Fitting the lock

[pjelect]

I was going to e-mail Don Roberson this question as I use his "My Way" methods for my linerlocks(only 2, so far), but I thought I would also like to post the question here for some feedback. As I said, I've used Mr. Robinson's methods for fitting the stop pin and detent ball with great success. So much so that it truely amazes me with its simplicity and accuracy.Then comes the part of filing the lock face to achieve the proper lockup. This is where I go bananna's, filing,checking,filing,checking,oops! Does anyone have a "my way" method for fitting up the lock as foolproof as Mr. Robinson's stop pin and detent ball methods, or should I buy a new file and shut up? Thanx, Pat McGroder

[Don Robinson]

Pat, you'll probably get lots of different ideas here on that subject.

Here's what I do. As you know, I scribe a line locating the end of the lockbar in relation to the end of the blade, then carefully cut the slot in the liner to establish the lock end of the lock bar. I carefully line up the dremel disk with the scribed line, and cut it leaving only the shiny scribed layout line on the bar.

Now I bend the bar, then make a trial assembly. When the assembly is done, I look thru the lock /bar interface and see if I can see any light, and if so, where the clearance is, so I won't remove any more material from that area. It helps to use a magni-visor or glass.

When I determine where material needs to be removed from the bar, I dis-assemble the knife, take a small piece of .050" Ti and pry the bar out enough from the liner to polish the end of the lock bar on a 6" deburring wheel mounted on a 6" grinder. The deburring wheel removes a small amount of metal and polishes the surface.

Make another assembly, and check the lock.

Repeat as many times as necessary. Be careful. Don't get too feisty removing metal or you'll remove too much.



It helps to blacken the end of the bar with a black felt tip marker each time, so you can see where the wheel is removing metal.

I've made many linerlock folders, and tried filing and that works, but I save lots of time using the 6" deburring wheel. It cuts fast, but carefully, a little at a time, and you have the added benefit of polishing the lock to prevent wear-in later.

Unless you have a factory and precision CNC machinery, there;s no way to avoid several trial fits before a knife is finished. Just don't leave more than .005" to .010" on the end of the bar so it doesn't take too much effort to achieve a good fit.

I couldn't do without a deburring wheel. Second to my belt grinder, it's the most used tool in my shop when making knives.

[Ray Rogers]

There is no way to avoid a few 'fit and try" cycles when first fitting a lock (as Don already pointed out). It sounds like you have a method that works and just need some more practice. Still, you asked for alternatives so I'll give you one.

You can see this method in my tutorial if you want to look at it (another thread a little further down the Folder Forum page). I start off like Don does by cutting the lock to match the lock notch at the back of the blade. The difference in my method is that after that initial cut (and maybe a little polishing) I never touch the face of the lock bar again. When I make the blade, I leave a little extra metal in the area above the lock notch - the area that contacts the stop bar. With the knife assembled at this point and the blade opened , the lock bar will not quite be able to fall into the lock notch because there is too much metal at the back of the blade. I use a worn 400 grit belt to reduce the metal. It is fairly easy to take metal quickly at first and try the blade until the lock bar is at the edge of the lock notch, about to fall in. Then take smaller amounts until the bar just begins to fall in the notch. Assemble the knife and you may find the lock is already near perfect. Sometimes, snapping the blade open hard a few times will finish the process. Anyway, this method gives you a little extra leeway to make small mistakes. Since I've done it this way I don't think I have ever taken off more metal than I meant to........

[pjelect]

Thanks, Gentleman, for your replies. Ray, I think I'll try your suggestion next time. Since the back of the blade is already been flattened and squared,it sounds like it would be easier for me to take minute amounts off the back with a little more precision. Thanx, again, Pat McGroder

[pjelect]

By the way, I was able to fix my sloppy lock job by rereaming the stop pin hole slightly bigger and upping the size of the stop pin to match. Pat

[Omega]

ive done this many ways the best way ive found (no fit and try) i cut my lock out fist then bend the lock how i want it then put the blade in between the liners at this point the end of the blade is past the lock so i user my scribe and scribe a line by tracing the lock face. then i take the blade and grind up to this line at 10 degress this way my blade is cut to my lock and ive never had to mess around with the fit.


bill

[Ray Rogers]

Pat,

Good for you, that's a pretty standard way to address the problem and it works well. Once the new stop pin is in place, you're back to being able to remove metal from the rear of the blade if necessary (or the front of the lock bar if you prefer)...........

[Frank Niro]

I'm always interested in a better way . If you grind the back of the blade where it makes contact with either a stop pin or the end of the spacer bar, aren't you going to change the attitude of the blade? The blade will keep moving upward at its tip will it not? Bill's thing to grind on the blade notch could work better than grinding on the front of the leaf since with the blade thickness there will be more resistance to the grinding and less chance to over grind. I will try this on the next one. Frank

[Ray Rogers]

Frank,

Grinding the face of the spring or the lock notch itself means that you have to be very careful to keep things lined up. In other words, it's easy to lose the fit that you originally had when you first marked the spring and cut it out.

You are right about the attitude of the blade but there is a process to deal with that problem - if you mark the spring and cut it loose exactly as in the other methods then the blade sits in the attitude that you desire. If you have extra metal at the back of the blade it is not possible to put the blade in the proper attitude because the stop bar is in the way. Obviously then, the process is to put the blade in the desired attitude, mark and cut the lock bar, and THEN install the stop bar (this also can be done when a spacer bar is used). With the stop bar installed the blade is now out of position. Removing metal from the back of the blade slowly brings the blade into position until the lock bar drops into the notch. At that time, the blade has returned to the desired position and the lock face and lock notch are back to mating properly.

It's all about the sequence in which the steps are done. My tutorial doesn't do anything significantly different than the way most other maker's make their folders. What it does do is offer a procedure that is as close to foolproof as years of trial and error could teach me.......