Bending 1/4" fuel vent lines

[SonexGuy]

I've spent 3 hours unsuccessfully trying to figure out how to make the fist few bends in the fuselage fuel vent line, when it comes off the bulkhead fitting through the side of the fuselage. The first bend needs to be nearly 90 degrees and needs to happen in less than an inch, to clear the angle directly above the fitting. I seemingly have every tubing bender known to man, but none can make such a tight radius. And after that first bend, it needs to make a nearly 180 bend, to go around the angle and back to the fuselage skin. Again, no tool I have or have seen, can make such small radius turns, and it has not been possible to do it by hand (not enough leverage without kinking the tubing).

And secondly, that first straight run from the bulkhead fitting needs to be VERY short. The AN819-4D sleeve needs to go on before flaring. So that means the flaring tool is holding onto the SLEEVE and not the tubing, so the tubing just slides through the sleeve as the flaring took tries to flare the tubing. Any neat solutions for that?

I just cannon see or find any way to have the sleeve in place, on an absurdly short straight run, and make a 90 degree bend all at the same time. And then make a 180 degree turn.

If anyone has any videos or photos of THAT particular process (not just the end result), I would be more than appreciative (dinner on me at Airventure?!)!

 

[PaulvS]

I've spent 3 hours unsuccessfully trying to figure out how to make the fist few bends in the fuselage fuel vent line, when it comes off the bulkhead fitting through the side of the fuselage. The first bend needs to be nearly 90 degrees and needs to happen in less than an inch, to clear the angle directly above the fitting. I seemingly have every tubing bender known to man, but none can make such a tight radius. And after that first bend, it needs to make a nearly 180 bend, to go around the angle and back to the fuselage skin. Again, no tool I have or have seen, can make such small radius turns, and it has not been possible to do it by hand (not enough leverage without kinking the tubing).

And secondly, that first straight run from the bulkhead fitting needs to be VERY short. The AN819-4D sleeve needs to go on before flaring. So that means the flaring tool is holding onto the SLEEVE and not the tubing, so the tubing just slides through the sleeve as the flaring took tries to flare the tubing. Any neat solutions for that?

I just cannon see or find any way to have the sleeve in place, on an absurdly short straight run, and make a 90 degree bend all at the same time. And then make a 180 degree turn.

If anyone has any videos or photos of THAT particular process (not just the end result), I would be more than appreciative (dinner on me at Airventure?!)!

Are you able to post a photo of the problem area? Drawing 36 section D-D shows the elbow bulkhead fitting and the initial bends in the vent line and these bends are less than 90 degrees. Mine was done per this drawing and there were no real difficulties so I'm wondering if your setup is maybe a bit different to the drawing? I think that I may have just bent them by hand while they were attached to a fitting.

 

[andoman]

Consider a “Rocket Vent. It’s a coiled up vent line in the wing root that vents through the lower wing root fairing.
It’s very simple to fabricate and works well.
The per plans vent into the cabin is an exercise in frustration…
Here’s a couple of threads:

Rocket style fuel tank vent

I decided to vent the fuel tanks rocket style instead of re-entry into the fuselage. The one thing I didn’t want to do was to put the exit in the wing root fairing so I went thru the wing spar and exited out the bottom skin. I also added a tiny hole on top of the line just before it exits in...

vansairforce.net

Question about Rocket style fuel vents

Probably rehashing old stuff here, but I didn't see the answer to my question in the archives. I understand the rocket style fuel vents are just coiled a couple of times and then out the bottom of the wing. Seems elegantly simple and right up my alley. I want to use this coiled vent system...

vansairforce.net

 

[dmattmul]

Are you able to post a photo of the problem area? Drawing 36 section D-D shows the elbow bulkhead fitting and the initial bends in the vent line and these bends are less than 90 degrees. Mine was done per this drawing and there were no real difficulties so I'm wondering if your setup is maybe a bit different to the drawing? I think that I may have just bent them by hand while they were attached to a fitting.

Pics are wonderful, please post !

 

[Kyle Boatright]

Pics are wonderful, please post !

This. You could even bend the desired shape from a clothes hanger so we can better understand what you're trying to accomplish. Or post a .PDF of the drawing of the line in the plans.

 

[rsultzbach]

Try Phenix catalog.

