RR congress killing my nails

[baxtrom]

Hi,
I recently purchased a RR Congress and the pen blades are absolutely murdering my nails. I have not experienced such hard to open blades previously. I tried to apply a little sewing machine oil, but there was no noticeable effect. Suggestions? I was thinking about possibly using a precision file to grind the “cams”.

 

[killgar]

I'm not sure what you mean by "cams". Springs?

I've reduced spring tension on a few lockback knives by grinding off a little steel from the springs at the point farthest from their tips with happy results. But that required disassembling the knives.

I suppose a similar procedure could be performed on a slipjoint without disassembly by removing some of the spring material above the pin but furthest from the tip, filing across the backs of the springs. This would likely require that material also be removed from the handle scales and liners as well if spring, liners, and handles are flush. Of course this would also affect the tension of the spring for the larger blades, which might not be desirable.

I would use a dremel with a grinding bit to grind only the pen blade spring, avoiding the other spring.

The thinner a spring is, the less tension it produces.

 

[baxtrom]

I'm not sure what you mean by "cams". Springs?

I've reduced spring tension on a few lockback knives by grinding off a little steel from the springs at the point farthest from their tips with happy results. But that required disassembling the knives.

I suppose a similar procedure could be performed on a slipjoint without disassembly by removing some of the spring material above the pin but furthest from the tip, filing across the backs of the springs. This would likely require that material also be removed from the handle scales and liners as well if spring, liners, and handles are flush. Of course this would also affect the tension of the spring for the larger blades, which might not be desirable.

I would use a dremel with a grinding bit to grind only the pen blade springs, avoiding the other spring.

The thinner a spring is, the less tension it produces.

What I mean is that in a slipjoint, the spring acts as a cam follower pressing down on a square-ish cam that produces the traditional 0 (closed), 90 and 180 degree (extended) “stops” of the blade. Theoretically, the cam corners could be softened, easing the operation. Again, theoretically, this could be achieved without disassembling the knife, using a small file. I’m wondering if there is a standard procedure for fixing this issue, because it is pretty bad in this knife! It’s chewing my nails

 

[fishface5]

There was just a post about this recently. A Dremel bit probably won't get into the channel to reach the spring - you want to carefully grind away spring material around the center pin on the side closest to the blade, not the butt. You can either do with a jeweler's file or with a Dremel large cutting wheel, but go slow and check results frequently!

In terms of rounding the tang or "cam," that can be done easily however it won't reduce the initial level of tension that needs to be overcome, it just smoothes the transition after it is at 75 degrees or so

 

[killgar]

What I mean is that in a slipjoint, the spring acts as a cam follower pressing down on a square-ish cam that produces the traditional 0 (closed), 90 and 180 degree (extended) “stops” of the blade. Theoretically, the cam corners could be softened, easing the operation. Again, theoretically, this could be achieved without disassembling the knife, using a small file. I’m wondering if there is a standard procedure for fixing this issue, because it is pretty bad in this knife! It’s chewing my nails

I see what you mean.

But I agree with fishface, although removing material from around the tang of the blade might make it easier to completely open the blade AFTER lifting it, I don't imagine that it would affect the spring tension on the blade when closed.

 

[baxtrom]

Thanks, will think about how to proceed.
Found this thread about nail killing slipjoints...

 

[baxtrom]

There was just a post about this recently. A Dremel bit probably won't get into the channel to reach the spring - you want to carefully grind away spring material around the center pin on the side closest to the blade, not the butt. You can either do with a jeweler's file or with a Dremel large cutting wheel, but go slow and check results frequently!

In terms of rounding the tang or "cam," that can be done easily however it won't reduce the initial level of tension that needs to be overcome, it just smoothes the transition after it is at 75 degrees or so

I see what you mean.

But I agree with fishface, although removing material from around the tang of the blade might make it easier to completely open the blade AFTER lifting it, I don't imagine that it would affect the spring tension on the blade when closed.

Here’s a picture for clarification
When the blades are closed, the part of the tang which I highlighted is in contact with the spring. Opening the blade means that the tang/cam pushes the spring away. Also, there is some amount of friction obviously. Grinding away some material on the tang surface should reduce the initial prestress of the spring, and ease the opening operation.
As you mention, an alternative is to file away some spring material, leaving the tang/cam. That would soften the spring and make the entire operation “smoother”, with the possible downside that the blades will be looser when open because the spring is weaker. That would be a theoretically advantage with instead machining the selected tang/cam surface.
Will continue to digest, luckily this is an inexpensive knife

 

[baxtrom]

Hi agan,
So i thought it could be interesting to try out my suggested approach and post the results here on the forum for future reference

To reiterate, my RR slipjoint’s pen blades were real nail killers. Looking at fig 1 below, when the blade is open, the part of the tang that is pushing back on the spring when opening the blade is exposed. I intended to machine this part, removing some fraction of a mm and rounding the corner.

