OK... you're talking tension on the action. How hard or soft the action/travel, is directly related to how tight you tighten a pivot screw.
With washers, you can't go very tight, and over time the washer will "wear in" and then the pivot will require adjustment.....that's just the nature of the beast with
folders using washers,
with any type of "screw" pivot. The cleanest, smoothest actions, all other things being equal, is pretty much always bearings. As I mentioned elsewhere, my preferred method is caged bearings with ceramic balls/bearings, counterbored in place.
Now, let's talk about the "bind" on the blade when you tighten down on the pivot screw. There are many factors, including how precise your parts, as in the frame/liners, blade, and how precision flat those parts are.
OK, let's assume that all of your parts of dead flat and finished/ready to assemble. Put everything together, and during the assembly, put a couple of "dabs" of good quality grease on BOTH SIDES OF EACH WASHER as you assemble. Tighten the pivot screw down to the point that it is difficult to move the blade by hand. Run the blade back and forth throughout it's range of action, lock, etc. for about 5-10mins. The action will likely loosen up during that time, and as it does, stop and retighten the pivot screw(s)...... basically what you're doing is "working in" the action.
Now, here's the part that you're likely missing/are searching for. Pivot screws ARE NOT TIGHTENED FULLY.....by the fact that they must be ONLY as tight as necessary for a smooth action, and yet as tight as possible without impairing or hindering the action of the folder. Now, since pivot screws are not fully tightened down, and subject to loosening with the action of the folder..... there needs to be some method/mechanism to keep the pivot screw from loosening.
I noticed that you are retired machinist, so that part of you might be convinced that "fully tightened" is required, and if that is the case, your answer MIGHT be press fitting the barrel portion of your pivot, and then trimming the screw threads until it bottoms out, and is fully tight at the same time. The issue with that, is that there is no adjustment left in the folder's action for when washers, bearings, or whatever pivot mechanism you use wears......and requires tightening the pivot screws.... which is why most choose not to go that route. First lesson of knifemaking..... EVERYTHING we do when building a knife is a "give-n-take"..... we give up something somewhere, to gain somewhere else.
There are a few choices that people use to "secure" pivot screws..... many use the Blue/medium strength thread locker (loctitie), others choose to use the Red thread locker (again loctite), There is also the mechanical means of making the pivot barrel itself a "D" shape by sanding/filing on side of the pivot barrel, and then center punching the INSIDE of one liner/frame to make the pivot hole a "D" shape (this keeps a pivot/barrel from rotating when the folder's action is worked and loosening the pivot screw).
Personally, I prefer to use threaded barrels for my pivots, with a screw on each end. I use small rubber O-rings, under the pivot screw heads.... which keeps just enough tension on the screws to keep them from loosening, yet allows me (or the new owner) to tighten the screws to achieve however heavy or light action is choosen.
Hopefully that answers your question....if not, and I misunderstood, we can sure try again.
