28mm copper pipe semicircular shape

yartin · Post by **yartin** » Thu Jul 16, 2020 11:30 am

Hi

I want to bend a 3.0m of a 28mm copper pipe to form a semicircular shape, radius is roughly 1.5m. I know I need a ring roller bending machine but expensive to buy and can't find one to hire.
I have 2 options left, either find another way to do it myself or take it somewhere who does such.
My question is: I have a template of the arc, can I use the idea in the photo attached? This is from a youtube video who is doing the arcs from 20mm metal conduits, he is bending them with ease.

Thanks

: snip1.png (585.5 KiB) Viewed 4972 times

Someone-Else · Post by **Someone-Else** » Thu Jul 16, 2020 4:18 pm

What are you making? (Sorry, can't help with bending)

wine~o · Post by **wine~o** » Thu Jul 16, 2020 4:45 pm

If you attempt that with copper pipe You will need a bl00dy long bending spring... otherwise the pipe will kink.

As above what are you trying to do ???

yartin · Post by **yartin** » Thu Jul 16, 2020 5:38 pm

wine~o wrote: ↑Thu Jul 16, 2020 4:45 pm If you attempt that with copper pipe You will need a bl00dy long bending spring... otherwise the pipe will kink.

As above what are you trying to do ???

Would it be same problem with steel or aluminium pipes?

Dave54 · Post by **Dave54** » Thu Jul 16, 2020 6:25 pm

Aluminium I'd have thought at least would be easier to bend effort wise, but also easier to kink.
Steel is less easy to bend, but not so likely to kink.
28mm copper takes quite a lot of effort to bend.
For that matter so does 22 mm.
I'd have though that as already said in the OP, if a smooth curve is wanted, it'll have to be rolled.

yartin · Post by **yartin** » Thu Jul 16, 2020 6:33 pm

Dave54 wrote: ↑Thu Jul 16, 2020 6:25 pm Aluminium I'd have thought at least would be easier to bend effort wise, but also easier to kink.
Steel is less easy to bend, but not so likely to kink.
28mm copper takes quite a lot of effort to bend.
For that matter so does 22 mm.
I'd have though that as already said in the OP, if a smooth curve is wanted, it'll have to be rolled.

I know the best way is pipe ring roller machine but expensive to buy and can't find one to rent.
In that picture of first post, it is a metal conduit pipe is used which I think is galvanised steel, probably I should do the same?

Dave54 · Post by **Dave54** » Thu Jul 16, 2020 6:48 pm

If it's 20mm steel conduit, galv or black, it'll bend OK like in the pic I'd have thought.
You can bend it quite tightly through a block of hard wood through one end. radiused a bit to allow it to be bent bit at a time.
I've got a circle of 20 mm conduit here somewhere, probably a bit more than 300 mm or so across that I bent that way to hold a fish tape when I was an apprentice.

adonis · Post by **adonis** » Thu Jul 16, 2020 7:23 pm

What about filling the pipe with sand, would that stop it kinking?

Someone-Else · Post by **Someone-Else** » Thu Jul 16, 2020 7:50 pm

The other thing to consider is it must be kept flat while bending.

How about This says it bends upto 70mm

yartin · Post by **yartin** » Thu Jul 16, 2020 8:35 pm

I have seen somewhere filling with sand to stop kinking which will do, don't how effective but won't do harm

Dave54 · Post by **Dave54** » Fri Jul 17, 2020 9:17 am

someone-else wrote: ↑Thu Jul 16, 2020 7:50 pm The other thing to consider is it must be kept flat while bending.

How about This says it bends upto 70mm

The machines I've seen for rolling tube are a lot bigger than that. I've never used one, but they definitely have bigger rollers than that shaped to carry the tube being bent, and I think (It's been ten years or more ago since I saw these machines) they may have had double rollers to keep the tubular form.

Rorschach · Post by **Rorschach** » Fri Jul 17, 2020 10:03 am

Fill with very fine sand and cap the ends. That should stop it kinking. Also by annealed/soft copper if you can.

How smooth does the curve need to be? You could do it by hand using two posts and working the curve slowly until you get what you want.That would be my choice for a one off job.

yartin · Post by **yartin** » Tue Jul 21, 2020 1:54 pm

Update:

The final shape I wanted is as the pic attached and in one part.
After doing some research, I found a company who can do for reasonable money and went ahead.
I couldn't find a ring roller to hire, wasn't worth to buy and wasn't too confident to do it by hand.

: shape.png (13.16 KiB) Viewed 4870 times

Someone-Else · Post by **Someone-Else** » Tue Jul 21, 2020 1:59 pm

What's it for?

Chippo1 · Post by **Chippo1** » Tue Jul 21, 2020 2:44 pm

What you want ideally is three decent rollers/wheels with a concave face to the tyre. Mount them on a bit of steel plate with the middle one adjustable . Pass the pipe through and keep adjusting middle roller until u achieve a nice smooth radius , a bit like an “English Wheel”

Or find a local fabricator with a set of rollers. Shame really not long ago I threw out some old Express lift door rollers would have been ideal nice bearings to