Flaring is the clearest case in the whole curriculum for distributed practice. It visibly improves with repetition and visibly decays without it, and the artifact shows its own quality permanently — anyone can look at a flare weeks later and see whether it was made well.
Three of General's five artifact-verified elements are in this unit (GEN-D §2). This is what the mailed kit is mostly for.
Read GEN-D Procedures first. This tells you what your first attempts will actually look like.
Session 1 — Cutting, before flaring
Materials: aluminum tube stock, tube cutter, deburring tool.
Do not flare anything yet.
- Cut ten pieces, about 150 mm each.
- On the first five, cut how you would naturally — a few turns of the wheel, tighten, repeat.
- On the second five, advance the wheel a quarter turn per revolution of the cutter and take your time.
- Deburr all ten, inside and out.
- Line them up and look down them.
What you will see: the first five are more ovalised and their ends are less square. The difference is obvious once they are side by side and invisible one at a time.
What you are learning: every flare defect in Session 3 will trace back to this session. A tube that is oval before you flare it cannot produce a round flare.
Session 2 — Bending
Materials: tube stock, a bender for the size.
- Look up the minimum bend radius for your tube. Write it down.
- Bend five pieces at that radius.
- Deliberately bend one tighter than minimum. Look at what happens to the outside wall and the inside wall.
- Measure across the bend in two directions and work out the ovality.
What will be wrong on your first attempts:
| What you will see | What it means |
|---|---|
| Flattening at the bend | Tube not fully supported in the former, or bent too fast |
| Wrinkles on the inside of the bend | Radius too tight, or wall too thin for the bend |
| Scoring along the tube | Debris in the former, or the wrong size former |
| Bend is in the wrong place | Mark before bending; the bend consumes tube length |
Step 3 matters. Doing it wrong once, deliberately, on scrap teaches you what "too tight" looks like — so you recognize it on an aircraft, where nobody will tell you.
Session 3 — The first flares
Materials: tube, flaring tool (37°), sleeves and nuts, a fitting to test against.
- Check your tool is 37°. If it came from an automotive supplier it is probably 45° (GEN-D Concepts §2).
- Slide the nut and sleeve on. Say it out loud. You will still forget.
- Clamp at the correct projection, form the flare.
- Offer it to the fitting cone and look at the contact.
- Repeat ten times.
What will be wrong on your first attempts:
| What you will see | What it means |
|---|---|
| Nut still on the bench | The most common first-attempt failure. Cut it off and start again |
| Flare cracked or split | Not deburred, tube work-hardened, or formed too fast |
| Flare too small | Not enough projection above the die |
| Flare too large, sleeve will not seat | Too much projection |
| Flare not square to the tube | Tube not cut square — Session 1 |
| Uneven wall thickness round the flare | Tube ovalised before flaring — Session 1 |
| Contacts on a line, not a face | Wrong angle tool, or flare not square |
Expect the first three or four to be scrap. That is the point of doing this at home with a box of tube rather than in the shop with an instructor waiting for the result.
Session 4 — Consistency, on separate days
Make five good flares in a row. Then leave it a day and do it again. Then leave it three days and do it again.
Do not do all your repetitions in one sitting. The skill being built is the one still present in a month. A candidate who made forty flares on one Saturday and none since has practiced flaring; a candidate who made five a week for a month can flare.
When you are ready to send it in: five consecutive flares that seat evenly on the cone, with even wall thickness, no cracks, square to the tube — and made on at least two different days.
Session 5 — A line with a flare and a bend (S1)
This is the assessed artifact. It combines everything above.
- Plan the run: mark for the bend, allowing for the length the bend consumes and the length the flares consume.
- Cut, deburr.
- Bend to the marked position, at or above minimum radius.
- Nut and sleeve on, both ends.
- Flare both ends.
- Check: does it match the intended dimensions? Do both flares seat?
What will be wrong: the dimensions. Almost everyone's first complete line is the right shape and the wrong length, because bends and flares both consume tube and the allowances have to be made before cutting.
Session 6 — Installing, and the twist you cannot see
If your kit includes hose and a fitting pair:
- Install a hose between two fittings, tightening normally with one wrench.
- Look at the lay line. It will probably spiral.
- Slacken. Re-install holding the hose fitting with a second wrench so the hose cannot turn.
- Look at the lay line again.
What you are learning: you introduce the twist yourself, during tightening, without noticing.
This is R5, and the two-wrench habit is the whole answer to it (GEN-D Concepts §3).
What to send back
| Element | Artifact |
|---|---|
S1 |
One rigid line with a flare and a bend, to the supplied dimensions |
S2 |
The same line installed between the supplied fittings, torqued and witness-marked |
S3 |
A flexible hose installed between the supplied fittings, lay line straight |
Send your scrap as well, with a note on what you think went wrong with each piece. A candidate who can look at a split flare and say "not deburred" has learned the unit. One who sends three good flares and cannot say why the fourth failed has learned a motion.
License
CC BY-SA 4.0 (Licensing).