How to bend 1/4" plate into 18" radius?

[IslandTractor]

I have an extra full skidsteer QA attachment blank and would like to fabricate a simple stump bucket by welding a radius bent 1/4 inch plate as in the attached photo below. The fabrication would be simple if I could figure out how to make the bend in the 1/4 plate. I'm estimating it is an 18", maybe 20" radius. Assuming I start with just a flat plate of 1/4" steel, pre cut to size, what is the best way to get the proper radius bend and hold it in place while it gets welded to the back plate?

I have at my disposal a 10ton "jaws of life" gizmo with a 5ton pull back ram. I have ratchet straps (thick ones). I have a 20ton brake press but it is only about 24" wide at the base (HF model) so I don't see that as useful (the bucket length is probably at least 30-36 inches long.

I was thinking that if I could get an initial bend in the plate just by putting the ends on blocks and driving the tractor through the middle, that I could then attach either a come a long or the pull back ram or even ratchet straps and then just continue to bend it to the correct radius by pulling the ends together. Is that nuts? Can anyone tell me the amount of force necessary to put a 18" radius in 1/4" x 36" tapered steel plate? I was thinking I could just weld some temporary hooks to the edges and use those for attachment points for the bending operation and would then just grind them off once I'd welded the thing to the back plate.

How would you suggest I proceed given this work would need to be done in the field rather than in a metal shop?

 

[sandman2234]

To get a true radius bend, it won't be easy. I bent some similar plate using a stitch cut and reweld, but that isn't a radius. Might be better to find a drop of 18" pipe and go from there. If you just have to use your plate I make consider farming it out. David from jax

 

[kencunningham]

A 36 inch pc of sch 40 steel pipe cut 36 inches lone will run you atleast 100 bucks a foot. A option you can consider is farming it out to a tank company, thats if you have one relatively close by. Have no idea what they would want to charge, but if you try to bend it without a roll forming machine you are likely to just bend it at a angle. Once the first bend line is created, it will want to continue to bend along that line.

 

[Zebrafive]

To get a true radius bend, it won't be easy. I bent some similar plate using a stitch cut and reweld, but that isn't a radius. Might be better to find a drop of 18" pipe and go from there. If you just have to use your plate I make consider farming it out. David from jax

For 18" radius he'd needa 36" pipe.

I would do two bends, maybe 135*. If I could not bend it I would cut into three pieces and weld it back together.

 

[LD1]

The method you describe has a major drawback. At the top, where the plate tapers down thinner, is where the bends will take place and NOT down at the bottom (along the 30-36" length) where you want the radius also.

I agree, consider farming it out or get some pipe or an old propane tank. If you find a shop with a roller to bend that for you, I dont think it would cost too much. Cause it would take maybe 15 minutes to do. And it would be done right.

 

[Baby Grand]

Long, strong levers welded to the ends of the plate, a rose bud on your torch and something stout, vertical and radiused to work it around (lally column?). Doesn't have to be perfectly smooth & continuous, does it? Trying to think like a blacksmith.

 

[IslandTractor]

Thanks guys. Appreciate the cautionary advice. I will look into farming out the bending. Would a standard ironworking business be able to do this or do I need to find a "boilermaker" or some specialized business?

The alternative is to just cut the plate into appropriate trapazoids and weld it back together for an angled type bucket. I kinda like the "cut barrel" style but if the fabrication is going to be too complicated or costly I can more easily just make it out of flat plate.

 

[Danno1]

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It can be done with an Oxy-A torch. Heat a line, let it cool, heat a line, let it cool, heat a line, let it cool, etc.

This is how boatbuilders form steel hull panels in the absence of a real shop. IE, back yard builders.

Now that I think of it, didn't 4Shorts describe something similar on a project a few years back? Or one of the other guys trying to describe how to straighten a trailer tongue maybe?



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[IslandTractor]

Long, strong levers welded to the ends of the plate, a rose bud on your torch and something stout, vertical and radiused to work it around (lally column?). Doesn't have to be perfectly smooth & continuous, does it? Trying to think like a blacksmith.

I wonder if I could do this using a 55 gallon drum as the mold? Maybe sink the drum a foot so so into the ground and fill with water to stabilize??? Probably a lot more prep work than just using the three sections of flat plate though.

 

[IslandTractor]

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It can be done with an Oxy-A torch. Heat a line, let it cool, heat a line, let it cool, heat a line, let it cool, etc.

This is how boatbuilders form steel hull panels in the absence of a real shop. IE, back yard builders.

Now that I think of it, didn't 4Shorts describe something similar on a project a few years back? Or one of the other guys trying to describe how to straighten a trailer tongue maybe?

Interesting idea. I'll file that one for consideration too. Probably cheaper to do it with propane though. I like the shipbuilder's association.