So, spending 20 mins with my dremel, starting with a “stone” and progressing via soft sand paper to polishing the edge and “flushing” away shavings with 5-56, the blades are now actually possible to open with my nails.

Compared to machining the springs:

Pros:
- when extended, the blades are held as firmly by the springs as before
- the knife smells beautifully of 5-56.

cons:
- the blades don’t have the same exact position when folded, and the point is slightly protruding. In this case, it is of no concern because the pen blades are next to the bigger blades which means their points are “shielded”. If it wouldn’t be the case, it would be possible to get caught on the point when folded.

 

[killgar]

Yeah, taking too much material off the tang where it contacts the spring when closed can cause issues.

As long as it works for you and your happy with the result .

 

[afishhunter]

I had the same problem on a Boker Magnum Scout Knife.
I used a mini diamond file to round the corner of the tang after fully opening the blade. (first corner that moves the spring when you open the knife)
Pull went from a "forget it without pliers" to a "5".
Because I didn't mess with the kick, the kick, the spring didn't become low, or cange the height of the blade when closed.

 

[baxtrom]

I had the same problem on a Boker Magnum Scout Knife.
I used a mini diamond file to round the corner of the tang after fully opening the blade. (first corner that moves the spring when you open the knife)
Pull went from a "forget it without pliers" to a "5".
Because I didn't mess with the kick, the kick, the spring didn't become low, or cange the height of the blade when closed.

Thanks, then we handled it in similar ways although I used a dremel instead. When you say the pull is a “5”, do you mean 5/10 or highest grade in school? When I grew up we have grades 1-5 here in Sweden, 5 being the highest... The pull on my Congress pen blades is still hard but manageable with my nails. Went from impossible to acceptable basically

 

[fishface5]

Oh I see, I thought you were just talking about rounding the base of the tang but instead you removed material from the side of it. Hey as long as it works for you great!

 

[baxtrom]

Oh I see, I thought you were just talking about rounding the base of the tang but instead you removed material from the side of it. Hey as long as it works for you great!

Actually I removed from the base, not sides. Maybe my sketch is a bit unclear. The idea is that by removing some material, the spring will not need to be pushed as far, lowering the initial pull out force. Worked for me, went from nail-murdering impossible, to somewhat hard but acceptable. I guess removing material from the sides of the tang could perhaps also make it softer, but then the blade could perhaps get a bit wobbly sideways

 

[afishhunter]

Thanks, then we handled it in similar ways although I used a dremel instead. When you say the pull is a “5”, do you mean 5/10 or highest grade in school? When I grew up we have grades 1-5 here in Sweden, 5 being the highest... The pull on my Congress pen blades is still hard but manageable with my nails. Went from impossible to acceptable basically

1 to 10 in resistance. 1 being the lowest, 10 the highest.
A 92/93 mm Victorinox Swiss Army Knife is the "standard" to which all others are compared, ("Everyone" knows how hard it is to open the blades on a 92/93 mm SAK) is by world-wide concensus a "5" pull.
At a pull of over 8 to 8.5 or so, most people need a tool to open the knife. Yes, there is a speiaized tool for opening a hard to open knife. I don't have one If a knife has a blade that is too hard to open, I fx it, or failing that, deligate it to the never useknife dawe or box until I dispose of it.
I found a picture of the tool in a wab search:

View attachment 1589105

 

[baxtrom]

1 to 10 in resistance. 1 being the lowest, 10 the highest.
A 92/93 mm Victorinox Swiss Army Knife is the "standard" to which all others are compared, ("Everyone" knows how hard it is to open the blades on a 92/93 mm SAK) is by world-wide concensus a "5" pull.
At a pull of over 8 to 8.5 or so, most people need a tool to open the knife. Yes, there is a speiaized tool for opening a hard to open knife. I don't have one If a knife has a blade that is too hard to open, I fx it, or failing that, deligate it to the never useknife dawe or box until I dispose of it.
I found a picture of the tool in a wab search:

View attachment 1589105

Funny, that I did not know. Seems to be a failure if the knife is sprung so hard it will delaminate one’s fingers. My Congress was really hard to open even with a coin or a barrette, I would say it was 9 or more then.

 

[killgar]

If I need a separate tool to open my knife, then I need a new knife.

It would be like needing a wrench in order to use a screwdriver .

It's my understanding that those "knife picks" are used by factory workers who have to open hundreds of knives a day for QC testing. Imagine having to use your nails for that job.