Has anyone tried to lap a folding knife that uses washers using a very fine diamond paste? The idea is to apply the paste to the washers, reassemble the knife and then open/close it some number of times which, theoretically would help mate the washers and knife blade thereby, making the action smoother. In my case I have some 9000 grit diamond paste and I have a Strider SMF and other folding knives that utilize washers instead of bearings. And I was wondering if I applied the diamond paste to the washers, reassembled the knife, and then cycled the action some number of times if the diamond paste would make the action smoother after subsequently cleaning and lubricating the knife. Some of my folders with washers have great action without doing anything and others just don't ever seem to get smooth no matter how many times I cycle the action. It's the suborn knives I'm most interested in making smoother. I have tried all types of lubricants (wet, dry, and grease) and brands and so far Gunny Slides has proven the most effective by barely beating out Finish Line 100% PFPAE fluorinated grease (same thing as Chris Reeves grease) and using Ox-Gard on the lock face interface to eliminate lock stick. Anyway, before I actually tried this I wanted to see if anyone has tried this and get everyone's opinions of whether or not this would work.
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Lapping a folding knife with washers with diamond lapping paste
- Thread starter MSimcoe
- Start date
The following is a response to jbmonkey's reply to my post. The follow up got to be too long and added a bunch of new information I thought would be pertinent to this post so instead of replying directly I thought I would add the follow up to this post.
I have already tried polishing the washers and it didn't seem to make much if any difference. Also, the other factors that can effect the action are the lock bar tension, detent ball, and pocket clip. I have already replaced the steel detent ball with a ceramic one. I have found this makes a very noticeable difference for the better in all types of folders which use detent balls. In addition, I have already experimented with adjusting the tension on the lock bar and this also helped to a degree. Also, if the pocket clip lies on the lock bar and is putting too much pressure on it this will also effect the action (learned that from my Chaves Ultramar knives) so I adjusted the tension on the pocket clip so I could just slide a piece of paper under it. To be clear, I have three Spartan Knives full size SHF's and they are "drop shutty" and very smooth. In every mechanical respect they are identical to the other knives I'm concerned with (polished washers, ceramic detent ball, no replaceable lock bar insert, and pocket clip not touching). I just want to know why my Spartan's can be so smooth and the others not smooth when they are so similar. I'm OK with having to use two hands to open some of my knives with washers but, I really want to know why there is a difference and what the solution is. Which brings me to my current thought process. In this situation most people will tell you to cycle the action a 1,000 or so times and it will be smooth as butter which, is probably true. And what I think is happening by doing this is the bronze washers are gradually getting thinner in all the right places so that there is a constant amount of friction/pressure across all points on the washers and blade. In addition, I think this will continue to happen until the washers get just thin enough to where the friction between the blade and washers is no longer enough to wear the washers down any longer and this is the point at which the knife becomes "broken in" and smooth as butter. Said another way I think it's the tolerance between the scales, washers and blade. The finer the tolerance the shorter the "breaking in" process. So, how can I/we make this happen without having to cycle the action a 1,000 times? This is the thought process that lead me to the idea of using a fine diamond paste to "hurry up" the breaking in process. Some people might say I'm over thinking the issue but, isn't trying to understand why things work the way they do part of the fun of this hobby?
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sorry i missed in your post where ya said ya already tried polishing the washers without the results you were looking for. if ya hadn't tried that, just seemed logical to start with that first, but since ya did already.....
That is similar to the ”fluff and buff” process often done to firearms to improve the trigger or clean up rough surfaces to improve their operation and function.
I am sure it will work if you use the fine paste. I am also sure it is only worthwhile if the knifes action is very rough. It sounds like you are going to try it so let us know how it goes.
I am sure it will work if you use the fine paste. I am also sure it is only worthwhile if the knifes action is very rough. It sounds like you are going to try it so let us know how it goes.
This is a follow up to my original question regarding lapping a folder with diamond paste. One thing I want to make clear, and this is important, is that before you try this process the blade should be centered in the handles. If not I think the process will result in making it more off center not less. So make sure the blade is centered to your taste before going ahead with this process. So, I tried lapping with diamond paste using the process I described above and I thought I would post the results. I have a new Strider SMF with a Lego G10 show side scale and a titanium lock side scale. Since it was new the action was pretty stiff. I didn't want to go through the process of opening and closing the knife ad infinitum to break it in so, I decided to apply some 9000 grit diamond lapping paste to each side of the blade where it makes contact with the washers. I took the knife apart and cleaned the blade, washers and scales around the pivot pin with acetone. Then I applied approximately 1mm (a thin layer) worth of diamond past on the blade where it contacts the washers. I then reassembled the knife but, and this is important, I only tightened the pivot screw until it just started to encounter some resistance and then backed off about 5 degrees. The point to be made here is that you don't want to tighten the pivot screw so much that the majority of the diamond paste gets squished out. Then I cycled the action about 25 times or so until the action was reasonably smooth. You can feel the difference as the lapping paste does it's job. I then took the knife apart, cleaned it again, and repeated the process with a polishing paste by the name of 'Pre-Lim' by the makers of Renaissance wax. The makers call it a 'metal burnisher'. This part of the process is the polishing phase and will result in a shiny surface where the metal contacts are being made. Interestingly enough throughout this whole process only about half of the contact area was being lapped and polished, meaning that it appeared that there was not 100% contact patch between the washers and blade. Another way of saying this is that the scales, washers, and blade were not perfectly square to each other. I then took the knife apart, cleaned and lubricated it sparingly with Gunny Slides. On the lock bar I use Ox Gard to prevent lock stick. The result of this process was that my Strider is now almost drop shut smooth which until I have more experience with this method is where I wanted it. Since this was a pretty expensive knife I didn't want to push the envelope too much until I know more about what happens when you over do it. I think the worst that will happen is that the washers might need to be replaced since the washers are the part that would have the most material removed. I think this is a pretty safe process because you can easily replace the washers or tighten the pivot more if you over do it. I feel like you would have to use a really coarse grit diamond paste and cycle the action a lot to remove a significant amount of material from the blade or scale to the point where you had blade play that could not be adjusted out. Since my first Strider turned out so well I think I'm going to do this with my new Strider SMF Performance Series. It has a pretty good action right out of the zip lock bag but, I think a light application would really smooth it out and make it close to perfect. Finally, I think that if the tolerances were such that the scales, washers, and blade were perfectly square to each other none of this would be necessary and essentially this is what this process is doing which is improving how square everything is. I'm going to continue to experiment with this process and as I learn more I'll post it here. One thing I want to try is to use Gunny Juice instead of diamond past and see if it works better or worse. But, I need to get some cheap folders with washers before I start getting too aggressive.
I agree and it's not easy keeping track of which washer is the left and which is the right and which side was facing the blade and which side was facing the scale. If you are going to try and improve the action doing what I'm doing you should do it once maybe twice and then leave it alone and let nature take it's course.
Bill DeShivs
Knifemaker / Craftsman / Service Provider
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I would think diamond paste would imbed itself in the softer metals and stay there. The washers used in knives are very thin
ferider
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Cool. On my PB knives, after break-in, it’s very visible which washer side faces the tang (the shiny one).