bending 12mm steel rod

[2zenmonks]

Hi folks

I have never really worked with metals before and I need some simple advice.

I want to bend some 12mm thick steel rod as per the attached illustration but have no idea how to go about it. It has a very tight bend which is about 12mm in diameter and this is what has got me beat. I've search the net and cannot find anything simple (meaning cheap) that can bend such a tight corner. Most of what I have seen has been for flat metal.

It is important to me to do it myself rather than give it to someone to do for me. I can't imagine it is that difficult and so it is a skill I would like to learn.

Thanks for any help.

zen monk

[BobL]

surely someone called "zen monk" should be able to just "will it into that shape"? :D

When you say the bend radius has to be tight you don't say how tight.
Also how much surface denting are you prepared to tolerate.

It depends how soft the steel is and how much strength you want it to retain after bending. If it plain mild steel and strength and a few surface dings are not an issue you should be able to bend it in a vice and using a decent hammer.

If not, a heat source and something like a brass hammer will be needed.

[Crunchie]

Get a piece of pipe that will slip on the outside of the rod with as little spare space as possible. Put the rod in a vice and bend the rod in the pipe by hand. You may get a little nick on the inside of the bend from the vice. A larger pipe will give a larger radius bend. Be careful in using any hammering as this will disort the rod or cause other sections to bend that you don't want to. 12mm rod should bend relatively easily when it is cold.
As BobL hinted, heating will give a much more controlled bend without the dents. The radius of the bend is determined by the length of the rod that is heated. If you heat it, be careful of plunging the hot rod into a coolant, eg water, as this will affect the hardness and brittleness of the steel. Letting it cool slowly will mean it will be very slightly softer than original but it will harden again with age.

[BobL]

Get a piece of pipe that will slip on the outside of the rod with as little spare space as possible. Put the rod in a vice and bend the rod in the pipe by hand. You may get a little nick on the inside of the bend from the vice.

Good idea. :2tsup: If you file a smooth rounded edge on the section of the inside rim of the pipe that comes into contact with the bent rod that will minimize any nicks.

[Dave J]

Bob has pretty well covered it all in one post.:2tsup:

Dave

[2zenmonks]

Thanks guys for your advice. I will give using a pipe a go.

By the way, you need two zen monks to do anything as in -

How many monks do you need to change a light bulb?
Answer: Two, one to change the bulb, and one to not change the bulb. :wink:

Also, I just found this site which all you guys into metal might find interesting - lots of 'How to's'.

FRETS.COM Machining (http://www.frets.com/HomeShopTech/hstpages.html)

[morrisman]

If you want a very tight radius on any mild steel, round, flat or whatever section .

For example in your case. Use a hacksaw and cut about 1/3rd through . Bend it over . The weld it up and reshape it with a file or coarse disc on a angle grinder .

I've done this many times and it works well, takes patience though. you have to plan ahead and do a few practice bends to gauge where the radius centre is . Its possible to get it very accurate .

I've cut a groove into 5mm plate and folded it over to a small radius , welded it up and filed it down smooth , you would never know its been cut at all

MIke

[dabbler]

Yep it can be done at home on the cheap but how easy it is depends on the properties of your rod and its quality. For instance I've tried for a type of "link hinge" using right angled bends in 10mm aluminium rod and if the bend radius is too small the result seems to be too weak and the bend fractures.

Anyway I've use two methods but with smaller dia. - about 8mm - both times with scrap steel/alloy rods that I have no idea what the material is called or it's composition. Both methods rely on brute force.

First one with a vice and a length of pine stock with 8mm (slightly larger than rod) bore augered by hand as deep as possible lengthwise. Make sure it's not too wide to grip comfortably. Insert the rod into your "sleeved handle" and start bending. I did it cold and tried to use a slow steady force. Leave enough space betwen the end of the wood and the bend to allow you to clear the vice jaw or the bend will not be 90°. First time I tried without the wooden sleeve but ended with a bow near the bend so next I tried to trap the rod. It stil has a very small bow but served my purpose.

Second one is with a jig. Three high tensile bolts mounted in a wooden block. Two fairly close together, third a greater distance. The rod should be pinned between the three. The first bolt the point of bend, with second and third to keep the rod from bowing. Applied heat until just glowing, quickly slid it into jig. Already had my wooden sleeve so slid it on and made the bend. Used my bro-in-law's mini gas powered brazing tool but then realised I *maybe* could have used my single burner camp stove. Bro-in-law uses just two bolts sunk to height of rod dia. so the bolthead traps the rod, gets it really hot and bends quickly as possible with a snap of his wrist.

