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37 Degree Flares

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  • 37 Degree Flares

    I'm not sure this is the correct forum for this post but it's the closest topic I saw.

    I purchased a Rigid 37 degree flare tool # 377 and either it is not performing correctly or I am doing something wrong. I am flaring 3/16" OD stainless tubing for a fuel injection system but my flares are turning out poorly. I do not get a complete flare. By that I mean that the tubing does not form a bell to match the die in the flaring bar. The pressure kick-out releases at what I would condsider 30 to 50 % of a complete flare. This is leaving me with a very small flare that I do not feel is going to provide an adequate seal.

    I am cutting my tubing with a cut of wheel, filing the cut end down so that it is square, filing the burrs from the outside of the tube then finishing with 400 grit sandpaper. I de-burr the inside of the tube with a small round file then finish with a rolled tube of the same 400 sandpaper. I clean the flare cone between flares with a Q-tip and alcohol the lube the cone with a Q-tip with WD-40.

    What else can I do? Is there an adjustment for the pressure kick-off that would allow for a better flare?

    The instructions state that for a bigger flare to leave the tube protruding a bit from the flare bar. I have tried this as well as flaring with the tube flush in the bar. The flares all appear incomplete.

    I purchased this tool based on the fact that it is rated for stainless and other hard metals.

    I welcome any advice.


  • #2
    I think what you need is a 45 degree flaing tool. Flares in tubing are made at 37 degrees, 45 degrees, or double flares ( usually used in high pressure applications such as hydrolics).
    the dog


    • #3
      Problem Solved

      Thanks for the reply. As I stated, I wasn't sure if this was the right forum or not.

      My project is an Enderle mechanical fuel injection for a race car. All fittings and hoses are AN style which uses a 37 degree flare to seal. A 45 degree, while more common, will not work on this application.

      I am happy to say that I solved the problem and that the problem did not rest with the tool or my technique. Rather it was in the material I was using. Apparently not all stainless steel tubing is created equally (I get educated every day). The tubing I was using was annealed to a harder standard than commercial / military grade stainless. Something NASA would use, I guess. Anyway, I replaced the material with some seamless 304 3/16" tubing from a local supplier (PAC Stainless in Des Moines, WA. Awesome service) and my flares are pure poetry. Well, maybe not poetry but they certainly have some symmetry to them.

      Thanks for reading and thanks Plumbdog for the reply.