Math...........ugh

KevinW - Sunday, February 7, 2010 - 10:07pm

Hey all,

I'm very tired of searching the web for an answer so I'm going to post it, go to bed, and see if the tooth fairy comes by.

How much pressure would be needed to bend 5 mild steel bars measuring 1/2" round at the same time? I'm trying to figure the best way to do this railing going up curved steps and the 5 bars are the scroll pattern. I'm leaning towards a h-frame or 4 post press and bending it every couple of inches.

Its been a very long time since I've 'tooled up' and I'd love to, but, I can't afford to shoot myself if the foot either.

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Math = heat

TheDragon - Monday, February 8, 2010 - 6:27am

Not knowing the full details of your piece, when I do this kind of work I usually make a mandrel out of plate radiused the same as the staircase. Then I heat my scrollwork and bend it over the mandrel.
You do need to pay attention to the radius you use though. If it is the plan radius you will have to angle your work across the mandrel based on the angle of your stairs. If it is the pitch radius you can lay your work straight across.

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No math...

Stephen Fitz-Gerald - Monday, February 8, 2010 - 11:27am

Stephen Fitz-Gerald
Dear Kevin,
I think you're choosing the hard way to go about this...
Here's a spiral railing i did a few years ago.
I spent a good deal of time getting the cap rail and the base rail accurate to the pitch and radius of the stairwell in bolt together sections.Once I knew the panels fit upon the stairway,I took them to my studio to fill them in.All the inner parts were made with simple bending jigs.Heat was used only in forging the tips,and only if there was a radical bend.
When you have the frame to go by you can site your pieces and tweak them to the right radius one at a time as you go.This whole thing was built to the 4" code.Most of the material for the squigglys is 1/4 x 1" mild steel flat bar.Took me 3 months.

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Hey Stephen, Maby so, I'm

visitor - Monday, February 8, 2010 - 3:55pm

Hey Stephen,

Maby so, I'm still working a my design for a better wheel. By the way I've enjoyed seeing your work here.

I dont see a link to that railing of yours though i think I remember seeing it b-4.

What did you use to bend the rails.

As to your question about my press on the sample pic page I accidentaly made while trying to reply to Dragons reply ,well, I don't have one! Thats why i'm so hungry for info. I'd like to just bend the scroll pannels a bit at a time, every 1 or 2 inches to get the slight radius I need. Hopeing 25t will get it. The curved section of this rail would be 97'.

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The amount of tonnage, and

Ries - Monday, February 8, 2010 - 2:09pm

The amount of tonnage, and the size of press, required to bend whole railing sections at once is huge.
I would guess that a 4' x 6' 4 post press of 200 tons or so might do the job, but it would require machined dies that were full size with the radius machined in both the male and female shapes.
If you needed 1000 of these a week, a press might be a way to do this.

However, when you try to bend assemblies that are welded together, they tend to break at the welds, as that is usually the weakest point.

As mentioned by the two other posters, most people just do this a piece at a time, either hot or cold.
Hot is easier, as it requires less equipment.

But you could, conceivably, bend these with a brake, or with rolls, or with a hydraulic press.

Hebo, the german company that makes the best ornamental iron equipment in the world, makes a 20 ton horizontal hydraulic press for making curved railing pickets- thats 20 tons, for each 1/2" or 3/4" round picket, bent one at a time. Very slick, but again, it uses heavy and expensive machined dies.
Check em out at
http://www.usahebo.com/
click on wzt24 hydraulic table.

I do things like this with the hossfeld, too. Its much cheaper than a Hebo, and a lot more flexible than their hydraulic table as well.

I have done a lot of curved stuff, and always found that its a lot easier to bend the parts one at a time, and build it up to a pattern or jig.

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Ries, The Hebo is slick,

visitor - Monday, February 8, 2010 - 7:11pm

Ries,

The Hebo is slick, tooo slick for me. Its not really what I need to do anywho, but its nice to see what 24 tons will do to a bar. I ment to have a picture going along with all this , it is " image sample pic KevinW ".

I thought about having it rolled but havn't found any one worth their salt in my area that could do it.

I believe in the KISS ( keep it simple stupid ) meathod but I'm having trouble visualizing a scroll jig thats not flat.

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No math etc...

Stephen Fitz-Gerald - Monday, February 8, 2010 - 7:37pm

Stephen Fitz-Gerald
I second Reis's notion about the Hossfeld bender.It's pretty damn versatile.And I don't think a 20 ton press is enough for your project.Here's the link to the spiral staircase I mentioned above.Sorry for the omission...
http://ou8nrtist2.deviantart.com/art/Spiral-Staircase-Railing-40164351
I forged the frames for each bolt together section from 1/2 x 1 1/2 mild steel flat bar.The inner squiggly shapes were cold formed by using a variety of simple bending forks,and only their tips were forged and hammered to a nice soft rounded finial.All to 4" code.Simple fast drying spray lacquer finish.

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Here is a link to a press

Ries - Tuesday, February 9, 2010 - 10:53am

Here is a link to a press brake tonnage chart-
http://www.powerbrakedies.com/TON.HTML

If you were going to try to bend a finished, 3 foot tall scroll railing, one bend at a time, to make a curve, you use the figure for 1/2" material, and its approximately 33 tons per linear foot- that adds up to a 100 ton brake to make a bend in your scroll work.

