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Thread: Bending brass

  1. #21
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    "Literally just take a chunk of steel and make a 1/2"-3/4" wide slot and break the edge. The punch should just be some flat bar machined to a point of around 30 degrees. The radius should be half of the hem gap."

    Rule of 8 gets me a female die opening for a 90* bend correct? that is if I bottom out? a 3/4 wide deep slot with a punch coming to a 30 bend will continue to press down until I get the 30* bend? I'm trying to visualize but if I go too far It'll bend the outer edges of the brass upward...
    .| |
    ..\/

    I would want to have a stopping point for a air bend to stop at a V shape. Am I on the right track here?

    Is a air bend or bottom out bend preferred?


    You said "brake the edge". bevel inside edges of female die?


    I understand the beveling the male die with 30* sides. "The radius should be half the hem gap", this is going over .020 material. What hem gap am I looking for? .010??


    Thank you again guys, as you each chime in I am googling what you are telling me to try and get the idea down.

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    Quote Originally Posted by Matt_50 View Post
    I understand the beveling the male die with 30* sides. "The radius should be half the hem gap", this is going over .020 material. What hem gap am I looking for? .010??

    Thank you again guys, as you each chime in I am googling what you are telling me to try and get the idea down.
    Yeah, the point of your V on the punch side is going to be quite sharp, .010" is barely an edge break. I'd expect some trial and error here with the punch cutting into the brass as it bends. Put some thought into lubricating the die side, but I'd still expect trouble here.

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    What will the flat press do to the radius? Will it crease it or cause a teardrop shape?

    Older backsaws had backs that were teardropped. If you look at the first post examples, it folds over fairly tightly.

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    I totally agree with Metalmagpie in post 11... Bar Folder.
    You owe it to yourself to go to an HVAC shop and watch one operate if you are unfamiliar with them. Old world, built like tanks, and they can't give them away around here on Craigslist, FB, etc.

    EVEN if you had to alter one of the beam surfaces on it to accommodate your thicker material, it would be way, way faster a machine to use if you could make it work for your application.

    I'm simply encouraging you to be open minded about what else is out there other than a press. YMMV

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    I understand and thank you. I dont think my area, Odessa, TX, has the same issue lol. I'm not finding any at all. I might call some sheetmetal shops and ask around

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    Quote Originally Posted by Matt_50 View Post

    I would want to have a stopping point for a air bend to stop at a V shape. Am I on the right track here?

    Is a air bend or bottom out bend preferred?


    You said "brake the edge". bevel inside edges of female die?


    I understand the beveling the male die with 30* sides. "The radius should be half the hem gap", this is going over .020 material. What hem gap am I looking for? .010??


    Thank you again guys, as you each chime in I am googling what you are telling me to try and get the idea down.
    No need for a stopping point, just stop the press before you bottom out. A V shaped die works fine, but if you bottom out in an acute die you will have a very hard time getting it back apart. I've personally gotten a piece of metal stuck in an acute die so tight that the force required to separate the punch and die was more than the weight of the 1300kg upacting ram.

    Yes, a smooth radius on the inside edge of the female die reduces marking. If tooling digs in, use urethane die film.

    Yeah, 0.01". For all intents and purposes, just a light filing on the sharp part.

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    I'm looking around for tooling thats already made. I'm finding acute 30* male dies with radius' around 1/32 and 1/16th.

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    Quote Originally Posted by Matt_50 View Post
    I'm looking around for tooling thats already made. I'm finding acute 30* male dies with radius' around 1/32 and 1/16th.
    1/32" will be fine. It'll squish tighter when you hem it.

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    Quote Originally Posted by Matt_50 View Post
    I'm looking around for tooling thats already made. I'm finding acute 30* male dies with radius' around 1/32 and 1/16th.
    On my computer if I hold down the alt / option key and then hit the zero key, the little degree symbol pops right up, º.

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    Lol I suppose I should have looked harder. I am on my phone and I just discovered a secondary keypad option. As ° and ♧◇■☆¿●£》. Lol never had a need for them.

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    One day I tried all the keys with the option key down, bored that day I guess. I did remember the degree symbol as the only one that might be useful to me.

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    I have been doing some searching. Came across this company. Your opinions?

    30 Degree Forming | Midwest Press Brake Dies Inc.

    They have a #15 with a #46. And a #17 with a #48.

    If you click on the dies, it pulls up some technical info. I suppose I could buy just a male die and cut a slot like mentioned above for a female die. Though I would need to ask a friend to cut the slot.

