View Full Version : Bending 1.5" 2mm thick tubing/Making template
Right heres the scenario:
Car is off the road, want to make up door bars and dash bar.
But obviously its got to bend. Now theres no hand hend pipe bender that will acommadate 38.1mm OD tubing, nor anyone thats strong enough to bend 2mm walled pipe! SO that idea's out the window.
A hydraulic pipe bender is designed for gas barrell, which is 5mm thick walled, so just crushes my CNC tubes. (tried it!)
So im stuck with needing a mandrel bender.
But obviously I dont have a spare ?5k, so cant get one of those!
So what i need to do is make up a template from something, then take my template+CNC tubes to a place to have them bent, anyone got any ingenious ideas?
Thanks
Paul
meritlover
29-01-08, 05:10 PM
you can fill thin walled pipe with sand and pack it hard. then you block off the ends to seal in the tight packed sand. this lets you bend thin walled pipe with a hydraulic bender ;) this is how i make my exhausts. its a pain and its messy. but it gets the job done in the end.
id suggestion trying it first on old exhaust pipes. happy bending.
kiln dried sand method eh, apparantely this will also not work...
meritlover
29-01-08, 05:21 PM
why will it not work if done properly? i use just a ordinary building sand.
how do i pack it tightly then?
Seal one end, pour in sand, tap on floor, repeat until full, then seal other end apparently. Adding water can help too, but I've tried neither myself.
Just take it to an engineering firm and tell them what you want, far easier and will probably cost a few beer tokens max :)
meritlover
29-01-08, 05:48 PM
i tend to crimp one end in the vice. fill with sand compress with a broom shaft and then crimp the other end. bend the pipe then saw off the ends and empty the sand. the pipe will obviously have to be over length before bending and the bend position will have to suit the fact that the ends will be removed.
yeh ideally I'd like to take it to an engineers to have bent.
But the thing is my cage is welded into the car, and my car is inbits still, so i need to make a template up somehow?
The template ideally needs to obviously keep its shape whilst its carried from workshop to engineers...
As they're door bars leave them stright, as a race car would have them stright. Cut each end at a angle to suti and either have one or make a cross with them,
dont forget the bit that comes down the A pillar and were the dash goes, thats got a slight bend in it benn..
KITT1972
29-01-08, 06:34 PM
why dont you make all the bar with copper pipe that you would use for plumping. yes its thinner but will hold its shape its yes to bend and easy to cut. you can use a pipe bender or use the springs that go inside the pipe while you bend it. I have one for 22mm pipe if you want to borrow it.
http://www.screwfix.com/prods/12076/Hand-Tools/Plumbing-Tools/Pipe-Bending/Monument-Tools-Pipe-Bending-Spring-22mm
What you making, Doorbars ??
Surely you can make them up without needing to bend the tubing ? Just have a single diagonal or make an X bar.
You lads like doing things the hard way lol
Take it youve never heard of pipe springs then (although incredibly hard to source in massive diameters) :thumb: and an Oxy torch hired from HSS :D
Copper tubing is a good idea yes, but it wont work without miticulous maths. As the smaller diameter pipe will end up bent at different angles to that of a larger pipe.
The angels of the copper will be smaller as its a smaller diamter tube.
right the door bars cant be straight as the cage has saddle brackets already on it for them, they do line up straight and i wish to mount the doorbars to the existing saddle brackets.
As for the copper pipe, that seems like an extremely good idea, as then i can get the Internal radius of the bends correct, and just have the CNC tube bent to match the Internal radius of each bend yes?
Paul
paulshears
29-01-08, 07:39 PM
i work for a hydraulic engineering company on the stores side
38x3 is popular in the marine industry
the lad's on the fitting side of the company have no trouble bending it with a hydraulic bender
The Simps
29-01-08, 08:28 PM
From what I saw on American hotrod they made a card template.
