Slipjoint question, is this normal?

I hope I am not overstepping here, but I would like to give a few suggestions and points that helped me make a nice working, smooth slip joint , single or multi blade.

I know that the tools and my processes maybe out of the reach of some, especially the guys starting out with slip joints. My processes worked for me and may not work with your style , tools , experience. And please do not think that a slip joint can not be made to be buttery smooth with proper walk and talk etc if not done my way. (just ask, if we could, the old Sheffield and early American slip joint makers! )

1. Good quality jobber style drill bits for pivot holes, edited to reflect that I use stub length drill bits.

2. Drill press with minimal runout and SQUARE to table.

3. I had the good fortune to have a good surface grinder and would surface grind the blade and spring together to get truly parallel parts after heat treat and draw. I used no washers but would mill reliefs and as such both spring and blades would be the same thickness.

4. I used integral 410 liners/bolsters and would surface grind the inside surface of each side to insure they were flat and square with the pivot holes.

I did all the fitting of the blades and springs sandwiched between the two integral liners bolsters BEFORE milling the bolsters and mill reliefs. This also greatly aided me in grinding the backsrping flush with the liner while keeping things square.

I believe these things eliminated a lot of the fitting issues and greatly helped in getting that great, smooth blade walk and talk. In my mind, hard to build a great house if starting with a foundation that is all cattywaumpas.

Again, if this is too much unwanted information I apologize .
 
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Agreed, It's great to have Ken's participation here. His well documented WIP posts in the past were/are inspiring.....it's a shame that so many disappeared when BritishBlade went down.

Regarding the galling that started this thread, there was an old Bladeforums thread from 2018 that discussed a couple of issues that can cause galling and what different makers do to prevent the problem. The thread is HERE

I recently came across a 1925 US Patent (see below) that addresses the issue of friction and wear of the spring and tang of slip joint pocket knives, so this is not a 21st century problem. The patent states the problems (particularly with stainless steels) and presents a solution that involves dovetailing in different materials to the wearing surfaces. The inventor was one of the founders of Latrobe Electric Steel Co. You can read the text of the patent at the USPTO website by searching the patent #.

Saludos
J

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ken erickson said:
I hope I am not overstepping here, but I would like to give a few suggestions and points that helped me make a nice working, smooth slip joint , single or multi blade.

I know that the tools and my processes maybe out of the reach of some, especially the guys starting out with slip joints. My processes worked for me and may not work with your style , tools , experience. And please do not think that a slip joint can not be made to be buttery smooth with proper walk and talk etc if not done my way. (just ask, if we could, the old Sheffield and early American slip joint makers! )

1. Good quality jobber style drill bits for pivot holes

2. Drill press with minimal runout and SQUARE to table.

3. I had the good fortune to have a good surface grinder and would surface grind the blade and spring together to get truly parallel parts after heat treat and draw. I used no washers but would mill reliefs and as such both spring and blades would be the same thickness.

4. I used integral 410 liners/bolsters and would surface grind the inside surface of each side to insure they were flat and square with the pivot holes.

I did all the fitting of the blades and springs sandwiched between the two integral liners bolsters BEFORE milling the bolsters and mill reliefs. This also greatly aided me in grinding the backsrping flush with the liner while keeping things square.

I believe these things eliminated a lot of the fitting issues and greatly helped in getting that great, smooth blade walk and talk. In my mind, hard to build a great house if starting with a foundation that is all cattywaumpas.

Again, if this is too much unwanted information I apologize .
Click to expand...
hello

you indicated jobber style drill, but perhaps you meant stub length drill?

you probably know that a jobber drill (aka standard length) has a long length relative to its diameter... and that a stub length drill is more accurate,

regards
 
HSC /// said:
hello

you indicated jobber style drill, but perhaps you meant stub length drill?

you probably know that a jobber drill (aka standard length) has a long length relative to its diameter... and that a stub length drill is more accurate,

regards
Click to expand...
Thanks for pointing out my error! Yes, stub length is what I preferred . (I knew I needed that second cup of coffee before I typed, lol. )
 
I used to polish my tangs and springs and had galling out the wazoo. Cut back to 120 grit on the spring and 240 on the tang with a quick fine scotch brite wheel pass on the spring and a few extra passes on the tang and no more galling. Definitely helps to have different grit finishes on each. Grind lines are in the direction of blade travel. Don't forget to lubricate.

