slip joint question...possible galling

Below is a photo of the type of "galling" that I was experiencing about six years ago when I first started using stainless steel. When trying to open the blade, it was very, very difficult - not from spring pressure, but some type of extreme friction ("cold welding" as Mete suggests?) On the radiused corner of the tang is metal that looks to have been pulled, or torn from the spring. No amount of clean-up, refinishing or lubrication fixed it. I thought maybe it was a defect of the steel. I had never had the problem with O1 carbon steel blades and springs.

After not finding help online, I called Brad Stallsmith at Peters Heat Treating. Brad was kind enough to offer his help. He stated....."Hardness differences between components that rub together of more than 5 pts. will cause galling." Brad said that a large factory customer was experiencing a similar problem, and so they lowered the tempering temperature of the springs (increasing hardness) and that solved the galling problem for them.

I took Brads advice. The galling stopped. But the springs started breaking. This is when I bought a hardness tester - without one, it's all guess work.

I'm not suggesting that this is the answer to your specific problem, but it's one possibility. As others have advised, it could be lubrication, finish or geometry (or a combination of all).

Like Javan, I study the work of the old Sheffield makers. I've been surprised to see how soft the tangs and springs often are. In some of the old films and photos that show the folding knife blades being heat treated, it appears the tangs are never even hardened.

In fact, Peters Heat Treating softens the tangs (for at least one of their customers) using an induction coil to quickly heat the tang. I do it with a torch.

Saludos
J
JDWARE KNIVES

gcuBdIP.jpg
 
jdware, Thanks for those details. When they started to use stainless steels in guns especially hand guns they had galling problems Adjusting alloys and hardness worked . They also used lubes designed for high pressure applications. My old favorite has been ' RIG" With galling a switch to their then new 'RIG +" solved the problem .There were many other high pressure lubes introduced for SS. A double barrel shotgun has very high forces on the hinge pin So the special lubes , even on carbon steel pins was a good idea !
 
Don Hanson III said:
I leave the end of the spring same hardness as the blade & never use stainless & always use lube.
So never any galling.
Click to expand...

It's interesting (and good) that there are different solutions to the same problem.

mete said:
jdware, Thanks for those details. When they started to use stainless steels in guns especially hand guns they had galling problems Adjusting alloys and hardness worked . They also used lubes designed for high pressure applications. My old favorite has been ' RIG" With galling a switch to their then new 'RIG +" solved the problem .There were many other high pressure lubes introduced for SS. A double barrel shotgun has very high forces on the hinge pin So the special lubes , even on carbon steel pins was a good idea !
Click to expand...

will have to try RIG+ instead of regular oil on my stainless knives.

Saludos
J
JDWARE KNIVES
 
Yeah, the soft tang thing isn't something I'm particularly a believer in, but there's no right or wrong way, just results. I'm of the opinion that this was mostly a by-product of heat treating technique 1, and 2 for ease of adjusting fitment. I've taken a ton of these old knives apart and the amount of wear on the springs is freaking insane on the really soft ones, but maybe it's just been my "luck" as to which ones I've disassembled. Most of the later (pre-1950's, but after say, 1900) ones, all seem to be more consistently hard in the tangs, and also show much less wear in the springs.

Personally I want my springs as hard as they can be without having breakage issues (fingers crossed, but haven't had a problem yet), so I shoot for 49-50RC on my springs, and any steels I use I'm always targeting 62+ RC for the blades/tangs.

My opinion and reasoning here is this: the harder the wearing surfaces are, the more wear resistance under load I expect them to have. However, complete deburring of all corners is mandatory.

Now, there could be a pretty good argument, when working with stainlesses, to not use the same alloy for both the spring and the tang. I haven't heard of the 5 RC point difference JD mentioned, but I do know that, it's common knowledge in the firearms industry, to typically use two different alloys at different hardnesses (I think it's typically more like 10 points difference though?), for the slide and the frame, to prevent galling, especially with customs that have really tight, break-in fitments. However, there also seems to be a "finish level" factor. Two polished surfaces, even at different hardnesses, are very likely to gall under pressure in sliding contact, make one of them polished and the other not however, and things change.


I have to admit, I haven't thought about leaving the end of the spring dead-hard like Don is describing. I'd be inclined to try that, although I'm not sure how I could accurately do it without using a torch to draw the temper on the spring? Any trick here Don that I'm not considering?

I did have a couple when I first started using AEB-L for both springs and blades, that I thought was general galling, but turned out to be the tenacious nature of stainless burrs. Once I started being much more aggressive with deburing, it went away, however, I don't think my AEB-L spring knives ever get quite the cherry "slick" action I can get with carbon. I've considered switching to another material for the springs.
 
About burrs...any advice/tips/methods for removing burrs?

You guys have given me a lot to consider on my next one, that’s why I love this place!
 
javand said:
I have to admit, I haven't thought about leaving the end of the spring dead-hard like Don is describing. I'd be inclined to try that, although I'm not sure how I could accurately do it without using a torch to draw the temper on the spring? Any trick here Don that I'm not considering?
Click to expand...
Javan, I temper the spring with the blade twice. Then draw the spring back with a torch while holding the end with vise grips. I just look for a light blue color. Springs test out around 50 Rc in the blue & 60-61 at the end. W2 blades are 62+.
 
Don Hanson III said:
Javan, I temper the spring with the blade twice. Then draw the spring back with a torch while holding the end with vise grips. I just look for a light blue color. Springs test out around 50 Rc in the blue & 60-61 at the end. W2 blades are 62+.
Click to expand...

Right on Don, that's kind of what I figured. I'll give it a shot! Yeah, I run your W2 for all my carbon mono and the same numbers.
 
javand said:
Right on Don, that's kind of what I figured. I'll give it a shot! Yeah, I run your W2 for all my carbon mono and the same numbers.
Click to expand...
It has worked well for 25 years. I've make springs from W2, W1, 1095, 01, saw blade, 1084 & damascus. All same heat treat.
 
Don Hanson III said:
Javan, I temper the spring with the blade twice. Then draw the spring back with a torch while holding the end with vise grips. I just look for a light blue color. Springs test out around 50 Rc in the blue & 60-61 at the end. W2 blades are 62+.
Click to expand...
I do the same for 1095 and 8670.
 
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