 

[SonexGuy]

Are you able to post a photo of the problem area? Drawing 36 section D-D shows the elbow bulkhead fitting and the initial bends in the vent line and these bends are less than 90 degrees. Mine was done per this drawing and there were no real difficulties so I'm wondering if your setup is maybe a bit different to the drawing? I think that I may have just bent them by hand while they were attached to a fitting.

 

[PaulvS]

I just went and had another look at mine and here are a couple of suggestions:

For the first flare - before bending the tube, put on the nut and the sleeve and slide them out of the way and then flare the end in the usual way. Once flared, slide the sleeve up to the flare and then make the bend, either with the tool, or by hand with a fitting temporarily on the end of the tube for leverage.

It appears that I cheated for the 180 degree bend and circumvented the need for it by running the tube straight up, so that it clears the rudder cable on the inboard side.



Some other comments about making the whole tubing spool: it really needs to be made on the bench because otherwise too many things are in the way if trying to do it in the cockpit. I measured the routing and drew a diagram of what the finished line needed to look like and then bent it up on the bench. There was some further tweaking to get it just right, while it was being installed.

When you have one side done, the other will be easier because it is simply a mirror image

 

[RV7 To Go]

I used this flaring tool bought at Spruce. I made the S bends first with the tail a couple inches long. When that fit I put on the sleeve and flaring tool snugged but not tightened with the tool tight to the sleeve on the tube up to the bend. Mark the end of the tube, remove the flaring tool and cut the tube and then flare. The nut can go on from the other end. As I recall it was a bit of a pain to get the bends all correct but it was doable. Sorry but this the only pic I have where you can just zoom and see the vent line. Hope it helps a bit.

 

[Toobuilder]

Are you using something other than the supplied 3003 alloy? The .250 3003 can be bent by hand. Flare the tube, install a fitting and use your thumb at the apex of the various bands. The first fitting provides something to grab on to as you break the tube over your thumb.

 

[SonexGuy]

For the first flare - before bending the tube, put on the nut and the sleeve and slide them out of the way and then flare the end in the usual way. Once flared, slide the sleeve up to the flare and then make the bend, either with the tool, or by hand with a fitting temporarily on the end of the tube for leverage.

I tried that, but with only about 1/4" of leverage, I can't conceive of any way to make that bend without kinking the tubing. No tool can do that, and 1/4" is not enough leverage to do it smoothly by hand. At least all the times I tried it. The bend happens in less than an inch from the flared end, and almost immediately after the top of the nut.

If making that bend with the fitting in place, and bending it (somehow) by hand, is what everyone else has done, then I'll just have to keep trying. But it would be good to either get some affirmation, or hear about another way.

 

[SonexGuy]

I used this flaring tool bought at Spruce. I made the S bends first with the tail a couple inches long. When that fit I put on the sleeve and flaring tool snugged but not tightened with the tool tight to the sleeve on the tube up to the bend. Mark the end of the tube, remove the flaring tool and cut the tube and then flare.

I have this flaring tool, and it requires the flared end to have a straight run of at least 5/8". The sleeve is 3/8" long, so a full 1" of straight section is needed for the flaring tool to grab the TUBING and not the sleeve. If I pre-bend the tubing with the very tight radius required to clear the angle, I don't have nearly the 1" of straight run that I need. If I do the flaring with the tubing straight, and not bent, then I haven't found a way to make a clean turn immediately after the top of the sleeve, per my other posts.

 

[SonexGuy]

Are you using something other than the supplied 3003 alloy? The .250 3003 can be bent by hand. Flare the tube, install a fitting and use your thumb at the apex of the various bands. The first fitting provides something to grab on to as you break the tube over your thumb.

I'm using the supplied tubing. I haven't been able to bend the tubing as you suggest, as the bend needs to occur directly after the top of the sleeve, leaving no distance for leverage. Bending by hand that way has so far only succeeded at kinking the tubing at the top of the sleeve.

 

[lr172]

I tried that, but with only about 1/4" of leverage, I can't conceive of any way to make that bend without kinking the tubing. No tool can do that, and 1/4" is not enough leverage to do it smoothly by hand. At least all the times I tried it. The bend happens in less than an inch from the flared end, and almost immediately after the top of the nut.

