Modify a folding knife to use a bigger diameter pivot pin

[Alan0354]

OK, I am CRAZY and have OCD. Please bare with me.

I have a few of the same knives that I really like and it's cheap like dirt($13 each). Everything about the knife is very robust EXCEPT it uses a pivot pin that is only 0.2" diameter. I want to change to 0.25" diameter pivot pin. I already ordered the 0.25" diameter pin that is a little longer. I can just grind to the right length for the thickness of the knife.

My question is about drilling the holes larger. The difficult part is on one of the liner, the hole is keyed, that is one side of the pin is slightly flatten that match the hole. This is to keep the pin from rotating during tightening. I have to drill that out.

I don't think it's good to just drill it as it might push the new hole a little away from the "keyed" side. My thinking is just use a diamond grinder bit on the Drammel and just grid the "key" to make the hole as round as possible as shown, then drill with the bigger bit.

Pivot hole.jpg (14.54 KiB) Viewed 1052 times

If anyone has better idea, I am all ears.

Thanks

[tallguy606]

,20 seems plenty stout already. Not sure what you will gain going to .25. Just my 2 cents.

[herbva]

I'm wondering what kind of knife this is? As already mentioned above, .2"is already quite large for a folding knife. I rarely need to use a pin size over 1/8" (.125). In fact, the only times I can remember needing a pin over 1/8" is for those Colonial and United WW2 pilot's survival knives when I'm replacing a broken saw blade.

[C-WADE7]

I would try to dremel it out as much as possible. Like you, I think the bit will walk on that flat.

[BIGHEAD]

I'm wondering what kind of knife this is? As already mentioned above, .2"is already quite large for a folding knife. I rarely need to use a pin size over 1/8" (.125). In fact, the only times I can remember needing a pin over 1/8" is for those Colonial and United WW2 pilot's survival knives when I'm replacing a broken saw blade.

Tactical he has posted about this before. .2 is plenty large enough. But some have to reinvent the wheel. JMHO

[dsutton24]

You'll weaken the liner.

[OLDE CUTLER]

It's possible the blade will be too hard to allow drilling the hole larger depending on the heat treatment.

[Alan0354]

Thanks everyone for answering. Yes, I am the crazy one that talked about this knife before. I have not decided whether to do it or not, it's just one project that keep my mind going. I believe in getting into different things to keep my mind active from designing extreme high end hifi power amps, to research into current affairs, to this. It's just a way to keep busy in my old age. I believe mental exercise is just as important as physical exercise in old age.

Yes, one thing I worry about is the blade might be too hard to drill the bigger hole.

I have another idea, I took a look, I can stack the two liners together, align the two by the stop pin(close to the pivot hole) with liner with flat key hole at the BOTTOM. Then use screws to fix them onto a piece of wood. With the stop pin, it should be easy to align the rest of the holes of the two liners and fix it good onto the piece of wood. Of cause I will try to use the drammel to grind out the flat key to as round as possible as described before. Then just drill down after stacking and fixed on the piece of wood, the round hole of the top liner will serve as guide as I drill down to the bottom liner when reaching the flat key at the bottom. Even if it walk ever so slightly, both holes should be well aligned when drilling like this. I literally using one liner to serve as a guide to drill out the flat key.

I am looking at some cobalt bits, any suggestion on drill bits?

What size drill bits should I use. Of cause the first bit come to mind is 1/4". BUT would the hole drilled by a 1/4" bit a little bigger than 1/4". I don't have good equipment, just a table top drill press. My other thinking is using a slightly smaller diameter bit like SIZE D BIT that is 0.246" instead of 1/4" bit.

Like I said, I have not decided to go ahead with it. I don't have much to lose as the knife is only $13 and I have a few. I just want to think through it.

Attached is the picture of the internal of this cheap knife. It is designed very robust. Even though 0.2" pivot is plenty, but with this design, it's still can be a weak point.

[ea42]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

[BIGHEAD]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

His other post about this was being afraid it would fail while PRYING with the blade which is 100% opposed from what a knife is designed for. Even if he were prying witn it the blade would break before the pivot would fail. The Pivot pin is NOT the weak point of a knife.

[Alan0354]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

I know, Like I said in the very first post, if I do it, it's just for the hell of it. I actually put one on the big vice, bend it side to side like prying motion with both hands to the point I rocked the whole bench that the vice bolted on. The knife survived with flying color.

Like I describe, I have a few of this knives, cost $13 ea. It's more for me to play with and satisfy my OCD.

I have not decide to go ahead and do it. It's more about whether I can even drill the pivot hole on the blade that is hardened.

Is 5% cobalt bits good enough or I have to get better ones to drill the blade?

[Alan0354]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

His other post about this was being afraid it would fail while PRYING with the blade which is 100% opposed from what a knife is designed for. Even if he were prying witn it the blade would break before the pivot would fail. The Pivot pin is NOT the weak point of a knife.

That I know and take into consideration. I expect the first 1/2" of the blade will break off at the very beginning. But still I have at least 2 1/2" of blade that I can still use. You look at the picture of my knife 4 posts up above, big part of the blade is at full 0.11" thick after the first 3/4" inch. That will survive all the prying.

Like I said, I am just thinking about doing for the hell of it. I know the pivot is strong enough, but it's more for playing around if I really decide to do it. All I waste is $13, I likely learn some good lessons.

[edge213]

With all of this "stuff" you are trying, why not just build your own "Sherman Tank" of a knife from scratch??

[Alan0354]

With all of this "stuff" you are trying, why not just build your own "Sherman Tank" of a knife from scratch??

