metalworking tool question.

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  #1  
Old 10-09-05, 06:33 PM
riptide
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metalworking tool question.

I am trying to find out what kind of tool I need to buy in order to make a custom bracket I have designed.

Each bracket starts as a 6" x 1/2" x 1/8"(thick) piece of aluminum. I then need to put in 4 90degree bends.

The end result I want is this:
Picture of bracket (50k in size)

I know that sheet metal brakes can be used to bend sheet metal (no brainer), but this is thicker, and there is only 3/4" between two of the bends.

What sort of equipment do I need in order to make something like this? And can I get it for less than $100.00? A hammer and vice just aren't working for me. They aren't exactly..ehrm... accurate.
 
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Old 10-10-05, 08:56 AM
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This ain't that cheap, but you could probably build your own for about what your budget is:

http://www.shopoutfitters.com/PressBrake.html

Your post says 1/8" thick; your picture says 3/8" thick; I'm assuming you need the latter.
 
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Old 10-10-05, 07:18 PM
riptide
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Sorry about that. The aluminum is 1/8" thick. The 3/8" has been on my mind all day because that's the length of the bolts I'm using for the bracket.

This thing is going to drive me crazy.
 
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Old 10-10-05, 10:24 PM
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The problem with 97% of the aluminum you can find, it is heat treated.
More then likely it will break when you bend it with any tool.

Your best bet is to get some aluminum angle material and have a welding shop, weld them on your longer strips of aluminum.

Get the welding shop some 3/4" steel spacers so they can clamp the material to.
 
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Old 10-13-05, 09:20 PM
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Aluminum is tricky stuff if you select the wrong grade, I would suggest a 5051 T1 or T2 series aluminum.
it is soft enough to bend without breaking, but try to allow for the largest radius possible in the corners. After the form has been made, the material can be heat treated to make it stiffer.

Is this something you need a few of, or is this a invention you plan on mass producing?
If you want a few prototypes to use, this can be easily machined from a solid piece of stock, if it is something that you plan on mass producing, or producing in larger quantities, I would suggest a getting the part quoted. There are shops out there hungry for work, and they already have made the investment in the presses and dies needed to produce these shapes. You would be amazed how fast a CNC nibbler could spit this shape out, and one or 2 press operations will finish the part.
A quick tumble in the deburring machine, and your done. I would estimate in quanitities of 10,000 you would pay less than 3 bucks for it...the smaller the quantities the higher the price.
 
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Old 10-14-05, 07:27 AM
riptide
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First, thanks for replying.

Second:

So far what I've done is make 3 or 4 prototypes by buying a 3' x 1/2" x 1/8" rod from Lowes. I cut it into 6" strips, drop it in my vice and use a hammer to make the bends.
Crude, but effective. The only issue is that they don't come out as exact as I would like. So I'm looking to presses and things like that.

Quantity wise it is unknown. I'm going to be using the brackets on a product that may sell well, but may not. This is why I'm looking to see what kind of equipment would be needed, and whether or not I can purchase it for a home shop. That way I can handle the quantity myself. As for price, the parts come out to around $.50 each, which is quite cheap.

The metal I got at Lowes doesn't show signs of breaking until I fold it past around 140 degrees. Well past the 90 degree bend that I need. The brackets don't need to take a lot of weight or stress either.

I've priced some machine shops, and for the amount I want to start with (100 pieces at the absolute most), I'm looking at around $10.00 each from some places (as high as $18.00 at one place).

If anyone has any suggestions on how I can modify my hammer and vice process so that I can get more accuracy in part production, that would work just fine too. My wife is not to sure about me spending $200.00 or so on a press and tooling parts, etc.

Thanks.
 
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Old 10-14-05, 08:50 PM
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I've designed many many sheet metal, machined, and fabricated parts that have been manufactured and stood up to their application. That said...

I would give up on trying to make this item yourself. The reality of making quality parts by hand is that you won't get good results and you'll waste much effort. You also didn't give any tolerances which is a big factor.

The brake reccomended probably can't make the close bends you need and is a slow machine to operate and set up for any type of quantity. (No ill will towards the maker - I'm just not familiar with it)

What you're really talking about is bar stock - not rod, and it's not the right way to make that item in quantity. Sheet metal is the way to go, but it has to be punched to size before bending. Material choice is a factor too, depending upon the physical requirements you need. While, it's not likely, it is possible some sort of dedicated tooling may be necessary for the bends. That depends on the shop you deal with and the dies they stock.

