Building Your Own Balancing Machine: Supports, Bed, Drive, and Measurement System

Building a balancing rig in your own shop is realistic, and it's done more often than people tend to think. The expensive part of a project like this isn't the electronics — it's the mechanics: supports, bed, drive, and rotor location. Below we break the construction down by assembly, show where the physical limits on accuracy lie, and give a step-by-step commissioning procedure. The Balanset-1A OEM serves as the measurement core in the examples, because for soft-bearing machines that's its standard application.

Updated 27 August 2026 · by AXILINE · Vila Nova de Gaia

Do You Need Your Own Rig: An Honest Fork in the Road

Your own rig is justified when you have a steady stream of similar parts and you balance them before assembly. Fan wheels, pump impellers, pulleys, screw conveyors, drums, knife rolls, motor rotors after rewinding, tooling. A rig gives you the same location from part to part, removes the hassle of mounting sensors each time, and lets you work from saved influence coefficients — the rig's remembered response to a trial weight, from which the instrument calculates the correction without repeat trial runs.

A rig isn't justified when the machine is already sitting on its foundation. Balancing in the machine's own bearing housings accounts for the real bearing housings, the real frame stiffness, the operating temperature, and the running condition. A rig doesn't reproduce any of that. You'd end up with a part balanced on an arbor, and you'd still have to go finish the job on site.

A ready-made machine wins wherever a certificate is needed. A factory machine comes with a data sheet, a stated minimum achievable residual unbalance, and a verification procedure. A homemade rig doesn't inherit those figures: you'll have to establish them yourself, and that's a separate job.

Practical advice: start with on-site balancing of your own part range. Over a month or two you'll build up statistics on masses, diameters, speeds, and the number of correction planes — rotor cross-sections where correction weights are mounted. Designing a rig from this data is far easier than designing it from guesses.

Soft-Bearing and Hard-Bearing Schemes: Where the Running Speed Sits

The entire difference between the two schemes comes down to one question: where the running speed sits relative to the supports' suspension natural frequency. In the soft-bearing (above-resonance) scheme, the support is compliant and oscillates noticeably under the centrifugal force from unbalance. The running speed sits above the suspension's natural frequency — hence "above-resonance" — roughly 2–3 times higher or more. What's measured here is the support's motion: vibration velocity or vibration displacement.

In the hard-bearing (below-resonance) scheme, the support is essentially motionless. It's built as a thick plate with a U-shaped slot that effectively splits the plate into a rigid part and a compliant part. Under the unbalance force, these parts shift relative to each other by microns, and this shift is picked up with a force sensor or a highly sensitive displacement sensor. The running speed is kept 2–3 times below the support's natural frequency — hence "below-resonance."

For a homemade rig, the soft-bearing scheme is simpler for three reasons. Amplitudes at the supports are several times higher, so ordinary accelerometers are good enough. The suspension's natural frequency is easy to tune with spring geometry and easy to measure. And finally, the support's response doesn't need a calculation model: the system calibrates itself with a trial weight. The Balanset-1A OEM fits into this scheme as a standard application: two accelerometers on the supports, a laser phase sensor on a reflective marker, a two-channel USB module, and software on a laptop.

A soft-bearing rig's support natural frequency depends on the mass of the mounted rotor. That means your working speed range will differ for a light blower and a heavy drum. Calculate the speed window for the extreme masses in your part range, not for one average part.

Supports: The Assembly That Determines Everything Else

The support is the rig's moving part that carries the rotor and passes its vibration on to the sensor. The requirements on it are contradictory: it needs to be compliant in the measurement direction and rigid in every other direction, while holding its own coaxial alignment and not losing its geometry over years of use.

The most common solution for homemade rigs is flat (leaf) springs. Two steel plates connect the lower base plate to the upper one, which carries the support assembly. Always make the springs from spring steel or good-quality alloy steel. Ordinary structural steel with a low elastic limit picks up permanent deformation under static and dynamic load, its coaxial alignment drifts off, and in the worst case the support loses stability.

