torx vs hex head screws

Lapedog said:
Saying there is no benefit to screws being harder, just don’t torque hard so you don’t strip them sounds alot like saying a car doesn’t need to be good at protecting passengers in a crash, just don’t crash it.
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o_O
 
Lapedog said:
That still doesn’t explain why harder screws would not be better. In no way am I saying that the screws should be made so hard as to be brittle.

What if the screws came in at 30hrcx would it not be better for them to be abit harder? Well whatever the screws are coming in at now, I think it could be better if they were closer to that 55hrc.

Saying there is no benefit to screws being harder, just don’t torque hard so you don’t strip them sounds alot like saying a car doesn’t need to be good at protecting passengers in a crash, just don’t crash it.

If one cannot tighten his screw down fully for fear of stripping it, how does one prevent it from backing out? Putting even purple loctite would requite more torque to undo the screw than was ever put on them just by tightening them down to a degree where they were fully seated.

I still don’t see how a hardened screw is useless. If it will allow a greater degree of user error then that doesn’t seem useless to me.

I still think the biggest issue is the use of t6 screws though. The camming surface on the heads is the tiny little interior points of the star. I would imagine if those tiny points weren’t so soft they would be less prone to stripping out.
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In what way would harder screws benefit the design? By not stripping out when being removed for maintenance is my assumption so i will go with that.
What percentage of people with this satisfy and what percentage will just want the standard stainless (303 I believe) back after having over torqued their fastener together against titanium. (fantastically grabby material by the way). People aren't going to be happy either way as they never are 100% happy.

Reason #2 to not change is the cost; The parts are already very tightly controlled..Especially the female end. It's part of the alignment structure of the whole assembly. Last time I seen the blueprint on the female side, the outer diameter was around .0002in controlled dimension.. After heat treating the parts, this is a bit of a moving target to achieve. (measure parts before and after heat treat- they change) Choices are post heat treat grinding or the old guessing game of turning them to a specified dimension and hoping the heat treat is very controlled and the majority of your parts are still in spec after.
It's not impossible to do but it is somewhat impractical.
Another factor is time. CRK is running at 100% capacity and have been for as long as I can remember. Changing processes isn't something they do at a whim.

At least, these are some educated guesses from my own experience..I'm sure there are other reasons that I am not currently seeing right now.
 
Josh K said:
o_O
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What that doesn’t make sense to you?

If you don’t overtorque your screws they won’t strip (dubious imho) - but people are stripping them. So how is it useless to make them less prone to stripping.

If no one ever crashed a car then crash saftey features would be useless. But people crash their cars, so in the same way those saftey features are a benefit.

Even without overtorquing just the wear of being used will cause the heads to wear. If extra hardness will prolong the life how is it useless.

I’m not trying to argue with you, I just want to know why hardened screws are useless. Especially when I see knife parts suppliers selling hardened screws, or screws made from 440 which they specifically advertise as hardenable. Are they trying to scam us to make an extra buck?
 
bhyde said:
In what way would harder screws benefit the design? By not stripping out when being removed for maintenance is my assumption so i will go with that.
What percentage of people with this satisfy and what percentage will just want the standard stainless (303 I believe) back after having over torqued their fastener together against titanium. (fantastically grabby material by the way). People aren't going to be happy either way as they never are 100% happy.

Reason #2 to not change is the cost; The parts are already very tightly controlled..Especially the female end. It's part of the alignment structure of the whole assembly. Last time I seen the blueprint on the female side, the outer diameter was around .0002in controlled dimension.. After heat treating the parts, this is a bit of a moving target to achieve. (measure parts before and after heat treat- they change) Choices are post heat treat grinding or the old guessing game of turning them to a specified dimension and hoping the heat treat is very controlled and the majority of your parts are still in spec after.
It's not impossible to do but it is somewhat impractical.
Another factor is time. CRK is running at 100% capacity and have been for as long as I can remember. Changing processes isn't something they do at a whim.

