action, but I am just not sure the best way to go about that to ensure it.

 

[J S Machine]

Not to hi-jack the thread - how well do bearings work with slipjoints or lockback folders using a peened pin for pivot rather than a screw type pivot?

Thanks to all for any guidance,

Ken H>

Not sure if anyone has ever used actual ball bearings in a slipjoint design. IMO, it would be extremely difficult to not peen too far, thus destroying some part of the bearing or surface it is riding on.

I could be clueless though..just the first thought that comes to mind.

 

[KenH]

" extremely difficult to not peen too far"

That's sorta what I was thinking also - I sure like the "silky" smooth action of bearings

Ken H>

 

[Frank Niro]

I was all set to give the bearing thing a try and was even given a lot of written help on how to go about doing it by Allan Davis. He did a good job of explaining how to do it. It seems some suppliers had "some" bearings but the tools to fit them with were "strange" in size. I thought a bit more about if it really was going to help my folders and decided the additional thickness was not something I wanted to work with and dropped that trial. I presently use .015 phosphor bronze washers. Frank

 

[Freds Edge]

I am working on my first liner lock and was considering bearings ,but since I am using a cam stop system I did not think I had room to fit a bearing ii without giving up pivot strength.

 

[Fellhoelter]

If you want to use bearings, size your material to suit.

For me personally, I would want at least 1/16" liners, and counterbore the liners for .020" gap.

.020" seems to be the magic number for me.
Anything less doesn't leave enough detent sticking out for my taste, or requires relief cut in the scale/bolster to allow for enough detent.

 

[J S Machine]

If you want to use bearings, size your material to suit.

For me personally, I would want at least 1/16" liners, and counterbore the liners for .020" gap.

.020" seems to be the magic number for me.
Anything less doesn't leave enough detent sticking out for my taste, or requires relief cut in the scale/bolster to allow for enough detent.

.020" per side?

 

[Fellhoelter]

Yes sir.
I know other use different numbers, or have work arounds for the detent issue though.
Flattening the ball, cutting relief in the liner/bolster, etc... to allow for enough of the ball to protrude and actually function as a detent and not bind.

My method is a .020" spacing, and press the detent ball so it protrudes .018"
On flippers, I press the ball in less, and flatten it a bit, presenting a steeper portion of the ball to the hole.
This same method works if you want less than .020" spacing.
I'm lazy though, and found a system that works 95% of the time.

 

[tomwatson]

I'll tell you that you won't like a slip joint or a lock back with bearings. Too easy to lose control on your blade opening. When you say that your liners are .048 and too thin for bearings, then get a thicker liner. When I started bearings I had a bunch of .050, .060 Ti. Still got it and use it for liner locks. You can't adapt everything to bearings. Think. In using .100" for liners with bearings, Like ed says, it makes the handles look bulky. I grind my handle material down to work with what I am doing. In all the talk about what a flipper, or a liner lock can do is getting out of hand. A folding knife is not going to stand against everything. I believe that bearings make the folder weaker in the pivot area and any small screw is going to aide that weakness. Add up all the weak points in a folder and you will see that they are in close proximity to the pivot area. Linerlocks are very useful around where you need a knife handy. Flippers are a cool toy. I can make a linerlock that opens with the thumb be as fast as a flipper. All of the military guys that I know still on duty in hostile territory, ask for a particular design I make for combat conditions. It is a fixed blade knife and none of them would use a folder. Bearings got too crappy with sand in them. I'll let you have your thread back.