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mcencula

Well Known Member
Does anyone have any tips, tricks, or recommendations for how to straighten 3003 tubing so it's really straight? So far I've been straightening it out with my hands which gets it mostly straight, but still has some waviness over short distance (perhaps every 2 - 3 inches) and usually a gentle curve over long distance (say, a 4 ft length).

P.S. Yes, I've considered 5052 tubing. I may or may not go that route for the brake lines, but prefer to use the cheaper stuff for the fuel lines. Really just looking for recommendations on working with 3003.

Thanks,
 
I used a length of 12" steel rod matching the I.D. of the tubing. Chamfer the edges, grease it up, push it through (using another piece of steel rod), and you have a reasonably straight piece of 3003. Not arrow-shaft straight, but far better than I could do by hand.
 
tubing lines

Have you considered replacing all of those lines with the ones that come pre-made from Bonaco?

I made all of the fuel and brake lines and then saw the ones from Bonaco and removed all of mine and replaced them. Wish I would have done it from the beginning, it would have saved a lot of time, money and scrap.

Mike Ice
Flying Rv-9
Alaska
 
roll it on the floor

Those aluminum lines come in rolls. Roll it out on a flat floor holding the loose end firmly on the floor, then unroll as much as you need (roll it like a wheel). You will need to hold the straight section that is thus formed firmly on the floor.

I tried unraveling by hand, but it really comes out lumpy and amateurish. Hope I understood your question correctly.
 
mcencula said:
Does anyone have any tips, tricks, or recommendations for how to straighten 3003 tubing so it's really straight?...
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It's hard to say. For most of these lines, straight enough for all practical purposes can be pretty wavy and still be 100% functional. So unless you're building a show plane, what you're doing hand and by eye and it will be fine.
 
3003

is soft for a reason---easy to bend by hand. Works ok for low pressures, to like 850psi for -4. If it's already bent, you may not get it "perfectly" straight. In shorter lengths, try rolling it on a flat workbench. IF you have good tubing bender, you can bend the radius the opposite way, and get it close, without constricting the ID too much. Then roll it out. Probably easier to start over, use 5052, or braided teflon. Teflon is more expensive, but easier to route. 3003 and 5052 is less expensive, but harder to work with. Just depends on what your trade off is.
Tom
 
Vice

I clamped (and crushed) about an inch of the raw end in a vice bolted to a heavy table. This allowed me to put reasonable tension on the tube while unrolling it and hand straightening the roll at the tangent point of the loop. It was pretty easy to hold tension and manually uncurl the roll to get a fairly straight 6 to 8 foot piece.
 
Custom made tubing straightener

rocketbob said:
On the mustang I helped redo all the plumbing in the gear wells on, we used 5052 because it is delivered straight.

Jeg's sells a tubing straightener perhaps you could get your EAA chapter to buy: http://www.jegs.com/i/JEGS/555/80082/10002/-1?CT=999
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I thought that was a really cool idea, but my chapter didn't seem too interested in acquiring one and lord knows I'm way too cheap to spring for one, so I decided to make my own.

Bought some casters at Harbor Freight:
20110126-01-tn.jpg



Used the die grinder and drill press to grind a groove in the outside:
20110126-07-tn.jpg


Some scrap maple and leftover plywood from Van's shipping crates to make a housing:
20110127-06-tn.jpg


...and presto! Straight tubing:
20110127-07-tn.jpg


This thing works so well, I couldn't stop giggling as I used it. Don't get me wrong...it doesn't make the tubing perfectly straight like aluminum extrusion, but it's better than I can do by hand and it's really fast. Cost? $17 for casters, $17 for nuts & bolts, $34 total.
 
mcencula said:
This thing works so well, I couldn't stop giggling as I used it. Don't get me wrong...it doesn't make the tubing perfectly straight like aluminum extrusion, but it's better than I can do by hand and it's really fast. Cost? $17 for casters, $17 for nuts & bolts, $34 total.
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Awesome! Great job. For a tool seldom used, this is a great compromise. I imagine if you run the tube thru it multiple times you can get them pretty straight.
 
rocketbob said:
Awesome! Great job. For a tool seldom used, this is a great compromise. I imagine if you run the tube thru it multiple times you can get them pretty straight.
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Ya know, I didn't really think of that. You're right, though...I just went down to the shop to try it...a few passes through the straightener and they're nearly arrow straight. Thanks again for the ideas, Bob. :)

Pat Stewart said:
I am curious why?
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Better results and super fast to use. Of course I spent about 8 hours making it, so I'm probably negative efficiency for building a single airplane, but I'm sure going to make it available to my airplane building friends.
 
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