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Old 07-06-2017, 10:29 PM
ArtAZ ArtAZ is offline
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Default Making bumper top piece questions

I would like to see if I have this planned correctly or if there would be a better way. The top bumper piece is from a 1974 Jensen-Healey. New pieces are practically non-existent and very expensive. So I thought I would try my hand at making one in 20 gauge steel first and see how it goes. The original were made from stainless steel and polished.

I have a hammerform for the bumper and cut out the blank and marked what needs to be done.

1. What I have planned is to roll the blank with the wheel to get the shape in it.
2. Then clamp the top and bottom pieces of the hammerform together and then slowly bend down the front edge. I figure I will need to shrink the corners or heat them to remove the pucks that will rise.
3. Trim the front bottom edge so it is level.
4. Use the bead roller to put in the channel at the back of the piece.

JH Bumper-1 profile.jpg
Showing the side profile of the bumper piece and hammerforms.

JH Bumper-3.jpg
Showing the bead at the back of the cover.

JH Bumper-4 blank.jpg
Showing the blank and the lines for wheeling and bending.

If it works out I plan on making a few out of stainless and selling them as I had had a few inquiries on making more already.
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Last edited by ArtAZ; 07-06-2017 at 10:41 PM.
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Old 07-07-2017, 07:32 AM
Rick Mullin Rick Mullin is offline
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If your plan is to practice to ultimately make this from stainless, I would suggest something slightly different. Stainless is not going to readily cooperate forming the leading edge over the hammer form. I would suggest wheeling the shape in and then setting the edge for the flange on your beader to establish a definitive line for the flange. Then walk the flange over on your form or with hammer and dolly. Stainless is going to give real resistance and move up into the top surface unless you have some serious holding power and a line to control it. If you use the hammer form, I would suggest clamping the surface with some steel bar stock and have it affixed to a sturdy bench. If the bend line distorts up into the top surface, it will be difficult to walk out.
Rick
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Old 07-07-2017, 11:18 AM
lots2learn lots2learn is offline
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I am a novice shaper but think I could probably make this from 20 gauge steel. From Stainless I would not even have a chance I think.
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Old 07-07-2017, 02:02 PM
ArtAZ ArtAZ is offline
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Thanks for the suggestion Rick. I did think of using the bead roller to start bending the flange but discarded it. Looks like I need to change my plan. I haven't worked with stainless before but have read it is harder to work with. Figured I would practice on the steel piece first. One of the metal suppliers has some scrap stainless I will get and practice on. They also have sheets there that are chrome on one side. But the guy had no experience on working with it.
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Old 07-07-2017, 04:35 PM
Rick Mullin Rick Mullin is offline
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I would avoid the sheets that are chrome on one side. Are you sure they are not just polished? Polished would not be a problem as long as you are not paying extra for it. Most likely you will be filing areas, sanding and polishing so it is no real advantage.
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Old 07-08-2017, 10:07 AM
crystallographic crystallographic is offline
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Agreeing with Rick ...

Stainless may need to be worked hot in some places or the fight will cost you dearly.

(Same time period the -'62-'66 Alfas had stainless bumpers, also, about 22 ga, as I recall. 18-8 alloy)
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Old 07-08-2017, 07:12 PM
ArtAZ ArtAZ is offline
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Thanks Kent,

I plan on getting in the garage Sunday to work on it a little.
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Old 07-08-2017, 08:43 PM
BTromblay BTromblay is offline
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Hi,

I recommend using the bead roller to help lock the panel at the bend lines as discussed above. I also recommend making a cut along the radius end. Once you have the material tipped, weld the seam and sand a polish the weld. This will make the part easier to make without trying to shrink alot of material. I would tip the edge on the cut line, this will help generate the radius once welded and help lock the panel to help prevent distortion.

Hope that makes sence.

Cheers,
Bill
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Old 07-12-2017, 09:15 PM
ArtAZ ArtAZ is offline
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Thanks Bill.

Like the others suggested also, the next practice piece I'll use the roller to turn down the front edge. Clamping the top and bottom forms together and then bending over the edge with a hammer or slapper was very challenging on the corners. It will take more heating to get the shrinking I need on the corners.

I'll try cutting on the other corner and see how it works out.

This sure has been different from the few patch panels I have made.
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Old 07-13-2017, 05:12 PM
Charlie Myres Charlie Myres is offline
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G'day Art,
Your hammer-form would be very easy to cast in aluminium, which would be a more suitable material if you need to use heat on the stainless, or as you say you get orders from customers.

If you can't find anyone near you, send me a PM; I do lots of one-off aluminium castings,

Cheers Charlie
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