How would I get nice, crisp corners?

[ARC-170]

How does one go about getting sharp, crisp corners on simple sheet metal bends? I have some magnetic jaws I use on my vise and a sheet metal bending tool I got at a big box store. They all have larger bend radii than I'd like. I've bent 18 gauge and smaller.

 

[mickri]

Probably not possible. The dynamics involved are that you are bending the sheet metal. No way to avoid a radius on the outside that I can think. You might be able to get a sharp corner on the inside of the bend but the outside has to bend around the jaw.

 

[Liljoebrshooter]

Using this style of top die with the matching bottom die. You are "air bending", these are 90-90 dies. At least that is what we call them at work. This takes a LOT more tonnage to form this way.
Joe

 

[RJSakowski]

I have made fairly sharp corners by secondary work with a hammer after the initial bend. To get a sharp corner on the outside of a bend, you have upset the metal which is a bit more work. After the hammer work, use a file to remove any hammer marks. And sand to a smooth finish as required.

 

[cwilliamrose]

If you have some firm (80+durometer) rubber try using that as the female die.

 

[Bi11Hudson]

Truing the outside corner is also going to weaken the metal along the bend. Either change to a sharper die or try a welded seam.

.

 

[Flyinfool]

Define what you mean by "crisp" corners.
IF you are using a punch with a sharp corner and a matching die AND you have enough tonnage for the bend you are making you can get close to a sharp inside corner. The outside radius of any bend will always be the inside radius plus the material thickness. Just the laws of physics, no way around that. If you need a sharp outside corner you will need to add weld and grind it to the desired shape.

 

[C-Bag]

How does one go about getting sharp, crisp corners on simple sheet metal bends? I have some magnetic jaws I use on my vise and a sheet metal bending tool I got at a big box store. They all have larger bend radii than I'd like. I've bent 18 gauge and smaller.

you don’t mention the length you are trying to bend. If it’s piecemeal, one section at a time you are fighting the unbent sheet and that causes problems. The small handheld bender is for way thinner the 18ga and needs a way to hold the sheet edge to be bent. Another trick is to make a guide on your inside bend line and score it with a cutoff wheel in a grinder. This reduces the material on the inside of the bend.

My bends are good to me since doing it all at one time in the 30” 3n1.

 

[Weldo]

you don’t mention the length you are trying to bend. If it’s piecemeal, one section at a time you are fighting the unbent sheet and that causes problems. The small handheld bender is for way thinner the 18ga and needs a way to hold the sheet edge to be bent. Another trick is to make a guide on your inside bend line and score it with a cutoff wheel in a grinder. This reduces the material on the inside of the bend.

My bends are good to me since doing it all at one time in the 30” 3n1.

I’ve done the grinder trick before! It works beautifully. As long as the parts your making don’t need to be super strong. I usually cut through about half the material thickness and just bend the part by hand over the edge of my work bench. It does work very well. Depending on the material thickness you may need need a kerf wider than a cutoff wheel. I did that trick with 1/4” steel once but I had to use a thicker grinding wheel and kind of “V” the kerf out a bit.

If ultimate strength is needed maybe you could run a few stitch welds on the inside of the bend, or figure a way to add some gusseting.

 

[ARC-170]

Thanks everyone. I'm really just trying to get minimum bend radii, not zero radius corners. It looks like the best way would be with some sort of male/female die and pressure. I've been "air bending" with my vise jig.

The next best way for me might be to score/saw cut along the bend line.