Ti Alignment

[juggaloslaya]

Hey Guys,

Wanted to get some input about Ti frame alignment. a solid tacking strategy and weld sequence are great but sometimes you still get movement.
Cold setting gets the job done but I've heard rumors of running over welds with a tig torch to pull things into alignment.

Are people doing that? And if so, what's the method?

thanks!
Cole - Weis MFG

[fortyfour]

Hey Guys,

Wanted to get some input about Ti frame alignment. a solid tacking strategy and weld sequence are great but sometimes you still get movement.
Cold setting gets the job done but I've heard rumors of running over welds with a tig torch to pull things into alignment.

Are people doing that? And if so, what's the method?

thanks!
Cole - Weis MFG

Best practice and strategy against movement is to make sure your miters are tight without gaps. When TIG welding, if there is a gap, the part/parts are going to pull in that direction. So this can be used to your advantage or disadvantage during welding. I rarely cold set. Typically the only cold setting I do is to spread the dropouts after welding out the seat stay bridge if the dropouts have sucked together a bit. I typically will leave a small gap at the acute connection between the bridge and the stay to help open up and pull those dropouts apart (using a gap to my advantage). Technically it's the entire seat stay, chainstay and dropout assembly - basically the rear of the bike.

After initial tacking, without seat stays in place, I'll march through the frame and make a series of checks to see where things are leaning if they are, and then proceed to lay down additional tacks or short segments of fusion / weld to pull the frame back into alignment. Once that's achieved, seat stays go into place, tacked and the entire frame is welded. Anything that needs correction is far easier to achieve without the seat stays in place. Once those go in, the frame has another layer of triangulation that makes many adjustments nearly impossible.

In steel I've passed back over short segments welds for this purpose but I haven't done that in Ti. Typically I can get movement quite easily just from the tacking/fusion in key spots before I start the frame weld out.

Hope that helps.

[Rody]

Cole,

I never cold set titanium...it has a more resilient memory than any other material and will strive to return to it's finished position. The thought that heat wanding a finished titanium frame into alignment is pure fiction.

I'll add to what Kris stated. There are three key elements that must be adhered to for consistent results, specifically targeted to folks early in their craft;

1.) tight, accurate fitment of the materials
2.) Sequence and heat control during welding
3.) welding as much of the frame in the fixture as possible.

If these are adhered to, you will find very little need for post weld alignment.

The greatest variable in the above list, and the most difficult to master, is learning proper heat control. This is a learned observation through thousands of joints and has significant impact on the final accuracy of the frame. Mastering sequence and heat control allows professionals to fine tune the structure before it is complete.

best wishes,

Rody

[juggaloslaya]

thanks for the input!
Looks like it was a rumor after all : )