Tube bender?

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David Leikvold
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Tube bender?

Post by David Leikvold » Thu Nov 01, 2007 8:37 am

Does anybody in Brisbane have a proper tube bender? I want to start building my roll cage and I've been in touch with every hire place but all they have is pipe benders which are not the same and are useless for making smooth bends in tube.
One place in Melbourne will sell me a proper semi circular former for 2" tube for $185 but he said it will still wrinkle the inside of the tube. Why would anyone want that?! And that's not even the whole bender, I'd still need to make the matching roller and the frame. If anyone knows where I could find some thick steel plate, ideally more than 2" thick and about 16" square I'll make my own. I could probably make it with 3 pieces of 1" plate if anyone is tripping over bits of that.
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Dr Goggles
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mock-up

Post by Dr Goggles » Thu Nov 01, 2007 11:04 am

if you make a 1:1 mock up and get chummy with a custom exhaust joint you could be in luck....I was talking to a header manufacturer here in Sunshine who said he could have made ours very nicely...
...few understand what I'm trying to do , but they vastly outnumber those who understand why..

David Leikvold
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practical

Post by David Leikvold » Thu Nov 01, 2007 10:52 pm

I think you might just be right Doc, even though I can't help wanting to have my own bender, making one would waste a lot of time and effort. And as you alluded to recently, these projects can drag on so easily if you let yourself get bogged down with unnecessary detail.
I must keep reminding myself that I only need 9 bends to do the whole job, everything else is straight. And with the engine mounted and the rollcage done, there's hardly anything else left to do. I wish!!
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Post by DLRA » Fri Nov 02, 2007 7:48 am

Good one Doc that was going to be my tip as well.
Done it before and works a treat.
Used heater hose (the one for air not water), bent it to shape and that was the template. Worked every time. If you know how many degrees they can do that to.
Keep the shiney side up........
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BIG GAZ
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Post by BIG GAZ » Fri Nov 02, 2007 8:57 am

David you are exactly right! Don't get bogged down in the detail but it is necessary to think things through. Like I said to Big Paul, building a salt car first time around is like getting a thousand piece jigsaw puzzle where every peice is numbered and has to go together in that sequence, just that they forgot to put the numbers on the peices!
I 'wasted' a lot of time on deciding to do my own cage and was lucky that I found someone to do the four bends that I needed. The less bends the better all round. Even if you had to put the car on a trailer and take it to the exhaust place when they are quiet it would be worth it, doesn't matter what they charged you. Just make sure the cage comes as close to the body as possible. I was able to weld the three basic parts of the cage while it was outside the vehicle (hoop& diagonals, rear legs & diagonals, and front legs) and then assemble inside the car for the last couple of welds. I used a 4" angle grinder to do the notching which had to be pretty accurate for the TIG. If you are going to MIG then it is not quite as important. Let me know how you go, I would be only to glad to help if I can. I would imagine you are using cold drawn seamless m/s?
BIG GAZ

David Leikvold
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Thanks fellas

Post by David Leikvold » Sat Nov 03, 2007 10:50 am

Doc, Greg & Gaz,
Thanks for your advice gentlemen, I could see myself heading off on a tangent for a while there. Sometimes the obvious answer isn't so easy to see.
I hadn't really considered exhaust shops because many of the exhaust pipes I'd seen had lots of deformation on the inside of the bend. Then it dawned on me that most of my bends will be very shallow angles anyway so the deformation won't happen. The biggest bend will probably only be about 60 degrees in the top of the main hoop and it will have diagonals welded into the middle of the bend so it will be OK too. I'll do a mockup with degrees measured and marked and let you know how it goes. Might be a while yet, I'm still mounting the engine.
As for the chosen material, I hadn't really considered anything other than ordinary mild steel. I had arbitrarily decided on 50mm x 3mm because I figured a bigger diameter is better but you've got me thinking again now. Is the cold drawn seamless much stronger in real terms than mild? If mild bends when I'm bouncing along the salt suddenly wishing I'd stayed home I won't use it.
Way back in 1981 I was building an EH Fender Bender for Parramatta Speedway (I was desperate to race again, gimme a break!) and I tried to cut curves in tube with an angle grinder. It wasn't pretty, so this time I'm buying a 50mm hole saw for my drill press just to ease my pain.
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Dr Goggles
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Rusty Cage