At least, these are some educated guesses from my own experience..I'm sure there are other reasons that I am not currently seeing right now.
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Crk’s screws have actually never stripped the head surfaces for me. I’m sure alot of it has to do with the deeper female slot. Also I’m not necessarily only talking about CRK screws.

But even if hardened screws were not being overtorqued. Would just the extended wear life not be a benefit. I know how grabby Ti can be on steel. We have all felt it undoing our CRK screws when they sort of “pop” off at the first turn.
 
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Lapedog said:
Crk’s screws have actually never stripped the head surfaces for me. I’m sure alot of it has to do with the deeper female slot. Also I’m not necessarily only talking about CRK screws.

But even if hardened screws were not being overtorqued. Would just the extended wear life not be a benefit. I know how grabby Ti can be on steel. We have all felt it undoing our CRK screws when they sort of “pop” off at the first turn.
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Sure..you could extend the wear life by doing that..but then you run into the law of unintended consequence..Firstly, you are not choosing a fastener for it's ability to hold two pieces together, but rather it's ability to withstand torquing with a tool. When you do this, you just move what breaks..which would probably mean the tool itself. Some of the point of the engineering process is to limit breakage to the cheapest possible replacement part if that makes sense.
 
bhyde said:
Sure..you could extend the wear life by doing that..but then you run into the law of unintended consequence..Firstly, you are not choosing a fastener for it's ability to hold two pieces together, but rather it's ability to withstand torquing with a tool. When you do this, you just move what breaks..which would probably mean the tool itself. Some of the point of the engineering process is to limit breakage to the cheapest possible replacement part if that makes sense.
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Those are all good points. If the idea is someone might overtorque the screw and thus the screw is better damaged than say, the ti threads on a knife where that screws into ti, definitely better the screw goes rather than the ti threads on the handle.

For CRK and knives that use chicago screws it would be less of a concern I imagine.

All I am asking is why not make the screw similar hardness to the driver bit of say a wiha tool. I guess I just will remain wondering.
 
bhyde said:
Sure..you could extend the wear life by doing that..but then you run into the law of unintended consequence..Firstly, you are not choosing a fastener for it's ability to hold two pieces together, but rather it's ability to withstand torquing with a tool. When you do this, you just move what breaks..which would probably mean the tool itself. Some of the point of the engineering process is to limit breakage to the cheapest possible replacement part if that makes sense.
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Just for the sake of argument... CRK charges less for the tools than the screws as it is. I'd almost rather the tool breaks by this logic.
 
Lapedog said:
Those are all good points. If the idea is someone might overtorque the screw and thus the screw is better damaged than say, the ti threads on a knife where that screws into ti, definitely better the screw goes rather than the ti threads on the handle.

For CRK and knives that use chicago screws it would be less of a concern I imagine.

All I am asking is why not make the screw similar hardness to the driver bit of say a wiha tool. I guess I just will remain wondering.
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A good question to ask the knifemakers or manufacturers that use screws I imagine. I'm sure most will tell you that there is less benefit to you taking your knife apart than to have a hardened screw. I would also imagine that many would rather stick to what is cheap and available off of the shelf.
Now, how many items are engineered to be taken apart in the same fashion you want to take down your knife? Most things, when screwed together are meant to be a semi-permanent assembly without regard to your need to constantly take them apart..Those that aren't use different ways of fastening..such as clips and clamps.
The cost of maintaining your folding knife is being paid in the occasional replacement of some fasteners here..The more you feel like you have to clean it, the higher the cost.
This is going to be a high number, but let's say you budget for one cleaning a year for your Inkosi. The cost of the screw kit including the wrench(s) is $12.00 (plus shipping- but the total cost won't be this high or shouldn't ever be this high).
12/365= ~.03
This is going to be ~.05 on a 21, but you get the idea- Pretty cheap IF you replace the whole fastener kit which is overkill and beyond.

If you find that you need to take down your folder and this cost is too high, I am going to postulate that you are carrying the wrong tool. Perhaps a fixed blade is in order.
 
FourD said:
Just for the sake of argument... CRK charges less for the tools than the screws as it is. I'd almost rather the tool breaks by this logic.
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See my reply to lapedog just above.
 
