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Small diameter pipe bending

4K views 22 replies 13 participants last post by  qwerty 
#1 ·
I am going to build luggage racks for my TW (based on Yamaha's factory rear rack) and for my boys bikes. Does anyone have any pipe bending techniques for those of us that 1--do not have a bender for 1/2 inch black pipe, and 2--do not have a dedicated shop to accomplish the work. Most of the fabrication will have to take place in the driveway. I do have a wire feed welder and grinder. I'm apprehensive about tight radius bends without a bender for that size of pipe. The material is 1/2 inch OD heavy walled seamless black pipe. Any advice?

If this works, I want to try some case guards too...

No, purchasing the right tool for the job is not an option...neither is it any fun...
 
#2 ·
I am going to build luggage racks for my TW ... I'm apprehensive about tight radius bends without a bender for that size of pipe. The material is 1/2 inch OD heavy walled seamless black pipe. Any advice?

If this works, I want to try some case guards too...

No, purchasing the right tool for the job is not an option...neither is it any fun...


I am not a welder or metal worker, but I wonder if you could design a rack with no bends? Butt weld the ends together at 45 degrees?
 
#3 ·
If you want bends and round pipe, I can't help. But . . . I found it much easier to work with square steel stock; I believe I used 1/2" and by cutting 3 walls and bending the fourth, I was able to weld up some big bends which had the strength needed. Please let us know how you solve your problem. Tom
 
#4 ·
Depends a lot on what you have available for tools.

With a little imagination and some more common shop tools you can bend smaller pipe pretty well.

A torch or even a good hot bbq can heat pipe that size to red or beyond for a much easier bend.

If you have a bench vise or better yet one of the wide jaw woodworking vises available you can make a functional bender with some wooden blocks and a little creative drilling and filing. Basically cutting a channel like a proper bender around the center of a piece of hardwood. Use the vise to support the wood from the ends it will not push apart, then use a heavy clamp to hold the pipe and bend away.

Pipe benders just make the job a lot faster. Make-shift benders can work well if thought out a little bit, but are likely to be a lot slower. All depends on your expectations.
 
#7 ·
Good stuff--I like the idea of a hardwood jig, and heating in the BBQ...I do not have an acetylene torch, but I do have a hot propane torch I used to sweat the copper in my house.

I think I will try the wood jig, heat to red before bend, and pack the pipe with sand...it all makes perfect sense.

I want to stay away from blunt corners and I have to use the pipe--it was free (7 each 10 foot sticks from a small grizzly set up on a chip box)...I have a bad habit of doing twice the effort and time with 'free stuff' than it would take to go buy the right stuff or have the right person do the work. You might say I am a 'bone head'. It will take a couple of weeks to complete, but I want to do some progressive pics from the 'driveway' fab shop.



Thanks for the input and suggestions...
 
#12 ·
Casper--the cycleracks are the bomb...but this is more of a 'father/son' project...the kid's bikes are not t-dubs. One rides a Lifan 200 enduro and the 2 younger ones are riding 125 pit bikes, so I would only need to purchase 1 rack. Once we tackle the dub--we are making racks for all. We like to pack extra gas, food/water, and tools. We are starting on the bike racks as soon as we finish rebuilding a set of truck racks one of my boys traded for...first he acquired a 14' sears canoe for $30.00 with an axe hole in the bottom (since repaired), now he has brought home a slightly damaged, over-sized lumber rack for me to fit and fix to my truck so I can pack his canoe... when can we start working on the new 28 hour days we all so desperately need?
 
#14 ·
Just a project update...lumber rack complete and load tested to the lake for a week...Kids happy.

Bike rack fab to begin soon...
 
#16 ·
I realize this is an old post. Sorry. But I found comments about filling pipes with sand, plugging the ends, heating and bending. Apparently this works, but I remember a neighbor telling this story:

"We needed a handlebar for a bicycle, and we had a pipe, so we asked Dad how to bend it. He said to fill it up with real dry sand, plug the ends,

heat it, and it could be bent. So we filled it and drove the plugs tight. Apparently the sand wasn't quite dry enough, because one of the plugs blew off and you know, it went right through the wood wall!"

