Bending SS tube

[Gordonmc]

What is the percieved wisdom re. bending 22mm stainless tube?
I want to replace the aluminium frame for the sprayhood. It has lost its finish and leaves black marks on the acrylic canvas.
Getting the tube and fittings should be OK but how to get the right shape. I have springs for 22m copper, but SS won't be as maleable.
Can I hire a bench mounted tube bender and will it work?

 

[Guest]

Why 22mm?

Most sprayhoods use 15mm, this you can bend by hand (knee really), better if you have a 3/4" ply former

 

[pvb]

Wouldn\'t even attempt it...

Getting a nice even curve in a piece of SS tube isn't a DIY job, and I wouldn't even attempt it. If you don't end up with a regular curve, you'll notice it every time you look at the sprayhood, and it'll bug you. You could still buy the fittings separately and make it up yourself, but it'd probably be best to take the old aluminium frame to a proper SS workshop and get them to bend tubing to match.

 

[Guest]

Re: Wouldn\'t even attempt it...

Sorry, i've done it

 

[FlyingDutchman]

Re: Wouldn\'t even attempt it...

There is a big difference between 22 and 15mm!
The 22 mm will be twice as difficult to bend and the risk of getting an uneven curve is realistic.
I agree with pvb.

(pvb, thanks for your comments on the purchase of a GPS! The Garmin 152 is discounted now to € 275 against € 229 for the 72 Marine Pack so I will go for the 152, it looks much better)

 

[tcm]

like pvb, i wd get someone else to do this.

But if you are keen to do it yourself, the accepted route is a pipe bender with springs. Other alternative to springs is packing the pipe with sand and block up with wood bungs, which again inhibits kinks developing during the bending.

Of course, the limiting factor as to whether you can bend the tube over your knee or not is the wall thickness of the tube - so presumably some 15mm o/d you can bend over knees, some you can't.

 

[pvb]

152 is a good choice...

You should find it very useful.

 

[Guest]

Re: Wouldn\'t even attempt it...

Agree about 22mm, much too difficult to bend manually.

I had a spray hood on a boat I bought which used 22mm, bent by a tube bender so it was sort of half octagaonal.

Was so ugly I thew it away.

 

[FlyingDutchman]

Re: 152 is a good choice...

Definately, the usefullness comes first, but good looks are also important! /forums/images/graemlins/grin.gif

 

[ashanta]

For rigid steel pipe such as Stainless (as opposed to copper) you could hire a pipe bend former which would ensure your bend is true. In the past a method was used by filling the pipe with sand and heating the pipe so it becomes maleable but it would leave black marks which would need cleaning up afterwards.

Regards.

Peter.

 

[oldsaltoz]

G'day Gordon,

You decide who does the bending, but make sure the stainless is not in direct contact with the steel bending block, or you will have a rust problem, good bending shops use composite blocks or cover strips.

Avagoodweekend.........

 

[cliff]

[ QUOTE ]
What is the percieved wisdom re. bending 22mm stainless tube?
I want to replace the aluminium frame for the sprayhood. It has lost its finish and leaves black marks on the acrylic canvas.
Getting the tube and fittings should be OK but how to get the right shape. I have springs for 22m copper, but SS won't be as maleable.
Can I hire a bench mounted tube bender and will it work?

[/ QUOTE ]Take the original into either Smillie & Cuthbertson in K/K and ask for "Billy" (the owner) or try A.G.B. Engineering in Irvine and ask for "Alex Burns".

A.G.B are at 2 Mackintosh Place, South Newmoor Ind. Est. Irvine. (near Grahams the builders merchant) T 01294 213555

Personal preference would be AGB as from personal experience he (Alex) is not into "marine pricing" and does a first class job.

As for size - 15mm is more than adequate and is the "norm" 22mm will be a bugger to get fittings for unless you already have them. (Original is 22mm?)
----------

 

[richardandtracy]

Make your own pipe bender. See http://www.lindsaybks.com/dgjp/djgbk/pipe/index.html for a possible design.

Regards

Richard.

 

[LittleShip]

Screwfix pipe bender approx £35 will do both 22mm and 15mm, clean stainless pipe afterwards with stainless pan scrubber. Forget trying to bend it over your knee or packing with sand. Any plumber worth his salt should be able to do this job for you.

 

[ongolo]

Whatever you do, dont force it, just use a bigger hammer.

Seriously, bending stainless is a bastard. Even solid round bar. I get conflicting answers from stainless steel workshops, whether to bend it cold or hot.


Ongolo

 

[Sammo]

Before you go on a bender.

22mm and 15mm used by plumbers is Inside Diameter whereas most (but not all) stainless steel pipe is measured in outside diameter.
Match your pipe to the former before you buy/hire.

.................

 

[VicMallows]

I'm paranoid, so had to get the calipers out. All the 15mm and 22mm copper tube in the garage is O/D 15 and 22. I agree though I'd be vary wary of trying to bend S/S tube

Vic

 

[Sammo]

Trust me Vic

I`m a plumber.

 

[alahol2]

Wouldn't it be possible to take the original and get it re-polished, or anodised or something?

 

[Sammo]

I did some checking at work and it seems that I was wrong and I was right. From what I can gather nothing is standard.
Copper pipe for water is 22mm Outside Diameter
If copper pipe is supplied with thicker wall thickness it`s Inside Diameter 22mm plus the thickness.
Copper used with Propane has thicker wall and is measured in Imperial.
Black iron pipe is measured on Inside bore with three different thickness in imperial.
Confused? It gets worse
Stainless steel comes 22 mm outside standard thickness, however for a spray hood the tube needs to be thicker than the standard which is a bit flimsy, when you order thicker walls the measurement goes on inside diameter, however the good news is you can have both metric or imperial. The bad news is you can only buy 6 mtr lengths at a cost of , for standard 22mm around £95 per length, for the thicker stuff that you need, around £155 per length, could cost more if you don`t get it right the first time. Then you have the cost of the bender hire then polishing.
Best advise is as above - sort out the original or get someone to do it for you.

Cheers
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