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brake line flare

PeterT

Ultra Member
Premium Member
#1
Brain picking you automotive types. I need to form (flare) the ends of brake line into a trumpet shape from the typical ductile copper nickel alloy 5/16" diameter. Its not for automotive hydraulic application, they will be the the induction & exhaust tubes for my model radial engine that seat into the heads. I can post pictures later, but my first experiment was a bit of fail. I made myself a split die plate with a 45 deg chamfer. It clamps the tubing which stands a bit proud. Then I just used a 45-deg tool to lightly tap-tap form the tube ID thinking it would expand the cone. This actually worked great using same diameter aluminum aircraft instrumentation tubing but the brake line is thicker & tougher. At some point I will make or buy the assembly that screws down the forming cone, but that isn't really the issue. The problem is the tubing slides down the die plate hole with much forming force despite it being clamped quite secure. If I support the tubing, I can form the trumpet shape but that wont be feasible on the bent header pipe.

I got looking at commercial die blocks & noticed some have micro serrations in the forming block which I'm guessing is to grip the tube & maybe my issue. Is this common? I thought i saw others that were smooth like a drilled hole but maybe those were cheapos or knock-offs?

My other issue is surface area. My grip band is only 0.125" whereas these blocks look to be 1/4 - 3/8". This might not be enough & root of my problem. Mine is thin because I was envisioning the tubes would be already bent & just the ends required flaring so that band was minimized to accommodate the bend.
 

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John Conroy

Well-Known Member
Premium Member
#2
Normally you would do the flares before bending. You need at least an inch of straight pipe to have enough to form a double flare and grip the tube. Do you need double flares or just single? For just a single flare the die block grip on the pipe doesnt need to super tight but for double flares if it's not really tight the pipe will slip in the die block. The die blocks do have serrations to grip the pipe and after a double flare is made the pipe will have visible marks from that. Copper should be easy to flare if the pipe is annealed before flaring.
 

PeterT

Ultra Member
Premium Member
#3
Thanks. Yes just a single flare trumpet shape upset.

Can this copper nickel stuff be silver soldered do you know?
 

Johnwa

Active Member
#4
Places like Canadian tire and PartsSource have loaner tools available. You put down a deposit (retail value of tool) and get it back if you return the tool.
 

John Conroy

Well-Known Member
Premium Member
#5
Thanks. Yes just a single flare trumpet shape upset.

Can this copper nickel stuff be silver soldered do you know?
Do you mean regular automotive brake line?

The stuff listed on Amazon says it's 88 % copper so it should be ahle to be soldered.
 
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DPittman

Active Member
#6
Thanks. Yes just a single flare trumpet shape upset.

Can this copper nickel stuff be silver soldered do you know?
So I"ve been learning about silver solder lately and while I'm no expert here is what I know so far...
You can silver solder a great variety of metals together, regular solder is more limited and is no where near as strong as silver solder. Silver solder also withstands much higher heat. There is also lead free solder readily available in the typical coils anywhere you buy solder and it says "silver solder" on it however this is not the high strength, high heat stuff that is known as silver solder (or apparently in some circles as hard solder or silver brazing). The high strength/temperature silver solder has a much higher silver content and is crazy expensive. I bought some a year or so ago and it was $35/ounce. Here is a pick of the different solders I mentioned. IMG_20190311_1717488.jpg
 

PeterT

Ultra Member
Premium Member
#7
Yes I think its similar stuff. Sometimes I see a name like Cunifer or an SAE# but I think its generically the same. It bends really well but is rather heavy for my application.
I was wondering if the nickel caused any soldering issues. I guess I'll just try. Another option if the flaring is problematic is just solder a ring on the end. That's fine for the induction tube, but not sure I'd trust it on the exhaust side.
https://store.fedhillusa.com/cnf-5x3ft-5168mmodtubingx3footcoil.aspx

Good lead on the rental/loaner tool Johnwa

Another dumb question. It comes rolled in a pizza box. How do automotive techs 'straighten' it for long linear runs? A different roller or maybe they buy it straight to begin with?
 

