Battery and electronic box, can you actually bend what you draw in sheet metal

T

temo

1 mW
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Jul 26, 2018
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Oslo, Norway
So how complex can a battery box be?

Maybe I just make trouble for myself here, but it would slide in and sit nicely in the frame then. Only need a removable lid on one side.

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Sheet metal works do require some tools and equipment. Your box is not very complicated, but it does require some experience to make it neat.
 
Start by buying a Press brake
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Or bend metal with some 2x4s and C-clamps.
To cut metal. I have had used a jig saw. Or email drawings to a Laser cutting shop.
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Here is a fun place to play with drawings https://www.emachineshop.com/

What program do you use to draw battery box?
 
Ha ha, no wasn't thinking of bending it myself, but it seems complex to me. Anyone made any similar?
 
I would say that as illustrated it is extremely difficult if not impossible to fabricate with conventional tools (shear, box brake, plate roller). In the absence of a custom die to press the radiused parts, it would need to be partially wrangled by hand.

The biggest problem with your design is the inside radiused tube saddles that are part of the single large sheet that forms the entire box. In addition, although this aspect of the design looks cool and gives some mounting stability, it offers no increase in usable internal volume and probably requires some internal spacers to be fabricated so the battery rests on flat surfaces. So you have a design that doesn't buy much at the cost of being very difficult to make.

I think you need to go to YouTube and watch some videos on sheet metal fabrication so you understand the tools and techniques. Twenty minutes will be enlightening and will help you weigh design features vs fabrication difficulty.
 
Look on you tube on how to make a simple angle iron sheet metal bender.
 

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Yes, that is what we call over-engineering to no use.

Wow, nice press and box!

Thank you Marty

So this would be doable I think.

Battery triangle 90+45 degree.JPG
 
temo said:
So how complex can a battery box be?

Maybe I just make trouble for myself here, but it would slide in and sit nicely in the frame then. Only need a removable lid on one side.
Click to expand...

I used to make all kinds of sheet metal boxes, covers, and panels when I worked doing prototyping for a power electronics company. The key element I had to master was called "bend allowance", which is how much stretch across the metal's surface you get when you bend it. It varies by metal type, thickness, bend angle, and the specific adjustment of the brake (I used a manual finger brake). So I always had to set up my brake for the material I was going to use, and then bend a sample or two so I could measure the bend allowance. Only then could I cut my flat pattern after taking the bend allowance into account.

You can get the shape you want, but you can't just flatten your solid model and expect it to come out the same. There's more to it.
 
craiggor said:
Look on you tube on how to make a simple angle iron sheet metal bender.
Click to expand...

I just may do this if I am up for it, but I doubt it!
Would look ultra cool though.
I got other batt box idea's that extend beyond duct tape and 1/8" mdf and spray paint.

Great tip though, ty for that!
 
Willow said:
make it out of a thermoplastic like polypropylene or HDPE... easy to cut out and you can fold it and shape it using a heat gun or heating element to soften it.
Click to expand...

We need a thread ond that. I'be been wanting to build a factory looking RIGID triangle frame box for long now. Metal is aesome but quite requires a lot of equipmement (wish I had a TIG welder in my appartment). Themoplastic is an avenue a hadnt thougt about. Thanks for bringing this up. I sure it'd make awsome battery boxes!
 
Although simple bends are easy to make with a simple homemade brake, equipment costs start ramping up when you go to large box brakes. Last year I tried a slightly different aluminum fab technique for a box-like enclosure. For this I broke the enclosure down into pieces arranged so there were 3/8" tabs running the length of an edge - similar to what you might screw on a cover plate. Each piece comprised one or two sides of the enclosure and were intentionally very simple to make. As Chalo said, bend radius, etc enters into it, but this approach allowed me to toss one side if it came out poorly without sacrificing the entire thing.

I then epoxied the enclosure together using epoxy on the tabs instead of mechanical fasteners. I used an aluminum-filled epoxy so the seams could be easily sanded and finished. The result was a really nice enclosure with no visible seams (joints naturally filled with epoxy and sanded smooth). This worked really well with almost no metal-working tools and I am about to start another similar undertaking.

If I was going to make a triangle box I would use this scheme and make u-channel pieces for the top/bottom/front/back and make the side plates separately. I'd make the glue tabs larger - maybe 1" or so. The sideplates hold the critical dimensions so epoxying the u-channel to one plate would yield a nice accurate fit. The remaining side plate becomes the removable cover plate. To even avoid bending the u-channels, you might just have a sheet metal shop run off a couple of simple 3 ft lengths of channel to your dimensions and then use that as stock that you cut up yourself for final construction. A small hand seamer or other very small ad hoc bender would make the end tabs.

This would be a little more labor-intensive means to build a box, but would require very few tools and no welder. The gimmick with the sheet metal shop farms out the more difficult long 90degree bends as something they can make for essentially no labor cost and leaves you with the more time-consuming fab and finish work that can be done with simple tools.
 
Matador said:
Willow said:
make it out of a thermoplastic like polypropylene or HDPE... easy to cut out and you can fold it and shape it using a heat gun or heating element to soften it.
Click to expand...

