Tube Bending Is Kicking My *** (T-01219B)

[Hairball192]

Uncle... I'm having a real hard time figuring out the bend template on P. 37-11 Figure 1 for the fuel vent tube. P/N is T-01219B made of 3/8" aluminum tube. I'll be ordering more tubing from Van's tomorrow so I can start over. The installed image of the part is on P. 37-08, Fig 3.

Is there a previous thread on this topic or part?

Is there a video somewhere?

And if anyone wants to share tips on flaring, I'm all ears there, too.

Thanks,
Harry

[Hairball192]

Another question I had was on good ways to straighten the coils of aluminum tubing. I found this video for a DIY straightening tool that looks promising:

https://www.youtube.com/watch?v=-Sj-vDn_O0g

What other tools or techniques do people use?

Thanks,
Harry

[Kyle Boatright]

My go-to bending tool is the wound spring type which slip over the tubing and help prevent it from kinking as you make the bend. Here's one example, but Cleaveland, Aircraft Spruce, and others carry similar products.

https://www.lowes.com/pd/Cobra-1-4-i...E&gclsrc=aw.ds

[Hairball192]

Thanks, Kyle... but the problem is not with my tools, it's with my brain.

I'm having trouble figuring out how to orient the bends in the vent tube because they're not all in the same plane. There are two drawings in the figure with a comment saying one is oriented 90 degrees from the other.

Thanks though.
Harry

[ILikePike]

Use a coat hanger to make a template.

[Hairball192]

Great tip on the coat hanger, Jeff!

Thanks,
Harry

[Hairball192]

After burning through another twelve feet of tubing I have a nice-fitting fuel vent tube T-01219B. Someday I'll be good at tube bending, but for now I'm just glad to have it done. I thought I'd have it all buttoned up tonight, until...

I'm stuck on the direction of the bevel on the portion that protrudes from the bottom of the fuselage into the airstream. Basically, I don't know what direction a "forward" bevel is.

Does the 45 degree opening face *into* the slipstream (creating a little bit of ram air pressure in the vent tube)?

Or does the 45 degree opening face *aft* toward the tail (creating a little bit of suction in the vent tube)?

Page 37-08 step 15 is what got me. And Page 37-11, Fig 1 has the diagram of the T-01219B with the bevel at the end.

Thanks in advance for un-confusing me.

Best,
Harry

[rapid_ascent]

The bevel faces forward. That allows the incoming air to pressurize the tank. Think about it like this. The fuel that is removed from the tank has to be replaced by air and that air has to come from somewhere hence the vent.

What I found that really helps with the bends is to position the tubing like it will be when installed. Then position the bender so that the bend is going in the correct direction. Its really easy to get confused without a reference. Also you need to figure out how to use the R and L markings so that your bends are in the correct place. Don't worry about wasting some tubing I have a ton of pieces that I have cut off due to bad bends. Its all part of the learning process.

[TS Flightlines]

would there be interest in a package with CNC bent tubes for the different planes? WE have the bender, the CMM laser scanner, the software and the other equipment to make them. Similar package to our RV12IS package, and RV14 fuel package. Let us know!

Tom

[wilddog]

I enjoyed making those tubes for my -8. Made all the lines before closing the fuselage with the fuselage rotated on its side for easy access while sitting on shop stool. Used the spring type and lever type benders and had return lines going to each tank so there were quite a few lines to bend. Used welding rod to make patterns. Still ended up with lots of scrap tube.