A band suspension for the carriage gives a very low natural frequency, on the order of 1–2 Hz, and therefore a wide working speed range. What matters here is choosing the band's thickness and width: it has to hold the rotor's weight while also ruling out torsional oscillation of the suspension, which shows up as face runout. Cylindrical compression springs under the plate are the simplest to make, but they carry a built-in flaw. With an asymmetric rotor, the front and rear springs compress by different amounts, the rotor axis tilts in the vertical plane, and forces appear that push the rotor in the axial direction.

• Stiffness and its direction: compliance only in the measurement plane — the support must be rigid crosswise and vertically.
• Suspension natural frequency in the transverse direction: at least 2–3 times below the running speed.
• Natural frequency in the axial direction: it caps the range from above — keep the running speed no higher than 0.3–0.5 of it.
• Matching frequencies across all the machine's supports: a spread between the spindle supports and the intermediate ones narrows the working speed window down to the worst case.
• Friction: any dry friction and play turn into scatter in amplitude and phase from run to run.
• Adjustment: in height for setting the support's coaxial alignment, and along the bed's length for different rotor spans.
• Axial force: the support has to absorb the axial force from the drive and from misalignment without its geometry drifting.
• Lock: a mechanism to fix the support during run-up and coast-down, or the suspension wears itself out passing through resonance.
• Rigid-support thickness as a guideline: about 20 mm for rotors up to 50–100 kg, 30–40 mm up to 300–500 kg, 50–60 mm and more for rotors from 1000 kg.

Adjusting the natural frequency of a leaf-spring support isn't hard. Mill longitudinal or transverse slots into the spring, lower the stiffness, remeasure the frequency. This is how spindle-support and intermediate-support frequencies get matched after assembly.

Suspension Natural Frequency: Calculate First, Then Measure

An estimating calculation is done using a single-degree-of-freedom model: a mass on a spring. The natural frequency equals the square root of stiffness over mass, divided by 2π. For a symmetric between-bearings rotor, take the mass as the support's moving-part mass plus the rotor's mass divided by the number of supports involved. Stiffness is easier to get experimentally: load the support with a static force using a force gauge, measure the displacement with a dial indicator, and divide the force by the deformation.

Two rules follow from this formula, and they're easy to forget. Frequency depends on stiffness and mass through a square root: doubling the stiffness raises the frequency by only a factor of 1.4, and doubling the moving-part mass lowers it by that same factor of 1.4. And second: a calculation from a simplified model carries a large error, so always get the final figure by measurement.

Two methods are used to measure it. Impact excitation works for both soft and rigid supports. Determination from coast-down only applies to the soft-bearing scheme: on a hard-bearing machine, the running speed is deliberately below the support's natural frequency, and coast-down won't be able to excite it.

1. 1

   Calculation

   Estimate the support's stiffness by static loading and calculate the expected natural frequency. This is so you know what order of magnitude you're looking for.

2. 2

   Impact

   Mount the vibration sensor so its measurement axis lines up with the direction of the impact. Strike it with a rubber-faced hammer or mallet whose mass is about 10% of the excited assembly's mass. Record the time trace and the spectrum of the decaying oscillation: the peak in the spectrum is the natural frequency.

3. 3

   Two directions

   Repeat the impact in the transverse direction (where you measure unbalance) and in the axial direction, along the rotor's rotation axis. On soft supports, the axial frequency often turns out to be the limiting factor from above.

4. 4

   Coast-down

   Spin the rotor up to maximum, disconnect the drive, and record the amplitude and phase of the running-speed component — vibration at the rotation frequency — through the cycle. Resonance gives itself away with a local spike in amplitude and a sharp roughly 180° phase reversal.

5. 5

   Speed window

   Set the working range: no lower than 2–3 times the transverse natural frequency, and no higher than 0.3–0.5 of the axial natural frequency. Check that the window stays viable for both the lightest and heaviest part in your range.

An example from practice. A leaf-spring support measuring 300×200×3 mm gave 11–12 Hz unloaded. That means balancing on this machine can't go below 22–24 Hz — roughly 1320–1440 rpm. The intermediate supports on the same machine, with 200×200×3 mm springs, showed 13–14 Hz, and their frequencies had to be matched to the spindle supports.

