Titanium?

[Wyverndude]

After more than 40 years of 'someday' I'm finally getting serious about actually making my own custom SAK.  I've got myself some (AlTiN carbide) tools and some titanium stock.  A test cut with aluminum looks good; I'm just about ready to cut the real thing.  I am checking on this regarding feeds and speeds... and getting worried. 
Basically, "everybody" says titanium is ever-so-difficult to work with.

I probably wouldn't be so bold ... except that I will be roughing the scales to shape -and that's only 1/8" thick anyway.  And the liners are considerably thinner, of course.  So it seems like it shouldn't be that hard; only because the material is so (relatively) thin, and I'm going to be cutting so little of it (although cutting the tool slots will require full radius face cutting; kinda no way around that).

So... I'm starting to have doubts.

Anybody here done much with titanium?  I tried doing a search and didn't find much.
Also on home machinist forums, but for the most part, they're talking about hogging out large amounts of material; full radius face cuts -of course, because -unlike me- they don't have just this one very specific thing they want to be able to do with titanium.

I could make my scales with aluminum; and I'm sure it would be hugely easier; but I am wondering if I wouldn't have an issue with the aluminum wearing off?  If you take plain aluminum, and rub it up against something, that something gets impregnated with dark gray aluminum powder.  I'm sure everyone here is familiar with the dark gray powder you find impregnated into the backside of the cellidor scales.

Not an issue with alox scales?  It doesn't do the same thing to your wallet or your pants pocket (or belt pouch)?


I really do carry my SAK every day; and I use it a lot, and it looks like it.  It gets bumped and banged and scraped.  As such, I don't want to think about putting any finish on it that is inevitably going to just wear off.

Does anybody know what -exactly what alloy- the alox scales are made of? 
I am thinking about using 7075-T6
As a harder/tougher alloy than most, I'm assuming it would have much less tendency to slough off like the usual aluminum does.


But then again, maybe it (cutting titanium) will work.
I might be ready to cut some -first time ever- tomorrow.  Wish me luck.

[Adam5]

I have no answers for you. But I do wish you good luck!
 

[Aloha]

Good luck.  I had a curious look in the interwebs and see a few articles that discuss approaches.  I'm sure you'll find the right one to help tackle this project. 

[kamakiri]

I know next to nothing about machining titanium, but I think you might as well try if you have enough access to carbide tooling and maybe a mill. 

I mean to try the same…at least for some liners. Seems to me that it ‘can’t be too hard’.  Famous last words. 

[tattoosteve99]

For the liners I would suggest cutting them by hand (rough shape) then gluing them together to drill all the holes in one go. Syph has done a lot of Ti scales etc. Maybe search his thread about some more info. I do know he used to cut them by hand with a jeweler's saw. There’s a lot of info in his thread. Ti is gummy, similar to aluminum in that respect. I do a lot of makers use regular ole high speed steel bits and some use speciality ones (like cobalt). Speeds and feeds, to me anyway, is all about your machine and how you run it. When I have done Ti I use run it slow feed with a medium spindle speed and light coolant or mist. That’s just me and how my machine works best. There’s a lot of variables there as well. I’d suggest getting some scrap and test. I hope this helps and good luck.

Quick edit. Here is the thread I mentioned

https://forum.multitool.org/index.php/topic,34772.msg562670.html#msg562670

[kamakiri]

(although cutting the tool slots will require full radius face cutting; kinda no way around that).

A woodruff key cutter or T-slot bit?   Not sure if those can be found in TiAlN…or if that would be needed to just cut a few tool slots. Pretty sure these can be found in carbide-tipped.

I always assumed most shops used an end mill to cut T&T slots for the cost. I always think the rounded exterior sides for the tool head looks cheaply done.

[Singh]

  I believe liner materials in pocket knives are softer than the tools, not harder (brass, aluminum, nickel silver, etc). I suppose there must be a reason for that.

