Bending 3/4" tubing (or maybe it's 5/8)

[mhorowit]

I need to put about a 5* bend in a piece of 3/4" tubing. Puttering around, I removed the trailer hitch (it's the kind that slips into a fitting on the chassis of the car), slipped in a piece of 1 1/2" thick wall pipe, then the piece to be bent and finally a breaker bar over the rest of the tube to be bent. I managed the bend, but there is a sharp crease in the metal on the inside of the bend. This even though I rounded the inside of the pipe I stuck in the trailer hitch. I'm going to figure some way to further round that tube to get a smooth bend, but I'm wonder if there is a simpler way. I'm open to suggestions - Mike

[Mark Julicher]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Dig a trench in your yard with precisely 5* angles in the trench wall. Lay the tube in the trench. Drive your car over it.

Take a longish piece of tube. grasp it like a baseball bat. Swing smartly at a round fence post. Using a calibrated break of your wrists you will get a 5* bend

Chuck the end of the tube in a vise. Heat about 3 inches of the (intended) convex side of tube to a dull red about 2 inches away from the vice. Push gently on the free end of the tube.

[mhorowit]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Dig a trench in your yard with precisely 5* angles in the trench wall. Lay the tube in the trench. Drive your car over it.

Take a longish piece of tube. grasp it like a baseball bat. Swing smartly at a round fence post. Using a calibrated break of your wrists you will get a 5* bend

Chuck the end of the tube in a vise. Heat about 3 inches of the (intended) convex side of tube to a dull red about 2 inches away from the vice. Push gently on the free end of the tube.

Well, that's not too far off my first attempt, which was to drive over the tube and use the car as a vice, but the rubber gave too much. I could raise the car, place the tube under the tire with both ends of the tub supported by 2x4 so when the car is lowered, the tire would push the tubing down. Hmmmmm. - Mike

[N96337]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Mike, try tightly packing it full of good wet sand first... helps a bit.
JH

[Ragwing nut]

Re: Bending 3/4" tubing (or maybe it's 5/8)

if it is 3/4 buy a conduit bender from the harware store

[mhorowit]

Re: Bending 3/4" tubing (or maybe it's 5/8)

if it is 3/4 buy a conduit bender from the harware store

I was thinking about renting a hickey.

One thing I ought to try, which even though I've been welding for a bit, never experienced, is heating up one side and allowing it to cool to see how much the metal contracts. You think that might be enuf to get my 5*? - Mike

[Howard Wilson]

Re: Bending 3/4" tubing (or maybe it's 5/8)

[QUOTE=mhorowit;50763]I was thinking about renting a hickey.

Is that legal in Virginia???

[Ragwing nut]

Re: Bending 3/4" tubing (or maybe it's 5/8)

I was thinking about renting a hickey.

One thing I ought to try, which even though I've been welding for a bit, never experienced, is heating up one side and allowing it to cool to see how much the metal contracts. You think that might be enuf to get my 5*? - Mike

it won't move much without quenching and you can't do that

[mohawktipi]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Depending on how long the piece is you want to bend, here is a way to make a simple tubing bender. Take a length of 2X6 and lay out the desired shape. Since tubing has a tendency to spring back a little, your layout should be about 1 1/2 degrees more than your final desired bend. Using a scroll saw cut the 2X6 in the desired shape. Lay the pieces on a flat surface and clamp one piece of the 2X6 down. Lay the tubing in between the pieces of 2X6. Use C-clamps to compress the shape. Usually 3 clamps, one at the center and one at each end will suffice. You may have to help it a little, by heating, but don't overdo it. Don't want to catch the wood on fire.

[Hank Jarrett]

Re: Bending 3/4" tubing (or maybe it's 5/8)

You can reduce the "surprises" by routing a half round cut into the two mating surfaces. The tube is like a spring as you apply pressure and will move towards the lowest energy position. If that is to twist out of plane and fly out from between the pieces of wood, it will do that and fly up in your face. Not recommended unless you take extra underwear to the shop with you.
When we bent tube in an industrial setting one of the key parts of the process was to have a smooth fit to the tube sides to prevent it flattening out (another lower energy state). The routed groove will help with that too.
The tube bender also put tension on the tube and actual stretched the tube around the mandrill. I don't think you will be able to do that so I don't know how successful you will be.
Go to a muffler shop and watch how the machine pulls and bends the exhaust pipes around the tooling. Exhaust pipes are mostly SS and mild steel of much larger diameters than we use, but the principals are the same.
Good luck and don't flatten too much tube (and especially don't put any round dents in your skull!).
Hank

[mohawktipi]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Thanks Hank. I forgot to mention routing the groove. The first time I tried this, the tubing popped up but the C-clamps caught it.

[mhorowit]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Why not simply go to a muffler shop with some scrap and see if they can bend it without crimping? - Mike

[Merlinspop]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Mike,

Muffler shops usually deal with bigger diameter, thinner walled pipe, or I would think so. Maybe your better option would be to call a shop that does sprinkler systems (the building fire suppression sprinklers, not the lawn kind). The building I where I used to work was having part of their system replaced and I saw them bending smaller, thicker pipe all the time.

Just a thought from someone who can be amazingly wrong here.

Bruce

Why not simply go to a muffler shop with some scrap and see if they can bend it without crimping? - Mike

[Hank Jarrett]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Muffler shops do work with MUCH larger tubes, but the sprinkler contractor is a great idea! Might also try a plumbing contractor. They might have to bend about the right size pipes. Also any company that does pneumatic pipe installs. They would be bending high strength pipe for compressed air where flat spots and kinks could get someone killed.
Hank

Take a pan of brownies or some cookies (NOT the store kind). They would probably bend it for you for nothing. Don't forget to get some business cards and pass the company on to the rest of us. If they help, we can get their name out for the work they actually do for money. A few references from folks who heard of them through you will make you well received next time.

[Guest]

Re: Bending 3/4" tubing (or maybe it's 5/8)

Has anyone tried using an electrical conduit bender?

oops! I see now that a Hickey bender is a conduit bender, my bad