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gpiney

Well Known Member
I've decided to fabricate my fuel and brake lines before skinning the Fuse on my -8. I have absolutely no problem getting a nice, 90deg bend. My problem is that I need to make some 180deg bends. I've tossed about 6ft of tube trying to get a decent, tight 180. one where there are no collapsed sections of tube. I've tried both springs (how do you get these suckers off?) and a cheap HF Tubing bender. The bender works reasonably well for the 90deg and less bends.

I need all the Tricks, Tips, and Hints you have. I have plenty of tube to destroy for practice.

Thanks in Advance,
 
Greg,

I was doing some of my fuel lines today. Long ago I bought one of these from Avery Tools and they do a pretty good job of 180 degree bends

828.jpg


http://www.averytools.com/p-828-imperial-eastman-370-fm-bender.aspx

Steve Hutt
RV-7
West Sussex
UK
 
A little history

Back in the big one, WWII, they employed many unskilled people to build airplanes. To form hydraulic lines they filled the tubes with one of two alloys called Wood's Metal or Field's Metal. They are strange alloys that will liquefy and melt at about 150 to 160 deg F (66 -71 C). After they bent the filled lines by hand to shape, they dropped them in hot water to melt out and recover the metal. The result was well shaped lines with no collapses made by unskilled labor.

Don
 
Tony Spicer said:
I made this 180:

http://picasaweb.google.com/tonyboytoo/RV3BMiscellaneous#5203701450446098130

with this bender from HF:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=3755

Tubing was 3003-0 x .035 wall.

Tony
Click to expand...

Yup, same bender. Like I posted, it (with me operating it) does a good job on bends to 90Deg, maybe a little more. As soon as I go beyond 150, the tube seems to 'pull away' from the groove and partially collapse. I gotta be doing something wrong.
 
Better tool versus better materials

gpiney said:
Yup, same bender. Like I posted, it (with me operating it) does a good job on bends to 90Deg, maybe a little more. As soon as I go beyond 150, the tube seems to 'pull away' from the groove and partially collapse. I gotta be doing something wrong.
Click to expand...

Greg,
All the above posted suggestions will work. However, if you buy some 5052 tubing, your current bender will work fine. You will also have upgraded the quality of the material your fuel lines are made from and spent less than the $55 the Avery bender costs. I made all my bends with the same tool you have, out of 5052. You can buy 5052 from the local aircraft supply shop or get it from ACS. Not the only way to do it, just another way.
Charlie Kuss
 
gpiney said:
Yup, same bender. Like I posted, it (with me operating it) does a good job on bends to 90Deg, maybe a little more. As soon as I go beyond 150, the tube seems to 'pull away' from the groove and partially collapse. I gotta be doing something wrong.
Click to expand...

I had a little trouble with these benders at first, too. Here's what finally worked for me: I mark where the 90 degrees of the finished bend will be (somewhere there's a table for calculating this, but I can't seem to lay hands on it right now; anyway, with a little practice you get an idea where this is) and also where the beginning of the bend should be. I place the first mark under the 'finger' of the building tool and use the tool to bend back to the beginning of the bend (this will be less than 90 degrees). Next, I open the tool again and shift the tubing up an inch or so, then bend again toward the last bend, until it's one continuous bend. I keep working this way and creep up on 180 degrees (or whatever you need). It took a little practice but I can make smooth 180+ degree bends with about 4 partial bends.
 
Found Two Problems

Well, just got back from the shop. I discovered 2 problems. One is me. At least my technique. The other is the cheap HF tool. I managed to get a good 180 and a good 90. Now I have a good Left tank fitting.
What I really needed to do is to put the fixed handle of the tool in a Vise. And use 2 hands to make the 180. I noticed that at about 135deg. the tube would start to pull away (slide) from under the holding 'finger'. So I held the tube near the finger with one hand and used the other to make the bend.

Still I think the tool leaves much to be desired so I am going to spring for the good tool from Avery.
 
flion has the right technique. I needed a 270 degree bend in a slight spiral to connect the left tank to a Andair fuel valve in my -8. The first one I did kinked up, but on the second one I did a 90, then slid the tubing about an inch, then a 90, up an inch and the final 90 so the fuel line crosses over itself. This made hook up to the fuel selector pretty easy.

I like the idea of putting one handle in a vice. I did not do that but will the next time. Good idea.
 
I didn't see it listed here...but filling the line with sand before bending will also keep the tube from collapsing. Just make sure you do a good flush/cleanout before installing. Another method is to use lead shot, or steel shot...but use the small ones. size 8.
 
Found the Cure

Well, after spending a month doing the plumbing for fuel and brake lines in the cockpit, I made a couple of 'discoveries'. First, the HF Bender. I was complaining about doing a 180 and after 90deg, it would start pulling the tube away and flattening it. The Cure: I put some bearing grease in the groove of the movable part of the bender. Works like a charm now.
Second, if you use a soft wire to make a template, the dimensions are off quite a bit because of the radius the bender makes. This means a bit of 'educated guesswork'. I subtract 1 to 1.5 inches from the straight length of the template before the next bend. This also seems to be working well.
 
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