Help me JOHN KELLY you're my only hope, Tuck issue Options

[scotty b]

I'm making a seat/rear fairing for a cafe racer conversion. I folded the lip on the lower portion last night using my bead roller with tipping dies and then shrunk it to smooth it back out. My problem is at the rear where the curve gets really acute. I had 2 small tucks on the side ( see pics ) that came out fine but the one at the dead center of the apex was less then satisfying to me. Did I do something wrong on the larger one or is it just not that possible to get it smoothed out? Despite all of the metal werk I have done this is the first time I have attempted a tuck job. At this point I'm happy with the results and will fix the fold with a vouple of spot welds but what about the next time?? How can I get a smoother tuck?

Thanks

[rick 918-S]

My 2 cents, What gauge are you working with? It looks like 22GA or something. It looks too light for a seat pan. I'd use 16-18 GA Aluminum and make as much of the lip as I could fold and shrink, then gas weld the sections that are too tight to gather and smooth. Nothing wrong with making a couple of pieces to save work and a possible do over.

Then did you want the crease to tip up like that? The reason I ask is I've had metal change direction on it's own as I tried a tight tuck. I'd cut it and smooth it then gas weld it. Hammer weld it at this point. That's alot of metal to gather in a thght radius.

Keep at it you get. Looks like your close.

[John Kelly]

Hi Scotty,

It looks like the center tuck has very steep sides. If the sides are steep, it will fold over on itself instead of shrinking. Rick is right, that's a lot of metal to gather up. It might have worked better if you had done a smaller tuck, shrunk it down, and then done another in the same place.

Did you use an edge shrinker? I think I see some marks from shrinker jaws in the one picture. The edge shrinker makes the metal kind of stiff and perhaps brittle as well... harder to tuck shrink.

Is that a steel hammer form or the bottom of the part? You could have done that part in a hammer form. It might have been a little more controllable. Still a lot of shrinking to do the really sharp corner there though.

At this point, you could gently heat the small folds with a torch and tap them over a hard surface from the back side to straighten them out a bit.

Looks like a really nice job you are doing. The customer is lucky to have you working on their bike. If you like, I will send you a free copy of my tuck shrinking video. Just let me know. Kent White has a video entitled shrinking magic that is very interesting. His web site:

www.tinmantech.com

John www.ghiaspecialties.com

[John Kelly]

I just noticed the little pick hammer marks on the tuck. You might try using a smooth hammer surface with less of a point on it.

John www.ghiaspecialties.com

[scotty b]

Rick it actually is 18 gauge sheet. In the past when doing something like this I would have simply cut a slice in the center of the tuck, folded it in, then cut out the overlap and welded it up. I decided this time to do it the "hard" way, and see if I could actually finish it out without welding. As for the pick marks, I used the pick end to tighten up the tuck in an attempt to prevent it from walking back out. Once I had done this I was afraid that I had made it too tight which sounds like what you and Rick are both saying. I also had planned on making it out of aluminum, BUT I don't have a sufficient tig welder and my attempt at gas welding aluminum a few years ago was not pretty (IMG:style_emoticons/default/icon8.gif) On and no hammerform. I did it all with the tipping dies and shrinker.

Is the tuck shrinking video a new one? I have your first video that focuses on the flares.

[JPB]

Carbon Fiber (IMG:style_emoticons/default/poke.gif)

[scotty b]

Carbon Fiber (IMG:style_emoticons/default/poke.gif)

(IMG:style_emoticons/default/finger.gif) (IMG:style_emoticons/default/av-943.gif)

[John Kelly]

Here is the description of the tuck shrinking video:

http://allshops.org/cgi-bin/community/comm...d=9980191607382

Different from the flare video which I have upgraded signifigantly. If yours is Custom Metal Bodywork #1 it is the old version. The newer version is just Custom Metal Bodywork and is far more tightly edited and has about 3 times as much information in it.

John www.ghiaspecialties.com