centering the blade

L6steel

L6steel

Joined
Sep 23, 1999
Messages
5,855
How do you get the blade to lay centered in the frame on a liner lock without tightening the pivot so much the blade is hard to open? The lock tab pushes the blade to the side so I don't see how it's done.
 
I haven't made any folders yet but I would think that if you had a perfect fit between blade and pivot pin (1/1000" or less)the blade would stay centered no matter how loose the pivot screws were. I believe that is the key to getting that silky smooth action we all love.
 
Match drill everything, starting with the pivot pin holes. Is yer drill press vertical? Anyhoo, works for me so far...
 
Getting a REALLY nice fit between the folder and the pivot is essential...and like the guy said above....it MUST BE 90 degrees to the flat of your blade....your blade flats MUST be parallel.... and the two sides of your liners MUST have all the holes lined up perfectly or else you are SCREWED! I havent checked my drill press table in a while, probably should, for squareness.....the easiest way is to take a piece of 1/8" brass or aluminum rod (bends easy thats why) and make it look like an L with an extra arm going the opposite of the bottom leg....use a piece about one foot long and bent two 3" pieces opposite to eachother....wish i could put up a pic...like a Z but make the middle piece straight up and down..chuck it in your drill and bend the bottom piece out so it is near the edge of your drill press table and rotate it BY HAND and see if it touches evenly all the way around!!!!!! You need to mike your pivots and get some reamers that are about .001" oversized....people say .0005" but I can never get them to work with that close a tolerance.....You want smooth turning with just the smallest HINT of looseness. good luck, youre going to need it!! :)
:p :)
:) :p

I get my holes perfect in my liners by drilling the pivot holes first (undersized slightly and reamed undersized) and then putting a pivot pin in them (sometimes I have to tap it thru) then drilling a hole in the back where a spacer goes....putting a screw and nut in that hole, then drilling the other standoff hole and screwing it down too, drilling the stop pin hole last with everything snug together... hope that helps
 
Your pivot needs to be within .0005 of your pivot hole. Your standoffs or back bar must be exactly the thickness of your washers larger than your blade. Another problem can be the liner material. If its bowed it can throw the whole works off. One key thing is I grind my blade in the knife frame that the blade goes in. That way Im able to grind the blade evenly.
 
one more thing....If the pivot is loose my blades rarely sit centered but are pushed over as you describe...it is also very important to have your spacers/standoffs/backstrap the exact size of the thickness of the blade plus your washers, and they too need to have sides that are FLAT and parallel to the holes thru them.....it aint easy... :(
 
Also don't overbend your lock arm. You just want enough bend so that it would barely touch the other liner with out the blade in place of course. Also the closer the end of the lock is to the pivot hole the less pressure is applied to the side of the blade.

Best thing I have found is mike everything and keep it parallel as others have mentioned.
 
Mike, we talked about this in chat a while back. Everything has to be very flat. Drill press as to be as close to 90 degree's with the table as possible. My pivot pins are snug but do rotate freely. The other big thing I do that I haven't seen yet in this thread is I drill both liners together. I use my pattern for the first liner and then use that liner to drill the other one. Once I have the shape pretty much where I want it I drill the backstop pin and then ream it to fit. Then dissasemble the halves and debur them. Then with the halves again together with the backstop pin in drill and ream the pivot pin. Feel free to debur as much as possible. I like everything as flat as I can get it. If it isn't flat you run into problems down the road. Lesson's I have learned the hard way.
 
I already do all these things. Thats why I don't get it. Maybe it's just stupid using 90 thousandths ti liners.Oh well, maybe the next batch with thinner liners will lay centered. Thanks guys!!!
 
Mike One thing I ran into is the detent ball sticks out farther than the washer is thick. If you have a .010" washer on each side, the ball cant stick out more than .010" or it will force the blade over to one side when tightening the pivot screw. Just relieve the bolster to give the detent ball some space. This may be your problem?
 
Bruce has a good idea. If the ball height is over the washer thickness you will also notice a track being scored into the blade after a while also making it hard to open/close the blade. I use .020 teflon washers and set the ball .003 under the washer thickness. Meaning liner thickness plus .017 for the ball height. Also are you using a bushing or just a pivot pin? Maybe to much play there. I think the .090 liners maybe a tad much and if you have bent the liner lock over too much this may be forcing the blade to the other side. Not a lot of force needed to work correctly. I have found that if a liner lock sticks it usually because I have the liner bent to far. Take a little off and it should help.

Also Darrel gave me this idea for this problem. You can use a bigger washer on the side that it leans too if you have the room. Not thicker but bigger meaning more force needed to push the blade to that side. I usually use a 3/16th pivot and a 1/2 inch diameter washer for each side. If I have a slight lean I will use a 5/8th inch washer on the leaning side.
 
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