Eric
 
Thnx for all the input, there is a lot to try out here.
I used a small filt polishing wheel on my Foredom to give the corners of the tang a quick polish.
I think I have to step that up a bit with a bigger wheel on a polishing machine. I have the machine but only loose wheels.
Schould I get a scotchbrite or a closely sewn sical wheel with compound?
I see scotchbrite 240 and 320 grit for sale, are they to coarse?
 
Hengelo_77 said:
Thnx for all the input, there is a lot to try out here.
I used a small filt polishing wheel on my Foredom to give the corners of the tang a quick polish.
I think I have to step that up a bit with a bigger wheel on a polishing machine. I have the machine but only loose wheels.
Schould I get a scotchbrite or a closely sewn sical wheel with compound?
I see scotchbrite 240 and 320 grit for sale, are they to coarse?
Click to expand...

If you go with a Scotch Brite wheel I'd recommend the convolute deburring wheels in fine grade (I don't believe they use numbered grits on those). Most important is the hardness which is usually a number proceeded by an "S". You want 9S or 10S, the harder the better. Softer wheels (lower numbers) will gouge quickly when using a thin hard piece like a blade tang. The wheels aren't cheap but they last forever. Here's what I use but they are also available in different diameters and thicknesses and with 1" arbor holes as well. Amazon carries them too, probably cheaper, as do many other suppliers. I've been using the same wheel for about four or five years now (over 3000 knives) for tangs, satin finishes on blades, Final run through on knives before polishing, and general deburring. For tight areas (such as the corner of the tang by the back square that you might want to round a bit) that you can't get to on the surface of the wheel due to its diameter I use the side of the wheel.


Eric
 
Years ago, when I made more folders, I was told never to polish the mating parts, nor to finish at the same grit. IIRC, I was told to do the tang at 220 and the spring, at 400. I was also told never to polish them. IIRC, I can't remember if it was Stan or Mete who told me that???

Back then, I had the idea of trying an experiment and doing the spring at high hardness and then torch drawing the spring to lower hardness except the contact area at the end, thus eliminating spring gouging and wear. Never did the experiment. Have any of you folder gurus tried that?
 
Thnx, I'll see if I can find something simular in Europe.
I'm a bit confused. I have three slipjoints back from HT and I'm trying different grit finishes on the tangs and springs.
I'm at 240 for the spring and 400 for the tang. I also used some scotchbrite by hand on the corners of the tang.
I have the feeling that blade opens/closes less smooth them before. Am I doing something wrong?
I always use lithium grease.
 
I used to assemble the knife, grease the joint heavily and then open/close 100 times. This seemed to burnish the mating surfaces, and they became much smoother. Then I would take it apart and clean it up well and reassemble.
 
Hengelo_77 said:
Thnx, I'll see if I can find something simular in Europe.
I'm a bit confused. I have three slipjoints back from HT and I'm trying different grit finishes on the tangs and springs.
I'm at 240 for the spring and 400 for the tang. I also used some scotchbrite by hand on the corners of the tang.
I have the feeling that blade opens/closes less smooth them before. Am I doing something wrong?
I always use lithium grease.
Click to expand...
I am curious , and know you mentioned the RC of your heat treated springs and tangs. Are you able to verify yourself or going by what the HT company says? The reason I mention this is that I am aware of a knife maker who had been heat treating springs and blades going by the available heat treat formulas. When he put in a hardness tester he was surprised to find out his springs ran about 10pts higher (dont recall the exact amount) than what the heat treat data suggested. An eye opener for sure. For a long time I would check every blade and spring after heat treatment until I was confident enough to check a sample from batches.

I wonder if perhaps we all might be zeroing in on the finish or lack of finish and to what degree. Might we be better served to check and recheck the blade tang/spring hardness's and geometry? By geometry I mean that the bearing surfaces are truly square to the sides. The corner radius's are proper. Pre-loading of the spring and blade are important also along with the pivot pins being square with the frame. The tightness or looseness of the pre peened blade and spring in frame can also cause issues giving false smoothness feelings or un-even digging in or galling of the bearing surface.

Not saying every knife I built had that buttery smooth action right from the get go. That being said when I had things dialed in very seldom would a blade and spring need a "break in period" or even anything but a light weight oil to lubricate things.
 
I have no way of checking the actual hardness of the spring, I go by what my HT-guy put on the invoice.
It does show small dents on the back of the spring from what I assume is hardness testing.

