Bending steel is cracking at outer bend:

[davidh]

why did no one mention "with grain " or "cross grain" problems. also what bjmh jon said about die opening sizes. I think heat or warm is always your friend.

metal bending is an art and talent needing experience.

good luck with what your doing. you'll get it. . . . .keep practicing.

 

[markknx]

One more thought metal has a grain and should be bent across the grain not along it. This tend to show up more in cracking at the ends of the bends. When I worked in fabrication we once had to scrap a skid of plates because of this. Could have heat formed them but the labor would have cost more than the steel. Cracking from vibration also becomes an issue when bending along the grain. Keeping a larger rad. in the bend helps.

If all you have are sharp bending dies and you will only need to make this bend a few times you could cut a slot in a round bar to fit on the die to give the rad. needed.

Just reread your post if you are bending .25x 1.25 bar 14" along the 14" then you are bending with the grain.

Mark

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why did no one mention "with grain " or "cross grain" problems. also what bjmh jon said about die opening sizes. I think heat or warm is always your friend.

metal bending is an art and talent needing experience.

good luck with what your doing. you'll get it. . . . .keep practicing.

I was I just type slower:roflmao:

 

[francist]

This might seem trivial and I don't know that you're doing this, but do not use a scribe to mark your bend location. The metal will crack at the scribe line. As a sometimes blacksmith we'll use a centre punch mark for location instead of a sharp line to do the layout.

- frank

 

[comstock-friend]

why did no one mention "with grain " or "cross grain" problem.

Bends with the grain on thick sections with sharp bends will get you cracks. As suggested, bend across the grain.

John Friend

 

[ome]

Cold finished bar already has a fair amount of stress in it, unless it has been stress relieved. Unlikely in off-the-shelf materials. If you have a oxy-fuel torch, heat it up low red for a couple of minutes, then after it cools, try it.

Otherwise, about the only other thing I can think of is that you are trying too tight a radius.

Thanks,
no wAy of heating and swagg is supposed to bend to 110 degrees.
Is there a better type of steel i could buy.
To be clear i am trying to make some shelf brackets for the basement.
Please advise best type of steel to buy. I do buy it from enco and order all but the lenght exactly as i need it.
Thanks,
jon

 

[Tony Wells]

Honestly, Jon....I wouldn't waste the money on the cold finished 1018. I'd get some hot finished A36 for what you are doing. It forms much better.

You have to remember that to bend metal, some of it gets compressed and some of it gets stretched. A larger radius would make it less apt to crack, as has been previously pointed out. I'm not familiar with that particular bender, but if it does have a sharp corner on the male member of the die set, that is working against you. You may need a sharp corner at times, if working on thin material, so it doesn't make sense (to me) to just modify the original. You could make a secondary ram for heavier bends, using a larger radius. The idea of making a temporary ram attachment by milling a slot in a short piece of round bar that fits the original ram profile is a great one.

Overall, you'll find the A36 easier to form and that may solve most of the problem.

 

[ome]

Thanks Tony
i will try some a36 and attempt to make a larger radius for male
Joni

 

[fi man]

As a rule of thumb for cold bending steel, you don't want the inside radius of the bend to be less than the material thickness, else the cracking you've experienced occurs. Even larger inner radii are preferred if your design will permit it.

Aluminum is even more sensitive, but don't remember min radii requirements for successful bending - been too long.

 

[ome]

Jon,

1-try breaking the corners on the outside of the bend.
2-air bend only, no bottoming!
3-female die opening needs to be 8-10 times the metal thickness, so 2-2.5 inches--bigger is better. Male die should have ~3/16 in radius.
This should result in an inside radius of .31-.39 in.

Even following the above guidelines, I've run across some cf that can't be bent a full 90º without cracking. It is then time for the hot wrench!

regards
Bob

Thanks,

could you please explain your #2 suggestion, i am new to this and just not getting it.
Thanks,jon

 

[Frank Fox]

I have a work bench, top made out of "AR-400", it was given to me by a friend that owns a metal fab shop It is 5/16" thick the edge on two sides were bent at 90* and showed cracks at the end of the bend, not full leingth.(200 ton break press) So he offered it to me for free to make a bench top. I welded 1/4" thick 4" SQ. tube legs on it. Now I have a bench that dose not fallow me around the shop when I pull on something clamped to it. He told me they tried to bend it to tight and did not want to chance it on customer's job. So I ended up with a nice work bench about 40"X84" HEAVY! and yes you need to fallow the recomended bend radis for the thicklness of the metal you are trying to bend, and know what type metal. The guys on this forum know there busness. Most of my knowledge comes from making mistakes.