slipjoint spring tension

HSC ///

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Nov 7, 2012
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question for makers - why is a spring tension of a 5 commonly used?
sure it's snappy....

recently I made this slipjoint shown below and the spring tension came out to by about a 3
I'm finding this tension to be much more pleasant to open. It's not snappy on the close though.
In general it feels almost silky and almost jewel like.

So why the 5 tension?

thanks
C5DB61DA-55FC-499B-B4D3-5BA067F4C617_zps7agefywq.jpg
 
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Collectors don't open/close a knife very often and they like the "snap" - for a using knife, I like something that's easier to open/close.

BTW, what's this "3" and "5" you mention - oz of pull to open? lb of pull?
 
Collectors don't open/close a knife very often and they like the "snap" - for a using knife, I like something that's easier to open/close.

BTW, what's this "3" and "5" you mention - oz of pull to open? lb of pull?

to be honest I'm not certain what the 3 or 5 is, for me it's not oz of pull or lb of pull
I thought it was a rough measurement of 1 being very easy and 10 being very hard.
I'm guessing 5 was in the middle, that's the extent of what I know :-)
 
I like the snap of a finger guillotine to play with:eek:, but for actual use, prefer a softer spring as well.
Darcy
 
I like a lighter spring level than many of the top slipjoint guys at the moment make personally. It's one of those things, the esoteric aspects, of which the enthusiasts of so many different things, tend to fixate on, and as is typical, at some point, a popular, default "opinion" ends up proliferating, based on what whomever was the most vocal and passionate about the issue, favored.

Much like all the exotic bearing systems in liner/framelocks and flippers, people fixate on some on the most minute mechanical functions, sometimes even ignoring the overall package or primary functions.


I should say though, that as you learn more and more about the deep complex geometrical relationships with slipjoints, you'll figure out there it is possible to make a very snappy, yet very light pull. A heavy pre-load, but thinner spring, is one part of the equation, the other, is the radius of the corners (cams) of your tang. If you have a heavy spring, you can have more radiused corners, and still get good snap, but if your spring is lighter, they need to be sharper, and you need a heavier pre-load.

I make most of mine with what's sometimes referred to as a "progressive" pull, meaning it's easier to open from closed to half, than half to open, this is my profound preference, and IMO, the only real reason to use a half-stop in the first place, is to make the pull function in this way, but that's my opinion, and isn't shared by all.

Another thing, because of the way I design many of my patterns, and my strong preference for hiding the back square, aka "sunken joint" design in all positions, open (obviously), half-stop even, and closed, and the aesthetics of the front of the bolster that flow to my eye without abbreviation (aka interrupting the flow), tends to dictate that my blade attitude at half-stop (half-open) is not, dead 90 degrees. I feel very strongly that the idea it must be dead 90 is simply an assumption that was defaulted to, and there's no mandate for it to be this way, and in many designs is a detriment to the aesthetic flow of the knife. However, I will openly admit, that it makes it near impossible with a progressive, light-ish pull, to avoid a little over-shoot when snapping the blade from open to half-stop. It's not "wobble" per say, they aren't remotely loose, just that it'll shoot a little past half and back to seated when snapping it.

Some collectors/buyers absolute hate this about my knives, they have very specific expectations about exactly how the walk and talk should function. Usually, based on, I presume, the standard set forth by whichever makers they revere as the "best". I disagree, and I'm happy to explain why to anybody that wants to discuss why I do things the way I do them. Ultimately though, it's good that we have different opinions and different makers make things differently, as long as we each know why we make things the way we make them, and don't simply make something because of the reverential/dogmatic excuse of "because that's the way it's supposed to be". If we all made the same knife, the same way though, it'd be pretty miserable for all of us, and our customers. There will always be a contingent of followers pushing for homogeneity, it's unfortunately the predominate flavor of human nature, otherwise society wouldn't be as consistent and dominating as it is. At the same time, there will always be some of us that do things different, or appreciate something that is done differently, with good reason and execution.

