Pressure Required to form fender

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Doublet United States of America
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Pressure Required to form fender

Post by Doublet »

Using a hydraulic press or other style press how much pressure would be required to form a garden tractor sized fender 16 gauge metal?
Fender would be similar to size and shape of a Case 130 fender. No very sharp bends required.

Or how would you go about do it?
130 fenders.JPG
Doublet (Terry)
"It is all about the history of the tractors. "One tractor at a time"
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thebuildist United States of America
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Re: Pressure Required to form fender

Post by thebuildist »

FROM WHAT I'VE SEEN ON YOUTUBE...

not from personal experience, It seems to me that you could do it by hammering the steel sheet over a wooden buck that has been carved to the desired form.

You'd basically stack plywood... 8 layers high? or 10? And then carve that stack of plywood to the curves and depths that you want the fender to have. (you can use other types of wood, but the plywood is consistent and won't crack and heave as regular timber would be prone to do)

then clamp the steel sheet to one edge of the buck and start hammering. You're hammering the steel down to mold it down and around the 3d shape of the buck. As the sheet bends down around the form, it wants to drape into "darts" aka triangular folds. You have to concentrate on those darts and hammer the peaks of them down, such that the steel sheet never folds over top of itself. You're actually getting the steel to dimensionally shrink in those areas.

Thousands of hammer strokes later, once the sheet has been deformed to smoothly cover the wooden buck, you trim off the excess steel around the perimeter leaving the exact desired shape of the original fender.

Along the way you can use a sheet metal shrinker and/or stretcher around the perimeters to help get the sheet to be flat and stable. And you could use an English wheel to smooth out and form the curves.
I think you could produce the whole thing using an English wheel and stretcher/shrinkers, but where the wooden buck method is more brute force, it's also more fool-proof for the beginner.

Ron Covell has a lot of interesting videos along this line, as does "make it kustom".

Bob
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Doublet United States of America
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Re: Pressure Required to form fender

Post by Doublet »

thebuildist wrote: Sun Feb 06, 2022 7:17 pm FROM WHAT I'VE SEEN ON YOUTUBE...

not from personal experience, It seems to me that you could do it by hammering the steel sheet over a wooden buck that has been carved to the desired form.

You'd basically stack plywood... 8 layers high? or 10? And then carve that stack of plywood to the curves and depths that you want the fender to have. (you can use other types of wood, but the plywood is consistent and won't crack and heave as regular timber would be prone to do)

then clamp the steel sheet to one edge of the buck and start hammering. You're hammering the steel down to mold it down and around the 3d shape of the buck. As the sheet bends down around the form, it wants to drape into "darts" aka triangular folds. You have to concentrate on those darts and hammer the peaks of them down, such that the steel sheet never folds over top of itself. You're actually getting the steel to dimensionally shrink in those areas.
Thousands of hammer strokes later, once the sheet has been deformed to smoothly cover the wooden buck, you trim off the excess steel around the perimeter leaving the exact desired shape of the original fender.
Along the way you can use a sheet metal shrinker and/or stretcher around the perimeters to help get the sheet to be flat and stable. And you could use an English wheel to smooth out and form the curves.
I think you could produce the whole thing using an English wheel and stretcher/shrinkers, but where the wooden buck method is more brute force, it's also more fool-proof for the beginner.

Ron Covell has a lot of interesting videos along this line, as does "make it kustom".

Bob
@thebuildist I have watched the Covell videos you are in reference to several times. I have considered the method.
A hundred years ago I was trained in Auto body paint and repair.

I thought possibly the mold could be formed faster and easier under pressure. That is the way that factories make car hoods and fenders. I understand the difference in the types and thickness of the metal they use vs the 16 gauge I am talking about.

Just trying to get some thoughts and idea on amount of pressure I would be talking about.

Thanks! I appreciate your response.

Doublet (Terry )
"It is all about the history of the tractors. "One tractor at a time"
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