Tidioute #81 Imperfections

ken erickson said:
You might be overpaying but here goes! LOL JK

Catch bits are really finicky to fit up. I included a very crude drawing that might help explain why a catch bit pivots slightly with either a at-rest backspring or when the tang of the blade has the backspring elevated from the frame.

There are two main fitting points on a catch bit. The inside tip and the point near the end of the backspring. These need to be fit very tight but not so tight as to support the backspring rather than the tension being on the blade tang.

If these two points are not fit tight enough the catch bit can pivot even with the blade at rest . Depending on how tight the blade has been peened this looseness or pivoting action of the catch bit might not be noticeable.

Now, things are different as the backspring is cammed away from the frame and catch bit as the blade starts to open. In effect those fitting points open up and WILL allow the catch bit to pivot. Typically not noticed as your opening or closing the blade if the catch bit was fit with tight fitting points to begin with.

The way I would overcome this when building a handmade slip joint that used a catch bit was to internally pin the catch bit to the frame with a blind hole. I would use a 1/16 diameter pin just forward of the main blade pivot pin hole. Even though it was peened into a countersink and dressed smooth the pin in never able to fall out or come loose due t be sandwiched in by the frame and blade tang.

One of the main take aways from all this babbling on my part is that pinning the catch bit is not feasible on a production knife basis. Probable would add 1/2 to an hour of hand fitting in a production setting adding $$$ to the cost of the knife. Making, properly fitting and pinning a catch bit in my shop added maybe 2 to 3 hours into the knife build.

Hope this was all clear as mud! :)

jJ4L39a.jpeg
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ken erickson ken erickson
Really appreciate this explanation! Especially the point about "not feasible for production knives."

I've become a BIG fan of GECs and sometimes I take certain issues with an understanding that Bill continues to produce the knives the way they've been doing it for sometime...with history and tradition...

Sure, there would be ways to improve and correct but that would only add to the process just as it has been explained, not to mention, modernize the process.

I don't think GEC is charging more for lesser quality...I think they are keeping up with current economy as best as they can as we all are.
 
ken erickson said:
You might be overpaying but here goes! LOL JK

Catch bits are really finicky to fit up. I included a very crude drawing that might help explain why a catch bit pivots slightly with either a at-rest backspring or when the tang of the blade has the backspring elevated from the frame.

There are two main fitting points on a catch bit. The inside tip and the point near the end of the backspring. These need to be fit very tight but not so tight as to support the backspring rather than the tension being on the blade tang.

If these two points are not fit tight enough the catch bit can pivot even with the blade at rest . Depending on how tight the blade has been peened this looseness or pivoting action of the catch bit might not be noticeable.

Now, things are different as the backspring is cammed away from the frame and catch bit as the blade starts to open. In effect those fitting points open up and WILL allow the catch bit to pivot. Typically not noticed as your opening or closing the blade if the catch bit was fit with tight fitting points to begin with.

The way I would overcome this when building a handmade slip joint that used a catch bit was to internally pin the catch bit to the frame with a blind hole. I would use a 1/16 diameter pin just forward of the main blade pivot pin hole. Even though it was peened into a countersink and dressed smooth the pin in never able to fall out or come loose due t be sandwiched in by the frame and blade tang.

One of the main take aways from all this babbling on my part is that pinning the catch bit is not feasible on a production knife basis. Probable would add 1/2 to an hour of hand fitting in a production setting adding $$$ to the cost of the knife. Making, properly fitting and pinning a catch bit in my shop added maybe 2 to 3 hours into the knife build.

Hope this was all clear as mud! :)

jJ4L39a.jpeg
Click to expand...
Ken Erickson, where have you been all my life?! That was a beautiful explanation!
 
ken erickson said:
You might be overpaying but here goes! LOL JK

Catch bits are really finicky to fit up. I included a very crude drawing that might help explain why a catch bit pivots slightly with either a at-rest backspring or when the tang of the blade has the backspring elevated from the frame.

There are two main fitting points on a catch bit. The inside tip and the point near the end of the backspring. These need to be fit very tight but not so tight as to support the backspring rather than the tension being on the blade tang.

If these two points are not fit tight enough the catch bit can pivot even with the blade at rest . Depending on how tight the blade has been peened this looseness or pivoting action of the catch bit might not be noticeable.

Now, things are different as the backspring is cammed away from the frame and catch bit as the blade starts to open. In effect those fitting points open up and WILL allow the catch bit to pivot. Typically not noticed as your opening or closing the blade if the catch bit was fit with tight fitting points to begin with.

