how much force to bend 1x1" solid steel

# Thread: how much force to bend 1x1" solid steel

1. WeldingWeb Apprentice
Join Date
Mar 2009
Posts
27

## how much force to bend 1x1" solid steel

I am trying to custom fabricate a machine. I need to know which bearings to buy. I am trying to make a scroll bending machine. So i got a few questions for you.

1. How much force or tons does it take to bend 1/2x1/2" solid steel
2. How much force or tons does it take to bend 1x1" solid steel
3. How much force or tons does it take to bend 2x2" solid steel (you get the point)
4. Also how much horsepower a electric motor must have in order to scroll bending those types of material? At least 5hp i figure?

So is their like a chart or something for metal maximum strength? Thanks ahead of time fella's.

2. ## Re: how much force to bend 1x1" solid steel

It all depends.

It depends on the steel alloy. Plain mild steel bends easy compared to trying to bend hardened and tempered tool steel!

It depends on how tight you are bending.

It depends on if you are bending the steel at ambient/room-temperature or if you are heating it to red-hot first.

3. ## Re: how much force to bend 1x1" solid steel

Yield strength, at room temperature, for mild steel is on the order of 40,000 pounds per square inch(PSI). Higher strength low alloy steels, or cold rolled steels have have much higher yield strengths; as much as 120,000 PSI

So, to bend your hypothetical 1"x1" square bar requires something on the order of 40,000 pounds of force. (not necessarily weight for you physicists in the peanut gallery)

That doesn't take into account a whole lot of other factors, like what happens as the steel bar bends, and work-hardens. Or how long a lever you apply to the bar. Or how tight a radius you're trying to achieve.

I can might be able bend a 1x1 bar by hand, if I'm 50 feet from the fulcrum and if I only try to bend it a few degrees. But it'll take a whole lot more force to bend a tight radius 90° corner in a 12" long piece of the same 1"x1" steel bar.

4. WeldingWeb Apprentice
Join Date
Mar 2009
Posts
27

## Re: how much force to bend 1x1" solid steel

Thank you very much for reply. Unfortunately there is a lot of confusing or time consuming math just for figure it out. So i decided to drop a youtube link here of a machine im planning to build. You can see how machine operates. I think this machine can bend up to 1x1" or 2x1/4" flat bar.

Judging by the youtube video, can you estimate what kind of die bearing is needed to support the tons of pressure this machine operates in? Also will a 220 volt 5hp motor do the trick?

5. ## Re: how much force to bend 1x1" solid steel

Pro - tools sells the dies.

I built my own bender designed by Frank Takacs.
It uses an air/hydraulic 8 ton ram. about \$90.00

My first bend I just used the hand pump. No problem at all.
A solid bar is EASIER to bend than a hollow tube. because area 1 is Zero.
Go to www.gottrikes.com
Check it out.
BTW.....Many people cannot view your You Tube MOVIE. Can you just post a jpg next time? Speeds up the whole site too!
Last edited by Donald Branscom; 03-18-2009 at 07:26 PM.

6. ## Re: how much force to bend 1x1" solid steel

I have to agree with you don those You tube movies do take up loads of space.
I prefer either JPG or a plain ole link of where to view it

7. WeldingWeb Foreman
Join Date
Feb 2007
Posts
557

## Re: how much force to bend 1x1" solid steel

Originally Posted by Donald Branscom
A solid bar is EASIER to bend than a hollow tube. because area 1 is Zero.
[/img][/url]
What???????

8. ## Re: how much force to bend 1x1" solid steel

A solid bar isn't "easier" to bend than a hollow tube. It will take more force to bend a solid bar than a hollow bar OF THE SAME OUTSIDE DIMENSIONS.

But with a solid bar you don't have to worry about collapsing the tube like you do with a hollow tube. The solid bar could still distort and wrinkle and so forth, but it won't kink or collapse like a hollow tube can.

9. ## Re: how much force to bend 1x1" solid steel

There is something to be debated here....hollow tubes are stiffer than solid bars, whatever the shape(square, round, hexagonal). I think this is what Donald was referring to. The stiffness of a hollow tube is a function of the wall thickness or the ratio of the inner diameter to the outer diameter.

Keep in mind that stiffness in this context means resistance to deformation or bending. Not strength or load capacity. A solid bar in tension will carry far more load than a hollow tube. But hollow tubes can be more rigid, pound for pound, than a solid bar.

Think about bicycle frames for a moment. They are typically large hollow tubes, rather than small solid bars. Each can carry the loads applied, but the hollow tube deflects less under the same load, than a solid bar.

I suspect that this is what Donald was referring to.

