I just discovered something a little different tonight. I finally got ambitious and went out to buy a little metal brake for aluminum. It's still very frustrating to get clean accurate bends, especially small ones and those in restricted tight spaces. You really are restricted in imagination unless you want to use multiple pieces and fasteners/rivits.
I was staring at my blank sheet of aluminum and suddenly wondered how I might borrow a trick from woodworking. It worked first time! I'm sure I'm not the first to discover this. But it might help someone here to point it out.
I traced out exactly where my bends were to be in order to form a box/chassis out of one piece with edges formed for rigidity and even a sloped section of the front panel made by bending a "Z" into it. Then I routered it! All routing is done on the interior radius of the bend.
I put a 1/4 round carbide shaping bit in my trim router, experimented on a piece to get the depth as close to exactly 1/2 depth of material as possible, arranged edge guides on my benchtop in order to route straight lines on the clamped flat aluminum, took a deep breath, put in the earplugs, and carefully traced my lines (changing the edge guides with each line of course - this won't work freehand).
A goodly amount of lubricant (i traced over all of my lines with parrafin) is a help, and a very good grip (the bit wants to wander). Since the lube is on the inside radius it's not a real bother to clean up before finish coating the alum.
A round nosed bit is going to serve better here than a pointed one or even a square profiled saw blade. The bend has an opportunity to spread over more of the radius and lessening the fracture of metal.
Now I hand bent the chassis into shape. Incredibly professional looking bends! There are no stress warps in the flat sections at all and I was able to make bends where no brake could possibly get to.
With relatively light gauge aluminum measuring the deviation made by bending radius is really not critical. Pretty much measure to the spot and the result will be VERY slightly dimensionally longer after the bend. If that's a problem, just VERY slightly compensate against this when tracing.
I was staring at my blank sheet of aluminum and suddenly wondered how I might borrow a trick from woodworking. It worked first time! I'm sure I'm not the first to discover this. But it might help someone here to point it out.
I traced out exactly where my bends were to be in order to form a box/chassis out of one piece with edges formed for rigidity and even a sloped section of the front panel made by bending a "Z" into it. Then I routered it! All routing is done on the interior radius of the bend.
I put a 1/4 round carbide shaping bit in my trim router, experimented on a piece to get the depth as close to exactly 1/2 depth of material as possible, arranged edge guides on my benchtop in order to route straight lines on the clamped flat aluminum, took a deep breath, put in the earplugs, and carefully traced my lines (changing the edge guides with each line of course - this won't work freehand).
A goodly amount of lubricant (i traced over all of my lines with parrafin) is a help, and a very good grip (the bit wants to wander). Since the lube is on the inside radius it's not a real bother to clean up before finish coating the alum.
A round nosed bit is going to serve better here than a pointed one or even a square profiled saw blade. The bend has an opportunity to spread over more of the radius and lessening the fracture of metal.
Now I hand bent the chassis into shape. Incredibly professional looking bends! There are no stress warps in the flat sections at all and I was able to make bends where no brake could possibly get to.
With relatively light gauge aluminum measuring the deviation made by bending radius is really not critical. Pretty much measure to the spot and the result will be VERY slightly dimensionally longer after the bend. If that's a problem, just VERY slightly compensate against this when tracing.
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