Go to the plumbing aisle at HW store. The flaring tools all include bending supports for copper tube. These are basically long coil springs. You slide them over the tube before bendin and keep the round shape while bending. You can still kink them if you try real hard, but they produce nice clean hand bends even with fairly small radii

 

[sf3543]

I've spent 3 hours unsuccessfully trying to figure out how to make the fist few bends in the fuselage fuel vent line, when it comes off the bulkhead fitting through the side of the fuselage. The first bend needs to be nearly 90 degrees and needs to happen in less than an inch, to clear the angle directly above the fitting. I seemingly have every tubing bender known to man, but none can make such a tight radius. And after that first bend, it needs to make a nearly 180 bend, to go around the angle and back to the fuselage skin. Again, no tool I have or have seen, can make such small radius turns, and it has not been possible to do it by hand (not enough leverage without kinking the tubing).

And secondly, that first straight run from the bulkhead fitting needs to be VERY short. The AN819-4D sleeve needs to go on before flaring. So that means the flaring tool is holding onto the SLEEVE and not the tubing, so the tubing just slides through the sleeve as the flaring took tries to flare the tubing. Any neat solutions for that?

I just cannon see or find any way to have the sleeve in place, on an absurdly short straight run, and make a 90 degree bend all at the same time. And then make a 180 degree turn.

If anyone has any videos or photos of THAT particular process (not just the end result), I would be more than appreciative (dinner on me at Airventure?!)!

Another method you can try is to fill the tube with some fine sand and plug the ends to keep the sand in. Then bend away. The sand will keep the tubing from kinking.
I’ve used this method to bend the 4130 tubing for tail feathers on a biplane build back in the day. So it should work for this.
Good luck

 

[scnovinger]

All were done by hand. Port side took about 1 hour with full installation. Starboard side took about 1/2 hour due to the shorter learning curve.

I can talk to you about my technique if you’d like.

 

[PhatRV]

For the fuel vent tube, brake tubes, and other small tubes that have the funny bends, I used these spring tube benders from Amazon

 

[Kyle Boatright]

Try this. Add the sleeve, flare the end. Insert the smooth end of the largest drill bit that will fit into the line. Slide it in to match the far end of the needed bend. Bend the line 10-20 degrees at that point using the bit for leverage. Pull the bit back 1/16” and bend again. Lather, rinse, repeat.

 

[mburch]

Lots of good advice above. Spring benders are great to have in the toolbox, and you can also make gentle bends with your bare hands.

And, +1 to the tip about making bends close to a previously-flared end with the Imperial bending tool. Try moving the flare nut out of the way and putting the sleeve as close to the radiused part of the tool as you can get it.

Another thing to consider is that the inexpensive Imperial bending tools come in two sizes. Most builders have the 368-FH because it can be used for fuel lines as well as brake lines. But the 367-FH is physically smaller and offers a tighter radius for 1/4" tubing - maybe just enough of a difference to get you out of a jam.

 

[FlyGuy65]

Used tubing bender, springs, and gentle hand pressure. FWIW I found the fuel lines more difficult. Needed to order more tubing for those lines as Van's supplies more than enough tubing, but not enough for multiple re-does. Ordered straight tubes from Wicks which is a bit easier to work with compared to coils from Vans.

 

[Desert Rat]

That whole area is a hassle to get bent properly, but you can absolutely make the required bends by hand. The drill bit method described a couple of posts up works for the bend next to the flare.

Note- I would absolutely never do that for a line carrying fuel or anything at pressure because it's pretty easy to scratch/gouge the inside of the tube. This is just a vent line with no fluid or pressure in it so the odds of a scratch on the inside tube wall causing a future problem are pretty low.

 

[Ralph Inkster]

I did that convoluted series of bends by angling that 90 degree bulkhead fitting about 45 degrees forward, doing more relaxed bends over the angle, than bending the tubing aft back to the vertical bulkhead.

Also another option- there wouldn’t be anything wrong if you routed the tubing forward towards the firewall, 90 degree bend vertical up to the longeron, 180 degree back down to the floor vent fitting. As long as you clear the routing from interfering with your rudder pedals & cables, and is well supported to solid structure should be fine.

 

[Toobuilder]

… as the bend needs to occur directly after the top of the sleeve, leaving no distance for leverage. Bending by hand that way has so far only succeeded at kinking the tubing at the top of the sleeve.

