Fill sch 40 with water to prevent kinks?

3152 Views 39 Replies 28 Participants Last post by tech, Dec 28, 2006

tech

Discussion Starter · Dec 13, 2006

so heres the scenario i've got the hf kninko-matic bender and i'm trying to bend 1" sch 40 for bumpers but its just kinking bad. its kinking on the side against the die and "flat spotting" on the other. the die has alittle gap on the sides of the pipe, but i know my pipe/die sizes match. i've lubed everything good.

heres my idea... fill with cold water, seal and cap both ends, then heat pipe to room temp, thus creating hydrulic pressure inside the pipe to prevent kinking. what you guy think?

i've tried using sand and it still kinks, may not be enough in the pipe? has sand worked for anyone?(personal experience, not "i've heard so and so")

1 - 20 of 40 Posts

Wicked_S10

· #2 · Dec 13, 2006

I think that you will probably injure or kill yourself if you do that. I have seen hastelloy schd 80 pipe burst just due to the fact that both ends got valved off and it sat in the sun. And that is not even considering the added stress of bending it. The die should be tight. Keep taking it back to HF until you get a good set of dies. That or order some shim stock, and shim the dies.

Later,
Jason

Richard

· #3 · Dec 13, 2006

I have heard of using sand

FF3PM

· #4 · Dec 13, 2006

I have used sand and it helps a lot and will not explode on you.

jays68yak

· #5 · Dec 13, 2006

Make the bend in 3 spots rather then 1.

For each mark bend a third of the bend.

| | |

If you are bending 1 1/4 pipe, then thats what I would space each spot.

Does that all make sense?

300sniper

· #6 · Dec 13, 2006

if sand didn't work for you i highly doubt water will do anything better.

...unless you could fill the tube with water and freeze it where you are going to bend it so it is effectively a solid bar. i have no idea how you would do that with out splitting the tube in the freezing process.

tech

Discussion Starter · #7 · Dec 13, 2006

for those who have used sand...

how full did it have to be, packed in?

how did you cap it? tape or welded? ie. how strong does it be?

72fj40

· #8 · Dec 13, 2006 (Edited)

I've use sand all the time and it works OK. I cap 1 end w/flat stk tacked in a couple of spots. Tacked enuff so I could knock it off w/a hammer(some times i have to grind). Fill w/sand tap the pipe on the ground to compact it a little and then fill to the top. Then tack another piece of flat stk on end then bend. Do all your bends b4 knocking off flat stk. It doesn't have to be jam packed..

Are you sure your using the right die? Pipe size is measured on the ID. 1" schd 40 will have 1.315 od, 3/4 pipe will have 1.05 od. Tube is measured on the od.

Trick-Tools.com

· #9 · Dec 13, 2006

tech said:
so heres the scenario i've got the hf kninko-matic bender and i'm trying to bend 1" sch 40 for bumpers but its just kinking bad. its kinking on the side against the die and "flat spotting" on the other. the die has alittle gap on the sides of the pipe, but i know my pipe/die sizes match. i've lubed everything good.

heres my idea... fill with cold water, seal and cap both ends, then heat pipe to room temp, thus creating hydrulic pressure inside the pipe to prevent kinking. what you guy think?

i've tried using sand and it still kinks, may not be enough in the pipe? has sand worked for anyone?(personal experience, not "i've heard so and so")

What size is the die? How tight are you trying to bend it?

tech

Discussion Starter · #10 · Dec 13, 2006

i'm using a 1" die and 1" sch40. i'm trying to bed some 45's and some 90's for bumpers. the pipe starts to kink at about 22* and is ruined by 45*. it would be a "v" by the time i got a 90* bend!

tech

Discussion Starter · #11 · Dec 13, 2006

Wicked_S10 said:
I think that you will probably injure or kill yourself if you do that. I have seen hastelloy schd 80 pipe burst just due to the fact that both ends got valved off and it sat in the sun. And that is not even considering the added stress of bending it. The die should be tight. Keep taking it back to HF until you get a good set of dies. That or order some shim stock, and shim the dies.