Post by Dr Goggles » Sat Nov 03, 2007 5:20 pm

We used black welded pipe.... :shock: :shock: :shock: however, not many people will have a cage that has such short runs as ours does and our drivers compartment is almost completely plated in.That said there are probably people who think we're mad...to them I say this .The force required to split that pipe will subject the occupant to a force that they will be lucky to survive whether they are crushed or not . Or , as a certifying engineer once said to a guy ahead of me who was asking about making bigger seat belt reinforcing plates, " by the time you've pulled that 3 by 3 piece through the floor of your car mate the seat belt will have cut you in half , regardless of whatever else happens you'll be in a spot of bother" . If I was building a cage like yours I would use the CDS , costs heaps more but when you've got long unsupported runs it's important to have high consistency because it's only as strong as it's weakest point....

Daryl Chalmers who ran a TC Cortina and now has an EL Falcon with Stew' Pennycook was telling me last weekend that they built the cage in the EL to have a lot of room between the body and the cage .His reasoning was that unlike a track car it wasn't needed for body bracing and if the car did roll that it would allow the body to absorb a lot of energy lessening the number of times it might tumble . Daryl tunes BMW's for racing so he sees a lot of cars .

As for notching and cutting pipe I found this. As a part timer at it it is very difficult to get the measurements exact , it is difficult to "nip a bit off" with a hole saw . If you cut a 90 degree point on the tube you can use a flap disc to round the tip off and to chamfer the inside of the tube to get a very nice fit...this way you can "fiddle" it in a bit if it is difficult to determine the exact length you need......This may well be unnecessary in what you are doing .In our build we didn't mock it up first...so there were pieces that had to go in to places that were difficult to accurately measure.....

All i'm getting at here is that a hole saw is the perfect way to do it , if the measurement is perfect...if it's not , it's um , not.

Hot tip: cut your longest bits first working your way down to the shortest , why? when you stuff up by cutting one too short there'll be something else you can use it for.
:wink:
...few understand what I'm trying to do , but they vastly outnumber those who understand why..

David Leikvold
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oh duh!

Post by David Leikvold » Sat Nov 03, 2007 7:06 pm

Doc,
I mentioned your suggestion today to my 15yo daughter who rolled her eyes, as most teenagers do, and said "Dad, go to Gun Exhausts in Stafford, they do all that sort of stuff". They are literally just down the road so I'll try them first, the place is always full of hot cars and they do turbos and intercoolers too.
As for your black pipe being strong enough for your application, your engineer mate is right, by the time it fails so has the driver. All it really has to do is maintain a survivable volume around you.
I like the idea of deforming the body first to absorb some energy before it starts on the cage. At this stage I'll have no barwork in front of the windscreen, slightly less on the left hand side of the cockpit and hardly any in the boot so that's a start. My half of the cockpit will have more steel than Simsmetal and the whole thing will essentially be a V8 Supercar style cage with most unsupported lengths only a couple of feet long and more triangulation than a geometry class. Plus I'll be bolting it to every available threaded insert in the body to help tie the two together better.
Most videos I've seen on You-tube seem to have sedans spinning 180 degrees, getting some air NASCAR style, then landing on the roof and sliding to an undignified halt with the parachute wrapped around the back axle.
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whitworthsocket
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Pipe Bender

Post by whitworthsocket » Sun Nov 04, 2007 1:44 am

David,
If you have no luck with the exhaust place. Telephone around a few big engineering workshops. Or try some of the steel suppliers. If you are only after black pipe they might just have some bends in stock.Ask for 90 deg sweep bends.
In the west I would try pipeline supplies (PSA). There should be a branch or an equivalent in QLD
Regards
Whitworth

whitworthsocket
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But wait there's more

Post by whitworthsocket » Sun Nov 04, 2007 2:04 am

If you do decide to build a bender this is one of the better homebuilt efforts.

http://www.metalwebnews.com/howto/tube- ... ender.html

And If you are bending seamed pipe make sure the seam is on the neutral axis. That is if you are bending the pipe in the horizontal plane the seam should be facing directly upwards or directly downwards.

