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Old 03-11-2014, 02:57 AM
axelkloehn axelkloehn is offline
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Default A Dino 206 build

Good morning guys

I am new to this forum and new to metal shaping as well, means I am a beginner and just have a limited number of tools right now.
I am building a 105% scale Dino 206 over a hacksawed GT40 fiberglassbody, and will try to build it all in metal. I have a planishing hammer and an english wheel, no stretcher/shrinker and no bead roller at the moment.










Yesterday I was working at the bonnet, and would like have a nice metal transition around the raised part of the bonnet in the center (see marking).
I wheeled up a test part, but figured out that at the front and rear 180 degree curves the metal transition needs to be stretched, and than the stretching needs to fade out.








How can I fade out the stretching with the english wheel cause there is no shrinker/stretcher at my shop.
I saw something with a rubber band around the upper wheel, which will just bend the metal , no stretching.
Can I start with this idea, and than use the wheel without rubber band to stretch-bend it at the halfcircle curves at the ends?
Or do you have another advice for me?

The original car:









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Last edited by axelkloehn; 03-11-2014 at 07:23 AM.
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Old 03-11-2014, 05:05 AM
Resto Rod Race Resto Rod Race is offline
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Thats a cool project, please keep us informed of your progress, and welcome to the site.
Cheers
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Old 03-11-2014, 09:01 AM
Mike Motage Mike Motage is offline
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Wow, nice start and very cool!
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Old 03-11-2014, 09:28 AM
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Steve Hamilton Steve Hamilton is offline
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Hi & welcome to the site

The rubber band is just to bend the metal.

you can stretch the metal by wheeling more at the edge and less as you move in on the panel.

you can stretch with a hammer that is wedge shaped. strike at angle so more force is at the edge. do this on a shot bag, or a wood block that has a v notch cut at the edge. Then wheel to smooth.

Steve
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Old 03-12-2014, 01:30 AM
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thingsthatfly2 thingsthatfly2 is offline
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oh that looks fun!!!
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Old 03-12-2014, 03:19 AM
axelkloehn axelkloehn is offline
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Thanks for the kind words and your help guys!

I did some tests yesterday with exchanging the solid wheel from my english wheel to a polyurethane one (pinched from a heavy load carrier), and the results were amazing.
I was able to easily bend the area around the blister, did the corners with the planishing hammer, and wheeled it afterwards with the solid wheel to partially stretch it and smooth it out.
I am pretty satisfied with the result as it was the first attempt!














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Old 03-12-2014, 03:24 AM
axelkloehn axelkloehn is offline
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One question, I guess I wheeled it too long at the marked red area on the right side and did get too much stretch, as a result it started to show waves at the left side.
I did wheel it in the yellow area too get rid of the waves but no improvement.

It seems to me as I have to shrink it at the right side (flange, red area) to reduce the stretch and get rid of the waves, but as there is no shrinker around at my shop, so how can I shrink it manually without cutting slots in it?

Any advice from your side?

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Last edited by axelkloehn; 03-12-2014 at 09:49 AM.
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Old 03-12-2014, 08:03 AM
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Axel,

Let's think about what might have happened.

First thing to know is when a soft upper wheel is used (or a rubber band on the upper), the metal is not stretched but only rearranged or bent. Now the affected area is in the vicinity of where the curve is in the shape you put in on the panel. I am referring to the red circle area you drew in on the photo next to the blister.

What you did on the edge of the panel was basically bent a flange upward. In the circled area the flange needs to be stretched. As the flange is bent up it needs more material to go around a corner.

This is a fact in any metal shaping operation. A flange on an inside corner needs to be stretched as it is formed. A flange on an outside corner needs to be shrunk ( or as in a square outside corner, notched).

So what about the affected area you circled in yellow? As you bent the flange up, you did not stretch the material being bent. (the stretch is only needed in the corner, however. Not the straight section). Thus, in that area a stress was created in the panel. The panel developed a wrinkle in the area you circled in yellow as a way of relieving the stress at the flange.

You can verify this analysis with a sheet of typing paper. Cut out the corner to match the shape of your engine cover panel. Then with you fingers bend up a flange, say 1/2 inch, on the cut out edge. Bend a right angle flange up, the effect is the same. Now observe the main flat part of the sheet of paper; you will see it does not want to lay flat any longer. If you attempt to push the paper flat down on the table it will wrinkle in the area your panel did.

Now to verify that the flange needs to be stretched in the corner, simply cut the flange from the edge of the flange to the bend, do so in several places. You will see the cuts open up (vee shapes) indicating a need to stretch in that area. An alternative would be to make a cut from the area on the outside edge of the paper (across from the curve in the flange) to the curve in the flange. Then you will notice the paper again lays flat.

So when you noticed the wrinkle, you wheeled the panel to resolve. This is in effect the alternate I mentioned. The reason it did not work was that you would need to stretch the entire area, edge to flange, to relieve the stress.

The sheet of paper is a very good tool to understand what happens when you form a panel. That is why the butcher paper pattern has been around forever and still is a valuable tool. The flat paper acts the same as the flat sheet of metal. It is easy to mimic shrink by folding in tucks( or pleats) and stretch by cuts in the paper.

So the solution would have been to go back to your flange in the curved corner with you metal upper and wheeled the flange in a six inch length to stretch it, I believe you panel would have then Lost the wrinkles.

Note: if you try to do this with a sheet of too stiff paper it will not work as well. If a lighter paper is used , as tracing paper, it will work. If you use a larger sheet the stiffer paper will be ok. Butcher paper and full size of the part will mimic the way the sheet metal behaves.
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Last edited by Richard K; 03-12-2014 at 08:13 AM.
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Old 03-12-2014, 08:17 AM
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As I read my above post I want to add a precaution.

It could be misunderstood that axel should have rolled the flange with the steel upper. This is NOT the case. If the flange had been wheeled in with the steel upper, the flange would have been stretched over the entire length causing a real mess in the entire panel. The entire panel would have curved upward in the center.
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Old 03-12-2014, 09:46 AM
axelkloehn axelkloehn is offline
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Hi Richard,
thanks for your help, I really appreciate that you are taking your time for me.

You're right, I did bent a flange upward with the rubber wheel at the long section of the flange, but as the hole horizontal surface actually needed a curve upward at its center, I stretched the hole flange at its upper part with the solid wheel to bring curvature in the horizontal panel, it worked fine at the right panel which did not show any wrinkles.

I somehow think I stretched the flange too much or to far at its lower part at the marked red area at the right panel- you can see there is a dark gap to the blister, so that may have caused the horizontal surface to show waves, but I could be wrong...I am just an amateur.
I will try your suggestion with some paper or some scrap material too learn more about metal and its behavoir during the shaping process.

What I have learned yesterday is if the panels starts to show waves or wrinkles, stop immediately and have a long break or a day off, otherwise the panel will be heading for the bin ;-)
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Last edited by axelkloehn; 03-12-2014 at 10:11 AM.
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