Ok lets see, the latch is probably the weak link on the balisong design. To latch effectivly closed the handles must flex a little over the blade "kick" or choil and the spine. To latch effectively open the handles "flex" over the little blade stop pin (or whatever the thing is called). In either case latching won't last due to wear, impact etc. In the case of that broken Mod 68 (I can't keep track of the model #s) the handles put too much stress in the latched closed postition over two offset points on the spine and "kick"/choil. The short drop, and it really was just a drop, aggrevated a possibly already cracked blade. I've actually seen a couple more PC balisongs that gave way in the same manner.
Anyway, getting back to the latch, we all know that it also hits the blade. To alleviate all three latch related problems at once the handles themselves should be "sprung" at the point of latch up so that they don't need to flex--however minute the flex really is. In order to do that the smaller balis in the images have some spring wire (actually from an old umbrella) inserted through the smallest skeletonized holes on the latch handle that the blade edge does not reach. The wire is then bent back over the handle to form a sort of leaf spring for the opposing handle to impinge on. The spring is also bent in a direction to stop the latch from traveling beyond 90 or 180 degrees where it can hit the blade.
On the larger non-custom bali (whatever the #is) Benchmade tried to alleviate the latch-hitting-the-blade problem by lengthening the handles a bit. This only helped ruin an already dismal blade to handle length ratio. The actual cutting edge is a good 2" shorter than the handle length. Anyway in this case to fix the latching up problem I decided to spring load the latch itself instead of the handles, first by drilling out the latch retaining pin and then filing the latch retaining pin hole into an oval (didn't have a mill in those days). A hole down the back of the latch (parallel to the length of the latch) was drilled and tapped for a 4-40 set screw. Then the latch was put back on the handle and long 4-40 set screw was used as a retaing pin in case I needed to get the latch off again. A small spring and ball detent was placed down the latch hole and the set screw was put in place to act like a plug. So now the latch is spring loaded. When the handles are closed or open the latch must be pulled a bit over the corresponding handle for a tight latch up. A piece of scrap 6061 aluminum the interior width of the handles was shaped and screwed through the last large skeletonized hole in order to keep the latch from hitting the blade.
Benchmades new balisong looks like it has a similar solution to the problem.
The large Scimitar balisong was obtained through a friend in between PC and Benchmade years. I had it made w/the latch on the opposite handle than normal (manila style?) thinking that I wouldn't need to do much to keep it from hitting the blade. Instead its the only bali I've never really used 'cause it was too nice.
That covers most of it, of course if you wanna keep things simple you can always beat that little pin down when it wears out as a way of keeping the latch up tight and you can use a strategically placed drop of epoxy on the inside of latch handle to keep the blade from hitting the latch. Both those things work just as well although they're a bit more temporary.