Ultimately we all fixate on certain quirks that are important to us, and the process which we come about those fixations is likely very complex. A combination of process, design, luck, complexity, and who knows what else. I think that's a really fundamental part of the organic evolution of each of our personal styles, much more so than us pouring out our artistic insecurities and trying to prove we can do something new for the sake of it, which so often seems to be the only motivation for many design quirks.


In the end, even the 1-10 pull level system we toss about is highly subjective, since we've never really established a baseline at either extreme publicly, we just make assumptions based on what we think the rest of us mean. Is 1 flying open with no spring resistance at all, and 10 locked up completely? I've met nail breakers I couldn't open, that bigger guys than me loved, and would call a 7, to me they were at least 9s.




LOL sorry, some of you guys that have talked to me on the phone know I get pretty philosophical on this subject, and I can talk for hours about it... Sorry if I've digressed too far again.
 
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The other thing to keep in mind is that if it starts as a 5, it will be a 3 in a year of normal use.
 
question for makers - why is a spring tension of a 5 commonly used?
sure it's snappy....

recently I made this slipjoint shown below and the spring tension came out to by about a 3
I'm finding this tension to be much more pleasant to open. It's not snappy on the close though.
In general it feels almost silky and almost jewel like.

So why the 5 tension?

thanks
C5DB61DA-55FC-499B-B4D3-5BA067F4C617_zps7agefywq.jpg
 
Spring tension and tang geometry is something that I have spent a lot of time thinking about. I have experimented with a lot of different "styles" in how I design my tangs, and how I set up my spring tension, and have kind of just settled on what I find is appropriate for the particular knife. I like using a "progressive pull" on a knife that I want to be easily pinchable, but want a heavy snap from half to open. On some patterns, I like it to be closer to equal, maybe 5 on the first half, and 6 on the second. All of it really depends on what I think fits best for the situation.

Now, I know there are collectors out there that want to feel an identical pull weight all the way through the action of the knife, but it doesn't make sense to me, so I don't do it. I build a knife to be used, no matter how "fancy" I make it, but I do keep the general market preferences in mind, cause I'd like to sell my work on occasion. I like a heavy spring in my knives with a pull around a 7 or 8, but I have seen a lot of people not even bother opening my personal knife, cause it'd break their nails. At the same time, I have made what I would consider a nail breaker, and have been scoffed at. I know that most people don't want a knife with a pull that heavy, so I usually try to shoot in the 4-6 range, again, depending on the knife.

About the so-called pull rating "system" people tend to use, I really don't like it for the very reasons that Javan stated above. It really is arbitrary, but it's the system we have.

As far as "why shoot for a 5", is, like Don mentioned, it tends to be the Goldilocks porridge for the general market. In terms of the knife's action, I shoot for a few things. I like a resounding snap for all of the positions, I like the blade to move smoothly and steadily, and I like the knife to feel very secure in the open position. Minimizing "rattle" or "wobble" in the half stop is also important to me, but with a progressive pull, it is damned tough to minimize it from the open to half stop position, the geometry of the tang just makes it want to overshoot.

I guess what I am really trying to say, without being overly verbose, is that you'll really have to find what works best for what you are trying to make. I don't think that there is a "wrong" or "right" way of doing things, cause, in the end, it all depends on personal preference. As long as it works, stick to what suits you. I also think that some of the best work, is that which suits the makers personal tastes. Not only can it show the truest form of the maker's style, it can better portray a maker's talents.

Sorry about the wall of text, but I could go on and on about these things. Probably why Javan and I get along. LOL
 
What collectors like is obviously very important to makers, unless we're making them all for ourselves, so yes to all the above.
Important too, not to lose what it's all about- firm engagement in the closed and open position keeps the knife from accidentally opening or closing, and that half stop saves your knuckles when you close it.
A soft spring on a gentleman's penknife is one thing, on a back pocket trapper it's another, and a hazard in use.
 
I asked Evan to get on here and contribute to this thread, cause it's something we've talked about on the phone in length, and I think this is a great discussion of the type we slipjoint makers should be having. We do of course, have them often at shows and visits, but there's not a lot of this type of discussion between makers available online. Much more of course available of the opinions of enthusiasts/buyers/collectors, which of course is just as important, but not the whole story IMO.


