Custom machined 2.2, 2.5, and 3.0mm pivots barrels for SAK mods

[papercut]

This is a spinoff thread from this thread:

http://forum.multitool.org/index.php/topic,40000.0.html

Recently I ordered and prepaid 100 custom threaded 2.2, 2.5, and 3.0mm pivot barrels each from a supplier in China.  Pretty much all of them are spoken for at this moment, but there may be a few extra here and there if the folks that reserved them back out.  Each barrel costs $0.66 and is 26mm long (may be good for two Saks).  The 3.0 barrel is in 304 steel, while the thinner ones are in brass.  More info can be found in the thread above.   

1.  3.0mm pivots with M2 thread all the way through, Stainless Steel 304
2.  2.5mm pivots with M1.6 thread all the way through, Brass
3.  2.2mm pivots with M1.4 thread all the way through, Brass

As production is still underway, there is the possibility of enlarging the order, so if you want some please let me know.  I will be carrying them to the USA early next month, or I can mail from Asia when I receive them projected end of next week.

I am not currently planning on supplying screws, but that may change if folks request and I can find some locally. 

Once the first order is delivered and everything is kosher, I will list the company and contact info so that anyone can order or future group orders can be made.  I don't expect to keep an inventory to sell individually.

Special thanks to all the modders out there, you have been a big inspiration.  I recommend that everyone when they have a chance go through 40 odd pages of the mod squad forum and check out the older ideas.  Some earlier dreams people had have become reality, and some really cool older mods and modders can be rediscovered. 

[HankSolon]

I'm interested in taking 15 of each size, shipped to Germany.

[crackout]

Oh you're making 2.2 as well? I'm in for that!

I'll take six or nine. Maybe we can do one Germany shipment and distribute it further then ourselves.

[HankSolon]

Sure, good idea.

[Lypse]

I would take 12 of each size

[papercut]

I have requested 36 units be added to each size, that should be enough for the requests so far.  Lets see if it is a go.

[papercut]

Ok, three dozen of each size has been added.  That puts me in at ~$300 in this order, a bit more that I am comfortable.  I hope the products are quality and folks don't back out.   

[Lypse]

Oh you're making 2.2 as well? I'm in for that!

I'll take six or nine. Maybe we can do one Germany shipment and distribute it further then ourselves.

Crackout, if you hear of more people around, I could join the shipment for Germany (I live in Denmark)

[lowtech]

I seem to have let this topic slip by...
Well, if any sets are left, i´d like to take some too, if not, I´d liek to be in for teh next round.
Thanks for tezh effort, Papercut!

[papercut]

Low tech, I think I can just squeeze you in. That is probably it for the first order unless there are some dropouts. Once I get the goods ill post pics and we can settle the details. The supplier seems to be capable of doing complex precision work, so this should be rather elementary for them. We shall see :p

[HankSolon]

@papercut: Since you took a costly risk, me for example, won't drop. If its perfect, or not.

[papercut]

I appreciate it!  Hopefully I can get an update this week. 

[WiSAKfan]

if there are any drop outs or space left for first order i'm game

[papercut]

Hmmm, the supplier has informed me that 26mm is rather difficult to tap in one go.  He asked if he could go in two directions.  I asked him to tell me the longest single tap he could make, as double taps are not ideal due to variance in the length of the used length of each barrel.  I also told him the length is a bit flexible, so we shall see.

So far I have 10 people interested in the barrels, I might need to jigger the unit up a bit so that everyone can get sufficient quantity (maybe 9 or 10 instead of a dozen or somesuch, and Tabasco slimming his order a bit. 

Crackout- your order is a bit of an anomaly as it is only for 2.2 mm, not quite sure how to handle it, maybe your European brothers will get their 2.2 shaved by a unit or two, or their others boosted by a few units.  :p

[papercut]

I was just informed that the maximum length of one continuous tap is 10mm.  Which brings a dilemma, 10mm in not long enough to do many popular mods.  According to Crackout "For a Farmer with scissors you need around 15mm and for a Pioneer with scissors around 12mm."  It is not quite enough.

Which brings up the alternative of tapping 10mm from both sides.  This would mean that each pivot would need to be cut twice to be of use, once on each side.  Its not ideal, but not a 100% dealbreaker either- one more step with the dremel.  Having a continuous tap would allow for ease of use as one would not need to worry about conflicting threads.

Also, if tapping from both end is done, what would be the correct length?  We need to consider the reasonably thinnest mod-a two layer cellidor.  What is the width of that (say a blade plus combo, then scissors mod)?  You would need to consider dead space and the length of screws. 

10mm may be ok too, a "marriage" screw could be inserted in the middle to join them (not sure about the right word).

Any ideas?  I will tell the supplier we are considering.

[crackout]

My custom pivots are also tapped from both sides because of the same problem.

However, a 10mm deep thread is long enough to work on all lengths. So if you have a 16mm pivot and tap both ends and then grind it down to 12mm you will have enough threading left.

Did we already discuss the length of the pivots?

[papercut]

I am thinking either 26mm with 6mm filled or 25mm with 5mm filled would be the most appropriate. It seems these measurements would be be the most flexible. You could still reasonably have a ~9 mm wide mod this way (taking into account the screw lengths).

