Sheet Metal Bending info - Loooong post

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Sheet Metal Bending info - Loooong post

Postby Nobody » Tue May 22, 2007 8:55 pm

for halfdome, Danny & critter (& any others interested ;) ). I'm gonna make a new post here rather than extend the 'tongue box' thread. To save bandwidth I'll not post all the pix here but they're in my album. Think there's 14 of them, titled Metal Bending Pic #2 thru #15. Was gonna post the narrative description there also but that's a different format & wouldn't go in my album :o . This will be rather long anyway. Some of the pix are annotated with text but my photo program (Dell Image Expert) won't add text without overprinting which leaves a 'shadow' behind the letters that is sometimes hard to read. If you can't read the annotation just ask & I'll try to explain.

I had some leftover .063" diamond tread aluminum sheet after trimming my TD. Wanted a tongue box but the only one I found of a design I liked didn't fit my tongue very well (DeeZee brand from Tractor Supply) so I decided to make my own. Needed a metal brake to bend the diamond tread into the correct shape so searched the WWW 'til I found a diagram & narrative for a 'makeshift' brake that I thought I could make without a lot of trouble. Scrounged/liberated some materials, welded the hinges onto the angle iron, bolted it to a hard yellow pine 2X4, cut a couple of spacers from a seasoned oak board & I was ready to go. Didn't take many pix of the brake or box construction so I had to improvise the pix for this post, using scrap material. One thing I learned that is pretty important is that the location of the clamping piece/fulcrum vs the hinge axis can be the difference between a sharp, well located bend & something else :roll: . The closer the clamp/fulcrum is to the hinge axis, the sharper, more abrupt & clean the bend will be. The narrative & diagram show the clamp/fulcrum is bolted to the 2X4 base but I decided for aluminum that "C" clamps should provide sufficient strength. Also, I didn't weld a handle onto the hinged bending angle, I use a large Crescent wrench, that way I can slide it to any location on the angle where I need more leverage depending on size of material to be bent. For heavier material such as the .063" diamond tread, annealing will aid in a sharper, cleaner bend, but the brake made a nice clean bend in the .040" siding material with no annealing required. Probably do OK in the diamond tread also if you place the clamp/fulcrum edge carefully. Anyway, the narrative from the website follows & the pix are pretty self explanatory when viewed in sequence (in the album). A couple of pix I'll post here after the narrative - The diagrams referenced in the narrative are the 1st two pix in the album - Pic #4 shows the brake with various angles, flats, I-Beam, etc, that I use for clamp/fulcrum to bend against.

NARRATIVE
Step Down #1 - A SIMPLE BRAKE - Part of what a brake does is grip the sheet metal and part applies even pressure all across the bend. If enough bending is done, a couple of angle irons will make the job easier. But there is a problem with the hinges. On a real brake, the hinge center line is exactly in line with the bend (A above), making life easier, but to do this, a heavy structure keeps the edge straight. Carving away at the steel angle could result in a home-built brake with the hinge in line, but that isn't simple any more.

The answer is to make the brake out of regular hinges and angle iron and use added strips to bring the bending surface out (B above) In the diagram a bolt holds the lower angle against a 2x4 with a wood spacer the thickness of the hinge barrel between. Above, the moving part is welded to the hinge which is screwed to the top of the 2x4 and a wood spacer brings that surface out also. The sheet metal is inserted vertically and tightened (and clamped), then the hinged angle is pulled forward to bend the metal. Mounting the lower angle as shown permits bending past 90° to allow for spring back. In this design, the metal is sliding past the upper wood, not just being pushed as in the ideal.

Step Down #2 - CUT TO FIT WOOD - The easiest way to get a crisp corner without a brake is to sacrifice some wood. That is, cut pieces of 1x2 or 2x4 to the exact inside length of the box and use this block, held in place by C or vise grip clamps (below) to produce good bends, finishing shaping with a rubber hammer. Depending on the width of the flange, a 2x4 can have grooves cut to fit folds. Also, with planning, the long bends can be done first, then the wood cut shorter for the short sides.

Three sample Vise Grip pliersStep Down #3 - USE SPECIAL WIDE PLIERS - I am not sure this is really a step down, because these pliers are used in sheet metal shops all the time. They are Vise Grip pliers with flat metal plates with beveled edges, as shown in the upper right of this image.
Slight upgrade - (C) It is very difficult to juggle angle iron and keep it aligned while clamping to the sheet metal. So take two pieces of angle iron and drill an place a bolt at one end after carefully aligning the edges. Sheet metal placed between the irons can be clamped on the other end and then use like a giant version of the wide jaw pliers, clamping with C-clamps or Vise Grip clamps, bending against a flat bench or concrete surface. 2006-07-11 edit


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Postby Duane King » Tue May 22, 2007 9:20 pm

Nice pictures Harvey. I like the idea that you can both read the narrative as well as see the pictures. I learn visually. So that is great for me and probably a lot of other folks. Well done. Thanks for taking the time to "splain" it. :thumbsup:
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Postby halfdome, Danny » Tue May 22, 2007 9:56 pm

Harvey, Thanks a lot for all those narrated photos of your metal bending jig. I don't have a project that's in need of a bending jig at the moment but now I know how to build one. The last bending project was the 3/16"stainless steel top shelf for my wood stove. It holds the top layer of fire bricks. It took me over an hour to bend two edges with a 5 lb sledge hammer and two 2x4's. After that job I may just pay the man for a bent one next time, what a job. Thanks, :thumbsup: Danny
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Postby tonyj » Tue May 22, 2007 11:07 pm

Thanks for the narrative and pictures. That sure beats a vise and a hammer.
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