[kamakiri]

  I believe liner materials in pocket knives are softer than the tools, not harder (brass, aluminum, nickel silver, etc). I suppose there must be a reason for that.

That’s not always true, and I don’t see the relevance to this thread.

I think you are perhaps (incorrectly) assuming Titanium and all of its alloys are harder than the typical tool materials.

You are also ignoring the fact that many, many knives and multi tools are constructed with same or similar hardness materials adjacent to the tools.

But to your supposition…it’s generally cheaper, simpler and easier to do so (use softer materials for liners than the tools).

[Singh]

I just remembered: I have a SAK with Ti scales and liners.I knew I was going somewhere with this.

I was thinking about dissimilar metals and galling.  Some folks carbidize  the Ti to prevent that.

[ComboTool]

I was thinking about dissimilar metals and galling.  Some folks carbidize  the Ti to prevent that.

I know Syph does this. I've never observed galling myself but out of precaution I add washers between the tools and the titanium scales or liners.

[kamakiri]

I just remembered: I have a SAK with Ti scales and liners.I knew I was going somewhere with this.

I was thinking about dissimilar metals and galling.  Some folks carbidize  the Ti to prevent that.

Wasn’t that just a fad for knife makers like a decade ago? Blade edges and lock faces and such mods to Ti to wring more money out of the knife market? 

Doesn’t seem like a great idea to try to make the liners that much harder than the tools. I don’t see the issue with dissimilar metals concerning Ti and Stainless. Galling issues sound more like fabrication and design issues to me. 

[kamakiri]

I know Syph does this. I've never observed galling myself but out of precaution I add washers between the tools and the titanium scales or liners.

Aha! Does he still do this?

Agreed about the washers, if need be lots of material options there, IMO. Lots of ways to ‘hide’ them too, if desired.

Carbidizing is like adding a carbide washer…again, not sure how much sense that makes. 

[Singh]

It's fascinating stuff. The SAK I have with Ti liners isn't carbized. No problems with galling or things getting sticky, but that's anecdotal evidence. Other folks mileage may vary.

I prefer brass liners, tho.

[kamakiri]

It's fascinating stuff. The SAK I have with Ti liners isn't carbized. No problems with galling or things getting sticky, but that's anecdotal evidence. Other folks mileage may vary.

Sounds like another one of those ‘overblown issues on the internet’ kind of thing stemming from some other issue as I suggested. ‘Improper’ tool finishing can easily cause such issues. So can operating a knife un or underlubricated.

I prefer brass liners, tho.

Nickel silver for me. But I wouldn’t discourage the use of Ti because of that. Like I don’t get anyones preference for brass aside from cost saving.  But I wouldn’t discourage anyone from using it. I’d never even stock any brass sheet, unless paid well to do it. 

[Singh]

Nickel sIlver is a great liner but it wasn't an option on my 91mm SAK mod. *shrugs*

back on topic: I don't think we (well, certainly me!) have any answers for the OP.

[kamakiri]

 

I suppose I only had suggestions. 1. Do it. 2. Cut the slot with a radial cut not a full face.

I’d add fire/safety precautions milling Ti for the first time. Bucket of sand at the very least.

I did end up getting some Ti sheet for liners. And it’s not that hard to cut…even with hand tools. The plan is to drill/cut holes needed much the same way I do nickel silver. By hand with sharp tooling. I sharpen and resharpen most of my own stuff including the carbide and drill bits. Just gotta know what ‘works’ for hand work. Requirements aren’t the same for a bit used in a mill. I rarely break bits and my stuff lasts a long time for what I do. Not really expecting it to be much different because I’m not working with a mill and shouldn’t have the same concerns the OP has on feed rates and the hazard of overheating the tooling.

[kamakiri]

Cutting the thinner stock for liners and spacers turned out to be easy enough with hand tools that I got some other thicknesses up to 3mm. In theory, the thicker materials should be easier to cut (able to use coarser cutters/blades, but maybe a bit tougher to drill.