Maybe 25mm would be best?

More ideas please. As things have already changed a bit, I don't want to unilaterally make decisions as there are 10 people on the waiting list.

Cheers

[crackout]

What do you mean by "25mm with 5mm filled"? 5mm the solid part in the middle?

I was thinking about something like this:



Using the maximum tap depth.

[lowtech]

...what Crackout showed would be teh best solution imho.
although i am not sure if they thread solid round stock or if they thread tubing, which would just leave an unthreaded piece of tubing in the middle.

I think i can work with anything you come up with.

[HankSolon]

Since there's a little barrier with the speech (native and non-native english speakers) I would suggest a little (and raw) drawing with the 2 or 3 options we have. Then I would say ok (ok to all or partly ok).

However: I'm with lowtech. It sound's, that you already have a good solution.

[papercut]

Crackouts drawing is pretty much exactly what I have in mind. Let me confirm with the supplier if it is what they can offer.

[papercut]

Actually, question for crack. In your drawing there is a bit of profiling of the ends of the pivots. In practice is this recommended or would it be better to be flush? I could see how the rounded edge might be useful when stacking things on the pivot.

Please inform.

Cheers

[crackout]

When assembling knives based on pivots it is crucial for the pivot to nicely penetrate the hole in the scale. Let's say you grinded off too much and the pivot barely goes inside the hole, then a nice sharp edge could help improving the overall tension.

But I think since everybody will grind those pivots down to some extent, it doesn't matter if you round off the edges in the machining process. I wouldn't do it, it's just one more step in the process.

When assembling 84mm knives using this method, it's even more important to have the exact length because the scales are much thinner and can therefore not accommodate as much pivot length as the scales of 93mm models.



I illustrated the problem here. The top cartoons show the case of 93mm scales. The thickness can buffer the pivot length to some degree. For 84mm scales (bottom) it's a lot less. You have to be spot on.

[papercut]

Gotcha, great illos.

Cheers

[Syph007]

What do you mean by "25mm with 5mm filled"? 5mm the solid part in the middle?

I was thinking about something like this:

(Image removed from quote.)

Using the maximum tap depth.

That should pretty much cover all your needs, good idea.  The longest pivots I've ever used are about 20mm and that was for my 5 layer big boy farmer mod.

You pretty much have the other pivot tips already since you've done them before.  Dont bevel the ends and when building pivot SAKs, keep as much of the pivot in the scale as you possibly can for strength. 

84mm mods are extra hard and what I do for those is to counter sink the pivot itself to 82 degrees so that the screw fits right into it and lets the thin scale have the max amount of pivot body extending into it.  So I will cut the pivot to length, and then countersink it until its just the right fit.

I'm super curious to hear how the brass pivots work out.  If I was using them the only thing I'd for sure recommend is to use long screws and try to 'fill up' as much of the pivot with screw as possible.  So instead of just brass threaded rod, you have steel inside as well, as much as possible.

[papercut]

The supplier has confirmed that they are using solid metal rods, not tubes, which is very good.

"Filled in" means solid metal, my bad, typing on the phone with a crying baby nearby can be a problematic. 

I think there may be some variance in the solid middle areas based on the suppliers last email, perhaps ~9-11mm tapped with standard being 10mm tapped, tapping to the limit seems to be a bit tricky. 

25mm overall length confirmed.

Thanks for the feedback guys, I was starting to wonder if this was still worthwhile.  With 10 "backers" it is good to know that many folks will get a chance to tinker, and no one person will be stuck holding the bag (that would be me )

Cheers

[papercut]

I'm super curious to hear how the brass pivots work out.  If I was using them the only thing I'd for sure recommend is to use long screws and try to 'fill up' as much of the pivot with screw as possible.  So instead of just brass threaded rod, you have steel inside as well, as much as possible.

Would brass pins and steel screws work well together?  Would brass pins and brass screws be a better idea to avoid wear? 

For steel in brass would locktite be required to avoid the wear?

[Syph007]

I'm super curious to hear how the brass pivots work out.  If I was using them the only thing I'd for sure recommend is to use long screws and try to 'fill up' as much of the pivot with screw as possible.  So instead of just brass threaded rod, you have steel inside as well, as much as possible.

Would brass pins and steel screws work well together?  Would brass pins and brass screws be a better idea to avoid wear? 

For steel in brass would locktite be required to avoid the wear?

Hmmm I'm not actually sure what's best, my instinct was just to go with steel screws for strength (and thats all Ive ever had available to me via knife supply stores), but Im not at all familiar with the metric M2/M4 screws to know how big they are.

[lowtech]

For the Imperial guys - M2 means metric standard screw with a nominal size of 2 mm (0,079) or 4 mm (0,16 Zoll).

I see no disadvantages in usin gsteel screws, thread wear should not be a problem as teh knife does not get disassembled too often and corrosion between the different metals should be sufficiently blocked by thread locking agent whci will keep oxygen away.
Brass screws should be strong enough, too and might look nicer.

[crackout]

Yeah, I also see no problem concerning the source material.
It will be a challenge modding 84mm though. Never did it with threaded pivots. Can't wait!