Think about order of bends and the clearance needed with jigs or vices but with a u-shape this may not be an issue. In my case I needed to fabricate some hidden braces for lightweight shelving but couldn't drill, cut or glue to cabinet itself. (Retro-fitting an antique dining room servery cabinet).

Heat very definitely helps.

Have you got enough stock to experiment a little? Is your rod even bendable by hand ?

[2zenmonks]

Thanks guys, you have given me many things to think about and try.

Also...
I found this on YouTube and I might give it ago as it seems simple enough - just a few holes drilled and a bit of tap and die and hey presto (just a bit bigger though).

How to Bend Metal Rod Using Micro-Mark #60346 Wire, Rod & Strip Bender - YouTube

As I do not have any experience with metal I think it's gona be a case of trial and error.

[Jayson]

Hi 2zenmonks,

That is a nice idea for a bender but you will need to be a gorilla to be able to bend 12mm rod in that manner.
I have recently bent some 12mm bright mild steel using a simple jig I made but it requires access to a small hydraulic press. It does give nice tight bends though.

Regards,

Jayson.

[Jekyll and Hyde]

Hi 2zenmonks,

That is a nice idea for a bender but you will need to be a gorilla to be able to bend 12mm rod in that manner.
I have recently bent some 12mm bright mild steel using a simple jig I made but it requires access to a small hydraulic press. It does give nice tight bends though.

Regards,

Jayson.

Now there's a design I like! A few bending tools for the press is on the to-do list, I reckon I might do one like that - the adjustable lower die positions is a very nice touch!

Do you find it tricky to keep the upper die in the right spot when starting the bend, or does it seem to sit there ok?



Get a piece of pipe that will slip on the outside of the rod with as little spare space as possible. Put the rod in a vice and bend the rod in the pipe by hand. You may get a little nick on the inside of the bend from the vice. A larger pipe will give a larger radius bend. Be careful in using any hammering as this will disort the rod or cause other sections to bend that you don't want to. 12mm rod should bend relatively easily when it is cold.
As BobL hinted, heating will give a much more controlled bend without the dents. The radius of the bend is determined by the length of the rod that is heated. If you heat it, be careful of plunging the hot rod into a coolant, eg water, as this will affect the hardness and brittleness of the steel. Letting it cool slowly will mean it will be very slightly softer than original but it will harden again with age.

This is the method I normally use, having only recently bought the press. The only issue I see is that for 12mm you may need a fairly decent vice (not a $50 chinese job with very thin casting at the join to the front jaw, they definitely break. DAMHIKT!) mounted to a heavy bench, and a good length of pipe. As already said, heat definitely makes it easier, if you have access to it - a mapp torch will do fine for this job.

[Jayson]

Hi Jekyll and Hyde,

after half a pump on the press everything stays in place.

Glad you like it, I wish I could remember where I stole the idea from to give them credit but I can't. I have a feeling this may be an old idea that they borrowed anyway.

Jayson.

[2zenmonks]

Thanks Jason

Your jig looks simple enough, but I don't think I could get the second bend as it would bend the rod again onto the downward plunging bar (if you get what I mean).

As for the video... I thought that a bigger version would overcome needing gorilla strength simply by extending the leverage. The longer the lever the less strength needed.

I am going to give the jig in the movie a try as it seems simple enough for me to make. I will let everyone know how I go.

Thanks for everyone's input, it was great.

[BobL]

Thanks Jason

Your jig looks simple enough, but I don't think I could get the second bend as it would bend the rod again onto the downward plunging bar (if you get what I mean). . . . .

This is pretty easy to get around by arranging a pair of downward plunging bars that allow the bending materials to pass in between. It depends on how many rods you need to bend as this would need more set up time than other methods, but the bending would be very quick and easy.

[Jekyll and Hyde]

Thanks Jason

Your jig looks simple enough, but I don't think I could get the second bend as it would bend the rod again onto the downward plunging bar (if you get what I mean).


That would depend on how you make the top 'roller'. On my press, there is a small removable part at the end of the ram, held in with a grub screw (the part that actually presses on whatever it is). It would be pretty simple to grab a chunk of round steel that fits in there, then weld it to the top roller, but off to one end. This would allow the steel rod you're bending to pass straight by the ram... Clear as mud?

*Edit* Added a very quick sketch to illustrate what I mean. If you don't have a removable piece in the ram like I do, you can achieve the same thing in other ways. If your press looks like Jaysons, weld a piece of tube to the top roller instead, that slides onto the ram, or if you have an upside down bottle jack where the pressing foot is attached to a smaller diameter threaded rod that can screw in and out of the press, you could weld two bits of angle iron to the top roller that allow you to slide it onto the pressing foot from the side. What you're trying to do is stop the top roller from being able to tilt and shoot the 12mm rod out the side.