PRIOR TO BENDING, flare and install a straight bulkhead fitting to the tube, which then acts as a “handle” for bending. Your thumb acts as the fulcrum at the apex of the desired bend. One can get very close to the sleeve this way, but you will never get a tight 90. And according to the drawing you supplied, you don’t need a sharp 90, just get the tube started enough to clear the F713 longeron and call it good.

The sand trick works too, but I recommend using sugar…. It won’t scratch the tube and dissolves in hot water.

 

[SonexGuy]

Try this. Add the sleeve, flare the end. Insert the smooth end of the largest drill bit that will fit into the line. Slide it in to match the far end of the needed bend. Bend the line 10-20 degrees at that point using the bit for leverage. Pull the bit back 1/16” and bend again. Lather, rinse, repeat.

That sounds like something to try!

 

[RV7A Flyer]

FWIW, I put in rocket-style vents in my 7A. Simple, effective, no additional connectors, etc. And not in the cockpit.

As they say, it's your airplane, do whatever you wish with it.

 

[SonexGuy]

Thanks for everyone's input. It took me another 3 hours to make one side, but I did make it successfully! Kyle Boatright's suggestion was the one that got me over the first major hurdle. I posted my process and photos on my log page.

EAABuildersLog.org - Free aircraft builders log website.

EAABuildersLog.org is a airplane builders log website to store your projects on the web for free. The EAA (Experimental Aircraft Association, Inc.) provides this website for it's members for free..

eaabuilderslog.org

 

[andoman]

A hijack since the OP’s problem is solved. But still relevant to the topic:
Here’s a better thread on the Rocket Vent and a pix:

Building Tip - Fuel Tank Vent Line

Here's a tip for running your vent line on your fuel tanks that keeps the line out of the cockpit, reduces the number of fittings, and simplifies the installation. This is a picture of my wing upside down. Inside the root, I ran a double loop of 1/4" aluminum tubing to a AN919-6D reducer...

vansairforce.net

 

[Norman CYYJ]

A hijack since the OP’s problem is solved. But still relevant to the topic:
Here’s a better thread on the Rocket Vent and a pix:

Building Tip - Fuel Tank Vent Line

Here's a tip for running your vent line on your fuel tanks that keeps the line out of the cockpit, reduces the number of fittings, and simplifies the installation. This is a picture of my wing upside down. Inside the root, I ran a double loop of 1/4" aluminum tubing to a AN919-6D reducer...

vansairforce.net

You can also pack the tubing full of fine sand, that will prevent it from collapsing.

 

[JeffPeters]

put a couple screws into a 2x8 and leave them sticking out 1/2", seperate them just enough to make your bends, place the tube inbetween them and you can easily bend around them. You can also place sockets over the screws of varying diameters to get different radius bends. I've used this method for doing brake lines with pretty good luck. Use something like a deck screw that has no threads at the top for a smooth surface.

 

[wirejock]

Yep. That was a PIA. Second one was much easier.
Flare and install the sleeve and nut first.
I used the spring type tool. If it's the soft aluminum tubing, the spring tool will bend it by hand pretty tight radius. I didn't use sand but did on the crankcase vent tube to eliminate the bend. It does help although it's critical you get all the sand out. Maybe not as big a problem on a vent line.

 

[rv6ator]

I also went with the Rocket vents in my -7 for 2 reasons.

-Simplicity and ease of installation/inspection.

- Stock vent lines exit on the belly, and an overturned or nose over condition may vent fuel down the belly to hot a exhaust. Having the vents in the wing root can minimize that risk.

 

[TS Flightlines]

Michael---you can use one of your benders to make a close bend near the flare- Since most hand benders have the bend die about 2 inches from the flare, just cut a slot at the 0* mark. Shorten the flare sleeve so it just partrudes from the back of the nut. I made various "mandrels" to screw into the nuts to support the tube against the post. This allows the start of the bend very close to the aft side of the nut, much closer to the flare than normally possible.

 

[SonexGuy]

Michael---you can use one of your benders to make a close bend near the flare- Since most hand benders have the bend die about 2 inches from the flare, just cut a slot at the 0* mark. Shorten the flare sleeve so it just partrudes from the back of the nut. I made various "mandrels" to screw into the nuts to support the tube against the post. This allows the start of the bend very close to the aft side of the nut, much closer to the flare than normally possible.

That's a neat trick, thanks.