Internal bend in cable tray

[Belle427]

Does anyone know the measurements required for hand cutting/ forming an internal 90 in a medium duty cable tray?
Its years since i last did this and would like to do some in a storage cabin in work. I know there is a requirement for pre formed stuff these days but i would like to do it old school!
Im looking for the measurements to mark it out for v cutting the return edges with a hacksaw
Thanks

 

[SimonH2]

If you're doing it with one fold then you need a 90˚ cut out - so that's 45˚ either side of square. If you do it in two folds then it's 45˚ per fold (22.5˚ either side of square).

 

[Belle427]

Thanks for that, i should have clarified i was looking for how to do the curved 90 with multiple cuts in the return edge

 

[SimonH2]

Well to a point it's a matter of dividing 90˚ by the number of cuts. Ie, 3x 30˚, 6x 15˚, 9x 10˚. In each case, divide that by two and cut either side of a perpendicular - so 3x 30˚ would mean cutting 15˚ either side of a perpendicular.
As the cuts get smaller, the size (thickness) of your cutting blade becomes a consideration as well.

As for where to start cutting in relation to where the bend ends up, I don't have any rules for that. But with a large number of cuts so you approximate a 1/4 circle, the tray making up that 1/4 circle will be approximately pi * r/2 where pi is 3.14, and r is the radius of the circle - so about 1.6 * r

 

[Belle427]

Thanks will have a practice tomorrow!