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The art of pipe benders etc...?


Seedy Al

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Hey chaps

So I have bought some tube to make a few bikes out of, mainly Slamcycle veladrome racer.

Pipe I have chosen is 1.5inch with a 2mm side wall

I have borrowed a hydrolic pipe bender from our Engineering department, and just had a crak at trying some bends.

Basicly its just crush tube central

So what Have I done wrong?

Should i be using a thicker wall thickness tube? I dont really think I am trying to bend if to far, campired to some exhuast bends I have looked at, they crush mothing liekt his.

Should I try packing the tube with sand and capping the ends? I have heard of this before but never tried...

Suggestions?

I got all excited and now that excitement has trned into me just wanting to opena beer and forget about it haha

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I've heard the sand trick works

I go down to the exhaust shop and get them to do mine, take a cardboard template of the angle I want.

Haven't had to pay them anything yet as they like talking about what you're building :)

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sand does work but i use lead sinkers strung on an old clutch cable with a crimp at each end to hold them together,

make sure you leave the adjuster on and hanging out so you can slide hammer your poor mans mandrel out of your bend's,

have seen one made with big ball bearings also that worked even better but lead sinkers are easy to source.

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Those hydraulic press type benders are a waste of time. You really need the type with the semicircular die that the pipe is pulled around as this doesn't compress it.

A bit of heat while your doing it might help the outer radius to stretch instead of compressing the inner radius though.

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If you are using the "bow and arrow" type bender, these are meant for pipe, not tube, and have pipe sized dies.

I doubt you will get a good results, especially with thinwall tube. I got the rollbar bent (for my paddock basher) in the local garage's exhaust pipe bender, which does a decent job, but crushes the tube somewhat.

The rollbar (same size) for my Morris project was bent by the shop that built it, and is nicely done, with no crush. I didn't see what type of bender they used though.

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And from memory the way you measure them is different, one is normally measured nominal bore and the other (tube I think) is usually measured on the OD?

The 3 point press benders work quite well if you are doing pipe and have the correct size former/die - it needs to be tight on the pipe to stop it deforming.

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Reminds me of this: Some basic guidelines.

1. All pipe is to be made of a long hole surrounded by metal or plastic

centred around the hole.

2. All pipe is to be hollow throughout the entire length - do not use holes

of different length to the pipe.

3. The ID (Inside Diameter) of all pipe must not exceed the OD (Outside

Diameter) - otherwise the hole will be on the outside.

4. All pipe is to be supplied with nothing in the hole, so that water, steam

or other stuff can be put inside at a later date.

5. All pipe should be supplied without rust; this can be more readily applied

at the job site.

NOTE: Some vendors are now able to supply pre-rusted pipes. If available

in your area, this product is recommended, as it will save a great deal of

time at the job site.

6. All pipe over 500ft (150m) in length should have the words "LONG PIPE"

clearly painted on each side and end, so that the contractor knows it's a

long pipe.

7. Pipe over 2 miles (3.2km) in length must also have the words "LONG PIPE"

painted in the middle, so the contractor will not have to walk the entire

length of the pipe to determine whether or not it is a long pipe or a

short pipe.

8. All pipe over 6ft (1.83m) in diameter must have the words "LARGE PIPE"

painted on it, so the contractor will not mistake it for small pipe.

9. Flanges must be used on all pipe. Flanges must have holes for bolts,

quite separate from the big hole in the middle.

10. When ordering 90 or 30 degree elbows, be sure to specify left-hand or

righ-hand, otherwise you will end up going the wrong way.

11. Be sure to specify to your vendor whether you want level, uphill or

downhill pipe. If you use downhill pipes for going uphill, the water

will flow the wrong way.

12. All couplings should have either right-hand or left-hand threads, but do

not mix the threads otherwise, as the coupling is being screwed on one

pipe, it is being unscrewed fron the other.

13. All pipes shorter than 1/8in (3mm) are very uneconomical in use, requiring

many joints. They are genreally known as washers.

14. Joints in pipes for piping water must be water-tight. Those in pipes for

compressed air, however, need only be air-tight.

15. Lengths of pipes may be welded or soldered together. This method is not

recommended for concrete or earthenware pipes.

16. Other commodities are often confused with pipes. These include: conduit,

tube, tunnel and drain. Use only genuine pipes.

17. Scottish Regiments in the Army use Army pipes in unusual ways. These are

not approved of in engineering circles.

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