Trials in Titanium

[RxDesigns]

Since I’m horrible at keeping notes and figured this may be a useful resource for others in the future, I’m going to log my initial experiences with working with titanium here.

I bought a titanium advanced kit from Joe at the Philly bike expo which is a great deal. Advance Level Kits - Titanium Joe

Test joint #1, 1.25" .028 wall to 1.5" .125" wall. I figured why not start with the largest wall thickness differential

Weld setup: Furick BBW kit from weldmetalsonline, 16 cup 3/32 tungsten. I noticed too late that I probably should be using a smaller tungsten, but it seemed to work ok 17/18/26 Stubby TIG Torch Kit for Stainless Steel

Tube prep: Sanded inside and out with 120 grit, then bathed in acetone. Need to wire wheel after sanding in the future, the surface was pulling out fibers from the microfiber towels.

Back purge 10CFH, torch 25CFH 8 sec post flow. 2 fusion tacks straight current @50amps, did not need nearly that much amperage

Fusion pass: (1Pulse/sec 30% on time 5% background @120amps), I was blown away by how nicely the metal melts down and sticks together. I don’t think I could ever fusion weld this thin of a tube in steel, but it seemed to work just fine with titanium. I was able to do most of the joint without filler, but keyholed when the intersection started to get tight so I used the .035 rod to fill on the “saddles” of the miter. I think someone with more skill than I could do a fusion pass without filler, but it seems like ti is more picky with torch angle than steel. I noticed when the torch angle isn’t perfect the rod will stick like everyone talks about, so the material definitely lets you know when youre off. Also noticed that you need a lot less amperage than steel to form a puddle. I was hardly stepping on the pedal on any of the stitches. Surprisingly I didn’t end up with any color and was able to fill the hole I made.

Filler pass was straightforward, easier than usual since there is already a seal between the two tubes. I used the .045 rod that came with the kit and it turned out ok. Not the prettiest but i’ll take it for now. Probably got lucky and ended up with minimal color on the outside, on the inside there was a small section that had some blue/gold but nothing terrible. That’s all for now, sorry for the lengthy post.

My questions for others:
Do you use different hole saws and or hand files for titanium?
What’s the heat tape of choice for sealing off ports and such?

[liberationfab]

That’s looking super nice for your first run at titanium, well done!!!

I think the real secret of titanium is that it’s super fun to weld! It’s so cool how it flows and floats more than steel.

For a joint that size, I think your back purge should be a bit lower, in the 3-5cfh range. Rule of thumb I use is 3-5cfh for subassemblies and 8-10cfh for a whole frame or front triangle.

To answer your questions - there’s some research out there about how ferrous inclusions in Ti can ruin the strength of a welded joint. How much you think this is important/likely to happen is kinda up to you. I think most shops that do Ti & steel end up with separate hole saws and files for each material. To me, the biggest practical reason is that Ti is great at destroying files & hole saws so you may as well get extras with that in mind.

I think most folks use some variant of polyimide or “Kapton” tape for sealing off ports. It’s pretty heat-resistant as tape goes.

Hope that helps! Excited to see your progress here.

[RxDesigns]

Thanks very much for the tips!

[Neuhaus_Metalworks]

As @liberationfab said, separate files and hole saws are up to the builder but standard practice in my shop because A) files and hole saws are cheaper than a broken frame down the road and B) I hate dull cutting tools, at least with the ti set I’m never surprised.

As far as the welding goes, try a lower amp and faster pulse for the root pass. All you’re trying to do here is fuse the root of the joint so that it doesn’t have the opportunity to bridge when you start adding filler. For the second pass I prefer a higher amp and longer pulse, this lets you push more filer to build the fillet and create the strength in the joint.

[RxDesigns]

Thanks for the insight. Unfortunately my cheapo welder has no setting between 1 and 2 pps, 1 has started to feel too slow but 2 is hectic

[liberationfab]

Oof that’s rough! I start to get motion sick at >1.7pps, 2 would be a lot!

[RxDesigns]

Finally got back around to more practice. Definitely got more comfortable with fusion and the filler pass was going well on the test joint without much color inside or out. Decided to try fusing a collar to a tube and fell flat on my face. Lost of color and not enough post flow for how much heat I was putting in. Didn’t have a heat sink so I’m sure that contributed, and I’m guessing the filler really helped keep the heat down on the other joints. Definitely have a lot to figure out.

[Neuhaus_Metalworks]

I wouldn’t say “flat on your face”, fuse with a fast pulse, if your machine won’t pulse slow enough just run straight current for the second pass and pulse with the foot. Expect to have to taper out as you go as titanium holds heat.

[RxDesigns]

Thanks for the tip, I’ll adjust my settings next try. I can see what you mean about tapering off, the beginning of each weld looked great and then color would creep in by the end. Need to get in the habit of letting off the pedal more as I go. This material is great for exposing where my technique is lacking

[Mark]

Trying not to start a new thread about this. Can anyone recommend another source for Ti other than Ti Joe? Some place in the States? Ti Joe is great and has all the tubing needed but shipping can be $$ for longer pcs. I found a few other places but selection is limited.

Thanks!

[Meriwether]

@Mark

Can anyone recommend another source for Ti other than Ti Joe? Some place in the States?

As far as I know there is nobody that does what he does in the “scrap Ti tubing” market (cut at different lengths and with so much variety).
I was sourcing tubing from Tiger Titanium but they are either owned by or a partner of TiJoe so you may end up getting a split shipment from Vegas and Canada and be even more expensive.

The other place I have ordered from is North American Alloys but I believe there is a min order size and tubing length, and the source of their tubing is overseas, at least for the tubes I bought while getting my handlebars dialed in. Cheaper per inch though so saves a lot if you stock up and know what tubing you’ll mostly use.

[Mark]

Thanks Whit!

[sikocycles]

My Ti welding rod will be here today to do some practice

[sikocycles]

Wow. Ti weld real nice.
I get some pinging and tinging. Sounds like it is cracking.
Is this normal?

[RxDesigns]

Got some more time under the hood. Keep making the mistake of not putting enough tacks and the joint popping out of place once I go to start fusion welding. This material really likes to pull itself around.

Any tips for shielding when trying to weld a plate style dropout to a tube? I can already tell there’s going to be a lot of turbulence and areas that aren’t well shielded

[sikocycles]

Here is my fusion pass. Only added rod went it started pealing away.

[Neuhaus_Metalworks]

Turn your amps way down for the fusion pass. The goal is the join the parent material at the root and nothing more. You don’t want to create a bunch of undercut that later has to be filled with your second pass.

[sikocycles]

I was at 45amps. What are you using?

[Neuhaus_Metalworks]

Was that 45 amps pulsed? That is 70a pulsed, I can go check the settings if you’d like but don’t remember off the top of my head.

[sikocycles]

Yes 45/50 pulsed. It was the first time with Ti. Seems much easier than steel.

Why fusion pass then filler pass with Ti but not with steel?