Bullnoise flashing

[jim"thetinman"]

Hi all back again for more help if you don't mind I have been asked to make a bullnoise and roll top flashing( on a keetona hydroform). Now the straight angled stuff ridge and barge flashing are easy set the angle dial press and go. Have tried to make the bull noise flashing can be as tight as needed as it needs to fold back onto itself at a 90 bend thought we be easy started by dividing 90 by 6 so gave me 6 folds at 15 but then realised I'm folding back on the already folded angle is there a calc or rule of thumb for this sort of folding only using .5-.7ml galv steel. Now the role top needs to have a 180 fold so I end up with a semi circle in the centre of the flashing and I can the adjust the wings to angle needed would think this would just be 2 bullnoised flashings back to back in the folding terms. Forgive me if I am being stupid with this as I have no engineering back ground. Thanks in advance if anybody can point me in the right direction

 

[nickk]

i,ve done roll top in copper & m/s by folding a large radius 90 bend ,then clamp a piece of round bar in the fold[8mm in my case] & hammer-with a hide/copper mallet around the bar you'd be surprised how uniform an edge u can produce.you may be over complicating the bull nose ,i do a bull-nose just by folding 3 ,90 bends so the last one causes the first to touch the sheet,your of course limited by your top tooling,hope this helps.

 

[jim"thetinman"]

Cheers my main problem is the flashings are all 2500mm long and need to get each one the same as the last so was hoping there was at set of bends I can use to replicate the same shape every time

 

[jim"thetinman"]

Have just re-read my post the bull noise flashing needs to leave me with an over all 90 flashing but bull noised instead of the standard sharpe 90 point

 

[Hitch]

Jim, are you marking 6 points, then going through folding

_1
_2
_3
_4
_5
_6

If you get what I mean....?


Tried doing them like this- probably easier with an odd number of folds....

_1
_2
_5
_4
_3

 

[jim"thetinman"]

Yeah 6 was just an amount i pulled out of the air due to wanted the fold to look as rounded as possible. Will try the 5 in the order you suggest, have seen them with with 8 or 9 folds but it seemed to damage the wing on one side just looking for the easiest but most pleasant to look at if i make any kind of sense
Due to the flashing only being a total 400mm wide i want to get the fold with least mm needed i'm looking for the roll top (semi circle) to be any where between the size of a golf ball to tennis ball size.

 

[Hitch]

If its a decent sized rad like you say do 7, just add one either side of the centre fold. working in the right order will make it so the last fold ends up being the one that ends up brings it up to 90(or over)

Even numbers will work, i just find it easier to do odds.

 

[nickk]

do u also want each length to interlock with an overlap during installation?

 

[jim"thetinman"]

Yeah that's the main reason I need to keep the uniform bend they need to over lap the previous by 300 mm to stop water penetration