Originally Posted by MoonRise
A solid bar isn't "easier" to bend than a hollow tube. It will take more force to bend a solid bar than a hollow bar OF THE SAME OUTSIDE DIMENSIONS.

But with a solid bar you don't have to worry about collapsing the tube like you do with a hollow tube. The solid bar could still distort and wrinkle and so forth, but it won't kink or collapse like a hollow tube can.

10. ## Re: how much force to bend 1x1" solid steel

DAB,

Notice I said the two pieces being compared in bending have the same OUTSIDE dimensions. In that situation, the solid is stronger/stiffer.

Yup, for bending a hollow tube would be stronger/stiffer than a solid bar of the same WEIGHT. Because for the same weight means that the hollow tube would have a BIGGER OD. And the strength/stiffness in bending has an h^3 factor in it, so the bigger the outside dimension item gets that dimension raised to the third power in its bending strength/stiffness. A similar idea as an I-beam versus a plain solid bar in bending, weight-for-weight the I-beam type shape is stronger/stiffer than a plain solid bar.

In tension, pound-for-pound they are the same. Because they would then each have the same cross-sectional area in order to have the same weight.

In tension, with the same outside dimensions, the solid shape would be stronger than the hollow shape because it has more material in it (and thus weighs more).

To the OP, "bearings" as in ball or roller bearings? To support the shaft/pin/die that the proposed 1x1 solid steel bar (of unknown alloy, heat treatment, and yield strength) is being bent around?

Forget it, most rolling-element bearings aren't made for that type of large static load unless you go HUGE. As DAB pointed out, that load/force is typically going to be 40,000+ pounds. Yes machines can do that and do it all the time. But a 'small' rolling-element bearing is not used. It will typically have a heat treated pin/shaft OD running steel-on-steel on the steel die ID. Or you would have to run something like an NTN 75mm (~3 inch) bore 22200-series double-row cylindrical roller bearing (static load rating 50,000 lbs) or BIGGER to support your load of 40,000 lbs to bend plain soft mild steel 1x1 bar. That bearing has an OD of 160mm (~6.3 inches), so that just pushed up your smallest possible bending die diameter BIGGER than that.

As to the power source, 5 hp electric motor may have enough power. But it wouldn't be easily usable as-is to power a bender. You would typically have to either use that electric motor to run some hydraulic system (pump and cylinder or hydraulic motor) or a mechanical power transmission (gears or pulleys or such) in order to slow down the motor rpm to usable shaft/machine rpm and boost the torque at the slower speed.

I can't see the youtube video, so I don't know what you are proposing specifically.

As Donald said above, you can look at existing benders at the gottrikes site or at the pro-tools site or so forth. Or let google or another search-engine help you look up existing benders and dies and such.

11. WeldingWeb Artisan
Join Date
Nov 2005
Location
Nashville, TN
Posts
2,555

## Re: how much force to bend 1x1" solid steel

I kinda thought op was actually a vendor of that machine.

12. ## Re: how much force to bend 1x1" solid steel

Originally Posted by specter
I have to agree with you don those You tube movies do take up loads of space.
I prefer either JPG or a plain ole link of where to view it
Thanks SPECTER !

13. ## Re: how much force to bend 1x1" solid steel

Originally Posted by KnightOwl
Thank you very much for reply. Unfortunately there is a lot of confusing or time consuming math just for figure it out. So i decided to drop a youtube link here of a machine im planning to build. You can see how machine operates. I think this machine can bend up to 1x1" or 2x1/4" flat bar.

Judging by the youtube video, can you estimate what kind of die bearing is needed to support the tons of pressure this machine operates in? Also will a 220 volt 5hp motor do the trick?

Iron is easy. They were bending wrought iron from what I could tell.

In this second movie below I am not even bothering to use the tapering volute shape to keep the ornament straight. When I get done I go over each piece with a rawhide mallet and really get them all the same.

But you can stop, drop the part down, and maintain a straight part. I found it is much easier to just bend them and straighten them. I can make all those pieces in an hour. And you get pretty tough doing it, or at least you get a good workout, Ha-ha.

For one inch square bar, wrought iron. It would be a bit harder, ha-ha. Probably impossible by hand. Once you spin a bar or twist a bar, it gets work hardened. Just keep that in mind.

But you could do a few pieces by hand if you had to.

I have bent steel bar on jigs, into ornamental shapes by hand, 5/8" steel bar in fact. Unhardened bolt blank 5/8' square bar. What a workout. We did an entire railing for a large North Shore home, out of this stuff. Not my choice of material. But we did it. Took weeks to bend it. You could not twist this stuff. It would just kink and break.