I will say that even though I often make my personal knives around a 5-6 pull, I love picking up a super slick sexy 3-4 that's just butter all the way through.


Another thing I think many of us can agree on, the strength of pull is secondary to the smoothness of the action, and silky smooth 7, can feel way better and even easier in some cases, than a gritty 4.


I will disagree with Stacy above however (he's not wrong, but it's highly complicated in my view), the lightening of a spring over time depends on MANY variables, such as spring thickness vs pre-load, and spring wear based on material, hardness, and the geometry of the tang corners. Sharp corners, with a heavy rise, especially on a very stiff, low pre-load spring, will wear the spring typically at a significantly faster rate, and the pull will decrease quickly over time. Gentle corners, with a lighter, but more loaded spring, can wear very slowly, even at 5+ pulls. At the same time, I've seen certain steels that work excellently as blades, wear insanely fast with the same HT regime, and tempered to 48-50.

I've said it a million times, and I'll say it again, slipjoints are the most deceptively complicated type of folder there is. This particular component of this type of construction is one I spend a huge amount of my waking time pondering, anybody that has talked to me about it knows I'm beyond obsessed with it, and I'm still constantly discovering some new variable. Of course, that's much of the appeal to me.

Many here don't know, but when I got started making knives 6 or 7 years ago, I had some ideas about what kind of maker I wanted to be, mostly it was fixed blades, with a minimalist approach, utilizing as little equipment as possible, I had zero interest in pocket knives at all, was never a collector or really even a user of such, so I didn't come into it with many expectations. It is of course pretty typically ironic that I'm known primarily for slipjoints and damascus, and have a big shop filled with large heavy machinery, but that's what captured my attention, regardless of my intentions, mostly because of the depth and complexity each of those areas has the potential for.
 
What collectors like is obviously very important to makers, unless we're making them all for ourselves, so yes to all the above.
Important too, not to lose what it's all about- firm engagement in the closed and open position keeps the knife from accidentally opening or closing, and that half stop saves your knuckles when you close it.
A soft spring on a gentleman's penknife is one thing, on a back pocket trapper it's another, and a hazard in use.


I can promise you that you can have a much softer spring than most people realize, with extremely positive engagement in each position, as I've mentioned, the trick is having a thin spring with heavy pre-load, but you have to be attentive to spring-rise as with all designs. You'll just have to trust when i tell you that you can make a 3 pull from closed to half, with a progressive pull, that will never open on it's on, or in your pocket, even dropped. In almost any case when one will open accidentally it's because of lack of positive loading in between the lower corner and the kick.

I agree that what collectors want is certainly something we all consider, although personally, I approach knives from the standpoint of making them all as if they were for me, at least fundamentally. I will make a harder or lighter pull if someone requests it, and I will take orders from my repeat customers with somewhat specific details, but personally I make what I make, my way, with few compromises. I'm not a heavily collected by the so called "big collectors" yet, may never be, but I have yet to have any trouble selling every knife I make, at prices I'm quite happy with, and am pretty proud that a large number of my knives sell to other makers, who I think often appreciate thing I incorporate, that non-makers wouldn't notice or understand. I don't personally make knives to anyone's design other than my own, and do not approach this trade from the standpoint of a "service provider", where the customer is in control. That being said, while I am currently full-time and have been for a while, I'll take a regular job at any point I have to, so that I can continue doing things my way.

My only point in saying that, is to re-iterate, that it's important that we have a variety of makers doing a variety of different things, different ways, when we try to distill it all down to one "right way", that's when our trade becomes stagnant and non-inclusive. Slipjoints are a very old style of construction, and I don't think anybody here is trying to re-invent the wheel, or encourage that type of fallacy, but it is our responsibility as makers to discourse about the advantages and disadvantages of various construction techniques and technical details, and educate our customer base, openly, and honestly. Nobody benefits from dogma or mysticism. Of course, nobody benefits from someone pretending a mistake is a feature either.


Sorry Harbeer if I've derailed your thread completely, but this kind of discussion is what I live for unfortunately.. =D

Cheers everyone for the construction conversation.
 
