M2.5 bolts

[batjka104]

Has anyone tried putting an SAK together using M2.5 bolts?

I am always weary about putting too much pressure on SAK tools for fear of bending/breaking pins. M2.5 bolts are made of steel and are correct diameter for the holes. I highly doubt they would bend or pull out before the actual tool breaks. Also seems easy to put the knife together without having to deal with pins and bushings. The heads on these bolts are about 1.5mm thick, probably not thicker than regular bushings. For the other side, an M2.5 jam nut can be used, with the same thickness as the bolt head.

Any thoughts?

[Neil]

Years ago I used them for doing test fits but then fitted brass rod for final assembly.  Don't think I ever fully assembled a knife with them though.

A chap over on SOSAK, might have been spudman made one like it.  I don't know how it turned out in the long run.

[Gareth]

Wasn't there an issue with the threads wearing down a little?   I could be making that up though.

[Neil]

Dunno, long time back.  To be honest peening brass is probably easier than trying to get bolts right and then trimming down and then getting scales to fit back on.

Alox is a different matter, bolts would be easier.

[batjka104]

I doubt the threads would wear down any faster than the brass rod. After all we're talking about steel vs brass.

[Gareth]

I doubt the threads would wear down any faster than the brass rod. After all we're talking about steel vs brass.

you could well be right, as Neil says it was a discussion on another forum a long time ago.  I now can't remember if the thread wear was just a prediction or an actual issue.

[batjka104]

Dunno, long time back.  To be honest peening brass is probably easier than trying to get bolts right and then trimming down and then getting scales to fit back on.

Alox is a different matter, bolts would be easier.

I don't see much of an issue with bolts. Tighten the nut, then cut it flush with a hack saw and file the remainder down. In my opinion, a lot more could go wrong with the peening procedure. Plus, bolts should be stronger as I have mentioned before.

As far as fitting the scales, it could be tricky, but I was thinking more of Alox, metal, or wood scales. My only concern would be the appearance of the nut on the outside of the scales. Guess they would have to have a countersink of some kind to get the bolt head and the nut flush.

Any way to find that old thread? I would love to read it and learn from other people's experience. After all, that's why I'm on this forum.

[Tofty]

Wear is inversely proportional to surface contact area.

The brass pin in making complete contact with the hole in the steel tool therefore the force at any one part of it is quite low, also lubrication is smeared around the pin every time it is opened and closed in a fine film. Brass is a very good bushing material against steels and stainless steels due to the relative hardnesses. There are strange laws governing working surface mating convention but they should not be ignored.

Using a thread as a bushing surface massively reduces the contact area to probably 1/100th of the brass pin. Lubrication will not stay on the thread tips so it will work dry very quickly. Moving dry steel on steel is not desireable. Wear will occur due to force being focused on the thread tips. Only a small amount of wear will change the outer diameter of the bolts enough for noticeable sideways movement to occur.

This is just my experience but i would advice to never move something across or around an exposed thread. Use a threaded tube as the bushing surface and screw into that. This way you dont have to make a nut at the other end.

[batjka104]

Thank you for the advice, but I would disagree. While you might have a point about thread wear in continuously moving surfaces, SAK tools only open once in a while, thus the wear would be negligible. If you were talking about a constantly spinning wheel, I would say you're right. 

Of course an inside-threaded tube with end screws would be ideal to use in this application. Unfortunately, I could not locate a source of anything like this. At least not with a 2.5mm outside diameter.

Maybe you can point me in the right direction.
 

[bushidomosquito]

Thank you for the advice, but I would disagree. While you might have a point about thread wear in continuously moving surfaces, SAK tools only open once in a while, thus the wear would be negligible. If you were talking about a constantly spinning wheel, I would say you're right. 

Of course an inside-threaded tube with end screws would be ideal to use in this application. Unfortunately, I could not locate a source of anything like this. At least not with a 2.5mm outside diameter.

Maybe you can point me in the right direction.

I'm after exactly that, a threaded tube to fit undrilled tools and accept a screw from both sides. I have spent many hours looking for them and it's just not happening without a custom order from a machine shop or your own lathe.

[Spork, Lord of Lime Jello!]

Do you have any links or photos of Spudley's modifications? Can I get in touch with this guy? I'm curious of how this thing had worked out and how he finished the heads. Honestly, I don't know why more people don't do this.

It's in the SOSAK Mod Index - The date of the original post is 2005 and Spudley hasn't been around for a long time - LINK

Note that you have to be registered on KF and have permission to see the the secret forum in order for the links to work.

[batjka104]

Thank you very much. Unfortunately, joining Knife Forums proved to be a challenge. For whatever reason I do not receive an activation email. I have tried several times. There must be a software glitch somewhere. I will keep trying. If anyone here has access, maybe a picture can be published here. Don't know if it will violate any policy of such a secretive forum. 

[Neil]

Thank you for the advice, but I would disagree. While you might have a point about thread wear in continuously moving surfaces, SAK tools only open once in a while, thus the wear would be negligible. If you were talking about a constantly spinning wheel, I would say you're right. 

Of course an inside-threaded tube with end screws would be ideal to use in this application. Unfortunately, I could not locate a source of anything like this. At least not with a 2.5mm outside diameter.

Maybe you can point me in the right direction.

I'm after exactly that, a threaded tube to fit undrilled tools and accept a screw from both sides. I have spent many hours looking for them and it's just not happening without a custom order from a machine shop or your own lathe.

+1

I've looked but never found and as I don't own or have access to a lathe I've pretty much given in on the idea.

[Metropolicity]

Thank you for the advice, but I would disagree. While you might have a point about thread wear in continuously moving surfaces, SAK tools only open once in a while, thus the wear would be negligible. If you were talking about a constantly spinning wheel, I would say you're right. 

Of course an inside-threaded tube with end screws would be ideal to use in this application. Unfortunately, I could not locate a source of anything like this. At least not with a 2.5mm outside diameter.

Maybe you can point me in the right direction.

I am not sure if I have such a small
Tap but I could make some brass tubes with an OD if 2.5. Just get me the exact length and we can work something out

mini-lathe to the rescue!

[Gareth]

Thank you very much. Unfortunately, joining Knife Forums proved to be a challenge. For whatever reason I do not receive an activation email. I have tried several times. There must be a software glitch somewhere. I will keep trying. If anyone here has access, maybe a picture can be published here. Don't know if it will violate any policy of such a secretive forum.

I think as long as Spudley is getting the credit then I can't see why he'd object to you guys seeing these:

[batjka104]

Gareth,

Thank you very much for posting these photos. I really appreciate you digging them out. The bolts actully look pretty nice. seems like this mod was successful.