The way I would overcome this when building a handmade slip joint that used a catch bit was to internally pin the catch bit to the frame with a blind hole. I would use a 1/16 diameter pin just forward of the main blade pivot pin hole. Even though it was peened into a countersink and dressed smooth the pin in never able to fall out or come loose due t be sandwiched in by the frame and blade tang.

One of the main take aways from all this babbling on my part is that pinning the catch bit is not feasible on a production knife basis. Probable would add 1/2 to an hour of hand fitting in a production setting adding $$$ to the cost of the knife. Making, properly fitting and pinning a catch bit in my shop added maybe 2 to 3 hours into the knife build.

Hope this was all clear as mud! :)

jJ4L39a.jpeg
Click to expand...

Thanks for the input, Ken (and the sketch!). Definitely seems like the catch bit on these GEC 81s isn’t fitted as well as it could be to prevent movement. On a production knife, do you think that comes down to the shape of the catch bit piece not being quite right?

waynorth said:
It was clear to me, Ken!! Good explanation!!
I must admit, I have never seen a catch bit move, or get displaced, regardless of age, old or new knife!! Most must be fitted well enough to work in practice!!
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I’ve never seen it before either, Charlie, and of course you’ve handled exponentially more knives than I have, but my one takeaway from messing around with a few other catch bit knives last night was that, in most cases, even if they did move, you might not ever notice. On the knives with rounded bolsters, the movement doesn’t cause any part of the catch bit to stick out like it does on the square bolstered 81s in question.

Unfortunately I don’t have many vintage (or even non-GEC) knives with catch bits to look at, but I did find a Case pen knife with a small brass catch bit, and it can also be moved with a fingernail.

To be clear, I’m not saying that the issue on the 81s isn’t a valid concern, but I don’t think it has anything to do with a change in GEC’s quality control or manufacturing processes.

I wonder if GEC has done any other square bolstered patterns with a catch but before? I’d be curious to see if those have any movement, and if so, if it causes that spring-side part of the catch bit to stick out.
 
btb01 said:
Thanks for the input, Ken (and the sketch!). Definitely seems like the catch bit on these GEC 81s isn’t fitted as well as it could be to prevent movement. On a production knife, do you think that comes down to the shape of the catch bit piece not being quite right?
Click to expand...
I do not want to speak for GEC or any current production knife makers because I do not know if they die cut, laser or water jet cut their parts out such as catch bits.

I will speculate and then tell you how I would make the catch bit.

Going to speculate that current production knives do use a catch bit designed from a prototype working knife and then reproduced by either a punch and die or a CNC controlled method such as laser or water jet. I do not know if any material is left proud for proper fitting or if these are drop in and forget parts.

What is important to remember is that ANY slight change in the tang for instance that is done to get a flush backspring in open/closed or half top if it has one, is also going to effect the fitting of the catch bit.

Removing metal off the end of the back spring which affects the open attitude of the blade , think opens too far, or not enough, will drastically effect how much the catch bit can pivot.

When I would build a knife with catch bit I would fit up the backspring and blade tangs before even making the catch bit. I would make certain I had the backspring adjusted for proper tension and all blades in all positions flush. Only then would I make a oversized catch bit and fit striving to get those two fitting points correct along with the opposing blade tip not hitting the catch bit.

Even a very small amount of stock removal on the blade tang with a very tightly fit catch bit could result in the backspring now resting on the catch bit and not the blade tang , which in turn would mean the blade would have a slight jiggle when closed or open.

A bit of side note. As I learned how a slip joint worked and tang geometry I was amazed at how removing material from one spot can affect things down the line! Even lessoning the tension on a back spring will affect flush in open closed position due to more "arch" that the spring will take.
 
Will Power said:
However, there's no guarantee that some dealers might just palm it off on the next customer who just MIGHT be a non user of knives and a collector of 'investment tubes' so who cares about functional issues?? :rolleyes:
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I'm just gonna go ahead and coin the abbreviation "WOKWLNT" to describe the knives which I expect will eventually come out of my hoard. It stands for "Worn-Out Knife With Like-New Tube." 😂

TouhouFan said:
I wouldn't go so far as to say that they have no QC, but perhaps they hired a new guy? 😉
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For a while now, I've been thinking that we, the Vox Cultri Populi, should at least have some say in the GEC hiring process. Anybody else feel this way? How about just a peek at the employment application, a few testimonials from previous employers, health screening - as well as the results of a drug test 🤣... too invasive?