You're facing the reality of small business and manufacturing. It aint easy. And if you're trying to compete against an existing item made outside the US, you will never hit their price point. The machine shops aren't ripping you off, just pricing something that's real. I know this sounds discouraging and makes me look mean, but with only a $100 budget, for your sake, I would pass on this concept.

Best of luck to you.
 
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Old 10-15-05, 09:02 AM
riptide
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I have to dissagree with you on passing up the idea. To many people have expressed an interest in purchasing the product I have designed. I can get away with my hammer and vice for this, however I am just looking for a more effective way of producing a consistent part.
Speed of production isn't a huge issue right now. It takes me around 10 minutes or so to make a single bracket (I have some drilling and tapping to do also).
As for "tolerance" I have only a vague clue what that means. All I know is that I've had the brackets installed and in use for quite a while now, and they work absolutely fine. Like I said, they have no real stress put on them. They are simple supports which are aluminum to avoid corrosion (and it's cheaper and easier to work with than stainless).
 
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Old 10-15-05, 07:31 PM
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To me, the image looks just like a slice off some stock tube extrusion. That would be square aluminum tube, 6" x 1" (outside dimensions), giving you the 3/4" inside wanted, provided the walls are 1/8" thick, not 3/8". But believe me, 1/8" is normal for this kind of stuff and plenty strong especially as it hasn't been stressed the way cold bending will.

See, you can make these without any bending, the corners will be sharp and square, and if you get into production then the drilling can be done all on one piece prior to cutting. The opening, again, can be cut out of one length of stock, by ripping it on a tablesaw with your ugliest carbide blade.

Just find 1"x6" square tube extrusion. I see a lot of 1"x2", 2"x4", 6"x6"... scrapyard litter... it must exist.
 
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Old 10-18-05, 10:48 PM
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The choice as to pursue your idea or not is yours. No one here knows what your product is even about.

Tolerance refers to the amount of allowable variation or size difference part to part. Think of an engine with parts that vary in size too much. In a real manufacturing environment it can have a big effect on cost. Tolerance does not go with the phrase "hammer and vise" since manufactured parts haven't been made that way in over a century.

If you don't have a budget and you believe you can develop a market then most likely the hammer and vise will be your only friends for a long time. The tubing idea is interesting, but I would guess it won't be easy to find that dimension and the effort is about the same as your existing method. Tubing is also soft.

Best of luck... let us know when you're selling a lot.
 
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Old 10-23-05, 05:01 PM
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Click here to see just what I meant by "square aluminum tube":

http://www.saf.com/recttube.html

What you want to end up with is something between a "rectangular tube" and a "channel"; we could call it "plain track". The link doesn't stock exactly what you need, but this manufacturer came off the top of Google; there are plenty more. You may find the right shape locally, at a scrapyard for example.

I think it'll be obvious to you how this stuff can be milled (table saw & drill press) so that a few perfectly repeatable operations produce a batch of products, with better tolerances too.

These extrusions are hard/brittle (not soft/maleable) and tear or snap before they bend much. At 1/8" though, 2"x2" is ideal scafolding; it's that strong, and I would trust my own weight on your bracket.

I just can't see any hand-hammered results being consistent or well-finished. Customers notice these things foremost. Could the hammer wrought look be a selling point?

Another way to bend metal strap is with a vise-mounted form, like this: Metal Bender
 
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Old 10-23-05, 08:48 PM
riptide
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Originally Posted by Kobuchi
Could the hammer wrought look be a selling point?
LOL!! That's not really possible, but it's definitely thinking outside the box.

I actually found a place within driving distance that sells extruded aluminum, and was able to purchase about 15" of 3" x 3" aluminum tube (1/8" thick) for about $10.00 (including some other scrap that I bought).

It's not the exact dimensions, but the first tests that I have done really look promising. The big barrier now is that the only way I have to cut it right now is a hacksaw, so the word "tolerance" applies here about as much as it applies to using a shot-gun to kill flies.

I'm looking into getting a bandsaw. Should make it a bit easier, and definitely quicker.
 
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