Slip joint critique

Not to hijack this thread but It's a question about slipjoint builds.

What makes you decide as to how far to put the spring pivot hole away from the tang notch ?

I learned thru some trial and error...
And now I can do it just by eye.
But I don't know if there is a rule of thumb.
 
I made the new back spring for knife #1 and heat treated both. I ended up messing up the blade on the 2nd knife so I started another one and got my first nail nick done. I'm not moving too fast.

IMG_20160303_005440_hdr_zpsv9xzrdzi.jpg
 
Taximanny said:
I actually printed that out and have it taped to my wall..when I started...lol
But it doesn't talk about the distance I was talking about.
I was just curious as to how others come up with there distance.
When NOT going off a pattern.
My first without a pattern made me learn as to about how far to set it back.
Click to expand...

Me too, i learned with my first slippie... by feel mostly.
There should be some relationship between spring height/pin position/preload, but generally i set the central pin between 1/2 and 2/3 of the handle lenght from the notch.... Longer handles allow for a more forward position given the same spring height. And of course, a 2/3 center pin allows for less grinding thin the spring flexing portion.
Good question, i would like to know other's rules of thumbs.


Lo/Rez: nice blade you have there, very neat nick!!
 
Lo/Rez said:
I made the new back spring for knife #1 and heat treated both. I ended up messing up the blade on the 2nd knife so I started another one and got my first nail nick done. I'm not moving too fast.

IMG_20160303_005440_hdr_zpsv9xzrdzi.jpg
Click to expand...

I like that nail nick. Did you mill that in?
 
Thanks. Yes I did. 1/16" ball nose end mill. I did a test run in some mild steel and then did this one. I'm new to all this. Just got my mill a week or so ago. It's around 50 thousandths deep. 3/32" blade stock.
 
stezann said:
Me too, i learned with my first slippie... by feel mostly.
There should be some relationship between spring height/pin position/preload, but generally i set the central pin between 1/2 and 2/3 of the handle lenght from the notch.... Longer handles allow for a more forward position given the same spring height. And of course, a 2/3 center pin allows for less grinding thin the spring flexing portion.
Good question, i would like to know other's rules of thumbs.


Lo/Rez: nice blade you have there, very neat nick!!
Click to expand...

Thanks.
 
I messed up the back spring on knife #2 and will be shelving that one for a bit. Thankfully I'm working on two knives. I have it somewhat close on the rise and fall indicator but am concerned about the blade and back spring fit. What do I do now?

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IMG_20160310_173647_hdr_zpswts8cbjt.jpg


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The spring is pretty strong still. Should I take more off the walk part or file some more off between the walk and the center pin?
 
You are going to have to get it lower in the open position, (more off the top of the tang)
then work half stop, and fully closed from there.
Ken.
 
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To lessen the stiffness you have to grind between the walk and the c.pin; now you see why the pin distance might have been a bit more than it is...
Be aware, before skimming the flex portion, that the stiffness will be somewhat less anyway after you have grinded the back flush.
It is coming nice :thumbup:
 
Thanks. I have the weekend off so I will be getting back at it later this week. On the other knife I was doing in tandem with this one I cut the pocket too deep so I am making (or trying) to do a lock back out of it. I don't know how smart it is of me to be doing two different kinds of folders at the same time when they are both firsts for me, but I'll give it a shot.
 
I don't see anything wrong doin'it in tandem...as long as you have time to dedicate it will be a crash course pratice!! You can learn much from each one and then decide what come next.
As far as the short pin distance concern, you can make up for this by setting a shorter preload (i don't suggest to grind the short flexing portion too thin). I don't prefer this route because often the preload gets "eaten" some by the final tuning, polishing of the walk and the like. Reducing the preload range demands for increased precision during fitting IMHO, while a longer flexing portion and a bit more preload allow more room for ending with a nice pull without getting mad.
 
Lo/Rez said:
Thanks. I have the weekend off so I will be getting back at it later this week. On the other knife I was doing in tandem with this one I cut the pocket too deep so I am making (or trying) to do a lock back out of it. I don't know how smart it is of me to be doing two different kinds of folders at the same time when they are both firsts for me, but I'll give it a shot.
Click to expand...



I wonder what would happen if the rear pin is eccentric ? That way you can preload spring as you wish ? Even when with time some wears come out It can be adjusted again ? Just me thinking out loud .......... never tried :) But I will !
 
Natlek said:
I wonder what would happen if the rear pin is eccentric ? That way you can preload spring as you wish ? Even when with time some wears come out It can be adjusted again ? Just me thinking out loud .......... never tried :) But I will !
Click to expand...

uhmm...
 
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Stezann , I think of something like this ..... or the same shape on both sides and two small bolt ? I think it is possible to do this .This will save you from a lot of trouble in process of making .... ?

2jadkzl.jpg
 
Natlek said:
Stezann , I think of something like this ..... or the same shape on both sides and two small bolt ? I think it is possible to do this .This will save you from a lot of trouble in process of making .... ?



2jadkzl.jpg
Click to expand...

If this was done it would only be a one time adjust...
Because you would have to grind the top of the spring flush with the scales.
If you adjust it again after the fact, you would need to sand again the top of the spring.
Interesting thought though...
I believe it takes away from a real slipjoint..in my opinion.
 
Hm , in future adjustments of tensions , displacement/movement of spring will be minimal ... I do not think that would be noted on the handle . Ok , as I say it s just loud thinking :thumbup:
 
Loud thinking and thinking out of the box are welcomed, but as Taximanny pointed out any movement of the spring preload will be spotted since you'll loose flushness.
It is easier tuning things before pinning, even bending the spring is doable as a last resort. A spring that is well heat treated won't loose strenght down the road.

Your idea may be useful, if wearing gets the spring lowered in front, an eccentric pivot could get back the back flush and recover preload at the expense of a minimal change in blade angle.
 
This is where I'm at right now. I think I may have made the spring a little too weak so I will make new liners if it is. I can use these ones for another build I hope. The tip is still too low, I hope I can adjust that without messing other things up. As of right now I just put the blade in the oven so maybe this weekend I will have some grinding to do.

[video=youtube;8Se-xvCIOYE]https://www.youtube.com/watch?v=8Se-xvCIOYE[/video]
 
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