Bending Mild Steel Flat bar

[Vincent CutajarParticipant @vincentcutajar96446]

[Vincent CutajarParticipant @vincentcutajar96446]

Hi everybody

 

I have a mild steel flat bar which is 18.5mm x 9.5mm and about 18inches long. I need to give it a small bend roughly in the middle. Can I try to fix it in a vice and bend it cold or do I need to heat the bend area?

 

Thanks in advance

 

Vince

[JasonBModerator @jasonb]

It will be a lot easier if heated and the bend will be in a smaller area, the risk of doing it cold is that you may get a curve along 4-6″ of the bar.

 

Jason

[Tony Pratt 1Participant @tonypratt1]

Hi Vince, yes you can bend it cold but 9.5mm is pretty thick and it will need a fair bit of force to shift it. Heating to red hot in the bend area will make it so much easier to work.

Tony

[Vincent CutajarParticipant @vincentcutajar96446]

Jason & Tony

 

Thanks for the reply. I suspected that I need to heat it. I am assuming red hot should be enough. I will experiment with a similar piece of scrap flat bar and see how it goes. I can’t afford to get it wrong on the original piece as too much work has already been done on it.

 

Vince

[Colin Jacobs 1Participant @colinjacobs1]

Can u heat it in a vice or would u need to heat it in a forge?

[Vincent CutajarParticipant @vincentcutajar96446]

I was thinking of holding one side in the vice and heating the bend area only with a torch.

[JasonBModerator @jasonb]

Depending on what form of heating you have it may be easier to heat it away from the vice and then quickly place in the vice and bend as the vice will act as a heat sink and draw a lot of the heat away from the bar.

 

If you have oxyacetalene or oxypropane then you can heat in the vice, if its just a propane torch then out of the vice may be the better option.

 

J

[Speedy Builder5Participant @speedybuilder5]

A barbeque, some charcoal and a hair dryer make a very hot, clean source of heat – just be carefull not to melt the hair dryer. Wear goggles as the flying embers are quite dangerous !!

[AlasdairMParticipant @alasdairm]

Posted by JasonB on 07/03/2011 18:31:32:

…heat it away from the vice and then quickly place in the vice and bend as the vice will act as a heat sink and draw a lot of the heat away from the bar.

 

J

As a matter of interest, if one were to put some temporary “soft jaws” (aluminium for example) in the vice and then clamp the piece before heating, would this help alleviate the vice as a heat sink problem?

 

Intrigued, A

[DustyParticipant @dusty]

As a matter of interest, if one were to put some temporary “soft jaws” (aluminium for example) in the vice and then clamp the piece before heating, would this help alleviate the vice as a heat sink problem?

 

Intrigued, A

I think you will find that aluminium is a better conductor than Steel

[JasonBModerator @jasonb]

And it may well melt at the temp you want the steel to bend at.

 

J

[Vincent CutajarParticipant @vincentcutajar96446]

I spent all the morning experimenting with scrap mild steel of roughly the same dimension. Using an oxy-propane torch I could not get it hot enough in the vice as it was dissipating most of the heat. After I ran out of scrap steel I gave up and went home.

 

In the afternoon I had a nice ‘siesta’ and when I woke up I had an idea which I had to try.

 

Went back to the garage, Fixed a milling vice (with smooth jaws) to the milling table, clamped the metal I wanted to bend, inserted a 6 foot metal water pipe to use it as a lever and pushed the pipe. And ‘viola’ the steel rail bent nicely. It took me less than 10 minutes to do. Can’t imagine why I did not think of this method before.

 

Thanks all for your input

 

Vince

[Gordon WParticipant @gordonw]

Can’t think why the oxy torch didn’t get it hot enough, must be a small one. If you bend in a vice or similar as described,try to bend it fast, get a sharper bend and less effort.

[Dan Hall-TrainorParticipant @danhall-trainor43503]

I need help im doin homework and I need help im not sure about some questions

can u bend it by hand?

Do u need a vice and do u need to heat it first?

Dan

[martin perman 1Participant @martinperman1]

I have no difficulty heating flat or round bar with my sievert propane gas torch whilst holding it in a vice, the only problem I have is stopping the edge of the jaws leaving a mark on the inedge of the bend.

Martin P

[Ian PParticipant @ianp]

Posted by Vincent Cutajar on 08/03/2011 17:41:26:

I spent all the morning experimenting with scrap mild steel of roughly the same dimension. Using an oxy-propane torch I could not get it hot enough in the vice as it was dissipating most of the heat. After I ran out of scrap steel I gave up and went home.

 

In the afternoon I had a nice 'siesta' and when I woke up I had an idea which I had to try.

 

Went back to the garage, Fixed a milling vice (with smooth jaws) to the milling table, clamped the metal I wanted to bend, inserted a 6 foot metal water pipe to use it as a lever and pushed the pipe. And 'viola' the steel rail bent nicely. It took me less than 10 minutes to do. Can't imagine why I did not think of this method before.

 

Thanks all for your input

 

Vince

That is one of the worst stories I have heard about cruelty to machines, it must have been a big machine bolted to the floor to resist the force you applied via a 6' lever too.

I presume the milling machine and vice was someone else's property!

I don't understand what you mean with 'ran out of scrap steel', or how it is connected to the part you are bending.

Ian P

[Neil WyattModerator @neilwyatt]

Posted by JasonB on 08/03/2011 16:38:37:

And it may well melt at the temp you want the steel to bend at.

 

J

it would certainly distort – when 'welding' aluminium using the wire method I found that clamps used left imprints in the aluminium even though it was far from red hot.

Neil

[JasonBModerator @jasonb]

Guys don't bother answering the old part of the thread. Dan has resurected it to help with his homework, though I expect it may be past his bed time now and too late to help

Dan, it really depends on the size of your bar. a bit of 1mm x 5mm can be bent cold by hand but a bit of 10×50 would need a lot more effort and heat would help.

 

J

Edited By JasonB on 09/09/2015 20:05:16

[norman valentineParticipant @normanvalentine78682]

Something I have done to bend heavy section steel when I did not have access to any sort of torch was to bring out my trusty arc welder and run an arc backward and forwards on the spot where I wanted to make a bend and then bending was easy when it reached red heat. I was just bending steel to be submerged in concrete for foundations of a house but if I wanted it to be pretty an angle grinder would have cleaned it up.

[Ady1Participant @ady1]

Arc welder vote number 2

Puts about 2500 degrees into the arc point

[Sam StonesParticipant @samstones42903]

Hi Dan,

It's worth knowing that the resistance to bending of flat bars is proportional to the thickness cubed. Double the thickness and the resistance to bending increases by eight times. It gets a bit complicated for irregular sections.

Good luck with your homework.

Sam

[jason udallParticipant @jasonudall57142]

On an aside..much decorative scroll work is done cold.

Much depends on the section and bend radius required.

[Author]

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