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This weekend I finished up the refinement on the end pieces of these dies and loaded them up with some tools and other material and took it all out to my remote shop where I have the press and the rest of it set up. I even took some blank material with a fond hope that I might get to squeeze another pan out yesterday. No such luck. I found another small issue with my first effort and now need to get some longer bolts for the the end pieces. I did some work on some of the edges in the base die and have it corrected pretty well, I think. I have to do a little bit on the upper center die, and then I'll need to bend a couple of work pieces roughly to fit in the dies and then press on. Oh, I'll need to mark and drill the holes for the hold down bars in the work pieces, and that will take a bit of time and effort. Then I'll grease up the work piece with lard and try again. I actually think the bulges or one of them will likely rupture next, but we will see.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
I was able to finish up what turns out to be my first effort at die refinement this afternoon and got the dies and press set up and pressed another pan. There is some significant improvement, but I am not there yet. This pan broke out in about 13 places, but not quite so much in many of the same places, particularly in the bottom ribs and corner stiffeners. I went ahead and trimmed this pan out so I can also use it to see if it is going to fit my 85. I'll do that before I work the pieces over again. The hold-down bars did their job very well and the bulges did not rupture in the process, as I had expected. I used the lard and I think that contributed a lot to this partial/limited success. I'll use it again even though it is kind of a pain to smear it on both sides of the work piece.
Last edited by Jerry Feather; 11-04-2020 at 10:07 PM.
That looks fantastic, especially the bulges. I have absolutely no qualification to make this observation, but if you reduced the depth of the rib by enough to compensate for the width the fracture it probably wouldn't reduce the strength of the rib much but might prevent fractures at those locations. That's probably obvious, and without a doubt you have better ideas and will solve this problem quickly. This has been a fantastic thread to follow!
That looks fantastic, especially the bulges. I have absolutely no qualification to make this observation, but if you reduced the depth of the rib by enough to compensate for the width the fracture it probably wouldn't reduce the strength of the rib much but might prevent fractures at those locations. That's probably obvious, and without a doubt you have better ideas and will solve this problem quickly. This has been a fantastic thread to follow!
Thanks, Martin for your thoughts and words. Your observations about the ruptures is pretty intuitive, but the problem is that after the aluminum ruptures it tends to deform away from the die form element that broke it. That tends to open up the gap much more than just amount needed to keep it from bulging; but your idea would certainly work - it would just make the ribs a bit shallower than they need to be, I think. Here are a couple of pictures of what I am saying. After the rupture the shape of the rib is no longer the shape of the die.
Last edited by Jerry Feather; 11-10-2020 at 09:58 AM.
One of the things that I find a bit odd about my version of this front belly pan is the prominence of the cross-ways channel at the back that appears to connect the bulges on either side. The Factory made at least three versions of this pan for the early cars and the last one of them has a similar channel. That is pretty much why I put one in my pan. However, I actually have no idea why it is there. Well, I do have an idea that it is merely to stiffen the pan cross ways at the trailing edge. In any case, for some reason, I think I'll reduce the depth of mine so that it is not quite so outstanding. I can't do much about the width on mine now, but I'm going to reduce it by 1/8 inch in depth and see how that looks.
Last edited by Jerry Feather; 11-05-2020 at 11:42 AM.
Seeing the stress fractures, why did you settle on the specific material you are using? Is there another grade available that is more malleable?
The choice of material was fairly straight forward. I am using 5052 aluminum sheet in .050 thickness. The alloy is the one that is readily available and is the one used by my supplier for most of their aluminum commercial fabrications. I think they have chosen it because it is weldable and can be bent in a sharp right angle. They used to use 3003 T-11, but I don't know why they have changed over the last few years. It had similar characteristics.
If the shape of this pan were somehow critical I think I might have had to use your approach to the material. That is, make the form to the exact necessary shape and then find the material that would form into that shape. However, since the shape is almost totally flexible I have chosen to pick the material and then work the shape of the pan to be able to form it in the material.
Last edited by Jerry Feather; 11-09-2020 at 10:32 AM.
Nice work and I second the recommendation of making more shallow indentations to keep the material from rupturing. By the way, do you use any lubricant while forming? If not, that might help.
It still amazes me that there are those people who will go to great lengths to support 928 owners which is a dwindling (and somewhat difficult) group.
Good luck with the rest of the fabrication tweaks.
Cheers.
Last edited by Constantine; 11-05-2020 at 01:32 PM.
Nice work and I second the recommendation of making more shallow indentations to keep the material from rupturing. By the way, do you use any lubricant while forming? If not, that might help. Cheers.
I greased both sides of the work piece with Lard. I think it helped a great deal; and I will keep using it until I think the pan might form without it, if ever. I think the biggest benefit of the Lard was in keeping the bulges from rupturing after I put the hold-down blocks and bolts into use.
11-02-2020, 10:27 AM