Sorry Harbeer if I've derailed your thread completely, but this kind of discussion is what I live for unfortunately.. =D

Cheers everyone for the construction conversation.

not at all, this is great learning for me.

I've got my questions(s) answered and more thinking to do on what's right for me,
This last slipjoint came out great in so many ways, despite making the spring lighter than I have been.
But I'm finding it the most pleasant to use.
 
I have been looking into start making slipjoints and this thread is only a little over 10 posts, yet has so much info. Thanks guys!
 
My pleasure guys, thanks for being patient with the ravings of a probable mad-man. ;)

I want to make it perfectly clear that I'm in no way trying to influence anybody's way of making knives or slipjoints, anybody that knows me in "real-life", I believe would tell you, I appreciate all way of doing things, especially in regard to making knives, as long as they're thoughtfully considered, and done with reason. I'm the last person in the world that wants everyone to make "my style" of knives. Frankly, I'd prefer nobody did but me! ;D In seriousness though, honest diversity in our market is incredibly good for all of us, as long as we nurture that culture, and pursue the best work we can, with an open mind toward always refining what the definition of "best" is to each of us, individually.
 
Sooo, I'm going to derail this thread a little further to expand on a point that Javan made.

Something that has fascinated me to no end, are the different the process applied, and methods/tools utilized by slipjoint makers. I cannot speak to any other type of knifemaker, as I have my head deeply and firmly planted in the bottomless abyss that is the slipjoint knife. I firmly believe that no two slipjoint makers have the same process. An insight into a maker's process is almost like a glimpse into how their mind works, and each one is unique in its own way. This not only leads to a diversity in method, but style, as well.

I have a theory that this is something that is unique to slipjoints, at least in the realm of the modern era of the pocket knife. I think that this is due to the lack of information out there on, not only how to make a slipjoint, but also the immense amount of ways that one can be made. At a glance, and to the layperson, a slipjoint seems like such a simple tool, but, in reality, the complexity is staggering. For this, I have an immense amount of respect for my fellow slipjoint maker. This is not to say that I lack respect for any other kind of knifemaker, it is just something that I am not educated in, therefore cannot fully speak to it.

So, we have spoken to the complexity of creating this knife in the modern era, but what is truly staggering is the unbelievable quality of work that was done in the golden age of the slipjoint. How those guys made the knives that they did, 100+ years ago, is mind boggling. The complexity of some of the old knives, executed with such precision, and with such (relatively) primitive tools, is truly the stuff of legends. This awe that I have may just be due to my inexperience in knifemaking, or working with tools, in general, but I still think it is something to be revered.

The history of these knives is what drew me into working on slipjoints, and the endless complexity, variety, and challenge is what has made me completely and utterly obsessed with them. It's my curse, and one I am happy to bear. My wife, on the other hand...

I'll stop here, before I further expose my lunacy.
 
Javand and HSC and all the rest,

Just wanted to add my thanks for the thorough responses and extra information. Keep it coming. I've made a few slippies as well, and enjoy them quite a bit. Its a fun topic and one not often shared, so its appreciated.
 
When we started talking about slipjoint spring tension x number of years ago here on BF, 0-1 was supposed to fall open while a "10"
was tension that required pliers. As far as drawing slipjoint patterns there has to be a couple thousand of slip patterns. Some of my more successful
patterns have been drawn -literally sketched on scrap paper all the way to paper towels.
Ken
 
When we started talking about slipjoint spring tension x number of years ago here on BF, 0-1 was supposed to fall open while a "10"
was tension that required pliers.

Now that sorta makes sense on the way to meaning of 0 to 10 scale, "0" is useless and dangerous because it will fall open, and "10" while not dangerous is still useless because you can't get it open.

Saying that "5" is the just right place doesn't mean much - my wife's "5" would be MUCH weaker than my personal "5", and I still like a softer action, but do wish to feel/hear the "Walk 'n Talk" action on a slipjoint. My wife (and other ladies I've made slipjoints for) don't wish to take a chance on breaking a manicured nail when opening.

Good discussion - and I forgot to mention to HSC///: good looking slipjoint - are those brass bolsters?
 
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