Thread: 1947 Biederman Truck Fender Repairs

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Had a question about placement of the thinning groove, so I thought I'd post the results of the test sample...

Originally Posted by WoodsTruck

Question about the use of your tipping die for bending a straight line.




What would happen if you made the divot on the back side of the bend instead of the front? I realize you are referring to this as "thinning" the metal, but aren't you actually forging it in a sense since you aren't actually removing metal but compacting it primarily? To my inexperience it would seem that a tight bend could be made without the resulting trough if the tipping die was used on the backside of the bend.




Fantastic work though, wish I had half the knowledge and tools to do that stuff. I'm a graduate of the BFH school.

Here's the test from tonight. The 16 ga thickness measured out to about .057, at the "thinning" groove it was .053, so we lost about .004 in thickness, or less than 10%. Put the thinning groove on the outside for this bend, it tended to stretch the deformity back out again where it looks like it could be more readily cleaned up with a file..

















So where the bending process allowed the groove to stretch back out....











...it also gave us a wider radius than when the thinning was placed on the inside of the bend...











So I'd say to use placement based on if a tighter radius is needed or whether you need it dressed out

Originally Posted by MP&C

Had a question about placement of the thinning groove, so I thought I'd post the results of the test sample... So I'd say to use placement based on if a tighter radius is needed or whether you need it dressed out

Robert, you're an amazing teacher! Thank you for taking time to do the tests to answer the question, document the steps with great photos, and then post them with good explanations. As Mom used to say, "You're a GEM!!"