Regards
Whitworth

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Greg Watters
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Post by Greg Watters » Sun Nov 04, 2007 8:23 am

I have bent exhaust tube by sand packing it and heating ,
can similar be done on thickwalled pipe ,
would using a bender on a sandpacked pipe keep its shape?

David how were you cutting the speedway car pipe ? blade edge making a V or angle cut the pipe making a C ?

David Leikvold
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more ideas

Post by David Leikvold » Sun Nov 04, 2007 10:00 pm

Thanks for all the input fellas, it really helps to get good advice from everyone on this forum. At this stage I'm tempted to use the cold drawn seamless tube but this very much depends on price and availability. If I use plain welded ms tube I'll remember whitworth's advice about seam placement.
For the moment I won't distract myself with making a tube bender. When the car is further along I might build one just for fun. It might come in handy for future car builders in Qld. For mine I like the simplicity and speed of using an exhaust shop. I bought one of those big builder's protractors yesterday so I now know what angles I need.
When I was building the EH I think I started with a hacksaw and finished with the angle grinder, a very poor way to do it. Doc's idea of an arrow head cut makes good sense, a straight cut at 45 degrees gives a perfect semi-circle. I'll do my initial cuts with a hole saw and if I get it wrong I can then attack the perfect curves with the grinder. And I now have a Supercheap hot saw that cuts perfect 87 degrees cuts, so I'll manage.
I sand bent the exhaust for my Formula Vee but this time I'll take the easy way out. A rollcage would use lots of sand packing and lots of gas axe.
Good, Fast, Cheap, pick any two!

David Leikvold
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how much??!!!

Post by David Leikvold » Mon Nov 05, 2007 11:16 pm

I rang British International Trading in Sydney today. They have stock of 2" x .120" Racetech 350 CDS/DOM tubing. It costs $27.24 a metre and comes in "random cut" 6 metre lengths. That's $163 a length, give or take a few cm and a few dollars. I hadn't given any thought to how much tube I would actually need for this wonderful cage I have planned, so tonight I measured up. Wow, all up I'll have about 45 metres of tube which will weigh about 160kg. Sure adds up fast! And all that weight is doing something useful. If I bought the lot in R350 I'd need 8 lengths and be spending about $1,400 including freight.
Time for a rethink, this car was inspired by Matthew Saunders' remarkable value for money Fiat E/GCC and has to be cheap or I won't be able to do it. So here's what I'll do. I'll use the R350 for the main hoop and the roof bars and some other critical tubes on my side and I'll use mild steel for everything else on the left hand side where I don't care so much if it bends. That should come much closer to halving the cost. I'd better price some mild steel now.
Mr Socket, that bender is a good one, a guy in Perth, Neil Marnie (the back shed) has a good site with even more ideas.
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DON NOBLE
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Post by DON NOBLE » Tue Nov 06, 2007 9:42 am

I get my pipes bent up by a company called RGC Metal Rolling and Bending at Beenleigh ph 38047385
NOW LIVE IN NEW ZEALAND
RED NISSAN WAGON 1986 # 281
2002 F/PRO 125.4 MPH RECORD
2003 F/PRO 140.2 MPH RECORD
2005 F/GC 137.9 MPH RECORD
2006 F/GC 141.1 MPH RECORD
1/4 mile ( drags ) @ Willowbank 14.15 @ 97.61 mph August 2006

David Leikvold
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thanks

Post by David Leikvold » Tue Nov 13, 2007 10:39 pm

Thanks Don, I got distracted and put more of this story on my Celica thread. There's an off road buggy place in Stafford that will probably do it for me. And barring unforeseen circumstance I'll be at the Christmas party, hopefully with some progress photos.
Good, Fast, Cheap, pick any two!

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