I checked the invoice:
The spring is 1.4034 steel which is close to 420 steel and came back 42-43 HRC
The blade is RWL34 which is close to CPM 154 and came back at 61-62 HRC

Just a thought, did I round the corners to much, having more/longer contact between the tang and spring?
Would that cause extra scratching?
 
Hengelo_77 said:
Just a thought, did I round the corners to much, having more/longer contact between the tang and spring?
Click to expand...

Possible for you to take photos similar to your very first post showing the tang and spring. Even if you can position the tang , closed, open and half stop positions onto the spring. As straight on as possible. Reason I ask is that I see some fitting point errors in your original photos. Not sure they would cause a galling or digging in issue but it helps me try and trouble shoot your issue better.

I know I keep bringing up the "squareness " issue but not sure if you have addressed this here in the thread? I am also wondering about the amount of pre load your dealing with and on that mystical "pull scale" of 1 to 10 what are you shooting for? Ten being almost impossible to open and a nail breaker for sure, 1 being just barely keeps the blade closed.

I hope you bear with me as I believe that your issues are deeper rooted than just the way you're finishing the tang corners and spring bearing surface.
 
Hengelo_77 said:
I have no way of checking the actual hardness of the spring, I go by what my HT-guy put on the invoice.
It does show small dents on the back of the spring from what I assume is hardness testing.

I checked the invoice:
The spring is 1.4034 steel which is close to 420 steel and came back 42-43 HRC
The blade is RWL34 which is close to CPM 154 and came back at 61-62 HRC

Just a thought, did I round the corners to much, having more/longer contact between the tang and spring?
Would that cause extra scratching?
Click to expand...
Since you're in germany, dictum does hardness testing (vickers) if you really want to know, of course with shipping it's not that cheap (I think 15€ for the test)
 
I realy appreciate all the help with trouble shooting why these slipjoints don't run well. Thank you.
I don't have the idea that there is steel moving from the spring to the tang, I have the idea that the tang pushes the steel aside on the spring.
My guess now is that there is to much contact between the tang and spring. But that is just an idea.

The spring is 1.3440 ~ 420 steel @ 42-43HRC
The blade is RWL34 ~CPM154 @ 61-62HRC

I'm working om three slipjoints and made pics per knife.
All three tangs are very scratched. I tried putting the together and opening/closing them 100 times.
Im my mind these three are written off, but I'd like to learn how to prefent this in the future.

First, this is my set up to sand the tang or spring and keep it square.
I have sandpaper glued on a granite surface and a 123-block on a flat piece of material so it hovers above the sandpaper.

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I use a 3mm pivot and the middle and back pin are 2mm
I use a reamer for the pivot hole and drill the middle and back pin with a good drill press.
The spring is 0.2 mm wider then the blade, the blades run between two bronce 0.1mm washers.
I use paper micarta scales first and when I am happy with everything I use them as templates on "real" materials.

These are the three knives.
The middle one has a 7mm washer, the bottom one has an 8mm one

20241206-155627.jpg
 
Knife 1
8mm washer

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Knife 2
7mm washer
I tried a scotchbrite belt on the spring because that is what I have at the moment. I thing that is why the wear on the spring isn't in the middle.

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20241206-160935.jpg


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Knife 3

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20241206-161436.jpg
 
Thank you so much for the great set of pictures! It helps me get a clearer view of your processes and methods.
Let me digest these for a bit. I will edit a few with arrows pointing out a few fitting areas. I will get some pictures uploaded of some of my tangs and springs and hopefully we can figure out what is going on.

It maybe later tonight or tomorrow before I get back, thank you for your patience!


One of the things you did not touch on was how much pre-load of the backspring and what amount of pull you shoot for in a finish knife on that scale of 1 to 10.
 
It may be just the camera angle, but Knives #1 and #3 look like they have too much torque point pressure on the backspring. Perhaps more and smoother radius on the corner would help. The spring also looks very stiff.
Also, #3 looks like you should lower the angle of the kick/tang frront so the blade drops a little lower in the liners. I have done what you have and after a year or so of re-sharpening the tip was proud of the liners. I had to take it apart and lower the kick angle to drop the blade back inside the liners. Would have been better to do it right the first time.

I also think the amount of galling on #1 and #3 is due to too soft a spring. I don't recall my exact spring hardness, but IIRC, it was 49-50 for the spring and 59-60 for the blade.

Don't take the above as a fact without folks like Ken chiming i because, I don't make all that many folders anymore, so I may be seeing this wrong.
 
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