Sincerely,

William McCormick

14. ## Re: how much force to bend 1x1" solid steel

Originally Posted by Donald Branscom
BTW.....Many people cannot view your You Tube MOVIE. Can you just post a jpg next time? Speeds up the whole site too!
How does it slow down the whole site, and take up space? Isn't the movie being hosted by youtube?

15. WeldingWeb Foreman
Join Date
May 2004
Location
Edison Wa.
Posts
753

## Re: how much force to bend 1x1" solid steel

I actually have a similar machine to the one in the video.
It is 5hp, 3phase, but then its geared down to something like 10 rpm, which increases the torque quite a bit.
You need a gear reducer to do this.
As for bearings- they arent huge- since the speed is so slow, the load on the bearings is not as hard on em as it would be in something like a car axle.

Mine will do 1" square, cold, no problem. I did a huge job a while ago with hundreds of scrolls in textured 1/2" round stainless. We did the very end of each one hot, as I dont like a straight section at the end- I want my scrolls to curve all the way to the very tip. But after that, cold, up to 24" in diameter.

Mine is a Hebo- there are vids online of it, as well.

here is my fence-
http://img.photobucket.com/albums/v1...emi/phx017.jpg

16. ## Re: how much force to bend 1x1" solid steel

Originally Posted by William McCormick Jr
Hi William McCormick I posted some of your photos on my site http://www.tekindoor.com/ketchikan/k...lded-handrail/ let me know if your ok with that.

17. ## Re: how much force to bend 1x1" solid steel

Originally Posted by Tom Kroscavage
Hi William McCormick I posted some of your photos on my site http://www.tekindoor.com/ketchikan/k...lded-handrail/ let me know if your ok with that.
Could someone froward this to William I lost my email privileges.
Last edited by Tom Kroscavage; 03-22-2009 at 05:44 PM.

18. ## Re: how much force to bend 1x1" solid steel

Originally Posted by Tom Kroscavage
Hi William McCormick I posted some of your photos on my site http://www.tekindoor.com/ketchikan/k...lded-handrail/ let me know if your ok with that.
I actually got a little sleepy remembering it all at once like that. Ha-ha.

What were you thinking of doing with it?

Sincerely,

William McCormick

19. WeldingWeb Foreman
Join Date
Jan 2006
Location
San Francisco Bay Area
Posts
984

## Re: how much force to bend 1x1" solid steel

I have to quibble with A_DAB_will_do when he says, "Yield strength, at room temperature, for mild steel is on the order of 40,000 pounds per square inch(PSI). ... So, to bend your hypothetical 1"x1" square bar requires something on the order of 40,000 pounds of force."

For a yield strength of 40,000 PSI it would take 40,000 pounds force to stretch the bar axially, not to bend it. Bending strength involves calculation of the moment of inertia of the bar cross-section and calculation of the tensile stress at the outer fiber of the bar.

According to Machinery's Handbook, the stress f in PSI at the outer fiber of an a" square bar subjected to a bending moment WL inch-pounds (W = weight in pounds at the end of a bar L inches long) is 6WL/a^3. Therefore, for a 1" square bar with a yield strength of 40,000 PSI the moment required to bend the bar would be 40,000/6 or 6666.7 inch pounds or 556 foot-pounds. That would be the theoretical minimum to start a bend. you have to factor in work hardening, an overload factor, and the largest bar and highest strength material you'd ever want to bend. The formula would be different for bending across the diagonal axis. It's in the book.

For the machine shown in the video the important parameter would be the torque you could generate at the spindle of the machine (along with a strong enough bed, gears, and bearings). Since they appear to be bending cold, speed of bending is not critical and you could perform the bending with virtually any practical motor power. Power is the rate of performing work, so the higher the power the faster you can perform the scroll bend.

As Archimedes is reputed to have said, "“ΠΑ ΒΩ ΚΑΙ ΧΑΡΙΣΤΙΩΝΙ ΤΑΝ ΓΑΝ ΚΙΝΗΣΩ ΠΑΣΑΝ.” Oops, I mean "“Give me a place to stand and with a lever I will move the whole world.” So all you need is a large enough gearbox reduction ratio and heavy enough bearings and gears to stand up to the torque and lateral forces.

awright
Last edited by awright; 03-25-2009 at 05:25 AM.

20. WeldingWeb Apprentice
Join Date
Mar 2009
Posts
27

## Re: how much force to bend 1x1" solid steel

Originally Posted by Ries
I actually have a similar machine to the one in the video.
It is 5hp, 3phase, but then its geared down to something like 10 rpm, which increases the torque quite a bit.
You need a gear reducer to do this.
As for bearings- they arent huge- since the speed is so slow, the load on the bearings is not as hard on em as it would be in something like a car axle.

