Titanium pinning

[ilknives]

Hi! I have searched this topic and found a thread from 2012 so thought not to Lazarus it.
I wondered two things:

Whether others also had the titanium crack or chip on peening 6-4 titanium pins in 6-4 titanium bolsters, this happened more than I cared for, and what solutions they used.

Secondly, I have started to use a 30T hydraulic press I built to press them and this seems to work much better. Perhaps because the force is delivered slow and gradually and there is some heat generation (compared to hammer blows) the risk of fracture is less. The other effect seems to be that the whole length of the pin swells, this was v handy as I used a strip of wood veneer each side to allow pressure to close the gap first before the dies contact the titanium pins. Problem was I then applied more pressure and the veneer deformed the bolster!! I was however able to grind down from the surface about a fifth of the thickness without the pins starting to show, to get it flat again.

Thanks

Ig

 

[John L]

Try ti grade 2 pins. They pin easily and anodize with color

 

[ilknives]

Thanks! Do they remain undetectable when polished? J John L

 

[REK Knives]

Not sure if I'm on the right track here... but I normally will undersize the hole only by .0005-.001" w/ a reamer, then press it in with my vise or arbor press (definitely not a hammer). Here's one I did recently when I had to plug some holes, it was such a tight fit you wouldn't have even noticed when it was sandblasted (no cracks) so it works really well this way.

 

[javand]

Try ti grade 2 pins. They pin easily and anodize with color

Giving away all my secrets John!

John is correct, the trick is using CP/Grade 2 ti. I do a *LOT* of domed Ti pins, and hidden ones. The trick to hiding it, as I'm sure you guessed, is using the same alloy for the bolsters.


Here's a couple examples, a recent one with ti liners, shadow bushing, and pivot, with domed ti pins (customer photo, makes it hard to see the anodizing, but they're all colored, and the streak on the blade finish is oil), rust blued W2 with black rag micarta scales, second knife is stainless with rag micarta and all Ti hardware, domed pivot, anodized gold.

If you think you can see the pivot hidden in the shadow bushing on the first knife, it's just the multi-color anodizing where I made the center darker purple, and the edges gold, you cannot see the pin at all. The second photo it looks like you can, but the pin is actually far below center of the shadow bushing, not where it looks like you can see it.

 

[javand]

I keep saying this, and I guess I'll continue; there is NO reason to use 6al4v on knives, except for springs. In any other circumstance I can think of, CP makes much more sense, it's infinitely more formable, and machinable.

 

[REK Knives]

I keep saying this, and I guess I'll continue; there is NO reason to use 6al4v on knives, except for springs. In any other circumstance I can think of, CP makes much more sense, it's infinitely more formable, and machinable.

Great points above Javan!! Do you have any recommendations where to get the CP Grade 2 Ti from?

 

[javand]

Great points above Javan!! Do you have any recommendations where to get the CP Grade 2 Ti from?

Ebay? I'm typically unwilling to pay retail for titanium, when there's such a huge surplus market.

 

[ilknives]

I keep saying this, and I guess I'll continue; there is NO reason to use 6al4v on knives, except for springs. In any other circumstance I can think of, CP makes much more sense, it's infinitely more formable, and machinable.

Thanks, I use it for the spring quality so I am resigned to 6-4 then in the pins... But this is very useful to know.

 

[Alpha Knife Supply]

I keep saying this, and I guess I'll continue; there is NO reason to use 6al4v on knives, except for springs. In any other circumstance I can think of, CP makes much more sense, it's infinitely more formable, and machinable.

It is true CP titanium alloys are softer. However, there are reasons why some knifemakers use 6-4.

CP titanium scratches much easier than 6-4. It is very difficult to match CP and 6-4 anodized colors. It is easy easier to smear and/or orange peel CP when buffing.

The machinability of CP vs 6-4 is debatable. I personally prefer machining 6-4 over CP.

We used to stock multiple alloys. Knifemakers had the problems listed above in addition to keeping track of which sheet was correct to use for the lock side of the knife. Now we stock only 6-4 and we do not hear complaints. Knifemakers who buy only one titanium alloy have fewer worries.

Chuck

 

[javand]

It is true CP titanium alloys are softer. However, there are reasons why some knifemakers use 6-4.

CP titanium scratches much easier than 6-4. It is very difficult to match CP and 6-4 anodized colors. It is easy easier to smear and/or orange peel CP when buffing.

The machinability of CP vs 6-4 is debatable. I personally prefer machining 6-4 over CP.

We used to stock multiple alloys. Knifemakers had the problems listed above in addition to keeping track of which sheet was correct to use for the lock side of the knife. Now we stock only 6-4 and we do not hear complaints. Knifemakers who buy only one titanium alloy have fewer worries.

Chuck

I understand what you're saying Chuck, and I don't disagree that 6al4v has advantages in certain use cases. I'm just offering an alternative perspective from my use case, that's contrary to the "default view".


I also have no problem machining 6al4v, but I still don't see it being necessary or advantageous for most uses. However, the vast majority of Ti that's used in making knives is used for liners and frames, for liner locks or frame locks, or other larger format pocket knives, at least, from my perspective. Clearly it's mandatory for those situations, i.e., as a spring, and also for higher wear areas like pivots for those style of knives, although I've been using grade 2 for pins for non-bushed slipjoints for 6 or 7 years now, and had zero issues with pre-mature wear, or any returns because of it.

The *MOST* important advantage here is that it's possible to peen to a fine domed head, or easily hide in heavily tapered bolsters. This is something you simply cannot do with 6al4v, sorry. I have seen some spun 6al4v heads that the maker was happy with, but I personally, wouldn't be caught dead with them on my knives, with all the micro cracks and tracks.


