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How to Correctly Flare Stainless Steel Tubing for either 37° Single Flare and 45° Double Flare

We recommend that you start by cutting the stainless steel tubing with a 32 tooth per inch saw (See Figure 1). A tubing cutter or die-grinder, will "work harden/heat treat" the material and make it brittle and prone to crack. Use light pressure while cutting so that the tubing stays round.

Figure 1
Figure 1
Here we are using a 32 Tooth Saw Blade to cut the stainless steel tubing.

Once cut, it's important to chamfer and debur both edges of the tube. This allows the tube to roll over to create a smooth edge. To debur the inside edges, use a step drill bit (The size will depend on the size of stainless steel tubing. On brake lines use a 13 step drill bit and on fuel line use a 9 step drill bit. We recommend part number 555-W9003) or a round file (See Figure 2). Rotate the bit or file in the opening of the tube. The outside edge can be done with a standard file. (See Figure 3) We recommend part number 555-W5390. Tube cracking is typically caused when the tube is not properly deburred.

Figure 2
Figure 2
Figure 3
Figure 3
Here we are using a step bit to debur the inside edge and a file to debur the outside edge.

37° Single Flare

When flaring the tube for a 37° Single Flare, you must use a flaring tool that does a 37° Single Flare. We recommend part number 555-80084. It's important to use lube on the flaring tool and the tube. To create a 37° Single Flare, first clamp the tube flush in the correct size fixture. When you make the tube flush, this will set the depth of the flare (See Figure 4). Next, the forming die must be centered on the tube or the flare will be off center. By using the "V" shaped die this will create the 37° Single Flare that you need for AN fittings (See Figure 5 & Figure 6).

Figure 4
Figure 4
Figure 5
Figure 5
Here we are setting the depth of the tubing. The tubing must be flush with the tool, once that's done, by using the 37° die you turn the tool to create your flare.

Figure 6
Figure 6
Here is a finished 37° Flare.

45° Double Flare

When flaring the tube for a 45° Double Flare, you must use a flaring tool that does a 45° Double Flare. We recommend part number 555-80087. It's important to use lube on the flaring tool and the tube. To create a 45° Double Flare, first clamp the tube in the correct size fixture. Set the depth by aligning the tube with the Bubble Flare die. The edge of the tube must be even with the edge of the Bubble Flare die. (See Figure 7).

Figure 7
Figure 7
Here we placed the tube in the correct size hole on the bar and we are setting depth of the flare by aligning the edge of the tube and the Bubble Flare die.

Next, the forming die must be centered on the tube or the flare will be off center. (See Figure 8).

Figure 8
Figure 8
Here we are inserting the Bubble Flare die into place on the tube (The tail of the Bubble Flare die will be inserted inside the tube).

By using the "V" shaped die & aligning it with the Bubble Flare die and the tube, you will start by turning in the "V" shaped die. The "V" shaped die will start pressing on the Bubble Flare die and creating a Bubble Flare. (See Figure 9).

Figure 9
Figure 9

Once the Bubble Flare is complete, (See Figure 10) the Double Flare is completed by removing the die & forming the tube with the "V" shaped die. This will create an inverted flare which will complete the flare. (See Figure 11 & 12)

Figure 10
Figure 10
Figure 11
Figure 11
Here is a finished Bubble Flare. Next we are using the 45° "V" die to create an inverted flare and complete the Double Flare.

Figure 12
Figure 12
Here is a Finished 45° Double Flare.