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At work we will be bending some steel pipes (1/2", 1" and 2").
We will be using a Bramley hydraulic bender, one like I haven't used in years.
I can't for the life of me remember, how it is that you calculate the amount of steel actually taken up by the bend itself.

I used to know this stuff off by heart at one time, but obviously, if you aren't using this sort of theory every day, it tends to slip your mind.

What we will be doing is making up a series of pipes with 90 degree bends at each end, these need to be done without cutting or welding any bits in after the bends have been made.
These pipes and bends need to be pretty much spot-on, so guessing is not really an option.

Can anyone please help?, I've looked all over the internet, but all people want to do is sell me benders.

Thanks.

The circumference of a circle is 2*pi*r (2 x 3.1415 x radius). There are 360 degrees in a circle, so just take the ratio- 90 degrees would be 1/4 of the circumference. You just have to know the radius of your bender. Be aware that the effective radius changes depending on what size conduit you're bending, since the inner radius will always be the same for your bender, but you need to use the mid-point radius for this calculation.

If it's a REALLY complicated bend, I'll just draw it in CAD and measure the arc-lengths there instead of trying to calculate it all by hand.

Beyond my scope.

Perhaps for missile defense we would need to be that precise.
Otherwise... Damn close is good!

I just looked at my "Ugly" book. He has a lot of stuff but the best tip was to mark a piece of scrap pipe of each size, bend it with your particular bender and see what the "take up" is.
In real life, if you make it "long" on both ends you can cut that one to fit and you then know where the rest should be bent.
I have done that before myself (starting "long") on a complex piece and cut it down to fit. When I was piping the lights into my screen cage I admit I was way over my head on this bending and I had lots of scrap but if you didn't know how many cork screws and crooked saddles I threw away you would think I knew what I was doing ;-)

"screen cage" ?

Larry C

Screen cage = Aluminum pool enclosure.

Take your Hickey bar along just in case

Yeah, I have the Ugly's Handbook here, (courtesy of Bill A a few years back) and it is the gift that keeps on giving.
Damn, have I learned a lot out of that book, I carry it with me everywhere I go.
Formulae, Trig, you name it, them books are always good value.

Mike:

FWIW, I use 'Ugly's' as the text for the 'Basic Electricity' course that I teach at UCVTS. It's a 'Great Little Book', starts with Ohm's Law & goes on from there, plus it's a relatively inexpensive book.

Also, Benfield has a good bending book.

Benfield's is outstanding.

I can't recommend it too highly.

Umm OK, like you can bend galvanised thick-walled pipe with one of them?

In the end it turned out OK, I did as Greg suggested and marked the bit of scrap and found the take-up.

I also have to agree with Greg about the number of bits of pipe that are laid to waste in any given job.

The one good thing about the Bramley benders is that if you need to do a compound bend (ie: 2 bends in the same length of pipe), all you do is level the bender and the pipe with a level on each end of the pipe and one on the bender, you don't get a cork-screw, if you are lucky, or you hold your face the right way or the wind doesn't change during the bend.

Trumpy.,

I have the hickey bender and this what I will recomonded to you is make serveal small step for each bend and do not try to bend too much otherwise you will make a kink in there.

The numbers of "hits or movements " on hickey bender it will depending on the amout of bend the last 90° bend with 3/4 hickey it took me 22 hits to make a nice bend I know it is alot but that is the only way you can do that without kinking it.

Otherwise a standard conduit bender will work just fine and it will be done quick.

There are few tricks I done with electrique benders and hydrallics { it will be much easier If I can catch ya in the loft { chat room } and expain how this work out }

Merci,Marc

Be careful using Ugly's. The offset tables are the same as the Benfield Bender and assume pipe is bent like a broken line when in fact it is bent on a radius. For pipe sizes larger than 1 inch or for IMC and Rigid this is a killer for pre cutting and bending.
Reference:
http://www.electrician2.com/electa1/offset.html
The same principle apply to 90 degree bends. The best practice is to know your bender by test bending and measuring the take ups, etc.