Pivot Bushing for a folder

rpttrsn

rpttrsn

Joined
Nov 1, 2006
Messages
1,347
I am not pleased with the fit of the pivot pin to the bushing. The bushing is .250 x.126 x.111. The pivot pin is .1245 dia. Here is my questions.

-Diff. between the pin OD and bushing ID
-Should the bushing be slightly longer/ shorter / or the same thickness of the blade material

I will try to purchase a 1/4" x 1/8" bronze bushing to replace the one in the knife. I no longer have access to a lathe so will be fitting it by hand.
Thanks for any help.
Ron
 
Where is the problem? Is this a liner lock or a slip joint or lock back? I don't believe it's the pivot to inside bushing fit. Is the bushing too long? When you tighten the screws does the blade have side play? Frank
 
Frank,
The folder is a liner lock. When I adjust the tension on the blade by backing off slightly on the pivot screw so that the blade is not to tight to open (with the thumb stud), the blade is no longer centered when closed. It almost rubs against the liner opposite the liner lock. The bushing is smaller in length then the thickness of the blade. There are two bronze flat washers (.005 ) each on each side of the blade. I placed a ball bearing on the bushing and gave it a tap with a ball peen hammer on both ends. This improved the off center but it's not where it should be. For this reason I felt that a closer fit between the bushing and the pivot pin would improve this. I also thought that the bushing being .0005 longer the the thickness of the blade would allow a snug lockup of the pivot screw. All the mating surfaces are very smooth.
I hope that I am making this clear. I have not made any folders so am not sure what dimensions to shoot for.
Thanks
 
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Well you give good information for help. So the pivot is too short as I read it. It should be the wideth of the blade plus thre thickness of the two washers plus the wideth of the two liners. Ut usually ends up a smidging shorter. The bushing should be shorter than the blade thickness and the hole sizes would be right. You should be able to in the end add a small drop of thread locker to the screws tighten them so they bottom and move the blade with ease. If tightening the screws causes the blade to lock up, you've got to know the pivot is too short. If you believe it to be just a very small amount too short you can get a very fine adjustment by using a dremei or such with a small grit impregnated rubber wheel - cratex wheel - to take the surface around the hole on the scale side down. Otherewise you will need to get a new pivot and start over. The proper settin is when you open the blade, hold it upside down with the leaf spring to the scale side, it doesn't have any play side to side, but still will open smoothly. Frank
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Thanks for the info Frank. The pivot is under the bolsters and does not go thru. The pivot just goes thru the frame on both sides and the bolsters are counter bored to accept the head of the screw. It was one of the makers first folders and I am trying to improve on it somewhat. In general I am pleased with this knife but the pivot does need some attention. Your info above should be the same regardless if it goes thru the bolsters or not. I thank you for the reply to my question. I am starting with a new bushing as soon as I locate one.
Ron
 
You didn't read my answer correctly. I said it went through the two liners, two washers and the blade. I didn't say it went through the bolsters. But you did understand anyway, which is what I wanted you to know. Your frame is really called the liners and there are two. If I can help more please ask. Frank
 
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