All you need is a contour for them to bend to.
you need a mandrel bender to prevent the pipe form collapsing (if you dont so the sand method)
you "could" use white waste pipe to get the size/length etc, bend might be tricky but you could get bloodly close. then get that replicated in steel
you need a mandrel bender to prevent the pipe form collapsing (if you dont so the sand method)
thats what a pipe spring does :thumb: stops the diameter on bends getting smaller, same as a mandrel.
hmm white waste pipe
i then could heat that up with a blow torch, and bend like that....
Where do i buy the plastic tubing from?
Thanks for all the input by the way gents :)
Paul
Oh yeh and where the funk can you buy saddle brackets? :(
Without paying ?20 per pair!
http://www.merlinmotorsport.co.uk/images/wobm.jpg
KITT1972
29-01-08, 10:00 PM
plastic pipe you can get from plumb base, homebase, b and q very cheap
Saddle brackets can be bought direct from OMP or Sparco :thumb: try Chris Astley, he may be able to get you some too
excellent, i have some 25mmx5mm bar, so i was kind of hapoing an engineering place may knock me some up, just wondering if they were used in anything else.
I'll see how much they are
Excellent, thanks very much for you help gents!
Do plumbers etc use a 38mm pipe, anyone know?
38mm is standard size roll cage tube for the likes of rear legs that mount to inner archs etc
yeh i was wondering if i can get the plastic pipe in a 38mm OD?
You lads like doing things the hard way lol
Take it youve never heard of pipe springs then (although incredibly hard to source in massive diameters) :thumb: and an Oxy torch hired from HSS :D
Copper tubing is a good idea yes, but it wont work without miticulous maths. As the smaller diameter pipe will end up bent at different angles to that of a larger pipe.
The angels of the copper will be smaller as its a smaller diamter tube.
Pipe springs are ****e, even if you could get them that size. And the angles would be no different on smaller diameter pipe, an angle is the same regardless of the material being bent.
Paul, can't you trailer the car to an engineering firm? making a template seems like too much hassle, and it'd be a shame to get the tube home to find it's wrong:cry:
Right, popped down to the plumbing shop this morning, was going to try the plastic pipe idea.
But as we walked in me and my mate both looked straight at the same thing, which is a 38mm OD hollow foam insulater (for copper pipes I think?) So we bought that and some 15mm copper pipe, with a pipe spring to fit.
The idea was to bend the copper pipe to shape, and the foam would follow the shape of the copper tubing and be 38mm so it would fit in the saddle brackets. Seemed to work ok, apart from getting the spring stuck a few times and ending up cutting it in half, doh! lol
Just taken them to be mandrel bent, popping back to the workshop this evening to see how well they fit.
Ill keep this updated and let you know how it goes!
Pipe springs are ****e
:confused: ive never had an issue with them at all??
first time i used one today, and seemed to work fine, apart from getting stuck in the tube a few times?
first time i used one today, and seemed to work fine, apart from getting stuck in the tube a few times?
If its not already got one, bend one of the end coils of the spring into a loop, and attach a lenght of wire/rope etc to the end, thus you can pull it out after bendyness
Well, I'm glad to say it worked a treat! Thanks for all your ideas, I was a little bit stuck last night! :thumb:
Anyway, for those who may be interested in how it turned out:
The template:
http://img.photobucket.com/albums/v14/lashednova/DSC00285.jpg
Dash bar, bent needs cutting + brackets making:
http://img.photobucket.com/albums/v14/lashednova/DSC00286.jpg
Door Bars:
http://img.photobucket.com/albums/v14/lashednova/DSC00284.jpg
http://img.photobucket.com/albums/v14/lashednova/DSC00282.jpg
http://img.photobucket.com/albums/v14/lashednova/DSC00283.jpg
All said and done, I now have to either spray the cage before paint, or just get the bars painted/powdercoated.
Stands me in at ?80 for a rear strut, a pair of door bars, and a dash bar, which IMO is very good :)
Paul
They're quite low... should they not be higher up at the back?
Looks good tho.... get that shell rubbed down!
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