Custom Slip Joint Discussion

[T.A.DAVISON]

Who knows what's the difference?
What do you gain or lose by making a slip joint a common or sunken joint?
Just trying to make some good discussion here.

I have two photos here, one knife is a sunken joint and one is a common joint.

I only make them with a common joint now.

So what is the difference in the knives?
What did I gain by making it a common joint?

Also what is your preference? common? or Sunken?


Todd

First knife is a sunken joint.​

Second knife is a common joint.​

.

 

[Chuck Gedraitis Knives]

It looks like the common joint has more of the blade sticking out of the handle when closed. I guess you could have a thicker spring and more mechanical advantage when opening the knife since it has less distance to travel?

I could be completely wrong?

 

[T.A.DAVISON]

It looks like the common joint has more of the blade sticking out of the handle when closed. I guess you could have a thicker spring and more mechanical advantage when opening the knife since it has less distance to travel?

I could be completely wrong?

Chuck,

On a common joint you could change the spring thickness?
But that is not what I'm looking at?
What changes on the knife? you have to really look at the detail.

I just put up these two pics.
Go look at other knives with sunken joints.
And ones with common joints, what changes?

Look close.

Todd

 

[VCM3]

I think,on a common joint,you get a taller blade size (spine to edge),to handle ratio
Obviously on the sunk joint,the tang (run) is less exposed w/closed
How'd I do ?
-Vince

 

[VCM3]

I prefer a sunken joint,but a lot of patterns I like are not made with it
-Vince

 

[T.A.DAVISON]

I think,on a common joint,you get a taller blade size (spine to edge),to handle ratio
Obviously on the sunk joint,the tang (run) is less exposed w/closed
How'd I do ?
-Vince

You are on the right track.

On a common joint you get a balance from bolster to blade.
And that makes the whole lines of the knife perfect, to me any way.
Also you get better strength out of the joint.
It is impossible to get that equalizem on the knife, with a sunken joint.
I've tried.

That is why the old fellers made them common joints, they KNEW what they were doing, and it stuck.
You just can't beat traditional.... :thumbup:

 

[T.A.DAVISON]

Was that all clear as mudd?


.

 

[T.A.DAVISON]

Here is another knife with a sunken joint.
See how the blade is not full width of the bolster.
That is why I went to common joints only now.
Look at #406 EBONY above, blade fills the front of the bolster all the way across.
Just much better lines, and more solid knife.

Later

Todd

Good eye Vince. :thumbup:

 

[Murray White]

TA -- this is an interesting discussion. A few years back in the TKCL there was a lengthy discussion regarding knives which you call "Common" but another acronym which I have since forgotten was attached. The concern was with the "common" -- the blade when closed into the frame has a sharp edge protruding which can be a pocket wrecker or can also injure the hand when trying to extract the knife from the pocket and thus the sunken joint was preferred.

 

[T.A.DAVISON]

TA -- this is an interesting discussion. A few years back in the TKCL there was a lengthy discussion regarding knives which you call "Common" but another acronym which I have since forgotten was attached. The concern was with the "common" -- the blade when closed into the frame has a sharp edge protruding which can be a pocket wrecker or can also injure the hand when trying to extract the knife from the pocket and thus the sunken joint was preferred.

Exactly!

The old timers as I will call them here, could of made sunken joints.
I know they could of, but they did not do it because of what I'm talking about here.

And their reasoning was probably more to the strength of the knife.
Than the lines - LOOK of the knife, that I am more after.
They really new their knives would be used, and that they had better be good. Or no one would buy them any more.
Those guys back then probably only had one knife, and used it, and probably used it hard.

So whats your preference?

 

[Durwood]

I may be off base here, but I don't think so. What makes the joint strong, among other things, is the amount of tang inside the frame, but the trade off is the more tang inside the frame the less blade length as compared to the handle. Here is an example of a sunk joint knife that has the tang the size of the bolster, but the frame is taller. I'm not saying your thinking is invalid, but you are only comparing examples of your own work. An error in logic, if you will In other words, "my knives with common joints have larger blades, all knives with common joints have larger blades..."

 

[rprocter]

Todd, i think #202 is a fantastic, elegant knife. a bit of a "Gentlemans" look and the sunken joint is appropriate.
a knife like #406 should have a common joint, because it's heavier duty and needs the extra strength, as it's more likely to be worked harder.
so to me it comes down to the intended purpose of the knife.
how about you start making a high end Gentleman's knife, slender, sleek, elegant, not intended as a camp knife. sunken joints, exquisite !
time to expand your repetoire. you could have 2 "lines": Babes and Brutes !
so i'm waitin' for a babe (like a slender Wharncliffe Whittler with elephant ivory, or a 2 blade serpentine candle end lobster, with sunken joints of course, these won't be "bush knives").
roland

 

[rprocter]

Durwood, your Ray Cover knife has half sunk joints.(ref. LGK 4th ed. pg. 236)
roland

 

[T.A.DAVISON]

Durwood, your Ray Cover knife has half sunk joints.(ref. LGK 4th ed. pg. 236)
roland

That is a beautiful cover.

Thanks Roland,
You look at that knife and what we are talking about and it is there.
That give and take balance.

More discussion....... :thumbup:

Whats your preference?

Todd

 

[Durwood]

Durwood, your Ray Cover knife has half sunk joints.(ref. LGK 4th ed. pg. 236)
roland

Ok roland, maybe by a 1/32"... This one has a completly sunk joint: and the blade tang matches the bolster.

I'm talking about the Wharncliffe in this pic:

 

[rprocter]

the sketch in Levine's Guide to Knives for half sunk joints, shows it protruding above bolster by just a "smidge", like yours.
roland

 

[Chuck Gedraitis Knives]

What it all comes down to is pivot placement, the size of the tang and the height of the spring.

Put the pivot a little lower than center and you can fit a wider blade into the handle but when closed you have more of the tang corner sticking out.

 

[Peregrin]

I'm learning some things here. Thanks for the informative thread. I tend to like the looks of the common joint myself, especially when the knife is open. The fact that it adds to the strength is another plus. The one pattern I can think of that seems to be the best of both would be the Copperhead.

 

[T.A.DAVISON]

I'm learning some things here. Thanks for the informative thread. I tend to like the looks of the common joint myself, especially when the knife is open. The fact that it adds to the strength is another plus. The one pattern I can think of that seems to be the best of both would be the Copperhead.

You hid the notch, but open the knife and the bolster is wider than the blade.
That is probably why those type patterns came about???


TA

 

[brightred]

todd,

good questions!

i agree that on the knives you posted, the common joint looks better than the sunk joint, knife open and closed. but we know that there are certain traditional patterns that have either sunk or common joints. my decision which knife pattern to to put in my pocket is based on the intended use (easy or tough tasks) and if i like the knife "naked" (sunk joints) or in a pouch sheath (common joints).

to give an example: the stockman has common joints, so it needs a pouch sheath, otherwise the trousers are ruined. but the bolsters are rather narrow and short, so, although the tang is exposed, the blades are not held very strongly, compared to the sowbelly where the joints are sunk on one side. here the bolsters are long and wide (so are the tangs), that makes a stronger knife. and then, i don't think that the sowbelly has less flow than the stockman, just because the bolsters are much wider than the tang.

so i think the equation sunk=weak and common=strong is only correct if you don't change the knife pattern, but the width and length of the tang and the bolsters.

best regards,
hans

(left picture: sowbelly left, stockman right. right picture: sowbelly right, stockman left)