Bending Stainless Tubing

[therrick]

I'm considering making some racks for the boat and plan to use one-inch stainless tubing, probably 316. I've been searching the Internet for information on how to bend it but haven't found any useful information as yet. What little information I've found makes me think that a standard plumber's pipe bender won't do the trick, but I'd like to be proven wrong.

Any tips on how to do it, or books or Web sites that provide step-by-step info for the uninitiated?

Thanks,

Tom Herrick

[Sea Wolf]

Tom-

1" stainless 316 tubing is WAY too tough to bend on your own, IMHO!

You need the services of a professional railmaker to bend the stuff at the right raidi, etc.

I did put a bend in a short piece with my van back in 2003, but it was just a kink, as bends go:



Is there a railmaker near you?

It's great stuff, and also deserves 1st class welding to preserve it's strength at joints and attachment points.

HTH

Joe.

[Da Nag]

I'm way out of my league here, but I also share an interest in learning how to work with stainless tubing...I've done a little bit of reading on the subject over the last year or so, but have zero practical experience.

A good place you might start - Google Groups. rec.crafts.metalworking has a lot if info in it - here's a query on tubing benders that has some info.

The one thing that does seem to be repeated by the pros, over and over...it can't be done with good results, without the right equipment. Pipe benders won't do it - and tubing benders are pricey.

On the low end (realtively speaking - they are still pricey), there are two that seem to get mentioned a lot. Again, no practical experience with either, but something to take a peek at.

Tube Shark

and

JD Squared

Good luck...I'd be interested in any additional info you might find.

[Da Nag]

Here's a video (Windows Media format) of the JD Squared Model 3 in action...looks pretty slick, and turns out a beautiful bend.

It's one of the cheaper models I've seen with good reviews...still, once you factor in accessories and some dies, you'll be pushing $1K.

[thataway]

I agree if you want quality bends, other than slight kinks--go to a tubing bender. I just had the camper back made--the outer bends were by a shop with a tubing bender--the canvas worker put the arc in by hand--you could see little kinks each place where he had bent it a little. Usually the tubing benders run the tubing between wheels, as it travels, different amounts of deflection are applied to give the bend or arc.

Way back when I was a boy scout, we did bend some aluminum tubing by filling it with sand. I don't know if this would work with SS or not. Remember that there are various thicknesses of SS tubing side walls.

[therrick]

[jflug]

Tom - Don't despair; it actually is possible without spending a huge amount of money. It's called a "Handle-Operated Tube Bender", and it's a geared bender that you can clamp in your vice. After lots of looking, the only place I could find a new one was at McMaster Carr. About $200 or so. Check it out at page 2183 in their on-line catalog [http://www.mcmaster.com/]. I was lucky enough to find one on ebay and still paid about $100, but it was a good investment. It makes a nice smooth 4" radius bends in 1" tubing. I've used it for several projects on the boat, including a radar arch. I found out about it when I went to a shop near here that specializes in winery equipment.

Jim

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[therrick]

Jim,

Does the tubing come out smooth at the bend? I've read that some benders leave small crimps along the inside radius. What is the wall thickness of the SS you're bending?

I hadn't thought to look on McMasters' site. They do seem to carry pretty much everything one can think of. A seller of a similar bender on ebay indicated that it could be upgraded to hydraulic if one so chose.

Also, on the arch you built, what kind of fitting did you use for attachment on the roof? I can't see clearly enough in the photo. Was the fitting angled or did you bend the tubing to fit the roof angle?

Oops, got interested again...

Thanks,

Tom

[jflug]

Tom - I think the tubing I used was 1/16" thickness, which is plenty heavy enough for a radar arch. It actually makes nice smooth bends with no crimps. Each of the 4 roof attachments is just a small piece of 1/8" ss plate with two 3/8" ss bolts, butt-welded onto the tubing ends. That was the other part of that project, an excuse to go out and buy yet another tool - a MIG welder. I think that wound up being one of my better tool investments; I've used it for lots of other projects.

Jim

[Da Nag]

Cool find, Jim - thanks for the tip. As an aside, here's a link to the page in question - the tool is about 1/2 way down the page.

What do you think of the angle gauge on this tool? I'm wondering about repeatability here...is the gauge good enough to give consistent results, or does each bend require a little trial/error?

Another observation...while the tool is relatively inexpensive, it's not cheaper than a set of dies for other models. This tool also has only one bend radius option per tubing diameter. So if one has needs for multiple tubing diameters and/or bend radii, the more expensive models with specific die sets would seem to be more flexible.

But Jim...you're the one with hands-on experience here. Sounds like you only needed 1" capability for the arch, but did you find the single 4" bend radius to be limiting at all?

[jflug]

Bill - You're absolutely right about the versatility - The bender only works for one size. But 1" seems to be really standard for most tubing I've seen on C-Dory's; the rails, the radar arches, stern rails, rocket launcher mounts, hand rails, etc. The other consideration for me is shop space - some of these other benders are permanently bolted to the floor, which I can't afford the space for. This thing can just get thrown in the drawer when you're done.

The angle measurement is definitely a bit crude and takes a little practice to get used to. You would want to use a separate, more accurate angle gage to confirm measurements. But once you get it down you can produce pretty consistent results.

I haven't found the 4" radius to be limliting. I haven't tried it yet, but you could probably use the bender to make a series of small bends to come up with a long radius bend - for example a rocket launcher rail that follows the roof radius. Someday when I get the time....

Jim

[MikeMac]

There's a guy in my marina, Buddy, who's made no end of SS doo-dads for his huge Hatteras MY. He fills the tubing with sand, fits a clamp of his own construction on one end and uses two very closely spaced utility poles at the marina as a vise. He hooks up the clamped end to his diesel pickup with a chain, lashes the other end between the poles, and slowly works the bend in. moving and pulling a bit at a time. I guess he's limited by the radius of the poles, but that seems to work for the stuff he's built. He does his own welding at a shop somewhere else, maybe where he works. I've only heard about his technique from him, I've never seen it in action. It sounds pretty scary to me, but then the Egyptians built the pyramids. Just an idea.

Mike

[therrick]

I only found one reference on the Internet regarding bending stainless tubing without machinery designed for that purpose. Some guy who had work to do for a stage set I believe. He said 'you're gonna get hurt; it's up to you how bad'.

Think I'll stick with machinery or pay someone who does...

I'm not healing as quick as I once did...

Tom