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sounds like you are ringing the wrong people. just buy individual bends and all you need is 2 welds. custom made mandrel bent pipes cost a fortune and very very few people would make use of them

jnt performance.com.au

I have the pipe made up out of pipes from cooler kiit, but it was for a pipe that runs across top of the engine and i wanted it to look schmik,no welds,..but not at that price

Lucky for me scotty is nearby and welded up the rest of my intercooler pipe madness , did a damn fine job too, but unfortunately i lost my phone with pics on it and its all painted up and hidden now...so i cant show ya.. :P

Ok, heres how to make a DIY lobster back bend:

1, Buy some pipe your going to use, this being stainless steel, you can use a wood cutting mitre saw for alloy pipe much easier but you wont get the same look as stainless.

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2, work out the distance, you have to work in and need the bend to fit,

in my case it was 90mm by 90mm

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3, set the bend out on paper(best thing i found was MDF sheet).

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4, ok this is where it gets a little tricky, take the life size measurements from that scale drawing, So if your using 3" pipe make shure the ends of that bend are 3", once you get the outside dia from the bend and the angle of the bend being 90". put all these measurements into a program found here (http://www.tyharness.co.uk/lobsterback/lobsterback.htm)

What this will give you is the amound of segments you want and a template you can transfer over to the pipe.

5,once you have the desired pipe and abount of segments you can transfer the measurements on computer to paper, what you see there is the measurement from the centre out in incriments of 10mm.

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6, transfer to a template, i used the cheap plastic cutting board you buy from the shops, its sturdy but not to flimsy, just cut with a pair of scissors.

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7, Tape the stencil together while on the pipe, much simpler this way,also not to tight.

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8, Now your ready to mark it out on the pipe, 1st put a straight line accross the pipe, this will be your center line so you dont get lost with the stencil markings.

Once you have marked the 1st segment, blow on it or wait for the marker to dry or you will smudge the line out, now spin the stencil around the pipe so that the smallest part of the stencill matches with the widest part of the previous marked segment, also remember to leave a slight gap between each segment for the thickness of the blade and other discrepencies.

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9, Once you have done a few you are now ready to cut, i would say about 10 is enough till you need more, otherwise you waste it.

first things first, wear thick gloves cause it gets hot, use a grinder with a 1mm cutting blade, buy about 10 because one blade is good for about 8 full cuts,

I layed the pipe on sonething with the stand having the ends holding the pipe in because i turned with one hand slowly while cutting the pipe, dont force the grinder, let it cut, if you keep it at the angle of the line at all times you should get a nice cut, but the 1st few always turn out bad, also wear Ear protection and Saftey glasses, if you get a bit in your eye, you will have to go and get it drilled out, they hold your eye open while your awake, never happened to me but i was told thats what they do.

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10,End result, your peices should come out like this, also for a better weld its best to grind each end of the segments flat on a bench grinder, using 120 grit (rhyno) stickon pads, buy quite a few cause your going to need them, also wear thick gloves because you thought these get hot on the grinder, its 5times worse on a bench wheel.

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11, fitment Just line them up where you want them, i could only hold a few at a time, tape together as you go.

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I bought mine to a fabricator to tack up, because i am no fabricator, i just decided to have a go.

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Edited by 24jzgte
Yeah it did take ages, this is just a practice run till i get my hands on some Ti and some one who can weld it.

If you can find some, let me know, the best I could find was full sheets at 2k each (Airport Metals), then I would have to get it rolled.

Fark that!!!!!!!! Im with zebra. They are fricken painful to do and I also dont have the patience. Mandrel bends ftmfw!

I do remember doing that at tafe, drawing the part and doing the layout for it and then transfering it to a paper cutout and taped together to wrap around steam pipe. I recall alot of frustration. The worst part of all that would be the amount of tig welding.....talk about time consuming.

  • 3 weeks later...

24jzgte nice work. I actually downloaded that program a while back and had a play with it.. Is it much more effective doing it that way than cutting 7 degree segments with a friction saw? Obviously the friction saw method is alot quicker, but does using the templates give a better finish? I just dont like the idea of cutting them with an angle grinder because if there is a 1mm gap and your trying to fuse weld it with the tig your going to blow through and need to filler rod it with looks messy on piping IMO.

As for the getting metal in your eye, ive done it 3 times in the last 2 years (at work) but now even at home I wear a face shield if using an angle grinder, as glasses aren't 100% effective. Only once I had my eye drilled, that was because I was hoping the metal would come out after a bit, and 7 hours later it had grown over :rofl: NOT ADVISABLE... only get one set of eyes, look after them people

This is the "Pro Weld" Tig welder I purchased off ebay for $850 delivered (not same brand as one in pic, and its red, but same internals)

Thats the 14" Hitachi drop saw I got for $350 brand new delivered on ebay too. Pretty happy with both of them, can't fault them yet

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  • 2 years later...

So everybody seems to be setting there saws for roughly 7 degree cuts.

What length does every one cut there segments ?

It does that vary which every bend ?

Any sort of guide ?

The angle and length of the segments will determine the radius and how "round" the lobster looks so it comes down to how much room you got and whether you want it to look like a mandrel bend with lots of welds or a few straight pieces of tube joined together.

I made mine 5 degree's and about 22mm long on the long side.

There is a few pics in this section somewhere

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