TO ALL YOU FABRICATORS OUT THERE

[bazzthebarra]

Guys,
I,m after some ideas on how to correctly measure between to rightangle bends. eg. i,m building a t-top for the boat and i need to know whether to allow for the bend on one side of the canopy and then how much will the next bend take out the distance between the two, if you know what I mean ??? Someone also said that you need to subtract the width of the tube as well. Any help would be appreciated. I,m using 25mm "od" STAINLESS 1.6mm thick.

[NQCairns]

Sounds like fun to me, here is what I do and I take it slow. I start with only one bend and get it perfect so I have got a big right angle with one length way long and the other just ready to trim to fit then I mark centre of job I am working on (like boat)then measure same distance from the outside of the vertical inwards on tube (bent end) and mark to find your fabrication centre. You now have half the job done and all the points you need to copy an exact replica on the other end ie your centre mark on tube is your reference point to measure the bend already done and transfer these measurements to mark out the second bend (the start point of the bend is the important mark.
Bet i just confused you #::) Made sense to me before I started typing. best of luck.nq

[blaze]

depends on the radius of the bend, my bender loses 35mm. you only need to work at what it looses once, but if all else fails and it is to long between bends, cut in half, remove offending xtra lenth and reweld
cheers
blaze

[BladeRunner]

Bazzthebarra
Why not buy stainless elbows or bend then all you need to know is the distance between. Can u weld ? [smiley=idea.gif]
Blade [smiley=bandana.gif]

[familyman]

Most engineering places will measure from centre to centre on tubes and in tube diameters for a radius depending on wall thickness .Most stainless suppliers will be able to supply this info as well as pre bent sections.If you are determined to diy then try your local exhaust fitter as they have hydraulic benders well up the job and will be able to do your bends precisely .I had a stainless pool ladder bent to my design for $20 in 10 minutes.Good luck.

[aido]

i can supply some info on bend allowance, setback,
sight lines and layout for bending sheet alloy.
the theory seems like it is similar to bending tube,
though i can't get the figures to pass any sort of
reasonableness test when i plugged a few in.
i will scan some of the stuff and put a link for it
if your really keen.
and very patient ;D ;D ;D

[aido]

part 1
http://www.ausfish.com.au/cgi-ausfish/board/YaBB.cgi?board=Test_Board;action=display;num=10917 19426;start=0

part 2
http://www.ausfish.com.au/cgi-ausfish/board/YaBB.cgi?board=Test_Board;action=display;num=10917 20752

part 3
http://www.ausfish.com.au/cgi-ausfish/board/YaBB.cgi?board=Test_Board;action=display;num=10917 21674

part 4
http://www.ausfish.com.au/cgi-ausfish/board/YaBB.cgi?board=Test_Board;action=display;num=10917 22794

hopfully that might answer some nagging questions.
if i was bending it, think it would be easier to just add
the radius length of the bend to the length of the straight
bits, using the centre line of the tube as the reference line.
that would get it pretty close... ::)

[bazzthebarra]

Great site this. Thanks guys for all your input. Has made it much more achievable. If i can push the friendships and ask is there an easy way to get a reasonable sweep bend. eg. the front of the canopy, a gentle sweep from gunnel to gunnel so to speak, just to give it a bit of shape?
Thanks bazz

[blaze]

do a search of this site for pipe bender, i posted a pic of one i built, if you make a small bend every inch or so, you can bend a slight curve with no kinking of tube etc.
The trick is to only do a little at a time and it will eventually form the radius.
Draw the desired radius on the floor for a template
if bending 2 pieces mark your bend points on each tube before ya start
cheers
blaze

[bungie]

Buy some mild steel tube the size you want. Plug one end and fill with dry sand, very dry sand or this will blow up, then plug the second end off. pin one end so that it will not move then heat the tube with an oxy set. Keep the heat to the outside of the radius and slowly move the heat up the tube, as you do apply pressure to slowly bend the tube. Once you have the shape you want. empty the sand out and take it to a chrome plating shop and get it dipped.

Its a lot cheaper and easier to take the boat to a company and let them make it