Bending stainless steel tube for a bimini

[Celestialsailor]

Originally Posted by GILow

I was gifted a lot of the stainless in the form of a bimini from another boat and it came with heaps of those connectors. I’ve kept them in mind but the design I am copying doesn’t need them.

I think they may come in handy for other jobs tho. I like the idea of welding them, I’ll give that a go.

It amazes me, here in the land of waste, how many "cool things" are discarded in the dumpsters at marinas. Next time I see parts of a bimini, I will start collecting.

[Dave_S]

Originally Posted by GordMay

Hand benders, for 1/2" [I.D.] EMT conduit have a minimum radius of 4" [8 x pipe I.D.].

This is similar to the one I used. They claim 112.5mm radius, I saw 120mm in practice using 25mm X 2mm 316SS. It's a bit over recommend material size but the result was reasonable. I spent a fair amount of time getting the roller tight on the tube but it didn't always roll and marked the tube which needed polishing out.


https://m.vevor.com.au/pipe-tube-ben...BoCehIQAvD_BwE

[GILow]

Originally Posted by Celestialsailor

It amazes me, here in the land of waste, how many "cool things" are discarded in the dumpsters at marinas. Next time I see parts of a bimini, I will start collecting.

I was very grateful for it. At $11 per meter there’s a few hundred dollars worth now sitting on my deck. Of course I keep tripping over it, but hey, I shouldn’t complain.

I’m still using the half dozen Caframo cabin fans that had been tossed in the dumpster because their control boards had failed. I fitted each with a AU$3.25 PWM controller from EBay and now have half a dozen excellent cabin fans with infinitely variable speed controls for AU$20 plus some solder. It makes me smile on the hot days.

[GILow]

Originally Posted by Dave_S

This is similar to the one I used. They claim 112.5mm radius, I saw 120mm in practice using 25mm X 2mm 316SS. It's a bit over recommend material size but the result was reasonable. I spent a fair amount of time getting the roller tight on the tube but it didn't always roll and marked the tube which needed polishing out.





https://m.vevor.com.au/pipe-tube-ben...BoCehIQAvD_BwE

That was the one a friend was going to loan to me until I realised the diameter was going to be a problem. Otherwise, I believe he has been happy with it.

[Celestialsailor]

Originally Posted by GILow

I fitted each with a AU$3.25 PWM controller from EBay and now have half a dozen excellent cabin fans with infinitely variable speed controls for AU$20 plus some solder. It makes me smile on the hot days.

That's interesting...do you remember which ones you purchased?

[GILow]

Originally Posted by Celestialsailor

That's interesting...do you remember which ones you purchased?

Well, I didn’t, but EBay did. [emoji848]

https://www.ebay.com.au/itm/4-Pcs-3V...154756-20017-0


Very nice units, the rotating knob is the sort that turns all the way down then goes “click” and turns off the circuit completely. (I confess, I’m trusting there is no parasitic loss, I never thought to check.)

They’ve gone up a little in price over the last few years. They are more like AU$4.05 now. [emoji853]

I’m using them for a number of other tasks too, like speed controls for my heater units.

[GILow]

Originally Posted by Celestialsailor

That's interesting...do you remember which ones you purchased?

I posted about it somewhere, including photos I think… I’ll see if I can find that post.

Edit: found it…

https://www.cruisersforum.com/forums...rd-235597.html

Edit again: for some odd reason that post says four fans, but it was six. I’m confident about that, they are dotted all over the boat. [emoji16]

Yet another edit: Nope, it WAS four. I just checked and only four have my modified controller. The rest have the original push button setup. Darn, I really thought it was six. ☹️

[carlosproa]

Originally Posted by GILow

My gawd, I wouldn’t trust that thing on a baby’s bassinet, let alone a blue water yacht.

And that looked like the bends were about 20D.

Well, you are now in Australia - the guy in the video is from Australia - maybe he can explain to you why a bend like that is stronger than your 2/1 radius. You do not have to be an engineer (I am) to understand that, specially if you get pooped from behind.

[vpbarkley]

There is an alternative to having access to the exact mandrel.
It is to prefill the tube with a low melt alloy, AKA bend metal or casting metal.
Unlike sand it will truly prevent rippling in the tube wall.
Once bending is done the alloy is melted out.
https://www.mcmaster.com/low-melting...rature-alloys/
https://www.belmontmetals.com/produc...melting-alloy/
https://www.thefabricator.com/tubepi...r-me-a-mandrel

[zstine]

You will most certainly have problems with creasing at a 2D bend in SS without a fancy mandrel bender and even then iffy. If you can weld, I'd suggest cutting and welding the corners. You can make 2 cuts and put a 45deg angle in to make it look nicer.


I bought a huge 4 bow bimini from a consignment shop for $250. I cut the straight sections, welded as needed and used the bends and fittings and was able to make a bimini frame AND solar arch!

[GILow]

Originally Posted by carlosproa

Well, you are now in Australia - the guy in the video is from Australia - maybe he can explain to you why a bend like that is stronger than your 2/1 radius. You do not have to be an engineer (I am) to understand that, specially if you get pooped from behind.

You are joking… right?

[GILow]

Originally Posted by zstine

You will most certainly have problems with creasing at a 2D bend in SS without a fancy mandrel bender and even then iffy. If you can weld, I'd suggest cutting and welding the corners. You can make 2 cuts and put a 45deg angle in to make it look nicer.


I bought a huge 4 bow bimini from a consignment shop for $250. I cut the straight sections, welded as needed and used the bends and fittings and was able to make a bimini frame AND solar arch!

I certainly see a lot of welding in my future.

[Dougtiff]

I have built Pulpit's, push pit's, bimini's and dodger frame's on the cheap for year's, the trick is to have the tubing bent and then use fitting's, i.e, T's, elbow's, ect. and instead of using the grub screw's in the fitting, remove and rivet using S.S. rivet's, the build is solid, no movement, some times i will drill an extra hole and add an extra rivet opposite the grub screw hole.

[GILow]

Originally Posted by Dougtiff

I have built Pulpit's, push pit's, bimini's and dodger frame's on the cheap for year's, the trick is to have the tubing bent and then use fitting's, i.e, T's, elbow's, ect. and instead of using the grub screw's in the fitting, remove and rivet using S.S. rivet's, the build is solid, no movement, some times i will drill an extra hole and add an extra rivet opposite the grub screw hole.

Good ideas.

I’m yet to see just how many fittings and of what sort I will need. My good mate is sending over the tube bender because, when we looked at the photos of what I want to build, we reckoned it might do most of the job.

The rest will be welding, lots of welding and, I suspect, those clamp/end fitting things.

I’ll keep the river idea in mind when if I need to use any of those fittings. I also liked the welding idea suggested up-thread. Maybe I’ll end up using both.