Lapedog said:
Those are all good points. If the idea is someone might overtorque the screw and thus the screw is better damaged than say, the ti threads on a knife where that screws into ti, definitely better the screw goes rather than the ti threads on the handle.

For CRK and knives that use chicago screws it would be less of a concern I imagine.

All I am asking is why not make the screw similar hardness to the driver bit of say a wiha tool. I guess I just will remain wondering.
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I’ve wondered the same thing, but knowing myself, I also know I have a habit of going too far on some things. Sometimes I think, that’s tight enough, but then invariably go just a little more and that’s when the problems happen :mad:. So, for me the softer hardware is probably a good thing to prevent any undue damage/stress to parts. I’d rather have to send one in to have a screw extracted than have one that has damage and can’t be repaired. I don’t know if over tightening hardware damages the stainless hardware or if you can damage the Ti over time. I would think not because the Ti is a softer material. I don’t know if having harder hardware would create a whole new set of problems that hasn’t been thought about.
 
bhyde said:
A good question to ask the knifemakers or manufacturers that use screws I imagine. I'm sure most will tell you that there is less benefit to you taking your knife apart than to have a hardened screw. I would also imagine that many would rather stick to what is cheap and available off of the shelf.
Now, how many items are engineered to be taken apart in the same fashion you want to take down your knife? Most things, when screwed together are meant to be a semi-permanent assembly without regard to your need to constantly take them apart..Those that aren't use different ways of fastening..such as clips and clamps.
The cost of maintaining your folding knife is being paid in the occasional replacement of some fasteners here..The more you feel like you have to clean it, the higher the cost.
This is going to be a high number, but let's say you budget for one cleaning a year for your Inkosi. The cost of the screw kit including the wrench(s) is $12.00 (plus shipping- but the total cost won't be this high or shouldn't ever be this high).
12/365= ~.03
This is going to be ~.05 on a 21, but you get the idea- Pretty cheap IF you replace the whole fastener kit which is overkill and beyond.

If you find that you need to take down your folder and this cost is too high, I am going to postulate that you are carrying the wrong tool. Perhaps a fixed blade is in order.
Click to expand...

I know you are saying “you” plural for the benefit of anyone reading. I actually rarely take apart my knives. There are some knives which I won’t even attempt to take apart because I know they have soft screws prone to being damaged.

However there are times where I have to take a knife apart. Especially my ZT 0620 which came with a weird early lock up that could be over come by putting a little pressure on the spine. I had to take the knife apart to try bending the lock bar in further, then put it back together to test what effect it had. It didn’t resolve it so I had to take it apart and try again a few times. Eventually I got it and the knife is working flawlessly.
 
I'm curious if harder screws would mate and hold as well in the female part. In other words would it tend to loosen by vibration easier, and require more frequent tightning?
 
In my limited knowledge, hardened hardware tend to gall in different materials faster. And that presents a whole new level of frustration.
 
Harder screws would be fine if properly set to the required torque.

Harder screws will definitely raise the stakes of damaging what they thread into. What's safer to fail; a screw costing pennies or a machined part costing hundreds of dollars?

And Dodecagon heads are better than both hex and torx.
 
I worked in manufacturing a long time ago (25+ years back), and we built some pieces for the military. Most of the fasteners were screws, but I do not recall any of them being Torx fasteners. The hex head connections were some of my favorites to install, because you could balance the screw on the tool without it dropping most times. You can tell quickly if you have the correct hex wrench based on the amount of slop when you applied torque. The hex heads also force the tool to be in line with the socket, not attacking it from an angle. We did have hex head ball drivers for those hard to reach places, but you could just use the other side of the hex key if you could reach the screw with it. You will snap any screw if you over torque it. Most of the heads which I snapped off were from a bad screw in the lot. Thread sealer would hold the screw in place after you have torqued it properly (remembering that the green sealer was permanent :eek:).

To me, Torx heads are easier to deform if you have the tool sized wrongly. If the Torx tool is too small you are putting the stresses on the points of the star. Where the hex head will put stress more towards the sides if the hex key is too small.
 
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