Inset panel
 

I need to put a trough shape into a larger fender. I'm thinking I want to put a small lip on the trough to give it some shape for assembly. This will make a small lap seam in the finished panel where the larger piece I'm insetting the trough in meet. If I keep the lip small, 6mm or so are there any downsides? Seems like it would help the smaller panel keep it's shape but might cause trouble in final planishing. Thoughts?

Here's the trough roughly shaped in tin foil, I tried to put a flange on the upper perimeter to show you what I'm thinking. The the larger panel would cover the flange and get lap welded into place. There will be two exhaust pipes in the trough, the upper one is not present in this pic.

https://i.postimg.cc/vm5Hg9PB/IMG-7626.jpg

This is a picture of the actual panel I'm asking about. Now I'm 50/50 on whether to flange the perimeter or not. It's more substantial than I thought and would probably hold it's shape okay without a flange on the edge. The flange would stiffen it up but then also might make tweaking the body line in final planishing impossible.

https://i.postimg.cc/W1BdzWYZ/IMG-7632.jpg

https://i.postimg.cc/Bv2XKTRV/IMG-7633.jpg

Hi,

How are you planning on fastening the piece to your body? You don't want to weld the edge to your body as it is very difficult to planish the weld to eliminate the shrink that occurs. If you are going to weld it, make the flange wide enough that you can planish it and not hit the broke edge, if that makes sense.

Bill

Jeff, I'm assuming that the recess panel for the exhausts is eventually to be welded to the side of the rear guard (fender). If that is the case, I'd be making as large a flange as I could on the upper edge of the 'trough' panel (so 3/4" or so) so that I could butt weld to the upper panel and have the weld as far away from the edge of the trough as possible. That way you can get in there to planish out the weld. Very difficult if you have only turned up 1/4". Basically what Bill has said now that I have re-read his comment.

If you were really keen, you could shorten the leg on the trough panel and create the mating flange on the upper piece so that the join would end up being less visible. Would be more difficult to planish however.

Yes, the panel will get welded in. So what I hear is make a wide flange on either the trough or the larger upper panel and make a butt weld at the edge of the flange. A flange on the trough would put the weld in the upper panel and make planishing easier.

Did I get your suggestion right?

Yes - you can make a butt weld disappear, but you can never hide a lap weld.

I mean you could corner to corner and file up if you didn't care about the back of the weld, but difficult to planish if it cups.

A butt weld seems like more work, but neater in the long run.

Definitely and butt weld. If you want to have a smooth binding of the shape. The colleague who welded my bodywork did the same. He leveled inequalities with hammer and flame. In one place I needed to raise the shape a bit, it seemed difficult and in an inaccessible place. He heated it with a flame and the shape rose just as I needed. I had to hold my eyes so they wouldn't fall out of their sockets.:lol::lol:

I can't get the multi quote to capture all of your suggestions but thanks to all of you, you guys are the best!

Here's how it looks so far.

https://i.postimg.cc/FRh5cRpv/IMG-7657.jpg

https://i.postimg.cc/pTkNBHcF/IMG-7658.jpg

https://i.postimg.cc/BbvrYVRw/IMG-7659.jpg

Jeff, it's perfect. Do as my friend taught me. Put the two layers on top of each other and cut through. In your case, a straight-line saw.
Make spot welds. Remove the excess material and you have it exactly where you wanted it. More in my thread. :D https://www.allmetalshaping.com/show...=20564&page=11
Attachment 64811

Attachment 64812

Perfect! Thanks!