Bending 12mm square mild steel bar

[modeng2000Participant @modeng2000]

What are my chances for bending 12mm square EN3B bright mild steel bar? I am aiming for a sharp 45 degree bend. Never done this before but have watched it being done but using oxy – acetylene.

I have propane sievert burners and the usual bench vice but that is it. I have considered removing a V section on the inside of the bend and then silver soldering the joint but would prefer not to have to do this.

John

[modeng2000Participant @modeng2000]

[bernard towersParticipant @bernardtowers37738]

depending on what its use the cut and silver solder route would give you a sharper corner, or it could be big welded.

[modeng2000Participant @modeng2000]

Thanks Bernard, it would also stop the spreading on the inside of the bend.

Probably the best answer.

John

[modeng2000Participant @modeng2000]

I think I just wanted convincing the cut and bend method would give a nice corner, better than just a normal bend.

John

[Ady1Participant @ady1]

It stretches the top part down and pinches the inner part out if you make it too tight

I suppose there are calculations for these things, so the bend radius loses the minimum of strength

Also depends upon the steel grade

Edited By Ady1 on 26/05/2023 13:38:35

[modeng2000Participant @modeng2000]

Ady, thanks I don't want to loose the square of the bar at the bend. I am going for a partial cut removing a wedge and then close up before silver soldering. I may need a shim to take account of the saw blade width.

John

[bernard towersParticipant @bernardtowers37738]

THis cut and shut idea is fairly common its quick and you don't need 3 hands!

[Mike PooleParticipant @mikepoole82104]

I think a blacksmith would upset the point where the bend is required to supply the material on the outside of the bend and then square everything up after bending. If you are after a bend that is very accurate the cut and shut is probably the most straightforward procedure, it could save some years of learning the craft of a blacksmith.

Mike

[Grizzly bearParticipant @grizzlybear]

Hi,

May I ask what is it for?

Good luck……………

[Howard LewisParticipant @howardlewis46836]

If you cut the bar ends at 22.5 degrees, bringing the two ends together should produce a 45 degree bend.

Whethyer you chamfer (As weld prep. ) weld, braze, or silver solder, is your chioce, depending on what facilities you have available.

Howard

Edited By Howard Lewis on 26/05/2023 17:57:43

[modeng2000Participant @modeng2000]

I am having another go at making a diamond tool holder. my first problem was how to get a square hole. Well I fabricated it from two V shapes quite sucessfully. Broaching is quite out of my ability.

So now I want to progress on to a good shape for the main body of the holder. I am going to try cutting at 22.5 degrees in one plane and a similar angle on the adjacent side. The aim is to leave a bridging piece that will be bent so holding the two halves together prior to soldering. There will might be a need for a shim to fill the saw cut if the two halves do not come close together.

I know that there have been plenty of designs for this type of tool holder but I've not seen one made like this. So here's hoping for a good result.

John

[Nick WheelerParticipant @nickwheeler]

How big is the hole you're trying to make?

I can't imagine a diamond tool holder that couldn't be made far easier by drilling a hole and filing the corners square.

[modeng2000Participant @modeng2000]

Nick, the hole is 1/4" square. Your filing abilities must be better than mine as having tried filing a square hole I was not satisfied that a lathe tool would be held securely enough. So this is why I fabricated the making of a square hole.

John

[JasonBModerator @jasonb]

I thought that most of these tools used a slot and separate clamping piece or other way to retain the tool in the slot rather than a square hole.

Knowing what it is for now I think I would make from some 12 x 25 or so  flat bar.

Edited By JasonB on 27/05/2023 07:27:08

[modeng2000Participant @modeng2000]

Jason, the square hole would be split so that a clamping screw pulls the slit closed to hold the tool bit.

This is really the same as having a separate clamp piece when gripping the tool bit.

John

[jaCK HobsonParticipant @jackhobson50760]

I'd go for slot etc. I can't imagine the 45 degrees bit… 45 or 135… still doesn't help my picture.

[Pete WhiteParticipant @petewhite15172]

Posted by Grizzly bear on 26/05/2023 17:55:07:

Hi,

May I ask what is it for?

Good luck……………

Yes I thought that before we knew and am now thinking a drawing of the project would result in productive comments to help solve the problems?

Pete

[Nick WheelerParticipant @nickwheeler]

Posted by modeng2000 on 27/05/2023 07:05:22:

Nick, the hole is 1/4" square. Your filing abilities must be better than mine as having tried filing a square hole I was not satisfied that a lathe tool would be held securely enough. So this is why I fabricated the making of a square hole.

 

??? There's not much filing to make a 1/4" round hole into a square one. And that's much easier than any of the other suggestions. Quicker too. You might even be able to use the tool steel to sharpen the corners…

Edited By Nick Wheeler on 27/05/2023 08:57:50

[Paul LousickParticipant @paullousick59116]

" I am aiming for a sharp 45 degree bend"

Instead of trying to bend a piece of 12mm square, why not cut it out of 12mm plate or flat bar like many other designs on the internet ?

[modeng2000Participant @modeng2000]

I am trying to copy the shape of the Diamond Tool Holder. This seems to be the definitive shape and it has a lot of users. I used to have one but it went when I downsized my workshop, regrettably!

Regarding the clamping method, I want to make a system that I can satisfactorily put together. So I have been looking at the various ways folk have used and taking into account my ability to cut metal the farrication method works best for me. The only milling I can do is on the lathe and so set-up is not as easy as on the mill I used to have.

John

[Paul LousickParticipant @paullousick59116]

OK.

But the shank on my Diamond toolholder is about 12mm square but the head that holds the cutter is 23mm deep.

[modeng2000Participant @modeng2000]

Yes Paul, I can get a depth approaching the longer measurement having bent the 12mm bar to achieve this.

It won't be an exact copy but hopefully something near enough. Time will tell.

John

[Howard LewisParticipant @howardlewis46836]

There have been at least two designs published for Tangential Turning Tools.

The first involved milling at compund angles, the second milled the shank at an angle, after the slot for the tool, had been milled.

Bother mwere for 1/8" toolbits.

In addition to making one , a second one was upscaled to take 5/16" toolbits.
Both produced very satisfactory results, comparable to the Diamond Tool marketed by Eccentric Engineering, (which sees a loit of use )

Howard

[HopperParticipant @hopper]

Ah ha. Penny just dropped. Had not realised a diamond tool holder was in fact a tangental tool holder, ala Eccentric Engineering etc. Thought it was to hold a diamond dresser on a grinder etc.

In that case, to hold a lathe tool bit, you will be far better off to machine a 90 degree V slot in two pieces of steel and bolt them together as a clamp, as Eccentric does and as many of the designs on the net also do.

Bending a piece of 12mm bar at 90 degrees is not going to give you the clearly defined smooth 90 degree surface you need to grip the tool bit that machining will give.

And cutting the 12mm bar ends at 45 degrees and silver soldering together to form the 90 degree groove is unlikely to last for very long. Clamping force applied by the clamping screw, plus the cutting forces transmitted through the tool bit will eventually break the silver solder.

Stick with the tried and true two-piece method with the machined grooves. If you don't have a mill I am sure it could be done in the lathe with the end mill cutter held in the chuck and the job mounted on the toolpost or cross slide with a bit of jury rigged clamping.

EDIT: BUT reading back through this thread, it is unclear whether you are wanting to bend the 12mm bar to make the square hole that the tool bit slides into for clamping, or are you wanting to make the bend in the main shank of the holder than drops the head down below centre height where the tool bit is clamped?

A sketch of what you want to do would be helpful.

Edited By Hopper on 27/05/2023 12:18:00

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