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  • Advice on turning an edge

    I'm working on the roof skin I posted about and doing it in sections as Peter suggested. What I'm finding is that I'm having difficulty turning the edge of the fairly low crown panels without everything going to hell. Rear roof section requires that I turn down 90 then turn back up 90.

    Lack of tooling is one problem. I've got a proper anvill ordered from Hoosier to help with turning the panels on the wheel. My cheapo bead roller with a tipping roll stretches it to much (maybe can be cured with better setup IDK) so I've been blocking in the first line and turning it down that way. I should add that I get the shape of the roof skin right first before I do this. That has been surprisingly easy it's the turning and dealing with the damage that has been hard.

    So after blocking it in and creating the line, and correcting/planishing everything (takes a long time) the piece needs more shape. I know that is from stretching from blocking the line and turning it with the sheet metal pliers. I have yet to be able to turn the line shrink where needed and be good. By the time I correct the shape, block in and planish/finish the line I have a large amount of time in a seemingly simple piece. But I have been able to get it all in control and back in shape.
    Then I attempt to turn the edge 90 degrees up again, this is where I lose control of it. I have been doing it as Peter did the door shut in Vid #8. I can turn it and create the line, but I lose control of the edge and not able to keep it uniform as I do this. When I do get it turned over I can get the lines correct and planished, and keep the correct profile on the bends but the top (actual roof part) goes to hell and usually shows way too loose. As does the top edge profile. I can correct it some by shrinking/stretching the upturned edge but can't get it back to the proper profile. I can get the edge of the top profile back in shape but as I go deeper into the panel is where it goes to hell. I'm about ready to trash my third piece (Lord knows how many hours in those) as it is way too loose (stretched). I have tried to correct it on the wheel but can't get back to where I was originally. Once it has those two turns in it the only way I can get any shape in or out is by stretching/shrinking the upturned edge. Wheeling doesn't seem to do much until the entire panel seems to be stretched to much. It's very frustrating, and I know there has to be a better, much faster way.
    So any advice would be appreciated. Specifically on turning the edges without doing so much damage.
    Last edited by Chris_Hamilton; 05-02-21, 04:20 AM.

  • #2
    Chris there are a few ways to turn the edge in question..... BUT! you need you to post a picture of the shape and profile of the panel ,I presume that you are talking about the rear section of the roof ? (outer rear Kent rail ) ........and the lip you are talking about is where the rear window rubber is attached to ? But again in order to help you I need to see the profile of that shape before the turning of any edges + a side view and a top view of the shaped panel + a measurement of the depth of the first flange facing down ( for example is it 10 /12/ 14 /15/ or 20 mm deep ?
    Peter T.

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    • Chris_Hamilton
      Chris_Hamilton commented
      Editing a comment
      Will do Peter. First thing in the morning (1:00 am here) Thanks.

      I'll post pics of the area in question on my good car, pics of all the relevant profile gauges I made as well. I'll draw out the profile on paper as well, just so everything is clear.
      Last edited by Chris_Hamilton; 05-02-21, 06:00 AM.

  • #3
    Complete dumbarse here, but what happens if you manually set the edge by fair means or foul - tipping wheels in the swage, tipping pliers, big crescent, vice grips etc... You will invariably lose some shape in this process (well I always do as I'm not a God like Peter) but this can be restored buy using the shrinker stretcher before making the second turn. I'd be inclined to put a fraction more shape in than needed as the next fold will likely suck some out again. Peter, please shoot me down in flames over this.

    If you are several pieces in on this, I'd be inclined to make a test piece just 50-100 wide x 300 or so just to prove the technique.
    Cheers, Richard

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    • #4
      Thanks Richard for the advice. Sorry for not replying sooner.

      I'm still going at it. Hard part on turning the edge for me is not the first turn, but when I turned it back up. Doing it over and over I'm understanding some of the mistakes I made. Made some progress and have had some success turning it with the wheel. Working on another section now. Pathetic how long it's taking me, but I find I'm learning a lot from my mistakes.

      Hard part for me is trying to control what I'm doing and have the panel react to what I'm doing, versus reacting to what the panel is doing and trying to fix that. Don't know if that makes sense but once I can do that I'll be on my way, so to speak.

