Bolsters on slip-joint.

Matt Rochester

Matt Rochester

Joined
Nov 28, 2014
Messages
1,864
I just started my first single blade trapper style slip-joint. Most of the tutorials I've seen folks use a spot welder to attach the bolsters. I don't have one so I'll be doing something else. I know I could pin and peen them but that would be 3 pins I need to hide including the pivot. How about TIG welding them? I could drill couple holes and spot them? Only problem I see is I may warp the liners from too much heat. Anyways thanks for taking the time to read this and I appreciate any advice.
 
If you're competent with tig, then it's absolutely an option. Hard or soft soldering is another widely used option however. I like a high silver hard solder myself, it's quick and easy if you've done any torch work. Once you're adept you can get a near invisible joint, if your mating surfaces are dead flat. Although a little bright silver line doesn't really hurt the aesthetic with most materials. If you decide to go this route, your local welding supply store can help you. Flat/ribbon style solder is really advantageous in this case, but you can use piece of round, and beat them flat.

Yes warp is a concern, with any method that involves heat, but with plug welding it'll be a bigger concern because it'll be harder to clamp the liner flat to a heat sink, with soldering you can clamp the entire liner/bolster down with solder between the two, on a piece of steel, and using a small sharp hot torch, heat just the bolster, helps mitigate the warp.

Obviously in all things related to knifemaking, a big part of the equation is knowing how to straighten things when they inevitably do warp, to which, most of us have developed methods that work for our particular materials and processes.
 
javand said:
If you're competent with tig, then it's absolutely an option. Hard or soft soldering is another widely used option however. I like a high silver hard solder myself, it's quick and easy if you've done any torch work. Once you're adept you can get a near invisible joint, if your mating surfaces are dead flat. Although a little bright silver line doesn't really hurt the aesthetic with most materials. If you decide to go this route, your local welding supply store can help you. Flat/ribbon style solder is really advantageous in this case, but you can use piece of round, and beat them flat.

Yes warp is a concern, with any method that involves heat, but with plug welding it'll be a bigger concern because it'll be harder to clamp the liner flat to a heat sink, with soldering you can clamp the entire liner/bolster down with solder between the two, on a piece of steel, and using a small sharp hot torch, heat just the bolster, helps mitigate the warp.

Obviously in all things related to knifemaking, a big part of the equation is knowing how to straighten things when they inevitably do warp, to which, most of us have developed methods that work for our particular materials and processes.
Click to expand...

Thanks for the informative response. I guess I forgot about soldering. I'll probably just go that route.
 
Matt R said:
Thanks for the informative response. I guess I forgot about soldering. I'll probably just go that route.
Click to expand...

That's probably the easiest option, and it works great when you're dealing with dissimilar metals, or when using damascus for bolsters, since it wont leave the discoloration that spot welding does (which you have to anneal away). On the other hand, if you start making these regularly, Harbor Freight has a 220V spot welder that works just fine for doing bolsters, that's not expensive.

Spot welding can be the quickest/easiest option in many cases, especially cranking out handfuls of stainless or carbon liner/bolster models. Although it has it's drawbacks also, I think it's less appropriate for high end pieces, because of the tendency to leave little craters on the inside of the liner that are a bitch to clean up unless you use thick liners (which I dislike highly). Not remotely an issue for a simple stainless or carbon slipjoint, but on high end pieces, even the finishes on the inside of the knife matter.

Mostly I'm doing integrals these days, because it's an appreciated construction aspect for higher end pieces, but I use all methods, even occasionally, screws, depending on the materials, and design of a knife I'm making. Ultimately, like all crafts, the more tools in your tool box, the more potential range you've got.

I'd recommend trying as many methods as possible, and eventually you'll settle on your "go-to", and once you've figured out how you like to build what you like to build, suddenly, you'll likely realize your "style" has found itself. If on the other hand, you only figure out how to do something one way, chances are, you'll pretty much only make "one thing", even if you've got multiple versions of that "one thing".



I wouldn't rule out TIG if you're competent, especially if you have a good inverter machine that does thin stock well, I can see situations where it could be really advantageous method of putting things together. You gave me an idea about how to solve a problem I've been dealing with on an auto, unfortunately I only have a big old transformer machine that's more likely to blow a giant hole in a liner, than stick something to it. =\
 
javand said:
That's probably the easiest option, and it works great when you're dealing with dissimilar metals, or when using damascus for bolsters, since it wont leave the discoloration that spot welding does (which you have to anneal away). On the other hand, if you start making these regularly, Harbor Freight has a 220V spot welder that works just fine for doing bolsters, that's not expensive.

Spot welding can be the quickest/easiest option in many cases, especially cranking out handfuls of stainless or carbon liner/bolster models. Although it has it's drawbacks also, I think it's less appropriate for high end pieces, because of the tendency to leave little craters on the inside of the liner that are a bitch to clean up unless you use thick liners (which I dislike highly). Not remotely an issue for a simple stainless or carbon slipjoint, but on high end pieces, even the finishes on the inside of the knife matter.

