What type of steel for machining press brake dies?

I'm thinking that the easiest way to make a lower v-block for a 24" long press brake is to mill one corner off two pcs of steel bar at 45
degrees and put them together to make a solid block with a v groove. Using two pieces is a solution to finding 3" square solid. I'm farming this out, so would it be easier for the machinist to cut a v groove in a solid block or cut the corner off of two blocks?
That being said, will mild steel suffice? Or what type of steel should I use?
Thanks for the help on this. - Loren
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I'm no expert, but I think the forces trying to pry the two pieces apart would be VERY large. I'd stick with the one piece approach. Cutting a V groove in a solid block is pretty strightforward. It might be cheaper as well, because it's one cut vs two.
Doug White
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Loren wrote:

Doug was right. You can do the math to see how the downward force of the ram/punch will drive your die blocks apart, but proper tooling design would frown on your approach. I wouldn't want to take the head of a broken bolt in my belly either.
Mild steel is pretty much exactly the wrong material to use. I'm sure there are specific recommendations on tooling steels used in press brake work, depending on what you're going to be forming, and its condition while forming. You will see severely reduced tool life if you use mild steel. The forces available from presses are easily capable of completely destroying a mild steel form in one (1) hit.
Indeed, tool steels used for forming are among the toughest steels found on a die. They are subject to the most abusive conditions (even during seeminly correct operation) and must be the most tolerant of incorrect use (hitting the press below bottom, for instance).
If you tell us more about your application, perhaps we can suggest an appropriate solution.
Why don't you just buy tooling made for your machine?
Regards,
Robin
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Here is what they should look like. http://www.fabsupplyinc.com/index.php?page=shop/browse&category_id )9e024b0b2daad635436f4103e995c3&ps_session­9ef6aeb94afcd0391a1c003cfc5e0a
definitely hardened and heat treated tool steel.
Often big machinery dealers have used press brake dies for sale. depends where you live, of course.
But this is one thing I would bite the bullet and buy the real thing. And I am sure they can make em cheaper than your corner machine shop can, if you figure in using the right steel, and heat treating.
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Thanks guys. Check out ebay item 320013540279 for an idea of what I want to make. It's a self containted press brake unit that is guided and has spring return for operation in a simple shop press. I want one 24" long. I would like a 1" and a 2" bottom die is possible. I would be willing to buy something used and modify it or cut it down but I don't have that source. I'm in Olympia Washington. Thanks - Loren
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Just buy one. Northern Tool sells a 24" model. It costs $279, which really isnt much for this.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_21896_21896
You realize they are a bit optimistic in saying that you will be able to bend 24" of 1/8" with a 20 ton Harbor freight press?
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Thanks for the dose of sensibility Ries. That unit is less than the cost of the steel I was going to buy for it. - Loren
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Loren wrote:

On that one the lower die block consists of two pieces of round stock welded to a base. How would *round* work as a die? I'd think that the bend could have an uncertain radius if it wasn't more constrained by the die. But that's just what I would expect, not what I know. Anybody with experience with a bender like that?
Thanks, Bob
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I have run a brake for several years as well as made up many dies for odd bends. The proper die steel is not that hard. It is very tough however. A mistake made by novices is to bend round bar in a set of Vee dies. It is a guaranteed way to mark the upper die and get an invitation to the road. Upper dies can be made from half inch by three flat bar with a half inch or larger cold finished bar stitch welded to one edge of the flat bar. The lower die can be made from a variety of things. One motivation for commercial shops to make up junk dies is to save their good dies when they are faced with the need to bend round stock. If you are doing some crude bending you can just stitch weld to one inch square bars to a base plate setting them three quarters of an inch apart. Two heavy pieces of angle iron set up to form a Vee works but the angle really has to be less than ninety to produce a ninety degree bend. ( 80 degrees) I have even used three inch pipe for the upper die to form a large radius on the roof edges of heavy equipment cabs. Generally you should follow the eight times rule. The width between the bottom dies should be eight times as wide as the thickness of the material you are bending. Eighth inch material should at least have a one inch bottom die. If you are using mild steel the dies will show significant wear on the corners after a hundred or so bends unlike commercially made dies. Randy
I'm thinking that the easiest way to make a lower v-block for a 24" long press brake is to mill one corner off two pcs of steel bar at 45 degrees and put them together to make a solid block with a v groove. Using two pieces is a solution to finding 3" square solid. I'm farming this out, so would it be easier for the machinist to cut a v groove in a solid block or cut the corner off of two blocks?
That being said, will mild steel suffice? Or what type of steel should I use?
Thanks for the help on this. - Loren
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