      Is it just me or are low crown panels far more difficult than medium or high crown panels? Certainly seems that way for me.

      When I get to a point where I'm satisfied with my progress I'll post some pics in the other thread I started.

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      • #5
        You are welcome Chis - but remember I'm a newbie too, so may well be putting you crook.

        Agree re low crown stuff, I struggle also.

        If your finished panel is Steel, you could try making test pieces in Alloy first to prove the concept.

        Give us all some pictures of what you are trying the achieve and where it is flying off the rails.
        Cheers, Richard

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        • #6
          Originally posted by Chris_Hamilton View Post
          Thanks Richard for the advice. Sorry for not replying sooner.

          I'm still going at it. Hard part on turning the edge for me is not the first turn, but when I turned it back up. Doing it over and over I'm understanding some of the mistakes I made. Made some progress and have had some success turning it with the wheel. Working on another section now. Pathetic how long it's taking me, but I find I'm learning a lot from my mistakes.

          Hard part for me is trying to control what I'm doing and have the panel react to what I'm doing, versus reacting to what the panel is doing and trying to fix that. Don't know if that makes sense but once I can do that I'll be on my way, so to speak.

          Is it just me or are low crown panels far more difficult than medium or high crown panels? Certainly seems that way for me.

          When I get to a point where I'm satisfied with my progress I'll post some pics in the other thread I started.
          ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

          Chris I presume that you are talking about the gutter ? Well it's simple really....... turn the first edge down make sure that all profiles are right shrink accordingly then turn that edge at right angle by using a pair of plies OR... on the wheel by tipping the lower anvils , once that is right ... use a piece of steel about 1 inch long and the width of the gutter wide and turn the rest upright , you need to have the right amount of steel length or very close to it . If you find that the part you are making start to go out of shape (normally it goes too round ) well then you need to stretch the area while you turning it ....MEANING the right angle and the upright

          To be sure...... just post some pics of the job BEFORE THE TURNING, AND AFTER I should be able to tell you more ?
          Peter T.

          Comment


          • #7
            Thank you Peter for the advice. The part that was giving me fits was on the front and rear cant/Kent rails. When you turn the flange back up 90 degrees (approximately) after first turning it down 90 degrees(approximately). I made multiple mistakes while trying to do that the first few times which lead to me posting this. I am making progress as I am understanding the mistakes I made (not bending it exactly at the radius, trying to correct that afterwards, allowing the angle between the top of the roof and the first bend to change, lots of mistakes.) I'm not good at describing this stuff exactly but maybe you can understand. I've gotten both of those pieces done and looking satisfactory. Working on the sides now. Thank you for all the help and advice. I'll take some pictures and upload them to show some of this. Right now though I'm making progress and feeling better about it. I'm just extremely slow, which is frustrating as well but I know you gotta crawl before you can walk.

            Comment


            • #8
              Hi Chris Is this the 240z roof ?

              Yep low crowns are the hardest for me too Can you post a pic or 2. I spent a couple of hours with Peter today and feel a lot more confident about making the area above the cant rails accurately. Mind you, what takes me 3 hours is a 20 minute exercise for him.

              My initial thought was to make a skin in 3 pieces ie 2 sides and a middle panel but Peter said to do all the perimeter sections and then a turret skin . Working alone brings another set of challenges . I will follow his advice and will post pics of the RHS panel Peter retrieved from the scrap bin (!)

              I thought it was irretrievable so went and folded the flange just because I could. That effectively precluded any further wheeling cause I had locked myself out.

              Novice mistake !!!!!

              I thought the piece was ruined because I got the middle of the radius wrong so just carried on to see how things would work. Turns out that the MR problem was not that much of an issue and if I hadn't folded the flange would have been an easy fix

              If I could make a suggestion. Post pics of the problem areas. When I run into problems I have the luxury of dropping in and picking Petes brain. Its not the big things we do wrong (mostly. please don't ask ! ) its the little one percenters that add up and cause the heartache.


              Cheers Johnny

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              • #9
                Click image for larger version

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ID:	6100 Hi Chris, Just spent the afternoon with Dr T. working on the 240z roof skin Check it out on my Z car post. I learnt sooo much and I hope it helps you too ! Click image for larger version

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