Now, granted, you are not actually bending a full sheet of 1/2", so you could derate somewhat- but a 20 ton machine is just not going to do it.

A press brake is engineered to support the tonnage- and a 20 ton press brake will probably "spring" if you tried to bend 1/2" in it, even if it was intermittent, rather than full width material. Thus ruining the machine.

There are benders called "bulldozers" used in industry for just this sort of thin- but usually they are 200 tons and up, weigh 10,000lbs or more, and, of course, are not cheap.

Another possibility would be huge rolls- to roll 1/2" material, you need a machine that is probably 15 hp or more, with 12" or so diameter rolls. But most roll owners wont roll intermittent welded assemblies like that- it tends to scar up their hundred thousand dollar machines.

A real press brake will have either dual rams, or in older mechanical machines, dual mechanical linkages, to ensure equal pressure across the bending beam. Homemade single cylinder H frame presses usually dont have this, and tend to perform pretty poorly when used as cobbled together press brakes- uneven application of force makes for funky bends.

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Hey Ries, Thanks for the

KevinW - Tuesday, February 9, 2010 - 2:20pm

Hey Ries,

Thanks for the link, I've found a few also and one has a calculator----http://www.accurpress.com/toolingref_tonchart.html

I'm not familliar with presses at all, but, know of one thats a 4 post style. The posts are 3 1/2" in dia, the top platten is 3 1/2" thick by 14" x 20" , the bottom platten is 4 1/2" thick (plate steel w/ many thredded holes). It is w/o cylinder and pump. ANy guess as to what kind of force its ment to take???

KevinW

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I can't answer your press

Rich Waugh - Tuesday, February 9, 2010 - 7:40pm

I can't answer your press question, but this doesn't seem to be a situation where you really need a press at all. As I understand the situation, you are making a railing that follows a curved stairway. The railing is composed of scrolls that create a pattern.

I'd just make a quick mock-up of the stairway curve from plywood and sticks, enough running distance to embrace one scroll motif, and wrap a sheet of 20-24ga. sheet steel around it to fireproof it. Then I'd commence forming my scrolls and fit each one to the curvature by eye and hand, welding them up against the form when I have enough for one pattern section. Repeat as necessary.

Rich

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I get your drift. I just

visitor - Thursday, February 11, 2010 - 4:24pm

I get your drift. I just wish I could get one motif in my forge, the motif is in 'image sample pic KevinW' Its 3 scrolls closing in on each other, about 20" across.

Thanks for everything you do kere Rich.
Kevin

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I have a Hebo- and its slick

Ries - Wednesday, February 10, 2010 - 12:06pm

scroll fenceI have a Hebo- and its slick all right, but the grin it puts on my face when I am using it balances that out. Mine is not the hydraulic ram table- its the basic twister/ power supply unit.
And I have a scroll attachment for it.
A couple of years ago, I did a fence with about 800 scrolls, made from 1/2" stainless, which paid for, and justified, the scroll attachment.

Anyway- to the point. On that fence, we needed to curve some of the scrolls, rather sharply, to make them bend around the fence posts.They go out from the flat plane about 4", go straight for about 4", and then back in again. 4 bends in all for each post.
The way we did that was to make all the scrolls in advance, then, one at a time, weld them on one side to the growing fence panel, and heat and bend each scroll in up to 6 or 8 places. We used a rosebud, and hammers, crowbars, bending forks, and big dies. I didnt take any process shots, but you can see how the scrolls bend right around the vertical posts in this picture. We bent each 1/2" round section one at a time. There is only 360 linear feet of this fence, in about 60 individual panels, so it hardly took any time at all.

Oh, and at 4 corners, we bent the whole scroll fence 90 degrees, too, using this same technique. Took two guys, but the heat did most of the work.
Scroll fence

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I like it. The difference

visitor - Thursday, February 11, 2010 - 5:10pm

I like it. The difference it your rail and the one I'd do (waiting on a possably prickely customer's decision) is all of my scrolls need to bend and none of them so sharply ,well, and its not stainless.

Hardly any time at all eh? I think machines are good, or, our friends, or whatever, but, it seems to me that sometimes they think they are better than me. They're all ways better at doing as they are told.

RIEs,thanks for your input and sharing your experience.
Kevin

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Its lots easier to bend em a

Ries - Thursday, February 11, 2010 - 6:24pm

Its lots easier to bend em a little bit than to bend em sharp like we did.
And mild steel is a lot easier to work with than stainless.

Really, it was about six months.

Build a bigger forge. Get a bigger rosebud, and more acetylene tanks. Get em hot. I would probably make up a small slumping form- a sheet rolled to the curve, with welded support under it, and heat up my scrolls, then clamp em down to the form.

You can often pick up Johnson Slot forges pretty cheap- they are big, heavy, hungry beasts, that slurp up propane, and are noisy and hot- but perfect for heating entire scrolls at once. Heck, I got one in the shed you could talk me out of for not much- but its up here in Edison, Washington.

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