PeterT

Ultra Member
Premium Member
#8
This is what I'm facing. Stainless is horrible, not even gunna try.
http://philsradial.blogspot.com/2013/08/tube-buckling.html

I bought some of this. Bends really nice. Flares quite well. Light. I could use it on the induction side. Soldering is doable with the right stuff but not exactly easy. I'm testing a thin joining sleeve with JB weld. In reality the real engine manifolds had upsets to allow tube within a tube or slight rotation between parts. It doesn't have to be scale, it just has to function.
https://www.aircraftspruce.ca/catalog/mepages/3003versatube.php?clickkey=4561
 

DPittman

Active Member
#9
Yes I think its similar stuff. Sometimes I see a name like Cunifer or an SAE# but I think its generically the same. It bends really well but is rather heavy for my application.
I was wondering if the nickel caused any soldering issues. I guess I'll just try. Another option if the flaring is problematic is just solder a ring on the end. That's fine for the induction tube, but not sure I'd trust it on the exhaust side.
https://store.fedhillusa.com/cnf-5x3ft-5168mmodtubingx3footcoil.aspx

Good lead on the rental/loaner tool Johnwa

Another dumb question. It comes rolled in a pizza box. How do automotive techs 'straighten' it for long linear runs? A different roller or maybe they buy it straight to begin with?
The other solider solder that is readily available is "nickel silver rod". Here's a pic of the label of some I have but because it's in a tube the label isn't real clear (also crazy expensive) IMG_20190311_1748244.jpg
 
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#11
I bought the "nickel silver" rod at Princess Auto (I think $20 for two sticks). And the silver solder wire (and corresponding paste) I bought at Western Canada Welding Products (Lethbridge)
 
#13
Another dumb question. It comes rolled in a pizza box. How do automotive techs 'straighten' it for long linear runs? A different roller or maybe they buy it straight to begin with?
Ive always used the “beer belly method” to straighten out a roll of brake line or fuel line. Nothing I’ve worked on has been that critical or fussy that it needed to be arrow straight.

Depending on where or what you’re doing, yes the straight pre-flared stuff works nice to start with

If you need to make any circles or half moons, sockets of various sizes work nice as a “die”

If you need to just make a 90 degree or other radius, they make a really nice forming tool
https://www.canadiantire.ca/en/pdp/...yyELOU_lHgU9rLyuAxZoOMaAo5MEALw_wcB#store=616
 
#14
I bought the "nickel silver" rod at Princess Auto (I think $20 for two sticks). And the silver solder wire (and corresponding paste) I bought at Western Canada Welding Products (Lethbridge)
Aaargh! I was grossly mistaken on the Nikel silver brazing rod price!!! I'm just in P.A. now and see that it is only $10 for 2 sticks not $20 like I thought! Sorry.
 

PeterT

Ultra Member
Premium Member
#15
If you need to just make a 90 degree or other radius, they make a really nice forming tool
Yes, after some so-so results hand bending around various shapes I ended up getting a handheld tool something similar to what you linked. It works well. It has a fixed die at the prescribed minimum bend radius & kind of a sliding shoe that is similarly recessed for the tubing OD. Minimal egging or distortion because both the aluminum & brake line are suited to this. I'm confident I can bend the shapes even though its a 3D path, just need to solve the end flare issue. If I pre-flare the tube, it doesn't lend itself to bending after the fact because the radius is so close to the end. These are actually very fiddly parts. I may try my first 3DP metal experiment on these. It would solve a lot of headaches that are more difficult to produce with forming tools.
 

CalgaryPT

Super User
Vendor
Premium Member
#16
If I pre-flare the tube, it doesn't lend itself to bending after the fact because the radius is so close to the end. These are actually very fiddly parts. I may try my first 3DP metal experiment on these. It would solve a lot of headaches that are more difficult to produce with forming tools.
I'm sure you've already considered this, but a cheap spring former sometimes works well when the tool shown above can't get close enough:

https://www.princessauto.com/en/detail/5-pc-spring-tube-bender-set/A-p8609638e
 

PeterT

Ultra Member
Premium Member
#18
Just search 'radial engine' on the forum.
After a long hiatus since last fall & getting the new mill settled in & then some family stuff that had to be dealt with... finally getting back on the project now.
 

PeterT

Ultra Member
Premium Member
#20
Well, not quite there but showing promise. On my first die I made a backside counter bore to accommodate the curved header. But it didn't have enough remaining surface area to grip the tubing so that was a fail. Then I made another die, tapped it 5/16-24, then drilled it one drill size under 5/16 tubing OD so the threads had just a bit of bite on the tube. It gripped much better, didn't move. But I was quite surprised how much clamping pressure it took in the vise to make the flare just using a dummy 45-deg form tool against the die chamfer. So I tried just peeing over the edge, first with a small drill punch which was ugly. Then a crudely shaped roundy tool that actually seemed to worked quite well. The brake tubing material is quite malleable. I need to improve the technique & make something like a ball ended punch maybe using a bearing ball or something.

When you guys use those flaring tools, does it take hefty torque? I've seen most with maybe 3" wings so assumed it wasn't much torque. Others have a socket wrench which I just assumed was for convenience. Mind you my vise is course thread so maybe the fine thread tools are more efficient.
 

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