stretch in my benders

[davidzeraschi]

Hi im on a plumbing course at weekends and next saturday i have a pipe bending exam i was wondering if any one could remind me how to work out the stretch on my benders as i have two 90 degree bends to do so simply chopping ends off is not an option! all help greatly appreciated!

 

[easyt]

There are tutorials on the web if you google.

I found this. Don't know if it is but saves a lot of words. http://www.diyfaq.org.uk/plumbing/Pipe%20Bending%20%28BillP%29.pdf

 

[davidzeraschi]

thank you very much. i have looked but it does not tell me how to calculate the stretch but not sure if i need to take it into account with that way of bending? will give it a go and see what happens ill let you know how i get on!

 

[Toddyplumb]

If its just copper there is no calculation. Square and tape measure or whatever method you prefer

 

[kay-jay]

a 90 degree bend stretches by the same as the pipe diameter. 15mm 90= length of 2 axis minus 15mm = starting length

 

[justlead1]

Practice on piece of scrap pipe to find out whats happening.

 

[Garryaca@yahoo.]

Length of the bend can be calculated with this formula

(Radius X 2 X 3.142) divided by 4

Useing 15mm pipe
Radius of bend is 4D, which is 4 x15 = 60mm.

(60 X 2 X 3.142) divided by 4

Length of bend 94.26mm

 

[dontknowitall]

Why do these examiners ask questions like this and demand the answers are known?

Plain stupid and time wasting to me and it's also a waste of materials (and world resources ultimately). Surely it's much quicker and more economical to insist that the pipe is oversized, bent then cut down to size and the offcut then used to fit another section of pipework?

I was shown that formula then went like a good student to complete my copper study. One bend in the pipe, followed by a cut (or two cuts knowing me) and hardly any waste because the smaller piece fitted another part of the copper study.

Surely it's better to cut 525mm then chop and re-use 110mm of the 125mm (so losing/wasting 15mm) rather than 400mm then find you're 2mm out and have to cut another piece of 400mm?

 

[kirkgas]

surely its better to be taught how to do it properly without any waste, bending copper is a skill and once learned and (often) practiced stays with you for ever,

 

[WaterTight]

If the extra time it takes to calculate each bend you pull doesn't cost you more than the cost of copper saved, you're not charging enough for your time. That's why plumbers just bend and chop. Saving 10p worth of copper isn't important enough to start measuring and calculating. It's the ethical way to do it yes, less waste, better for planet. Still doesn't mean anyone does it.

 

[WaterTight]

But it is probably good that everyone is taught the right way. Like being taught to drive. People develop short cuts and bad habbits no matter what you do. So you damage-limit by raising the starting bar high enough that they end up somewhere that's still acceptible.

 

[Henno82]

easy way to get 90 degree bend is measure the legth that you need and go back 70mm and put the 70mm mark on the edge of the former that way you get your bend simples!

 

[helpsy]

I think you may find some info at www.ukcopperboard.co.uk .
There are many different methods to do pipe bending its just what you remember easier or prefer.