Formula for working out countback...

[Smcart5]

I was given a formula by one of my tutors at college for working out the countback length for using a pipe bender , i noted down for learning off by heart later and i lost the notes.

I have a vague recollection of it and it was something to do with the degree of bend , the travel distance along the former and some other numbers.
Was anyone else taught this and could you post the formula for me, there's a different travel distance for 22mm

I tried searching for it on google with no luck

 

[justlead1]

Hi, May i suggest you use the method where you always measure from the back of the bender. having bent tube with a bender all my working life i can only recall half a dozen times when i have needed to measure back. I can not remember the figures, however all i do is mark a datum on a bit of scrap, bend it and calculate from there for the intended pipe. Good Luck

 

[anz]

http://www.diyfaq.org.uk/plumbing/Pipe Bending (BillP).pdf

 

[Avatar]

Just bend it ya donut - if you like maths then become a scientist or sommat!!!!

 

[Alanka]

The 'countback' or 'markback' figures for 15mm pipe that I have seen years ago are approximately as follows:

30deg bend -- 23mm (27mm)
45 deg bend -- 35mm
60deg bend -- 46mm
90deg bend -- 70mm (67mm)

You mark back along the pipe from where you want the centre of the bend to be, then position the pipe in the bender with the mark against the quadrant former.

From my own experiments I have changed two of these figures to those shown above in brackets -- but perhaps it's just my Hilmor bender, or the way I bend pipes!

Hope this helps.

 

[Smcart5]

Thanks for the replies, i don't have on job experience yet but i get the impression that by the book and accurate measurements are not a necessity in the trade..