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Flaring bent tubing

Mark Jackson

Active Member
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I am building the selector valve to filter fitting. The tube has a 90 degree bend and then a 180 degree bend to connect to the filter. The end of the 180 bend has 1/4 of an inch straight before connecting to the filter.

Problem: I cannot flare the end near the 180 bend before as it will then be crushed by the pipe bender. To be able to bend 180 degrees without collapsing the tubing, I had to have an extra inch of tubing downstream of the bend that is then trimmed off. The problem is that I cannot get the AN818/AN819 nut and coupler on. The nut navigates the the 180 curve easily but the couple won't go past the straight section.

I've used about 4 feet of tubing trying to make this work.

Anyone have any ideas?

P.S. Using a ATS flaring tool, the kind that has blocks that grip the tube and then a flaring tool that you screw down but hand. Requires about 1/2" of tubing to make the flare.
 

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TS FLIGHTLINES

Contact Tom @ TS FLIGHTLINES. (843) 271-2329 .....explain what you need and he WILL have a solution.....unbelievable customer service at great price ....
 
Tom had a trick where you make a mandrel piece that you slip in the end of the tubing. That allows you to do the flare first and then use the mandrel as the bearing surface when you do the bend.
 
My take

I would Do the all the bends except the last one nearest the flare. Put the collar and b nut on and do the flare. Wrench on a union. Do the last bend by hand slowly with even pressure to avoid kinks. You might even use the bending tool to support it but do the bending by hand. You should be able to get real close to b nut and collar. You need the union to avoid distorting the flare
 
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Straighten it out to measure the length. Flare both ends of a new length of tube. Cap one end, fill with fine sand, pack it with a wood dowel, cap the other end. Bend where you can, the sand should prevent collapse, allowing some free hand bending where it won’t fit in the bender. Empty the sand, flush out, use a tube brush or pipe cleaner.
 
I would agree Tom, its not ideal but another way. Not sure of the room he is working with but extending out the 180 deg loop would also give a longer straight to have room to flare the fitting. Bending with sand can be done but that close to the bend will be a pretty good trick.
 
Straighten it out to measure the length. Flare both ends of a new length of tube. Cap one end, fill with fine sand, pack it with a wood dowel, cap the other end. Bend where you can, the sand should prevent collapse, allowing some free hand bending where it won’t fit in the bender. Empty the sand, flush out, use a tube brush or pipe cleaner.

That's a new one for me. I'll write that trick down for when I'm cutting, bending and flaring.
 
Flaring bent tube

I was able to flare the end. The test version was acceptable albeit not too pretty. I was using scrap tubing and nuts so forgive the picture quality.

Steps:

  1. Make the bend.
  2. Install the sleeve so about 1/16 or more is out the top of the sleeve.
  3. Wrap the tube & fitting in masking tape.
  4. Install the fitting in the flaring tool so the body is in the clamp and the thick collar is in what is normally the flared area.
  5. Clamp the yoke assembly in a vise so the flaring cone is just above the tube end.
  6. Slowly (and with lube) screw down the cone.

My real takeaway from this is to do a better job planning. I think in each case I could route the tubing in a way that doesn't require these whacky bends.

I have ordered by second 12' of tubing from Vans. Hopefully this will go better.
 

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...
My real takeaway from this is to do a better job planning. I think in each case I could route the tubing in a way that doesn't require these whacky bends. ...
This was exactly what I learned from a very similar situation.
 
The issue isnt necessarily the bender, but the width of the flaring dies. I have 3 tools. A Parker Rollo flare, a Rigid RFT37 that has a narrower flaring bar and an Olsen roll flare machine. Thats only if you bend the tube first. The big trick is flare the tube first, trim 1/2 of the tail of the 819 sleeve so it just protrudes out the aft of the nut, install the sleeve and nut. I made a threaded mandrel the screw into the nut, and rests against the fulcrum on the hand bender. Biggest trick is to cut a relief slot in the bend die at the 0* mark so the sleeve and nut can rest in that space. It effectively moves the flare aft towards the bend.

With our production flare machine we had special dies made with a narrow grip range and an open relief in the aft section of the die so a pre-bent 90* tube can be flared.

Tom
 

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I ran into the same problem making a couple of fuel line pieces. Found that I needed a minimum of 1.5" straight line to make the flare and hold the flange on. As long as whatever needed that line could have 1.5" of straight line leading into it it was fine.
 
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