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Bend Tolerance?


Warthog
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Evening all,

What level of deformation/flattening generally would be acceptable in a bend tube/pipe?

On 1 1/2" Pipe, 1.900" Diameter. I am experiancing 80 thou on diameter of deformation/flattening through the actual bend.

Havnt got an example of a stock cage present to compare at present.

I'll put a piccy up if my description sucks......... :huh:

Cheers

Mark

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Aspect ratio > 0.9.

(So diameter 1 = diameter 2 +/- 10%).

I think... Al.

So i should be looking at 19 thou differance on 1.900" Dia

Cheers Al

Would the wall thickness change the parameters? Using 1/8th wall (0.125")

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What are you using Tube / bender and former.

If they are not 100% matched you will find the wall will ovalate (if there is such a word - come on you know what I mean :P)

However this is different to wall failure where when you rub your paw around the curve on the inside you can see / feel 2ridges" and "Ribs" which indicates too tight a radius

There is a difference between the 1st and the 2nd, the 1st is sort of OK ish live with it due to equipement, the 2nd is dangerous and risky with the ribbing

HTH and makes some sense, without a full manderl bender you are going to get deformation, and more than you might wish for, so no 1 and 2 can be the key towards compromise

nige

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Yeah, I meant the first case - ovalation - difference between diameter in plane of bend and 90 degrees to the bend.

If you are getting creasing of the tube at the bend, then its getting a bit crappy. (But I don't think thats what you meant?).

Wall thickness shouldn't change the criteria I don't think.

Al.

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Yeah, I meant the first case - ovalation - difference between diameter in plane of bend and 90 degrees to the bend.

If you are getting creasing of the tube at the bend, then its getting a bit crappy. (But I don't think thats what you meant?).

Wall thickness shouldn't change the criteria I don't think.

Al.

I have seen a lump of Blue band go into a former in a cr*ppy bender and it sort of went horrible

Then a the same OD but Red Band and it was fine, the only difference was the wall thickness.....

However the bender was more at fault via the former than the Blue band which was BS1387 and I benmt it fine with a better former.

Its all connected / interlinked

Tube qulaity and wall thickness, bender and former / radius

Nige

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A bad workman blames his tools... :P

No seriously, yes of course its linked, but I don't think the 90% rule has any allowance for wall thickness - I mean it should be within that aspect ratio regardless of wall thickness.

I have no idea (full stop?) how to judge how much rippling is 'too much'. But not a lot I guess...

Al.

:)

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I cannot blame the Bender (JD2 Mod3) I am using dies that are for 2" Tube. But have been testing 1"1/2 Pipe 1.900" Dia. Why you my ask? Well i have a good few metres of Galvanised pipe to practice with, but i am not going to use it for any production of parts. But if it were to have satisfactory outcome bending Pipe in with the 2" dies? Then i had the possibilty to use Bluband with the same die set.

No krinkly effect, but some oval deformation. Using Al's formula the "Galv Pipe" is coming out with a higher percentage than 10% more like 25% <_<

Here's a few piccies, to get an idea of what the bends are looking like:

IMAGE_3.jpg

IMAGE_2.jpg

IMAGE_1.jpg

I know Galv pipe is poo! But its available to get to grip with the bender characteristics.

Cheers

Mark

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AH HA !

Gavanizing tube changes it in a massive way, amkes it more brittal amongst other things (ask a grown up to exactly what).

So, bending Galv pipe will give a differeing result to bending non galv pipe

Then as you have sussed your bending an OD Pipe with the wronbg former :)

So, all in all when you move on to either non galv or I'm guessing CDS with the right OD things will be far better than now

As to Als "How much is too much" Q, its difficuly, but if you can seriously feel and then see the ripples then its too much IMHO - thats why Jon W and I made our cages the Cr*p being offerred to us inc delivered by a well known compnay went back with the courier as the inner was rippled to hell :o

Nige

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80 thou in 1.9" is 4% so is well within the 10% limit for a 0.9 aspect ratio, 10% is 190 thou not 19.

Knew there was a reason why i should use a calculator and a not my fingers and toes........

:hysterical::blush::rolleyes:

Well spotted........... Cheer Mark90

By the way the pipe in the piccies is bent to 93 degrees not 90. ;)

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Knew there was a reason why i should use a calculator and a not my fingers and toes........

:hysterical::blush::rolleyes:

Well spotted........... Cheer Mark90

By the way the pipe in the piccies is bent to 93 degrees not 90. ;)

Don't let 3 degress get in the way of a good song

Nige

I've got me coat and am leaving OK ?

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Measured the difference on a couple of cages yesterday. Both from a reputable cage manufacturer. The bends averaged around .120" difference through the bend area opposed to the pipe original diameter (1" 1/2 Bluband 1.900 Dia average bend deformation diameter 1.780")

So im gonna take that as a guage on what would be acceptable. Which equates to the bends im producing are good enough :i-m_so_happy:

Mark

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