Mills

Bending pipe

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I am bending pipe into a half circle. Specifically 2" pipe 19'9" long, in a 4'10" radius. 2 foot is left on the ends to bury in the ground which leaves 15'9". radius is approximate as long as I get a smooth arc and the ends are 9'8" +/- 2" its fine. Currently I am using a harbor freight bender and have a pattern board to check curve. It is taking a long time to do this. I can't seem to find a technique that allows me to get the same amount of bend each section. so I have a flat spot then too tight. lots of rework. have done stroke counting now i have a wire marking the deflection. still having issues.

what say you?

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Every pipe I've bent I did by making the appropriate size jig and then heating in forge and using Oxy/Acet torch to help the bending. It's a touchy thing to keep pipe from crushing or getting flat spots......you'll have it down pat just as you're finished.

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Had to do an art piece for family. Needed to arch 2 20 foot 2x2x11ga sq tubes. Asked my suppliers if they could do
it. No but knew of a place about 110 miles up the road. Called and asked if they could do 2x2. Said as tight as ya want. I have one of those bottle jack benders. I would be looking for someone with a rolling machine.
Ken.

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I have done similar bending on smaller squre and round but not on 2" pipe. The larger dia wants to collapse easier. One way I bend radiuses is around plywood forms I ase 2 pices of 3/4 plywood screwed together and clamp to table and bend the pipe around it. You may have a hard time doing it by hand. The other way is in a bending fixture that I made that is two curved pieces of 1/2 X 1 1/2 flatbar welded to a plate. Kind of looks like )( . I will post pic soon. Each half of the radius pieces are bent to a different radius so to get different radius bends you use a different part of the jig. Nomater what I would pack the pipe with sand if I wants to collapse. Be sure the sand is very dry if you heat the pipe!!
Rob

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Mills
I've done a lot of conduit bending as an electrician, thin wall (EMT) sch. 40 ridged in sizes up to 31/2" using several different types of benders.

It sounds like you are doing what is called segment bending.

Dividing the radius of your bend into segments, then bending each segment a few degrees to create desired bend.

Is your pipe flattening out?
Can you post a pic of your bender and how you have it set up.
Set up really is the key to accurate bends.
Are you using the developed length formula?
Are using a protractor on the end of your conduit when bending?

Glad to help in any way I can.
Mark

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mark so good of you to offer. HUH? :rolleyes:

It would be segment bending and I have not thought of a protractor.

Developed length formula? its google time.

I did put an indicator on the ram so that I can track how much the pipe moves at the ram. Every thing else I've tried has been to see what happened after the fact. Kinda like driving using you rear view mirrors. I'll take some pictures tomorrow hope to report success based on todays work. Still need this knowledge to fully develop this process. It'll likely come up agian.

There mus t be somebody rolling pipe around here but I haven't found them. The profits from this job will be used to get me closer to a roller. Then everybody will know about it and THATS when I'll find the guys doing it.

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Are there any refrigeration installers near you? Back when I was doing commercial installation, we had pipe benders up to 2.5" iirc. If you can find someone with the gear benders that'd be the easiest way. Mind you I can't recall the diameter of the bend they form.
Could also try your local refrigeration parts trade counters. One of them would be able to get you the 2" benders I'm sure.

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Monstermetal I'd drive it up there so to get a chance to meet you and see your shop. If only my truck was up to it.

the developed length formula I worked out. it is what I did in setting this up except for the angle of the bend. I went with how much was bent so I did not build a protractor. I'm not sure given this set up that I could.

I also considered building a jig as described here using my truck as the motivation. I opted for the bender and now it seems that I may have been better off building the bending jig.

Had not thought of refrigeration. I'm sure somebody is.

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Here in the UK we can hire pipe benders from Tool Hire Shops or Plant Hire (Mechanical not floral) Shops, Don't you have similar ?

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Is the curve you are attempting a constant radius or a compound curve. If its a constant curve in my opinion I'd find a metal fab shop that has a section rolling machine. 4'10" rad is gonna be a hard thing to replicate over a number of bends with a pipe bender and get it looking nice and matching. I've been smithing for a fair few years now and I know when to get someone else to do a job for me now. If you can find a firm with rollers they probably can roll them quicker than you can even think about it, they'd do this all the time and can get the accuracy you desire, with minimal stress. That way you can do what you do best (bash hot steel) and they do what they do best. If you can't find someone with section rolls, I'd try making a jig to bend them on, get a fairly long good heat clamp one end and pull it around the jig, I've had a bit of success with this method especially when the curve is a compound curve (eg it is not constant and is not able to be rolled). If the curve is not too severe I have'nt bothered with filling the pipe with sand, 4'10 rad you should be OK.

Phil

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not that I have seen around here, John. this is actually starting to be exciting, this may be a moneymaker for me since I am surley not the only one who needs pipe and tubing bent and rolled.

No pictures it was too hot and I had too many interruptions. I have wrapped a piece of wir to the ram and put tape on the cylinder so that I can track the amount of bend. It works the best of anything yet but still finicky.

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The cheapest and fastest way is to fill the pipe with pea gravel, crimp both ends (do not seal!) and heat in the forge. Bend as desired, let cool, and saw off the crimped ends. Simple.

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The cheapest and fastest way is to fill the pipe with pea gravel, crimp both ends (do not seal!) and heat in the forge. Bend as desired, let cool, and saw off the crimped ends. Simple.


the problem doesn't seem to be the bending, it's the "as desired". :P

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as MarcB said, we Electricians bend pipe a lot. 1/2 up to 6 inch diameter, and collapsed pipe wont allow wire to pass. We can do the small radius's up to smooth curve of pipes matching the stair railing going up a gas storage tank to its top. Hire an Industrial Electrical Company to make your bend. If they have a 555 or 855 power bender it will be great for your desired look, and fast enough to not cost an arm and a leg.

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I wasn't aware a condiut bender would accomodate 180s. The shoes only go a little over 90, don't they?

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Sure they can, Example while your legs are less than about 3 ft long, how can you walk for miles ? one step after another. Its the same thing with large compound arc's.

one job we did: bend 3.66 degrees, advance 4 inches, repeat... for a 115 degree arc over a food line, we did the math for the arc needed, the span, (about 39 inch sweep) and came up with these numbers, made a test pc, then knocked 100 or so of them out. client was happy

Before you math people do the calc's for these 13 bends to each pipe and say the totals are off, there is another issue with bending pipe, its called spring back. the bend radius is what the bend is taken to, the result is always less after the metal returns partially to its prior shape. there is also shrink and stretch to account for, this is why I advised sub-ing the bending out to a contractor, rather then just renting equipment.

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