panel problem

[redoxide]

Help! Ive got a problem with the top section of the rear body on the Alvis special body Im building.

The tail section is of the boat tail type. The top panel doesnt have a great deal of shape, but thats where the problem seems to be. Im not to bad at stuff that has a good bit of shape, but things with light shape give me lots of grief.

The panel in the picstures has lots of bad faults, from wheeling marks, low spots, ripples, you name it.. Every time i try to put some contour across the top, as would be expected, the arc at the front gets greater and wont sit on the frame ... If I push it down on the frame the panel dips in the middle with humps either side .... a king size pain in the neck..

So what would be the best process to folow to make this lightly crowned panel with a tight radius on the edges to flow into the side panels?

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[Kerry Pinkerton]

From what I see in the photos, you need to shrink where it stands off the sides. In one shot, I can see a natural 'tuck' that was formed when you pushed the rear down. If you shrink that area, it will lay down. I'd probably make a tuck shrink. How far in you need to go is a function of the curve in the cross section.

Your wheel marks are pretty bad. Is your wheel out of alignment or is your anvil too aggressive?

[redoxide]

The wheeling is terrible, no disagreement on that score That resulted from making to much shape the first time, then flipping it over and wheeling it to flatten the panel out, then making to much shape, flipping it shape flip etc... Its fair to say the panel in the picture is scrap... but If it was possible It could be an exercise in sorting out the mess ( but would be quicker starting again)

I do think that the lower wheel has to much radius and apart from my inexperiance, its not helping.. Ive only got 2 lower wheels and both have a fair old radius..

I ust kept going with the pael to see what it would end up like ( and hoping by some mirracle it would come out correct, dent, wave and wheeling mark free)

I had used the shrinker at an earlier stage where the peaks are o the edges, they returned when I wheeled it out again..

I think my biggest problem ( apart from the attrocious marking on the panel) is wheeling it to acieve the crown but not end up with a huge ark that needs pushed down to fit..

Could the problem be the narrow contact point between the upper and lower wheel???

[Kerry Pinkerton]

Originally Posted by redoxide

....Could the problem be the narrow contact point between the upper and lower wheel???

the problem with the skinny contact is inconsistent stretching on the panel. You can use a skinny contact but you to REALLY be precise with your tracking pattern.

I'd probably be using a 3/4" contact flat...perhaps a 1/2"...hard to tell from the photos. I always use the FLATTEST anvil that will fit inside the shape without touching at the edges. Only having two anvils makes things a bit more difficult.

If your anvils are true radius perhaps someone else can chime in. I don't know anything about using true radius anvils other than I mess up every panel I use them on.. Low crown panels are especially difficult for me to use TR anvils on.

[redoxide]

I will take some pictures of the anvills and post here.. I think they may be what you call true radius ie there is no flat or land at the peak...?

[Kerry Pinkerton]

Yeah, that would be a TR anvil. Different techniques and I can't make them work because I learned with contact flat anvils and really stiff frames. TR anvils can work with softer frames because the profile is the same all over. MOST the traditional cast iron ENGLISH wheels, are actually pretty soft and use TR anvils.

It's possible to do great work with either style but I can't because I don't have that knowledge and skill.

[Dyce]

Looking at the panel it looks like it has a slight reverse curve in the upper section. I would wheel the full length in the center to start out, and once you get about half of the shape there just work the lower, or rear part of the panel. Then the upper part of the panel I would turn the panel 90 degrees and wheel it side to side for the reverse.

Are you able to support the panel when you wheel it? If the panel is curling up you might be letting front or rear edge of the panel fall out of alignment with the wheels. Without flats it must be tough to work aluminum.
Jeff

[David Gardiner]

Ian I think you need to invest in some more wheels. It is possible to get a reasonable result with what you have but you will have to go very gently so you dont put the marks in in the first place.
You can always resort to planishing the panel by hand.

When you are wheeling you should use a wheel which closely resembles the shape of the panel you are working on.

I would start where you need most shape and blend out from there.

The work you have done so far looks pretty good though!

David

[redoxide]

Took advice from everyone who responded and invested in a 52 inch radius lower anvil for the Ranalalah wheel...just waiting patiently for it to arrive, then its out to the garage to make more scrap..

[David Gardiner]

Ian I have used a Ranalah machine, I used to use one to make SS100 and SS90 wings. Nice machine to use but the bottom post can come loose in the lead it is set in. The one I used had about 1/4 inch movement but still wheeled ok, god knows how.

David