Problems bending Kunifer pipe

[JOEPRO]

I am restoring a Mercedes w140- I am currently replacing the fuel hard lines now as the originals were mild steel and 25+ year later have surface rust so I want to renew them with Kunifer.

8mm outside diameter fuel pipe.

Problem is the pipe Is so hard that when using a small hand bender it kinks the pipe.



I am using an eBay bender like this one- any better ones out there?




The small indents are from the tool itself from the die when starting off a bend.

 

[Guineafowl]

Try annealing the pipe by heating to cherry red, then allowing to cool normally.

 

[JOEPRO]

Try annealing the pipe by heating to cherry red, then allowing to cool normally.

I have 20 - 30 bends to do over 3x fuel pipes. Point taken but would require alot of heating!

 

[dan.taylor.1]

These be any good?

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[JOEPRO]

These be any good?

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I have a pair of those - they are good for tight bends on brake pipes.

This is a 8mm fuel pipe I am bending however.

I am thinking I may try to die grind / soften the edges of the die which are biting onto the pipe. Searching the interwebs I am not seeing many other styles of benders for 8mm pipe.

 

[Bornfree]

I have one of these works a treat up to 10mm

 

[8ob]

The Rothenberger crossbow benders are good for kunifer.

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[JOEPRO]

I see this bender also but it's spendy!! I have 10x classic MBs so it would pay for itself as most of them will be getting new fuel lines in the coming years

RIDGID 38038 Model 605/608M Heavy-Duty Pipe Bender, 5/16-inch Tubing Bender https://amzn.eu/d/isgVOS6

 

[doubleboost]

You could always use plastic fuel lines .
Most modern lines are now push fit plastic .

 

[dan.taylor.1]

The Rothenberger crossbow benders are good for kunifer.

• 

Think I've got some plates for one of them, might have to make a handle...

 

[MetalMonkey]

You could try this type, I've used them on smaller sizes.
Obviously not at that price..

https://www.mscdirect.co.uk/RTX-00211B/SEARCH:CATEGORY/product.html

 

[8ob]

Think I've got some plates for one of them, might have to make a handle...

They are a nice bender to use,they come up on ebay from time to time.

 

[tigdlo]

https://www.lasaero.com/products/article/R03RDJXXX

I have used this for 5/16" Kunifer, worked well, 8mm should be close enough to 5/16"

 

[JOEPRO]

You could always use plastic fuel lines .
Most modern lines are now push fit plastic .

There is one of the 4x fuel lines in hard black plastic on the car. I think it is a vent pipe running under the car.

Can you buy universal hard plastic fuel line? Heat it with a blow gun to bend it?

This car has alot of electronics in it even for a 1995! Lots of stuff everywhere including an LPG system. A fuel leak would be catastrophic!! So many hot things and services it would be a fire ball in seconds hence probably prefer Kunifer on it.

 

[doubleboost]

To put tight bends in we use hot glycerine to soften the pipe .
Wagon air brake line and fittings can be used .
As has been stated the pipe needs to be well away from direct heat .

 

[JOEPRO]

https://www.lasaero.com/products/article/R03RDJXXX

I have used this for 5/16" Kunifer, worked well, 8mm should be close enough to 5/16"

Now that looks promising. Having rollers and nylon dies should mean less chance of kinking.

I think I'll order one of those first and if any issues then the Ridgid one. Pitty it's so expensive as it has all rollers too and looks like it would be perfect but hard to justify spending that much just for a fuel line bender.

 

[JOEPRO]

https://www.lasaero.com/products/article/R03RDJXXX

I have used this for 5/16" Kunifer, worked well, 8mm should be close enough to 5/16"

Unfortunately with me in NI my postage options are dearer than the item itself

 

[Neilj]

View attachment 386914


The small indents are from the tool itself from the die when starting off a bend.

Which bit of the tool is making the indents, it is the profiled pad below the 'Eclipse' label or the curved former?

 

[JOEPRO]

I went ahead and ordered the Ridgid bender from amazon. I don't want to damage any more Kunifer! If it works I'll be happy. Don't mind paying for good tools. If it also kinks the pipe amazon returns are free and easy and it'll go straight back.

FWIW I paid £135 on amazon. Then the price immediately went up to £167. I wouldn't have stretched to £167!

 

[JOEPRO]

Which bit of the tool is making the indents, it is the profiled pad below the 'Eclipse' label or the curved former?

It's mainly the start of the dies. The curved bit. But the holder also puts a little dink in the pipe.