That's too much work and I don't have the equipment.

[Alan0354]

With all of this "stuff" you are trying, why not just build your own "Sherman Tank" of a knife from scratch??

Actually, I am starting to get use to flipping the Cold Steel type of folding knives. I have been practicing while watching tv on both hands. If I can get good at it, Cold Steel is another one that build like a tank as Steel Will. I am practicing on the Rajah III, the SR1 Lite is coming next week, That is a hell of a tank. JoeX did not manage to break it, not even the tip. Then there is the AD-10 Lite( that is pushing the price limit on me).

We'll see how good I can flip those Steel Will in a week. The liner lock ones are just so much easier to deploy.

[ea42]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

I know, Like I said in the very first post, if I do it, it's just for the hell of it. I actually put one on the big vice, bend it side to side like prying motion with both hands to the point I rocked the whole bench that the vice bolted on. The knife survived with flying color.

Like I describe, I have a few of this knives, cost $13 ea. It's more for me to play with and satisfy my OCD.

I have not decide to go ahead and do it. It's more about whether I can even drill the pivot hole on the blade that is hardened.

Is 5% cobalt bits good enough or I have to get better ones to drill the blade?

It all depends on the heat treat of the blade. If it comes in anywhere near 60RC you're probably not going to be able to drill it but at that price point I have my doubts it's that hard. Will still likely be difficult but give it a try with a cobalt bit. I'd say a carbide bit might work too but that'll cost you way more than the knife!! Still not sure what the whole point is if the knife survived that abuse with no issues.

Eric

[Alan0354]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

I know, Like I said in the very first post, if I do it, it's just for the hell of it. I actually put one on the big vice, bend it side to side like prying motion with both hands to the point I rocked the whole bench that the vice bolted on. The knife survived with flying color.

Like I describe, I have a few of this knives, cost $13 ea. It's more for me to play with and satisfy my OCD.

I have not decide to go ahead and do it. It's more about whether I can even drill the pivot hole on the blade that is hardened.

Is 5% cobalt bits good enough or I have to get better ones to drill the blade?

It all depends on the heat treat of the blade. If it comes in anywhere near 60RC you're probably not going to be able to drill it but at that price point I have my doubts it's that hard. Will still likely be difficult but give it a try with a cobalt bit. I'd say a carbide bit might work too but that'll cost you way more than the knife!! Still not sure what the whole point is if the knife survived that abuse with no issues.

Eric

I am more and more discouraged from doing it now. It's good to talk it out loud, it's not the liner that is the problem, that can be done. It's the blade that is hard. I am glad I came here. I really have to think twice before doing. It's not about the cost, it's just my adventure. But I am not going to start a losing game. Like you said, the knife survived my prying with flying color.

It's a lot of trouble for me to try drilling the blade, I don't have a milling machine, just a small bench top drill press. I have to figure a way to secure the blade on a piece of wood so it won't move.....Worst is it catch on the bit and fly out!!! It can be dangerous, not like people that do this before sharpening the edge.

thanks

[OLDE CUTLER]

A weak point for what? Batoning a steel pole? Before you go through all that trouble why don't you try to see if you can make the pin fail in one of those knives? I'd think some other part of the knife would fail before the pin which would negate making the pin more robust. Of course if you just want to do it to see if it can be done then by all means give it a whack, should work as long as your holes are lined up. For drill size see how much room they left in the holes for the existing pin and try to mimic that clearance with your drill size. The blade and liners might have different size holes.

Eric

I know, Like I said in the very first post, if I do it, it's just for the hell of it. I actually put one on the big vice, bend it side to side like prying motion with both hands to the point I rocked the whole bench that the vice bolted on. The knife survived with flying color.

Like I describe, I have a few of this knives, cost $13 ea. It's more for me to play with and satisfy my OCD.

I have not decide to go ahead and do it. It's more about whether I can even drill the pivot hole on the blade that is hardened.

Is 5% cobalt bits good enough or I have to get better ones to drill the blade?

It all depends on the heat treat of the blade. If it comes in anywhere near 60RC you're probably not going to be able to drill it but at that price point I have my doubts it's that hard. Will still likely be difficult but give it a try with a cobalt bit. I'd say a carbide bit might work too but that'll cost you way more than the knife!! Still not sure what the whole point is if the knife survived that abuse with no issues.

Eric

Carbide bit would do it, currently about $49 for a 1/4" bit from Jantz.

[C-WADE7]

I’ve used carbide tipped masonry bits from Erwin to drill hardened steel. $5 from the lumber yard and good for a couple uses most of the time.

[Alan0354]

I know, Like I said in the very first post, if I do it, it's just for the hell of it. I actually put one on the big vice, bend it side to side like prying motion with both hands to the point I rocked the whole bench that the vice bolted on. The knife survived with flying color.

Like I describe, I have a few of this knives, cost $13 ea. It's more for me to play with and satisfy my OCD.

I have not decide to go ahead and do it. It's more about whether I can even drill the pivot hole on the blade that is hardened.

Is 5% cobalt bits good enough or I have to get better ones to drill the blade?

It all depends on the heat treat of the blade. If it comes in anywhere near 60RC you're probably not going to be able to drill it but at that price point I have my doubts it's that hard. Will still likely be difficult but give it a try with a cobalt bit. I'd say a carbide bit might work too but that'll cost you way more than the knife!! Still not sure what the whole point is if the knife survived that abuse with no issues.

Eric

Carbide bit would do it, currently about $49 for a 1/4" bit from Jantz.

I found this, hope they don't delete my post.

https://www.amazon.com/gp/product/B0BWC ... RSCL&psc=1