Mostly I'm doing integrals these days, because it's an appreciated construction aspect for higher end pieces, but I use all methods, even occasionally, screws, depending on the materials, and design of a knife I'm making. Ultimately, like all crafts, the more tools in your tool box, the more potential range you've got.

I'd recommend trying as many methods as possible, and eventually you'll settle on your "go-to", and once you've figured out how you like to build what you like to build, suddenly, you'll likely realize your "style" has found itself. If on the other hand, you only figure out how to do something one way, chances are, you'll pretty much only make "one thing", even if you've got multiple versions of that "one thing".



I wouldn't rule out TIG if you're competent, especially if you have a good inverter machine that does thin stock well, I can see situations where it could be really advantageous method of putting things together. You gave me an idea about how to solve a problem I've been dealing with on an auto, unfortunately I only have a big old transformer machine that's more likely to blow a giant hole in a liner, than stick something to it. =\
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I've got a dynasty 280 and some 1/16 tungsten I may give a try at some point. I have another question if you don't mind. Right now my lock it at .110" at the top end where it meets the blade. The pivot end on my blade is .109". This seems it would help give a little clearance to the blade when opening but I haven't seen this detailed in any tutorials. I understand we want things as flat as possible but what are your thoughts? Thanks again.
 
Matt R said:
I've got a dynasty 280 and some 1/16 tungsten I may give a try at some point. I have another question if you don't mind. Right now my lock it at .110" at the top end where it meets the blade. The pivot end on my blade is .109". This seems it would help give a little clearance to the blade when opening but I haven't seen this detailed in any tutorials. I understand we want things as flat as possible but what are your thoughts? Thanks again.
Click to expand...

The way I build them (I'm sure somebody else has a different opinion), in a perfect world, you want your spring thickness to be the same as your blade tang, you want both, to be as close to perfectly parallel as possible. I surface grind them together personally. If these aren't extremely close, or there's a little taper to either, it will affect you, depending on where and what. A little taper to your tang will cause your tip to move one way or another, as little as a couple of thou at the tang, can translate to 1/16 at the tip of the blade, and is brutally obvious only heavily tapered blades, as I make.

Now if you're pinning a non-damascus knife together completely, then attaching the scales with screws, and grinding the blade after it's pinned, this won't matter, you simply grind it to center. However, if you're using exotic materials, where each individual component has to be completely finished before you finally assemble everything and pin domed pins, and you've got one shot or you have to disassemble, spend hours fixing whatever you broke or scratched or bent when you took it back apart, only to try again, then it's critical.

Any inaccuracies here also greatly affect the flushness of your fitment between the liners and the spring. Bear in mind that your spring and tang are basically the support pillars of the construction of the knife, they're the foundation of the whole show. Anywhere it's tilted or inconsistent, will show somewhere else, once it's all fastened together.

Even just deburring on a surface plate, the blade or the backspring by lapping them flat on a plate with paper glued down, can cause you to have issues, in fact I make sure to always lap the same way and try to lap both the spring and the blade at the same time while I'm doing any fitment, being very careful not to throw anything off.



Another thing to consider is that a tiny burr on any corner of the spring, tang, any of the pin holes or pivot, can affect fitment. You can have your backspring perfectly dialed in, with temp pins, landing flush at each position, riding a bur on one corner, and once you pin it all together, break it in, see it landing low in one or all positions, after the bur is rubbed off, and usually, you'll feel some friction in the action then also.


I've said before, and I'll say again, slipjoints seem (deceptively) like the simplest type of folders, but they are in fact, the most complicated general form. Yes you can make some really mechanically complicated autos, but very few if any of those require the complex relationship between so many multi-point mating surfaces as a slipjoint with a halfstop that walks, talks, times, and lands perfectly, let alone has timeless style.
 
I should also add, that the above applies if you're doing construction without a pivot bushing, if you are using a pivot bushing, there are multiple ways and types of doing such, but the way I do it, you surface grind the blade and spring together, with the bushing inserted, then, remove the bushing and spring, and grind the blade a certain amount more so that it clears barely, without wobble. Everyone has a magic number of this based on how they make their knives, 0.5-1 thou or so. Too little, and you wont get a smooth action, too much and your blade may wobble.

Otherwise, you want your spring and tang to be as close as possible to the same thickness and parallelism.
 
I had not planned on using a bushing but it seems it would be smoother and reduce wear from opening and closing. I will look into them.
 
Tony Bose did a series of videos covering bolster soldering I highly recommend watching them. I use his method (thanks Tony) and you will find its quick and easy and works every time.
 
Very interesting thread!
For soldering the bolsters i use the method Tony Bose made popular with the above posted tutorial. It requires a bit of time due to the pre-tinning of all the 4 mating surfaces, but it works well for the same reason. In the case you'd scorch some edge you can rub the black spots with fresh flux and restart clean.
A lot of people gets by with clamping ribbon solder & flux all at once, but i am not yet as adept at this....i don't know if it is for perparation issues or because i'm clumsy with the torch, but i cannot avoid some minimal black line somewhere around the bolster.
With Bose's method you'd get complete soldering all around...every time.
 
Glad somebody referenced the Bose soldering tutorial. That's how I do mine as well, without problems.
 