[tattoosteve99]

Not a myth or a way to generate more funds. Titanium is actually a softer metal, at least what most of us use, which is a alloy. Here’s some real info on the subject.

https://www.azom.com/amp/article.aspx?ArticleID=1219

And most real knife makers don’t carbidize they use washers or bearings. If you don’t believe anyone take two pieces and rub them together with a little force. Titanium is “gummy” with lack of a better word.

[kamakiri]

Not sure if that’s info for the OP gone MIA?

But yes, actually many common knife materials have issues when un or under-lubricated. Stainless on stainless has a huge coefficient of friction dry. Even when highly polished. But nobody makes a big deal about it and we all know to oil our knives. So unless there’s some other unknown about stainless and titanium interactions, I don’t think any of this side discussion relates much to the machining, cutting or shaping titanium. 

Seems like there’s enough myth and mystery about working with it.

I recently got an alox scaled knife that’s over 50 years old. Good shape but locked up pretty bad. Just needed a good lube and operation to work all or enough of the oxides out for proper operation and snap. Care was only needed to prevent the aluminum oxide from marring the stainless while dry. Because that is a material that’s significantly harder than SAK stainless.

Is anyone claiming that lubrication doesn’t fix or prevent galling issues between Ti alloys and stainless?

[kamakiri]

Just to make the point…even this ragged old SAK metal saw from 1958 is capable of cutting grade 5 titanium. Just used to notch these marks, but Ti isn’t hard as many seem to think.

[tattoosteve99]

True. I say it’s more like aluminum “gummy”. But I don’t have any pure Ti to test. That stuff is expensive for pure. Nope not me lol

[Wyverndude]

Hi, I'm back   
I set up my mill with a mist coolant system, and a vacuum duct to suck it up so it wouldn't make a mess.  That took a while, but it's working well; when I get done cutting, the tool is still cool.

I've been experimenting with 7075-T6 and did some tests; this is my first attempt at machining titanium.

This is the first step: I have managed to drill and countersink the screw holes, and cut out the outline of the scales, and radius the edges.  I have the tool slots programmed, but I haven't cut them as yet, that's the next step.


 

Vic91mm titanium scales.jpg (Filesize: 130.01 KB)

This still isn't quite right as the screw holes are not coming out clean, but I'll make some adjustments.

[Aloha]

Nice progress.   

[Vidar]

Looking good What kind of milling machine do you use? Any special titanium tools or cutters?

[Wyverndude]

Hi Vidar
I am machining on what is mostly a Sherline 2000; although the differences (between mine and a stock model 2000) are for increased work envelope and don't affect these nice and small pieces.
I'm using carbide endmills, TiAlN or AlTiN.

The parts that cut properly were a 1/4" 2 flute, and a 3 flute 1/8" radius endmill. 
The screw holes were cut with an uncoated endmill, but I don't really think the problem was because of the lack of coating.

[Vidar]

Interesting.

I have't milled titanium as there has never been a use for that around here. Is it a bit gummy like aluminium or more steel like?

[Wyverndude]

Well...  I gotta say, I used the same G-code on the titanium there, that I used successfully on the 7075; and the screw holes came out the correct size in the aluminum; but they are undersize here.
So; ya, titanium, living up to its reputation. 
I have a couple of ideas to try.

[Wyverndude]

Progress update: worked out the screw holes. 
Not much progress, but some.

Haven't cut the tool slots yet.

Pretty well decided to use standard-factory size pivot pins all the way around; with ... probably only one of the ones in the middle with a M1.6 screw in it; the other going into blind holes in the scale.  Y'know, like ... everybody else   
 This one in this picture is drilled out with 2.5mm pivot pins and M2 screws all around.

[SteveC]

Nice job, looks awesome !   

[Annihilator]

Wow, that looks neat! Keep us posted