← Balanset-1A Knowledge Base — all chapters
Real support stories. Each comes with a lesson.
Case 1. The record: a 24-tonne rotor (India, sugar mill)
A fiberizer (cane shredder), rotor mass 24,000 kg, ~750 rpm. Initial vibration 3.2–5.7 mm/s.
Standard-method balancing: trial weight, calculation, 7.8 kg installed at 270°. Result — 0.47 mm/s.
Урок: the influence-coefficient method does not limit rotor mass — only the weights grow. The same mill balanced German centrifuges — initially 9.26 mm/s, corrected with a 2585 g plate inside the basket:
Case 2. A Seppi mulcher: the checkbox that cost a week (Germany)
A Seppi mulcher, initial vibration 83–128 mm/s — extreme. The program calculated weights, the customer welded them on — no luck.
The cause hid in the settings: the “remove mass” checkbox was ticked while the customer was adding weight — the sign was inverted.
After the fix: balancing at 700–900 rpm, half the calculated mass, final 3.4 / 8.3 mm/s — “Der Mulcher läuft spürbar sehr ruhig”; both the customer and his client happy.
Урок: check the correction-method setting before starting. And: above 50 mm/s — always a two-stage balancing at reduced RPM.
Case 3. The tachometer saw two pulley holes (Switzerland)
A mulcher wouldn’t balance for months: the program demanded huge masses (1466/1494 g) and the RPM read ~4000.
From an installation photo Nikolai spotted it: the pulley has two holes, and the tachometer caught them as two marks — the RPM doubled and the phase was meaningless.
Урок: if the program’s RPM differs from reality by an integer factor — hunt for extra “marks” (holes, glints, blades). Always verify the shown RPM against the real one.
Case 4. “Unbalance” that turned out to be a destroyed clutch (USA)
A Morbark M15 chipper drum. The customer’s first-ever balancing job — and a hard case at once: unstable readings, masses that wouldn’t converge. The spectrum showed the main peak at ~70 Hz (≈4000 rpm) against a working 1800 — the source wasn’t the rotor.
After a month of searching the clutch was opened: the twin disk was destroyed inside, invisible externally.
After the clutch was replaced, vibration dropped from ~14 to 3–4 mm/s even before balancing. The remainder was read from the spectrum: 2x above 1x → misalignment/looseness; too early to balance.
Урок: unstable readings = a mechanical problem. The spectrum answers “who is shaking” before you weld your first weight.
Case 5. A ladder’s resonance, not unbalance (Belgium, combine)
A forage-harvester drum after knife-mount repairs (new welded mounts, ~500 g unbalance). On the drum’s bearings — 0.3–0.5 mm/s (excellent), but on the ladder/cab — up to 9 mm/s.
The rule: vibration must decay as you move away from the rotor. If it grows — that’s structural resonance. The customer found a torn pipe and broken mounting bolts. After the repair: 0.9 / 1.6 mm/s.
Урок: measure at several points. If it shakes harder away from the rotor than at the supports, there is nothing to balance — find the structural resonance.
Case 6. A bent shaft: balancing with a mechanical discount (France)
A mulcher with a badly bent rotor. Initially 25 and 40 mm/s. Following support’s hints: start at a reduced 600–700 rpm, RunDown for resonances, sensors moved horizontal, the loose flap welded to the housing. Result: 3 and 11 mm/s — the ceiling for a bent shaft; the customer was satisfied and paid cash on the spot.
Урок: a deformed rotor can’t be balanced out completely — part of the “unbalance” is geometric. The honest outcome: reduce to acceptable and tell the customer the truth about the shaft.
Case 7. The 120 mm/s epic (Spain)
A 230 cm mulcher: vibration up to 120 mm/s, resonances almost everywhere, 2 mm of bearing play, a worn shaft journal, housing cracks.
What was done, in order:
- Bearings replaced (twice), the shaft journal built up and re-machined.
- Cracks welded, the flap welded on.
- Balanced in stages at 950–1000 rpm, installing 1/3–1/2 of the mass.
The outcome at the working 1600 rpm: 16 and 18 mm/s — not ideal, but the machine became workable. The customer: “if it weren’t for your help I wouldn’t have managed”.
Lesson from the same chat: “practically every second mulcher balances only after both bearing sets are replaced; second place goes to housing cracks”.
Case 8. A 4500 kg crusher rotor in three days (France)
A two-day battle: the hammered rotor behaved nonlinearly; after correction one plane got worse. The findings:
- the ~8 kg trial weight was far too big (the optimum ~1 kg) — it broke the linear model;
- the report showed doubled RPM (713 and 1440) — the mark was caught twice per revolution;
- percent mode instead of grams was on.
The second rotor (4500 kg, 605 rpm), with mistakes fixed: from 6 and 8 → 0.9 and 1.3 mm/s.
Урок: a trial weight should change the vibration by 20–30%, not by hundreds of percent.
Case 9. A university fan: not everything is cured by balancing (Portugal)
A ventilation fan: 4 and 7 mm/s. Balancing brought it to 0.5 / 0.6 mm/s, but a dominant ~600 rpm (~10 Hz) frequency remained — not the rotation frequency. Verdict: aerodynamics — duct suction with insufficient housing stiffness. Recommendations: clean the filters, stiffen the structure. The customer got both a result and honest diagnostics.
Урок: a residual peak at a “foreign” frequency after balancing is a cue for diagnostics, not for more weights.
Case 10. The angle-counting mistake: 70° vs 290° (Romania)
For several days a mulcher “wouldn’t balance”; vibration grew with every weight. It turned out the customer counted the angle срещу rotation (placing at 360−70=290° instead of 70°).
The explanation that clicked: “it’s not you walking around the dial — it’s the dial turning while you stand still”. A bent shaft and a ~755 rpm resonance were found there too.
Урок: the angle — from the trial weight, in the direction of rotation. Always.
Case 11. A cardan shaft and hose clamps (Croatia)
A car’s cardan shaft: weights fixed with worm-drive hose clamps (faster and simpler than welding; secure the thread). Along the way: the program froze on the COM port ~10 times a day — cured by an experimental software build; the sensor coefficients were recovered from the econfig file on the USB stick (the box had been thrown out). Result — 0,5 мм/сек.
A peak at ~1810 rpm remained in the spectrum against a working 1189 — a “foreign” source (the engine).
Урок: clamps are a legitimate way to fix weights on shafts; the coefficients live in three places — losing all of them at once is hard.
Case 12. RunDown finds the test-rig resonances (Romania)
A DIY rig with an impeller: balancing wouldn’t work. The coast-down chart showed three resonance zones: ~420, ~644 and above 960 rpm. The fix: balance at ~844 rpm (between resonances) and put the rig on springs.
Result: 23.26 → 0.905 mm/s.
Урок: RunDown is the fastest way to pick “clean” RPM. A proper rig rocks by hand on its springs.
Case 13. A ~600 kg rotor, a faulty unit, a 2-day replacement (Poland)
The customer collected the device in person; three days later the unit stopped being detected (a factory contact defect). A replacement shipped by DHL the next day. Then normal work: a ~600 kg mulcher, trial 400–600 g, weights 494 g @3° and 486 g @331°, final ~5–6 mm/s (inside the 6–7 mm/s soft-support tolerance).
Урок: this is what the complete cycle looks like on screen on a real machine.
