What’s the purpose of the slotted hole in spring?

[Jeffinn]

This is the second easy open 4 line Camillus knife that I’ve had apart recently. Both of them had slotted holes in the spring. Does anyone know why they decided to use slots as opposed to a drilled hole?
Assembly was a bit different. Had to compress the springs as usual but then had to tap the springs into place to get the pin in.

[OLDE CUTLER]

Slotted holes do not need to be precisely located, speeds up production, less rejected parts. Also maybe by making it slotted, that spring would fit more than one model of knife.

[orvet]

I believe if you line the holes in the liner up to the spring, the slot allows the rear pin for the handle as well as the clevis pin to go through the back spring and out the other liner.
Also what OC said, less need for precision with a slotted hole than with two small and the possibility using one back spring in more than one pattern.

[btrwtr]

The hole has to be precise to keep the back spring from wobbling and pivoting. Precisely drilled holes are the norm for factory pocket knives. If not precise it will compromise the function of the knife. I think the slot must be done to accommodate the shackle or bail.

[Jeffinn]

Both of the knives I purchased were missing the bail. But now that I look at it, you guys are right, it’s to accommodate the bail.
Thanks.
Jeff

[OLDE CUTLER]

The hole has to be precise to keep the back spring from wobbling and pivoting. Precisely drilled holes are the norm for factory pocket knives. If not precise it will compromise the function of the knife. I think the slot must be done to accommodate the shackle or bail.

The rocker pin hole must be precise, but on the outboard end of the butt end spring, an oversize hole, a slot, or no hole at all will do. Once the rocker pin is in, spring tension will keep everything tight. Check this old Keen Kutter jack, it has ho hole in the butt end at all. If you look closely, you can see the pin as there is no hole to conceal it. The pin just bears against the edge of the spring.

[orvet]

I think you are right OC, about just the rocker pin hole being precision both in size and location.
A lot of Jack patterns and single blade patterns, especially old German ones, seem to use the open rear pin without the pin hole in the spring.
It makes them more difficult to assemble without a jig, but as far as I can tell they work just fine once you get them assembled. I've not seen one fall apart due to the lack of a rear pin hole. On the contrary they all seem pretty tight for the most part.

[btrwtr]

The hole has to be precise to keep the back spring from wobbling and pivoting. Precisely drilled holes are the norm for factory pocket knives. If not precise it will compromise the function of the knife. I think the slot must be done to accommodate the shackle or bail.

The rocker pin hole must be precise, but on the outboard end of the butt end spring, an oversize hole, a slot, or no hole at all will do. Once the rocker pin is in, spring tension will keep everything tight. Check this old Keen Kutter jack, it has ho hole in the butt end at all. If you look closely, you can see the pin as there is no hole to conceal it. The pin just bears against the edge of the spring.
IMG_3206.JPG

I think we are saying the same thing. I have seen many examples of knives with no hole at all in the spring on the tail end of jack knives. Given this there still has to be a very precise point of contact between the back spring and the pin that is used. A drilled hole can be much larger than the pin but the contact point where the spring touches the pin has to be precise for the spring to align properly with the frame and function properly. The center pin hole must be precise in the same way. The center pin contact point is no different in that it receives pressure on only one side of the drilled hole so it could also be larger than necessary. As an optimum holes are drilled to a minimum OD. Having both the center and tail pin holes drilled over sized would not work well and could allow the spring to move laterally in the frame. There has to be an anchor point somewhere on the spring regardless of the type of knife. The holes can be larger or as in the example above no hole at all but the points of contact pressure still have to be precise.

[OLDE CUTLER]

The hole has to be precise to keep the back spring from wobbling and pivoting. Precisely drilled holes are the norm for factory pocket knives. If not precise it will compromise the function of the knife. I think the slot must be done to accommodate the shackle or bail.

The rocker pin hole must be precise, but on the outboard end of the butt end spring, an oversize hole, a slot, or no hole at all will do. Once the rocker pin is in, spring tension will keep everything tight. Check this old Keen Kutter jack, it has ho hole in the butt end at all. If you look closely, you can see the pin as there is no hole to conceal it. The pin just bears against the edge of the spring.
IMG_3206.JPG

I think we are saying the same thing. I have seen many examples of knives with no hole at all in the spring on the tail end of jack knives. Given this there still has to be a very precise point of contact between the back spring and the pin that is used. A drilled hole can be much larger than the pin but the contact point where the spring touches the pin has to be precise for the spring to align properly with the frame and function properly. The center pin hole must be precise in the same way. The center pin contact point is no different in that it receives pressure on only one side of the drilled hole so it could also be larger than necessary. As an optimum holes are drilled to a minimum OD. Having both the center and tail pin holes drilled over sized would not work well and could allow the spring to move laterally in the frame. There has to be an anchor point somewhere on the spring regardless of the type of knife. The holes can be larger or as in the example above no hole at all but the points of contact pressure still have to be precise.

I remember the first time I took apart a knife that did not have a hole for the pin in the butt end. I was thinking "what the heck?" But then after you look at the way it works it quickly becomes apparent that the spring is loaded in one direction only and does not need an actual pin hole.