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    Those seem fine. Not sure how much they cost from there, but if it feels right, go for it. Otherwise used dies or polyurethane dies are available on ebay generally.

    In any case I recommend urethane die film for soft materials.

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    I'm sure this is a stupid question. Could you buy brass tubes in the right diameter and wall thickness, press it flat, then saw it down the middle to make two parts?

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    Strostkovy, forgive my ignorance once again but polyurethane dies? I'm looking these up now. Are they as strong as metal dies or are they made only for certain metals and thicknesses?

    David_M, that's not a bad idea to think on... at least something to maybe experiment with.

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    This one is a female die. Says up to 16 ga Mild Steel. But the brass is closer to 13 ga but correct me if im wrong I read somewhere brass is 50% as strong as mild steel? I'm worried about bottoming out or coining (correct term). This one is small enough that I could still grab the strip... so can't get stuck?

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    Quote Originally Posted by Matt_50 View Post
    This one is a female die. Says up to 16 ga Mild Steel. But the brass is closer to 13 ga but correct me if im wrong I read somewhere brass is 50% as strong as mild steel? I'm worried about bottoming out or coining (correct term). This one is small enough that I could still grab the strip... so can't get stuck?
    They are not as strong and need a good support to hold them. But they are still quite strong.

    Bottoming involves much more tonnage than air bending. The goal of bottoming is to press hard enough to reach near the yield strength of the material and get it to keep it's position without springing back. Coining is going even further and actually upsetting the material. You will feel it in the press handle when you bottom out.

    The reason the punch and die can get stuck is because you are pressing a taper into another taper with many tons of force. Consider that tooling is often held in a spindle with a tapered fit alone. If you don't apply bottoming tonnage then the sides of the punch don't engage much and can easily slip back out. The workpiece is then only held in by friction and it's own spring back, which is generally easy to remove.

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    Ok, I'm finally a punch and die. I'm a little confused on how you match a punch to a die. Do the radius' need to match? Tip of punch and bottom of die radius'.

    For example... 28° punch with a 1/32 radius. Do you use a die with a 30° or 32° vee?

    Rule of 8, says .093 brass will need roughly a .75 inch vee opening. Correct? How much does this matter? I'm seeing 5/8 inch die openings, 1/2 inch and so on.

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    Quote Originally Posted by Matt_50 View Post
    Ok, I'm finally a punch and die. I'm a little confused on how you match a punch to a die. Do the radius' need to match? Tip of punch and bottom of die radius'.

    For example... 28° punch with a 1/32 radius. Do you use a die with a 30° or 32° vee?

    Rule of 8, says .093 brass will need roughly a .75 inch vee opening. Correct? How much does this matter? I'm seeing 5/8 inch die openings, 1/2 inch and so on.
    Angles only need to match if you are bottom bending. For air bending, you can use any angle combination so long as you stop just before the angle of the most obtuse tool.

    8 is a rule of thumb, 4-12 works fine. At 4x you might run into bad material gouging. 5/8 should be fine. I use 5/8 for 1/8 aluminum and 12 gauge stainless often at work.

    The die radius is completely independent of the punch radius. The die radius mostly determines the depth and width of the die marks on the bent material. A larger radius will result in wider but shallower marks, and a sharp radius results in deeper but narrower marks. A larger radius is ideal for metals that like to gall and smear like aluminum. Anything from 1/16-3/16 would be ideal. Sharper could leave marks, and broader would work fine but result in a die that limits your minimum flange size (maybe you don't care) and doesn't follow the radius of the punch well because the wider starting point of the die causes reduced tonnage for the first 5-10 degrees, which distorts material just outside the intended bend.

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    Ok, so they don't need to match.

    Is 1/32 too sharp a radius for 260 brass? I see options for 1/16 and so on. I'm not sure how critical the radius will need to be since I will be flattening the teardrop shape I get.

    I will still bottom out in the die correct? If I want consistent bends.


    Edit..


    Again, please forgive my ignorance. Still learning. I'm seeing different pictures with descriptions that were throwing me off.

    Air bending. Doesn't just mean a punch pressing into a channel? Looks like it means just pressing into a shape. Where I'm getting a little confused is when this differs from bottoming or coining.

    Coining. Does this mean pressed into a die like air bending but taking a step further? Get to shape then press in really hard?

    Bottoming. Is this pressing the punch and die together and stopping as soon as you make bottom contact with die? How does this differ from air bending?


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