I think not. Not for my hoard!

oldmanwilly said:
Thank you for this! I wish every detail of knife construction could be explained so well, and with diagrams. It makes more sense to me now and I do not blame GEC for choosing not to fit these bits with blind pins.
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Agree completely! ken erickson ken erickson , please write and publish an illustrated book! For some reason, I seem to understand what you're saying when you say it! This is a novel experience for me in the slipjoint arena!

ken erickson said:
I do not want to speak for GEC or any current production knife makers because I do not know if they die cut, laser or water jet cut their parts out such as catch bits...

...A bit of side note. As I learned how a slip joint worked and tang geometry I was amazed at how removing material from one spot can affect things down the line! Even lessoning the tension on a back spring will affect flush in open closed position due to more "arch" that the spring will take.
Click to expand...

Again, Ken, please write this stuff down! I've bookmarked all of these posts for future reference but, man, this is invaluable stuff! If you ever do feel the need to set it down for posterity, and find you need an editor - I'll make the time!

Thank you again!
 
ken erickson said:
I do not want to speak for GEC or any current production knife makers because I do not know if they die cut, laser or water jet cut their parts out such as catch bits.

I will speculate and then tell you how I would make the catch bit.

Going to speculate that current production knives do use a catch bit designed from a prototype working knife and then reproduced by either a punch and die or a CNC controlled method such as laser or water jet. I do not know if any material is left proud for proper fitting or if these are drop in and forget parts.

What is important to remember is that ANY slight change in the tang for instance that is done to get a flush backspring in open/closed or half top if it has one, is also going to effect the fitting of the catch bit.

Removing metal off the end of the back spring which affects the open attitude of the blade , think opens too far, or not enough, will drastically effect how much the catch bit can pivot.

When I would build a knife with catch bit I would fit up the backspring and blade tangs before even making the catch bit. I would make certain I had the backspring adjusted for proper tension and all blades in all positions flush. Only then would I make a oversized catch bit and fit striving to get those two fitting points correct along with the opposing blade tip not hitting the catch bit.

Even a very small amount of stock removal on the blade tang with a very tightly fit catch bit could result in the backspring now resting on the catch bit and not the blade tang , which in turn would mean the blade would have a slight jiggle when closed or open.

A bit of side note. As I learned how a slip joint worked and tang geometry I was amazed at how removing material from one spot can affect things down the line! Even lessoning the tension on a back spring will affect flush in open closed position due to more "arch" that the spring will take.
Click to expand...

Thanks again, Ken, for the insightful information. :thumbsup:
 
birdsbeaks said:
For a while now, I've been thinking that we, the Vox Cultri Populi, should at least have some say in the GEC hiring process. Anybody else feel this way? How about just a peek at the employment application, a few testimonials from previous employers, health screening - as well as the results of a drug test 🤣... too invasive?
Click to expand...
Here in northwest PA, there was an ad in our local paper that GEC was looking to hire an EDM specialist, and also a CAD engineer. I think quite a bit of their process has modernized over the past 15 years.
 
Rookie82 said:
Here in northwest PA, there was an ad in our local paper that GEC was looking to hire an EDM specialist, and also a CAD engineer. I think quite a bit of their process has modernized over the past 15 years.
Click to expand...

No wonder they’re making mistakes! I don’t think I could focus on making knives if I was forced to listen to Electronic Dance Music all day… 😁

I am happy to report that I got three more 81s in the mail today (yes, I have a problem 😉), and the catch bits on all three of these are solid, no movement.
 
btb01 said:
No wonder they’re making mistakes! I don’t think I could focus on making knives if I was forced to listen to Electronic Dance Music all day… 😁

I am happy to report that I got three more 81s in the mail today (yes, I have a problem 😉), and the catch bits on all three of these are solid, no movement.
Click to expand...
I just untubed a Navy Riverbottom Richlite and, try ever hard as I might, that catch bit doesn't seem to budge.🤷
 
oldmanwilly said:
HF7YdVf.gif


Why do the Simpsons always seem prescient?
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I imagine it went something like:

"Hello TV exec, I am from the future and am here today to pitch a cartoon show to you in which I will be able to warn people about coming events without revealing that I am, as I previously stated, from the future."

I picture a similar pitch being made for "Idiocracy." 😂
 
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