what is the best way to bend thin metal rod?

[loose stools]

I am Building a project that has moving parts I need to bend a thin piece of steel rod (4-5 mm in diameter). I need to make a number of small 90 degree angles to make a small crank shaft shape. I have very limited tools only having a vice and hammer at the moment. Is there any small jig or any heating techniques I could use? I have no experience in metal working so any advice will be greatly appreciated. Thanks

 

[RogerP]

To make a jig you could just bang a few 6" wire nails into a large piece of wood.

Or for a fiver buy one of these...
http://www.ebay.co.uk/itm/Wire-Bend...Crafts_JewelleryMaking_GL&hash=item566fe5b621

 

[AndyT]

One obvious tip - if you are bending wire cold, it's much easier if you keep the rod as long as possible and only cut it off when the shape is finished.

 

[loose stools]

Thanks for the help guys. Would it be easier to heat the metal before bending and if so what is the easiest/cheapest way to go about this?

 

[RogerP]

A propane/butane blow lamp would do the trick.

Something cheap and cheerful like this for instance.

http://www.ebay.co.uk/itm/Parasene-...Home_Garden_PowerTools_SM&hash=item1c4a67679d

 

[-Matt-]

Don't forget than in folding that you need to shorten your material by its thickness twice on outside edges.

In my example (below) I have drawn a simple bend in 5mm rod. It is required to be 50mm on the outside edges and would therefore be cut at 90mm, to gain the 5mm each way from the thickness of the material itself.

Hope this helps

-Matt-

 

[loose stools]

Don't forget than in folding that you need to shorten your material by its thickness twice on outside edges.

In my example (below) I have drawn a simple bend in 5mm rod. It is required to be 50mm on the outside edges and would therefore be cut at 90mm, to gain the 5mm each way from the thickness of the material itself.

Hope this helps

-Matt-

Thanks for the advice. I see what you mean and the diagram is great that for taking the time. How do you go about doing this?

 

[-Matt-]

Quite alright, I'm terrible at explaining things verbally and a forum makes it even trickier!

Something such as that, I'd have a few pegs set up. One to bend around and the other to trap it against.
Be warned though that this won't give you a clean square corner and will give you a radius on the outside.

If bent cold, you may struggle to get a tight enough bend and will have to go past your required angle to account for material springyness.

If done with heat, take care not to melt the bend point, nor bend in such a way that it misshapes the bend (think of a piece of tube crumpling and creasing when bent)

-Matt-

 

[MusicMan]

You can bend with vice and hammer if you want sharp bends. The technique is to clamp the wire vertically in the vice at the point where you want the inside of the bend. Then do not follow your instincts and bash it just above the clamp, but hit or push it well away from the clamp point at first. Only when you have the approximate 90 degree bend done do you hammer near the clamp (now using the top of the vice as the anvil) to sharpen up the 90 deg corner.

If the steel is cold drawn, it might crack when you do this. If so then it is worth heating before bending. A dull barely-red heat is fine (using e.g. a propane torch), and let it cool in air. You are not trying to do any radical heat treatment or strengthening, but to soften out the work hardening. If it has been hot drawn or extruded then this won't be necessary. Without examining it with a microscope, or seeing the manufacturers spec, the only way to tell is to try bending it and see if it cracks!

Keith

 

[Eric The Viking]

Following on from Keith's post above, there is a blacksmith's technique used for making holdfasts with squared ends to them, called 'upsetting'.

It's demonstrated by blacksmith Peter Ross, in this episode of the Woodwright's Shop, when, IIRC, he makes both the English (simply curved) and French (upset 'corner') styles of holdfast. The whole thing is about moving the metal into the right place to give you the square corner, otherwise the natural tendency is for it to just curve on a radius.

Obviously, your requirement is for a much smaller item, but the principle holds good. You can do a lot by cold working the steel, but sooner or later you will need to relieve the work hardening by heating, or settle for a rounded corner shape.

HTH,

E.