So if you choose this method, dry the sand thoroughly, vent it so the steam can get out, plug it not so tightly, and handle it like a gun- or all of the above.

--Greybeard
 
#17 ·
GB, I was thinking the exact same thing . . . reminds me of the canon building project myself and a couple of buds once attempted. As it turns out, you really really need to match projectile gauge and bore size correctly. Ah, pressure and steel tubes . . . . did I mention that we barely excaped with our lives? Not from the canon . . . from my Buds Dad when he saw the damage the exploding canon did to his tractor!!! (and the shed it was parked in)

Anywho . . . wonder how that rack project turned out? I have some 5/8 square tube I'm imagineering into a rack . . . .





Bag
 
#18 ·
It seems there is a lot of fear of using sand to bend pipe.



I have done it dozens of times with no problems. If you are bending pipe or tube to make something presumably you are going to be welding. So weld a plug on the pipe ends and unless you do it intentionally and lay down an air tight weld the hot air, steam, gas will escape no problem.



I wondered if I was the only person who still does this so had a look on google and found this quote,



"Ive been using sand for about 20 plus years, it is an old school technique, and is low tech, but just the same, if you do it right, will produce mandril quality bends, even better? if it is mastered. and you can bend contenuous complex bends this way, all along the stick.



Reason that it works is that it translates energy to the opposite side, you push on the bottom, you push on the top too.



As long as the sides are supported, it works very well.



I have pushed this concept to the extreame, and never had an "expolosion." though I once tore the seams a few times, and the packed sand mearly poured out as soon as the steel gave way.



once I rotated the seam to the inside of the radious, tearing ceased.



one trick is to pack the sand very very tight, using very fine sand. but, it is very time consuming, as drying the sand, screening the sand then packing it"



Use common sense and if you are not confident in your abilities don't do it.
 
#19 ·
Bag,

Good story! Wish I'd been party to it.

Probably my most sinister accomplishment was to blow out a window with nitroglycerine I was brewing up. There wasn't anyone to teach me how unstable it really is.

These sort of memories usually do far more good than the damage causes, in my opinion. I would like to see how Mom views it currently, but she is 97, and has a bad heart. We were generally encouraged to experiment, but I don't think this extrapolates to messing with heart conditions. Or nitroglycerine, for that matter. Never thought about, but maybe they are related.



One of my ideas for a rack since I currently don't have a welder, was to drill two frame rails of square tubing and run All-thread through them for the width I wanted, like rungs on a ladder. Small tubing over the rods would cover the threads as well as space the rails. Acorn nuts outside would keep it together and dress it up. I have some stainless steel that might influence my design. GB
 
#21 ·
GB, I like the rack idea. I do have a welder . . . just not very good with it!

Right now I'm strugglng with the design of the rack . . . I want it fairly wide, but I ride THROUGH alot of greaswood and sage and can see me regretting the width later . . . sigh, decisions!!





Bag
 
#22 ·
Ha! I'll have to tell you the story of my experiance with nitro someday
. . . hahahahahaha...... damn that hurt.






Bag
 
#23 ·
End of 5th grade I got beat up by a couple highschool kids.



Spent 6th grade studying chemistry--napalm, nitroglycerine, plastique, sulfur compounds, LP, ... .

Spent 7th grade studying delivery systems--solid and liquid fueled rocketry, piston engined aircraft, ... .

Spent 8th grade studying ballistics and guidancwe systems--wire-guided, wireless, inertial, gyroscopic, ... .



Got it all together end of 8th grade, actually hit a 3-foot tall tree stump from 800 meters 3 out of 3 attempts, and the bullies moved away. Probably a good thing--3 pounds of plastique makes a big mess of things.



Needed a physics project in 12th grade, so designed an implosion-triggered firecracker that could be:

1) Made of commonly available materials;

2) In the high school machine shop;

3) Fit in a typical 4x8-foot enclosed rental trailer or 1/2-ton van or pickup with camper shell, and;

4) Could be fueled by the Pu239 that came up missing from U. S. labs each year.



The NRC was not happy.
 
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