Later,
Jason

googled it, 1" sch 40 has a burst rating of 15171psi and a working pressure of 3793psi

72fj40

· #12 · Dec 13, 2006

I've bent pipe 90* in that size w/sand in it w/no problems. So the OD of your
pipe is 1 5/16"?

tech

Discussion Starter · #13 · Dec 13, 2006

72fj40 said:
I've bent pipe 90* in that size w/sand in it w/no problems. So the OD of your
pipe is 1 5/16"?

i'm using the home depot chinese pipe, what were you using when you bent your 90s?

Trick-Tools.com

· #14 · Dec 13, 2006

tech said:
i'm using a 1" die and 1" sch40. i'm trying to bed some 45's and some 90's for bumpers. the pipe starts to kink at about 22* and is ruined by 45*. it would be a "v" by the time i got a 90* bend!

Do you have a ram bender or a rotary draw bender? This is critical:

If you have a rotary draw bender, what is the CLR (center line radius) of the die?

If it is smaller that a 3.5" CLR you could have problems trying to get a good looking bend.

The tighter the bend, the thicker your material has to be. The thinner the material, the larger the radius needs to be. There has to be enough tube wall thickness to support the bend without collapsing, rippling or kinking the tube. Moving to a larger die usually helps with this problem.

72fj40

· #15 · Dec 13, 2006

tech said:
i'm using the home depot chinese pipe, what were you using when you bent your 90s?

I was using used sch 40 1" ID 1 5/16 approx OD and some sort of Harbor Freight style hyd bender. We paid like $89.00 for it. I think I had the rollers closer to the center.
Nothing special!

Big_Ern

· #16 · Dec 13, 2006

quite possibly its the type of the pipe you're using and not the bender or method of bending.

A buddy of mine had this problem build his bumpers & sliders. He had a few sticks of pipe that bent perfectly with no kinking. But then he ran out and got some more pipe, but it was a slightly different type that kinks very easily. If you're interested send me a PM and I will ask my friend what markings where on the pipe that bent better. I do remember the good stuff had a smoother finish/coating on it though and had a bit of a redish tint to it (not rust tho) where as the crappy stuff was the starndard black finish.

Stuckle

· #17 · Dec 13, 2006

i got this aaron

we have 2 different types of pipe we get up here.

one is the cheep ass black stuff. Probably like what you get from home depot.
it is cheeper to make, therefor the company makes mre money off of it. BUT the quality just isnt there.

we also have pipe with a glossy dark maroonish coloring on it. Both types of pipe have the same markings on them (a53a sched 40) but the maroonish pipe bend much nicer and doesnt kink at all

i took a sample to a local steel place and they told me the steel comes from different plants in China. i have him making some calls for me and ill get you more infoon it when i get it. he said its a fluke to get the good stuff and when it comes in it gets bought up quickly because people realize its better quality.

ill see if i can dig up some pics for yah

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snowshoebrue

· #18 · Dec 14, 2006

move the rollers as far out as they can go. i bent my bumpers & sliders with 1 1/4 sch. 40 without filling with sand and they were fine. the closer i moved the rollers to the center the more it jacked up the pipe.

Ghetto Fab.

· #19 · Dec 14, 2006

I've allways been able to get decent bends out of 1/2", 1" and 1 1/2" pipe up to 90*. However, I've never been successfull with 3/4" or 1 1/4" pipe. I've tried packing sand in and no luck it just kinks over.

I'd bet quality of pipe has something to do with it. Water ain't gonna work.

Kevo

tech

Discussion Starter · #20 · Dec 14, 2006

it seems that quality of the pipe has somthing to do with it, because people get such varying results with the exact same tool, setup the exact same way

is it true that the steel quality of sch 40 pipe is regulated?

i might get the ol' chop saw out and just angle cut all my corners, might look cool with bumoers with pointed "bends".

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