It might seem tedious the first time because you are not sure of set ups materials like solder and flux and how much heat is required but once you've done it you will find how clean and smooth the joint finishes. I tend to do a batch of 6 or more slipjoints at a given time to make best use of the set up and fixtures so the process is less time consuming overall.
 
Because I started out in silver fabrication, back in high school, I'm ears-up to the vagueness of language describing various kinds of soldering and brazing.
In silver work, the "soldering" is actually brazing- working temps are up around 1300F, and air-acetylene or oxy-acetylene are required.
This would certainly be a workable method for bolsters, but it's way more than is needed for a good strong durable bolster.
Standard silver "solders" in this range are a real problem solver because they work on such a wide variety of materials, with proper prep.
One of the best tips I've found for bolsters, and I've forgotten who suggested it but it's widely used, is Harris' Stay Brite solder. It has fairly low silver content, but works really well, especially on non ferrous materials.
I use almost exclusively stainless liners and brass/bronze/stainless bolsters, and I find that it's pretty effortless to get a thorough bond without pre tinning, though it's not a bad idea to tin by any means.
The best part is that you're working with a propane torch at 500F or under, so heat issues are dramatically minimized.
The only thing I use a true silver "solder" (actually brazing) material for is ferrous to stainless, such as a damascus bolster to a stainless liner.
The Stay Brite solder claims to work well for that, but hasn't for me- again, pre-tinning may make a huge difference.
Just my own experience, YMMV.
Have a blast!
Andy
 
Matt R said:
I had not planned on using a bushing but it seems it would be smoother and reduce wear from opening and closing. I will look into them.
Click to expand...

Don't over complicate your first one Matt. Bushings are a very nice feature, and many of us eventually decided to use them in most cases, but I'd argue it's important to learn how to pin a pivot using just rod well enough that you can hide it, and get a good slick action. It's trickier to pin, but it'll teach you what's what, and if you lock it up, you'll understand why, if it wobbles, you'll understand why.

Bushing's add an extra bit of learning curve, a few caveats, and while they've got some major advantages once you cross those hurdles, I wouldn't want to be reliant on them. There's certain types of construction that make them difficult to use in complex multiblade scenarios, etc, and they don't encourage finesse when pinning the pivot, which can hurt you later.

Try to resist the urge to run before you walk. Millions of slipjoints were built for a couple hundred years, and all during the golden age of slipjoints, without bushings, most of which still function today if they survived neglect and abuse.

If you don't have a surface grinder, you'll need jigs to lap the bushing correctly, and you've got a much higher chance of having or causing issues in other areas, that you won't be sure what or why it's the case. Without a lathe, you'll likely have to buy premade bushings, which limits your options further.


IMO, build a few without them, I'll be happy to discuss your options based on techniques and equipment when you're comfortable with pinning them the old-school way, and ready to move on.
 
Hey Matt,
please follow Javan's guide, i can testify he is a damn wizard when it comes to this kind of knives!
By the way, Javan if you'll give advice to Matt please put me in copy as well, you know my email ;)
 
javand said:
Don't over complicate your first one Matt. Bushings are a very nice feature, and many of us eventually decided to use them in most cases, but I'd argue it's important to learn how to pin a pivot using just rod well enough that you can hide it, and get a good slick action. It's trickier to pin, but it'll teach you what's what, and if you lock it up, you'll understand why, if it wobbles, you'll understand why.

Bushing's add an extra bit of learning curve, a few caveats, and while they've got some major advantages once you cross those hurdles, I wouldn't want to be reliant on them. There's certain types of construction that make them difficult to use in complex multiblade scenarios, etc, and they don't encourage finesse when pinning the pivot, which can hurt you later.

Try to resist the urge to run before you walk. Millions of slipjoints were built for a couple hundred years, and all during the golden age of slipjoints, without bushings, most of which still function today if they survived neglect and abuse.

If you don't have a surface grinder, you'll need jigs to lap the bushing correctly, and you've got a much higher chance of having or causing issues in other areas, that you won't be sure what or why it's the case. Without a lathe, you'll likely have to buy premade bushings, which limits your options further.


IMO, build a few without them, I'll be happy to discuss your options based on techniques and equipment when you're comfortable with pinning them the old-school way, and ready to move on.
Click to expand...
I will pin them. You've been more help than you know and I appreciate the time and thought you put into your response. I am waiting on some bolster material to show up and I'll keep it going.
 
stezann said:
Hey Matt,
please follow Javan's guide, i can testify he is a damn wizard when it comes to this kind of knives!
By the way, Javan if you'll give advice to Matt please put me in copy as well, you know my email ;)
Click to expand...


Will do Stefano, good to hear from you buddy. Hope life is well!
 
javand said:
Will do Stefano, good to hear from you buddy. Hope life is well!
Click to expand...
So I picked up some 5 percent silver solder and flux. Either it's the wrong type or I'm doing something wrong. I can't get it to flow out on the bolster while I'm tinning it. I found another thread that recommended some ss solder from k and g and ss flux. I've checked their site and found some low temp silver solder and was wondering if that was what I needed?
 
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