Mine will do 1" square, cold, no problem. I did a huge job a while ago with hundreds of scrolls in textured 1/2" round stainless. We did the very end of each one hot, as I dont like a straight section at the end- I want my scrolls to curve all the way to the very tip. But after that, cold, up to 24" in diameter.

Mine is a Hebo- there are vids online of it, as well.

here is my fence-
http://img.photobucket.com/albums/v1...emi/phx017.jpg
You have that Hebo machine? Doesn't it use bearings? Can you tell me what kind of bearings it uses and also what horsepower of motor they have. How much did you pay for one?

21. ## Re: how much force to bend 1x1" solid steel

Originally Posted by William McCormick Jr
I actually got a little sleepy remembering it all at once like that. Ha-ha.

What were you thinking of doing with it?

Sincerely,

William McCormick
Just what you see, a display of your work. I thinks its great that you can change style so freely. All my handrail looks the same.

22. WeldingWeb Journeyman
Join Date
Feb 2009
Location
Virginia
Posts
100

## Re: how much force to bend 1x1" solid steel

I have an Eagle Bender CP 30. It will do 1 x 1 without straining . But it also depends on to what radius. A 3 ft radius no sweat. 1 ft radius and the metal is 160 degrees when it's done! Yup - stretching and contracting steel does work, and work makes heat.
My bender runs on 220V 9 amps - not sure of the HP. But it's geared down from 1800 to 9 RPM! That's where it gets its torque.
I'm guessing the load bearing shafts have bushings, not bearings. At 9 RPM, who needs bearings? It's tolerances that make the difference there.

By the way William - nice railings.
Last edited by artworksmetal; 04-08-2009 at 10:32 PM.

23. ## Re: how much force to bend 1x1" solid steel

Originally Posted by Tom Kroscavage
Just what you see, a display of your work. I thinks its great that you can change style so freely. All my handrail looks the same.

There is something to be proud of about consistency. If everyone in the town had a different handrail design it might look a little strange. I just get most of these jobs because no one wants them. To much work not enough money. Ha-ha.

Sincerely,

William McCormick

24. ## Re: how much force to bend 1x1" solid steel

Mr McCormick I sure enjoyed the videos, as always

Twisting the full stick is smart

I don't know the theory behind it, but a long section has difference response to torque. Less torque applied will do more work. Sort of like using a long screwdriver, as opposed to a short one, to break a stubborn screw loose. (Bearing in mind that the hardened tool steel will carry the torque rather than bending as the square stock did)

I think on the opposite end of the pole, if the material is relatively weak (like the bar being bent here), it's not good at carrying the torque, and deforms before applying the torque to the vise in this case. But the really cool thing is that this allows the twist to be made with a lower power machine.

Probably totally way out there wrong, but you made me think about it.

25. ## Re: how much force to bend 1x1" solid steel

Originally Posted by farmersamm
Mr McCormick I sure enjoyed the videos, as always

Twisting the full stick is smart

I don't know the theory behind it, but a long section has difference response to torque. Less torque applied will do more work. Sort of like using a long screwdriver, as opposed to a short one, to break a stubborn screw loose. (Bearing in mind that the hardened tool steel will carry the torque rather than bending as the square stock did)

I think on the opposite end of the pole, if the material is relatively weak (like the bar being bent here), it's not good at carrying the torque, and deforms before applying the torque to the vise in this case. But the really cool thing is that this allows the twist to be made with a lower power machine.

Probably totally way out there wrong, but you made me think about it.

How you doing out there in farm country. Need a farm hand out there? Dollar a day plus all the farm cooking I can eat, Ha-ha. It is rough here by me.

Believe it or not, it does not take much force to bend a short piece either.

That machine will do half inch square bar for sure. For hours. And I have done short pieces of half inch square bar with it.

When you twist a bar, it takes very little pressure to twist it. Look at the car axil, on ice. If you do not destroy the universal, your shaft will either twist or break. Depending on what it is made of. I have been in a car that broke a cast axil. Wow, it sounded like someone dropped a manhole cover inside the car. The sound went right through my body.

And I have seen a lot of twisted axles made of softer pliable material. So it really takes a very small amount of energy to bend a square bar.

Take a half inch bolt, and a breaker bar, and tighten the heck out of it. You will have the head in your hand and not work up a sweat.

After me saying that last line, I can see why you would not want me at your farm. Ha-ha.
Good to hear from you!

Sincerely,

William McCormick

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•