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Land Rover bonnet rib.

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  • Land Rover bonnet rib.

    This is as exciting as my shaping projects have got so far, so at the risk of boring the pants off everyone – may I offer my miserable experience to anyone new to shaping?

    Those familiar with the older Land Rovers, will remember that the aluminium bonnet is supported by a steel frame. Unfortunately, with time and condensation, the frame rusts badly and an otherwise perfectly good skin, starts heading for the scrap man's furnace. As far as I can work out no one is making new ones, so when a couple of people on a Facebook forum I frequent, asked the question about replacement ribs, I thought it would be a good challenge.

    Click image for larger version  Name:	Bonnet rib 2.jpg Views:	0 Size:	2.26 MB ID:	2335
    Photo above; is of the bonnet rib assembly with the skin removed and turned upside down. The new rib is resting on top of the frame and is a copy of the rusty rib at the bottom of the picture.

    Step 1; was to take a paper pattern of the rib, as per Peter's DVD and to mark out the shape. Material used was 1.2mm gal; same thickness as the original steel.

    Step 2; having marked the fold lines and profile, was to cut the curve of the flanges. I used my bench-shears for that and then folded the two straight edges on the magnetic brake, to form a "C" section.

    Step 3; was to fold the flanges. I decided to use a hammer-form so using the paper pattern I made a template in 4mm MDF. The template was used to mark out the shape of the curve for the wooden formers and it can be used to mark out the shape of the metal for any subsequent ribs that I make.

    Click image for larger version  Name:	Bonnet rib 1.jpg Views:	0 Size:	2.65 MB ID:	2336
    Photo above; shows the shape of the curve on the finished rib.

    Click image for larger version  Name:	Clamped formers.jpg Views:	0 Size:	2.44 MB ID:	2337

    Photo above; Three formers were used with the "C" section clamped between them. The middle form is to stop the "C" getting crushed; while the top and bottom formers, allow most of the flange to be bent in the right place. Problems arose; despite using three very strong clamps the formers shook loose if I used a hammer and towards the end where the curve is tighter the flanges could not be bent much beyond 45 degrees because of the puckers. Both of these situations were expected, so I proceeded to plan B.

    On the second rib that I made, I dispensed with a hammer and made a tipping tool as used by Peter in his DVD's; see photo below. So, some flat bar suitably radiused with a piece of 1.2mm sandwiched between them was used to tip the flanges in increments, as far as possible. Some gentle hammering afterwards had the flanges heading in the right direction as in the photo above.

    Click image for larger version  Name:	Tipping tool.jpg Views:	0 Size:	1.27 MB ID:	2338

    Step 4; This is the point where things slow down a bit, as one realises that more special tools are needed and that one will have to make them. If you are impatient and don't think about it or take the time, good metal turns to scrap quickly. The first new tool was a stronger tucking-tool, than the miserable thing I had made a couple of years earlier; I used two high-tensile bolts from an old engine and turned them on the lathe. It worked, but even so the points bent a bit moving the 1.2mm, so I think I might make a flat-bar one like Peter has.

    Click image for larger version  Name:	Tucking.jpg Views:	0 Size:	2.49 MB ID:	2339

    Pause for a cup of tea and to post.
    Last edited by Chazza; 14-12-19, 12:07 AM.

  • #2
    Step 5; Time to do some shrinking with a hammer and stake. Good news and bad news; the good news is that I have some nice hammers and some bad ones, but all proved to be useful.

    Photo above left to right; 1. planishing hammer left to me by the man who taught me panel beating, nice to use. 2. cheap Chinese crap very heavy and horrible but was useful on the heavy metal. 3. Peter's small blocking hammer used to flatten the puckers, superb. 4. Planishing hammer probably bought by Dad, absolute delight to use, light and perfectly balanced, never get tired using it; coveted by the man who taught me panel beating.

    The bad news was that I had no stake to planish against. Fortunately the planets-aligned; in the off-cuts shelf was a piece of 25 x 25mm square bar. Using the press, I formed the bar until it fitted the curve on the template perfectly. Oh the joy of templates!

    Next new tool was a post on which stakes could be placed; previously I had bought a stake from Peter, so I made the post with a socket on the top, to suit his stake and then made a male piece on my new stake, to suit the socket.

    One day later, I returned to the task of making the bonnet rib.

    Step 5; The puckers were shrunk on the new stake and then more puckers were formed, until eventually the curve tightened, to fit the curve on the stake. This had to be done for 4 different curves of course. Planishing was done with a flipper and my Dad's planishing hammer; keeping in mind that it was desirable to preserve the galvanised coating, no sanding, or filing was undertaken. I keep a time-sheet when making parts for customers, so that I can work out a reasonable price for them and myself; 90% of the time was spent on shrinking and planishing the curves.

    Photo below; shows the post I made for the stake; the stake is under the rib and rather difficult to see; the clamp is holding the rib to the stake for the purpose of taking the photo. The curve in the stake can be seen closest to the viewer, the far end represents the curve in the the middle of the rib i.e. the middle of the bonnet.

    Click image for larger version  Name:	Planishing stake.jpg Views:	0 Size:	2.02 MB ID:	2342

    Step 6; As the part drew closer to its finished shape, I could test it on the skin until I was happy that it would fit nicely when riveted.

    Photo below; I made a very simple scribing tool to mark the edge of the flanges, so that the waste could be trimmed with snips. Here it is lying on its side; a piece of wood with a hole drilled in the right place; the scriber is a bit of sharpened 1/8" high-tensile, welding rod. The end of the block is held against the vertical face and the other hand pushes down on the scriber.

    Click image for larger version  Name:	Scribing block.jpg Views:	0 Size:	2.01 MB ID:	2341
    So at the end of it all, I had three happy customers and one happy metal-shaper!

    And I will take this opportunity to thank everyone who contributes to this forum, because it is your skill and knowledge, which has got me to where I am today,

    Cheers Charlie
    Last edited by Chazza; 14-12-19, 12:55 AM.


    • neilb
      neilb commented
      Editing a comment
      good job charlie i will add that in future when using hammer forms i found that by making them either longer than needed or with an area you can drill through (without drilling the part) you can bolt the forms together so they don't move.

  • #3
    Those came put very well, Charley. Thanks for posting.

    I also made a tucking tool like yours in the first post. Didn't make me happy. Made another one from a section of bent rebar. Same story. Finally made one from flat bar with slot as mentioned. It was the easiest & fastest to make and is still working great.. Live and learn.


    • #4
      Thanks Cliffy,
      When I saw that Peter had made one I knew it had to be a winner,

      Cheers Charlie


      • #5
        Nice job Charlie!


        • #6
          That's the way ! Well done !
          Peter T.