I don't do buffed finishes except for my domed pins to refine them after peening them, and never had any issues with such, so, that's not a concern for me, but I'll definitely take your word for it.

As far as keeping track of alloys, it's no harder than keeping track of different alloys of steel, and I've got a sharpie to make certain, but from a business perspective, in your case, I can see the reasoning. I would also mention that in any gauge that you can deform with your hands, it's pretty damn easy to figure out which is which, even if they aren't marked.

You are absolutely correct that the two alloys don't match when anodized at the same temp or voltage, and you'll never make the colors of the two alloys match exactly. I don't personally see this as a disadvantage, I prefer to capitalize on it, like you guys do, with your timascus, which wouldn't be viable otherwise right?

Anyway, I'm just offering a differing perspective, I have no dog in this fight, I don't sell ti, I just use a lot of it, but for very different things than the tactical/large frame folder crowd.

I did however, come off sounding a bit "absolutist" about it, I apologize, and appreciate the counter perspective. Like 416 (which I detest, compared to 410), I've been trying to get people to understand that there are always trade-offs between alloys. In steel, typically, the more machineable it is, the less formable it is. I see zero reason to use 416 for fittings or pins (except in the case where heavy machining is necessary), over 410, and can list a number of reasons why 410 makes more sense, but much of this craft is simply "so and so did it this way, so it must be the right way", which I've got a bit of a ideological objection to making leaps based on assumptions like that.

 

[javand]

To add and summarize, I think all I'm trying to promote here is a culture of makers asking their selves "Why do I use this?", frankly in the case of any and everything in their shop and process, as opposed to jumping on a "default" and then coming here wondering why something doesn't work, that they would have known wasn't likely, if they'd asked themselves that question in the first place. No offense to the OP, I'm not trying to call them out.

You'd be amazed how many people at shows ask me how I get titanium fittings to do what it does on my knives, it's not magic, or any special tricks, just most people aren't aware of any other grades of titanium other than grade 5, or some crazy odd-ball alloys used for blades. It only takes about 10 minutes of "research" online, to find the information about the various standard alloys. When I started wanting to use titanium on my knives, I knew within those 10 minutes, that CP would do what I wanted it to do, but I already felt pretty sure, 6al4v, wouldn't, before hand.


So if (sorry to the OP if I'm derailing your thread), just one person that reads these posts, takes a bit of time to look into all the options in titanium alloys, and more importantly, starts to ask themselves, "why do I use this or that, in particular?", then it'll be infinitely worth the discussion.


Yes, I know I'm like some crazy ideologue when it comes to philosophizing about this art, that most of you would probably rather I shut up so you can "just make knives". Sorry!

 

[Bob Ohlemann]

Javan, I appreciate you putting this info out there. I have a project coming up (actually I should already be working on it) that I'm dreading because it will require blind tapped 2-56 holes in the bolsters. I've not thought to try other Ti alloys but, I ordered some CP grade 2 after reading your comments. If it is even slightly more forgiving than 6al4v then it's worth using. Thanks for sharing!

Bob

 

[ilknives]

OP is chill with good discussion, having popcorn and learning

Bob Ohlemann I have not blind-tapped anything other than 6-4, and well, that has not been great, to say the least, but I cannot say if it is better or worse than other grades. At least I got to learn which acids will dissolve the broken tap (2-56) more than once. A warm mixture of ferric chloride with 30% HCl and I think I had sulphuric acid in there as well (cannot access nitric acid where I am), did the job in about 10 hours. I wanted the bolsters to be defined from the liners for this one, hence the reasons for the taps from behind.

 

[javand]

Javan, I appreciate you putting this info out there. I have a project coming up (actually I should already be working on it) that I'm dreading because it will require blind tapped 2-56 holes in the bolsters. I've not thought to try other Ti alloys but, I ordered some CP grade 2 after reading your comments. If it is even slightly more forgiving than 6al4v then it's worth using. Thanks for sharing!

Bob

Haha yeah I was just having a discussion about this issue with another maker earlier today.. The takeaway: "Be very careful using carbide taps in this scenario", yes they can make it a little easier, until one breaks in a blind hole and you can't get it out with acid easily, like HSS. Plus, titanium is resistant to all the acids you normally use to get a HSS tap out, so it won't screw anything up, but the only acids that are capable (that I'm aware of) dissolving carbide, will wreck the ti also (and are extremely dangerous to your health; hydroflouric acid for example).

With CP and good quality HSS taps, I don't think you'll have a problem though Bob, just practice a few times.


With carbide taps, the easiest way to extract a broken one in a blind hole is usually the "break it up into smaller pieces" method, but with really small ones, it's insanely tricky, and you typically ruin the hole in the process.

 

[Bob Ohlemann]

Haha yeah I was just having a discussion about this issue with another maker earlier today.. The takeaway: "Be very careful using carbide taps in this scenario", yes they can make it a little easier, until one breaks in a blind hole and you can't get it out with acid easily, like HSS. Plus, titanium is resistant to all the acids you normally use to get a HSS tap out, so it won't screw anything up, but the only acids that are capable (that I'm aware of) dissolving carbide, will wreck the ti also (and are extremely dangerous to your health; hydroflouric acid for example).

With CP and good quality HSS taps, I don't think you'll have a problem though Bob, just practice a few times.


With carbide taps, the easiest way to extract a broken one in a blind hole is usually the "break it up into smaller pieces" method, but with really small ones, it's insanely tricky, and you typically ruin the hole in the process.

Yeah, I don't use carbide taps. They're too fragile. For through holes I use HSS form taps in a Tapmatic and I've been using the same 0-80 for over a year. For occasional blind holes, I have a fairly sensitive hand tapper. Haven't been willing to risk 0-80 in it but, it's been great for 2-56 in other materials like 416, zirc and bronze. The CP has shipped so I'll try it out next week.

Bob