We need a thread ond that. I'be been wanting to build a factory looking RIGID triangle frame box for long now. Metal is aesome but quite requires a lot of equipmement (wish I had a TIG welder in my appartment). Themoplastic is an avenue a hadnt thougt about. Thanks for bringing this up. I sure it'd make awsome battery boxes!
Click to expand...

It's very easy using PVC 2" diameter water pipes, cut to length, flattened into PVC strip with a heat gun, then heat formed to shape for the battery box frame. Side plates I made from 2 laminations of 3mm thick veneer board, lacquered to finish...
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Man I am glad I stumbled upon this thread.
pvc piping is cheap! I would have never have thought about that.
You know what I was thinking of, 2L bottles and flattening them with an iron, then using epoxy if need be.


Johne-bike said:
Matador said:
Willow said:
make it out of a thermoplastic like polypropylene or HDPE... easy to cut out and you can fold it and shape it using a heat gun or heating element to soften it.
Click to expand...

We need a thread ond that. I'be been wanting to build a factory looking RIGID triangle frame box for long now. Metal is aesome but quite requires a lot of equipmement (wish I had a TIG welder in my appartment). Themoplastic is an avenue a hadnt thougt about. Thanks for bringing this up. I sure it'd make awsome battery boxes!
Click to expand...

It's very easy using PVC 2" diameter water pipes, cut to length, flattened into PVC strip with a heat gun, then heat formed to shape for the battery box frame. Side plates I made from 2 laminations of 3mm thick veneer board, lacquered to finish...
Click to expand...
 
Johne-bike said:
It's very easy using PVC 2" diameter water pipes, cut to length, flattened into PVC strip with a heat gun, then heat formed to shape for the battery box frame. Side plates I made from 2 laminations of 3mm thick veneer board, lacquered to finish...
Click to expand...
Nicely finished project!
Clever use of PVC pipe as a construction material - locally available everywhere.
 
i must be missing something that absolutely no one seems to have a problem with surrounding a splodey prone chemistry (but any battery really) with a ready made & all too willing short circuit conductive metal enclosure when all it takes is one small trip to the ground denting the case into the cells (which of course never happens).

to a lesser extent pvc not the best choice either compounding your problem should it catch fire gives off chlorine gaz at least it's not a source of ignition.
while those are design choices i wouldn't make don't say you haven't been made aware of the risks if you find them acceptable & that you're potentally adding fuel to the fire if law-makers needed any more excuses handed to them on a silver platter.
the possibility is small & remote but it don't take much to make it zero (added risk) when there are plenty strong plastics around.
 
Bending metal exactly requires some skill. I find it easier to use multiple pieces and join them. You might be able to use U channel to grip the bike frame instead of a curved section. This could be found off the shelf.

Plastic is lighter and easier to work with in general, but not as strong and useless in the event of a fire. From a fire safety standpoint, I would definitely go for metal and line the inside with Nomex, fish paper or some other durable insulation material.

Another approach I've seen recently is to 3D print pieces and use them in combination with sheet (either metal or plastic). You could 3D print the edge pieces and use plain sheet metal for the sides. The 3D printed parts could have grooves to hold the sheets in place and make fastening easy.
 
Toorbough ULL-Zeveigh said:
i must be missing something that absolutely no one seems to have a problem with surrounding a splodey prone chemistry (but any battery really) with a ready made & all too willing short circuit conductive metal enclosure when all it takes is one small trip to the ground denting the case into the cells (which of course never happens).
Click to expand...

Yes. Probably your thinking that lithium batteries are "prone" to explode. If I thought that was true, then I wouldn't use them. I wouldn't have them in my phone that I carry in my pocket, in my tablet, or in my laptop either. Yes, they do present some hazards. I just think you are exaggerating them. That said, building, fusing, packing and insulating lithium batteries are things that should be done thoughtfully and with consideration for thing such as what might happen in the aftermath of a crash.
 
Yes when bending sheet metal copper whatever when it goes around the corner and lose a lot of Length and you got to get long enough to start with as you need one piece try it first out of cardboard free and cheap cut it too with and cut it longer than you need and that could be your first step of making a template for any material. Lead or gold.
 
temo said:
Very nice box from PVC-pipe, how did you make the tabs to hold it together?
Click to expand...

The Tabs or brackets are also made from the very same 3mm thick, PVC water pipe, heat flattened cut to size, and heat formed to shape. I tapped 4mm threaded holes into the brackets, and use 4mm button head socket screws to hold them to the PVC battery frame, and the same bolts are used to attach the Veneer board side plates. The finished battery box is incredibly rigid, and is such a perfect, tight heat moulded to fit inside the triangle, only requires the 2 water bottle screw mounts to hold it in place, and doesn't need any other mounting points!
Interestingly enough, the front and rear fenders, crud guard and my Android 7" Tablet mount are all made from the same 2" diameter 3mm wall thickness Thai PVC water pipe, cut, heat formed and covered with black carbon fibre vinyl wrap. I have also made similar items to fit my Daughter's 20" Fatbike.
Pvc works brilliantly in these applications, is very inexpensive to make and is available freely I believe in most countries. Here in Thailand, it is available in just about every store in the villages, and has many creative uses including piping water on occasions..!
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