25mm Stainless Steel pipe bending to make a 3 bar Bimini

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seumask

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My winter project is to make a 3 Bar Bimini for our SO 37. I'm confident I can do all the canvas work but I would much appreciate the forums input to making the Arches. I am planning to use 25mm 1.5mm wall polished stainless steel and in particular need advice on how to achieve the 2 90 degree bends. on each. I have seen comments that it is possible to use pipe benders with formers, something like this one from ebay
Pardon our interruption...

1729688756986.png

Having read this thread Bending Stainless Tube
I intend to hire a similar bender to do the main corners on each arch and I understand the pipe will need further polishing. What advice and experience does the forum have for the bending and polishing process!

I see that I may also need to make a Crown arch of a large radius and wondering if there is a way to do this by hand!

All thoughts and Input gratefully received.
 
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I know it doesn't answer your question and maybe you've seen this video already. If not, it's enlightening how easy the bending can be...


I've often wondered about getting a few others together to buy the CrownArc and BendArc.

For what it's worth, I did manage to go from this..

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Using a bench mounted vice and some thick rubber hose..

20241023_143919.jpg

To this..

20241023_143937.jpg

In about ten minutes...

Not necessarily the recommended method but shows that (as a Practical Boat Owner) it can be done!

Edit: It was just the gradual crown that I did by hand in the vice.
 
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seumask said:
My winter project is to make a 3 Bar Bimini for our SO 37. I'm confident I can do all the canvas work but I would much appreciate the forums input to making the Arches. I am planning to use 25mm 1.5mm wall polished stainless steel and in particular need advice on how to achieve the 2 90 degree bends. on each. I have seen comments that it is possible to use pipe benders with formers, something like this one from ebay
Pardon our interruption...

View attachment 184621

Having read this thread Bending Stainless Tube
I intend to hire a similar bender to do the main corners on each arch and I understand the pipe will need further polishing. What advice and experience does the forum have for the bending and polishing process!

I see that I may also need to make a Crown arch of a large radius and wondering if there is a way to do this by hand!

All thoughts and Input gratefully received.
Click to expand...
I did mine last year with pipe bender, the issue was the formers were not quite the exact fit of the od of the tube as they are designed for copper tube. The result was ok for the spray hood hand rail I was doing but not as good as I had hoped. I think a sharper radius would probably been better. Did take a lot of huffing and puffing, this was 20mm stainless
 
Daverw said:
I did mine last year with pipe bender, the issue was the formers were not quite the exact fit of the od of the tube as they are designed for copper tube. The result was ok for the spray hood hand rail I was doing but not as good as I had hoped. I think a sharper radius would probably been better. Did take a lot of huffing and puffing, this was 20mm stainless
Click to expand...
Electricians bender is for 25mm conduit.
 
When using the pipe bender you will probably find that you run out of clearance, as the leg of the tube will meet the floor before you get a 90deg bend. I had this problem and had the bender placed on a raised patio so the leg went down further.
 
I tried to bend 1" stainless tube with a pipe bender and it failed miserably. The former was similar to the one in your link. The tube deformed around 20 degrees and started to kink. I got a refund as I specifically asked if it could bend stainless tube. The formers size is critical for the tube OD.

Good luck.
 
I put a couple of slight bends in 25 mm tubing for a stern ladder using a conduit bender similar to the one show. Fortunately the bender was bolted to the floor. A 6 ft extension was needed on the handle and even then it took considerable effort to put in a 5 - 10 degree bend.
 
You can buy SS tube in various states of anneal.
You can also buy a lot of bends for the price of the tools to do your own.
 
And a link to the BendArc and CrownArc products, in case you were interested in their price..

BendArc / CrownArc

Oh and they have software that works out the bend angles and where to place the bends.. Remember that when you bend the final top crown, the bottoms of the legs will end up a lot closer together.
 
Hunterlees said:
When using the pipe bender you will probably find that you run out of clearance, as the leg of the tube will meet the floor before you get a 90deg bend. I had this problem and had the bender placed on a raised patio so the leg went down further.
Click to expand...
I was planning to make the Bimini demountable and break into pieces that can be stored using sections of 22mm pipe as inserts so I may be able to get round the problem of long legs scraping the floor when using the bending machine.
 
AntarcticPilot said:
If you can produce a dimensioned drawing, I am sure that a local metal fabricator would be able to do it for much less than the cost of equipment to DIY, and do a better job. As @vyv_cox notes, bending a stainless tube is not easy!.
Click to expand...
Definitely going to talk to some local fabricators to work out if I cant get one of them to do the bends or wether I can do it. Any suggestions, I'm between Portsmouth and Chichester. I already have a length of pipe from a previous project that would allow me to try out bends!
 
Martin_J said:
And a link to the BendArc and CrownArc products, in case you were interested in their price..

BendArc / CrownArc

Oh and they have software that works out the bend angles and where to place the bends.. Remember that when you bend the final top crown, the bottoms of the legs will end up a lot closer together.
Click to expand...
So I guess the top corners probably only need to be bent to around 82-85 degrees before the crown arch is applied bringing the legs parallel
 
seumask said:
I was planning to make the Bimini demountable and break into pieces that can be stored using sections of 22mm pipe as inserts so I may be able to get round the problem of long legs scraping the floor when using the bending machine.
Click to expand...
My solar panel arch was made using only standard fittings and straight tube. It is possibly not the most beautiful arch around but it has worked well for many years.
 
Old woodworkers will remember achieving a bend by means of "saw draughting" (or drafting). Material is removed from the inside of the curve by making multiple saw cuts. I made a substantial davit for my outboard, using 33.4mm OD x 3..4mm thick stainless tube. That's 1" nominal bore schedule 40 tube, and considerably more than the capability of any pipe bender that I could borrow. I made enough cuts three quarters through with a chop saw, to allow the pipe to be bent to the required 45° off the straight. It was then just a case of welding up the cuts, cleaning up the welds, and polishing.
 
seumask said:
Definitely going to talk to some local fabricators to work out if I cant get one of them to do the bends or wether I can do it. Any suggestions, I'm between Portsmouth and Chichester. I already have a length of pipe from a previous project that would allow me to try out bends!
Click to expand...
Sorry - I'm based near Cambridge where the go-to people would be Mackay's Metal Warehouse.
 
When I decided I wanted a cockpit overall cover, I used the local stainless fabricator to make the hoops, both with long legs which could be cut shorter if necessary. Worked for me.
 
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