Bearing Assemblies and the Sensor Location

The bearing assembly is what the rotor actually spins on. It determines friction, the repeatability of location, and runout that no amount of weights will ever balance out.

Give separate thought to the sensor pad. Mount the vibration sensor on the support's moving part, as close as possible to the line of load action, on a clean, flat, machined surface, using a stud or a magnet. The measurement direction is usually horizontal-radial, perpendicular to the shaft, and it needs to stay the same from one reading to the next. A non-rigid pad, a bracket made from strip stock, a sensor on a cover or a guard — these all introduce their own resonances into the measurement band and phase scatter.

• Roller and bearing fits with no play, with runout checked after assembly, not taken from the bearing's data sheet.
• Assembly adjustment in height, for setting support alignment, and along the bed's length, for different rotor spans.
• A machined pad for the vibration sensor on the support's moving part, close to the line of load.
• The same measurement direction at every support, fixed in the operator's instructions.
• The sensor cable is secured and doesn't act as a spring: a dangling cable adds its own oscillation.
• Repeatable rotor location: a stop, a mark, a fixed position, so the part seats into the supports the same way every time.
• Spindle-bearing outer-race temperature no higher than 70°C, and for high accuracy, no higher than 40–45°C.

The Bed, Installation, and Vibration Isolation

The bed holds the whole rig's geometry. Four requirements apply to it: bending and torsional stiffness, geometric accuracy of the ways, vibration resistance, and wear resistance of the ways. The bed's mass needs to noticeably exceed the mass of the heaviest rotor in your range, or the supports will start rocking the base, and you'll end up measuring the structure's behavior instead of unbalance.

The fastest route for a shop is a cast-iron bed from a used metalworking or woodworking machine. You get a rigid load-bearing frame with ways right away, and any type of support stand can be mounted on them. The main work comes down to restoring the ways' geometric accuracy, which in shop conditions is done by fine scraping.

Welded and bolted-up beds made from channel steel also work, but demand discipline. After welding, stress-relief heat treatment is needed, or the bed's geometry will drift within six months. A bolted joint lets you skip that step, since it doesn't introduce welding distortion. Either way, the channel's top flanges will need machining: grinding or fine milling for the ways.

• Polymer concrete with a vibration-damping coating: a higher damping coefficient, lower thermal conductivity and thermal deformation, no internal stresses, doesn't corrode. The top section is reinforced with steel inserts for the ways.
• Floor mounting: either rigidly anchored into the foundation, or on vibration isolators. Rigid mounting holds the geometry better; isolators protect better against external interference from the shop floor.
• Bed resonances: check them with the same impact method as the supports. A bed resonance peak inside the working speed range produces unstable amplitude and phase, and no software setting fixes that.
• External sources: a press, an overhead crane, a compressor near the rig all produce vibration at frequencies that fall inside the measurement band. Synchronous filtering suppresses them, but not without limit.
• The ways: their length and accuracy determine what rotor span you can service and how repeatably the intermediate supports land in the same spot.

Geometry guidelines worth aiming for at acceptance: bed leveling in the longitudinal and transverse directions no worse than 0.02–0.04 mm/m, straightness deviation of the ways around 10 µm at lengths up to 500 mm, 15 µm up to 1000 mm, and 20 µm up to 2000 mm, and way twist no more than 10 µm. These are working guidelines for a homemade rig, not normative requirements.

The Drive: How to Spin the Rotor Without Ruining the Measurement

The drive exists for one purpose: to bring the rotor up to a stable speed. Anything it adds to the vibration goes straight into the error. Hence a simple rule: the less the drive is involved in the measurement, the cleaner the result.

The overwhelming majority of homemade rigs are built on an induction motor with a VFD. It's cheap and gives a wide adjustment range. Rough main-drive power ratings: 0.25–0.72 kW for rotors up to 5 kg, 0.72–1.2 kW up to 50 kg, 1.2–1.5 kW up to 100 kg, 1.5–2.2 kW up to 500 kg, 2.2–5 kW up to 1000 kg, 5–7.5 kW up to 3000 kg.

The type of drive transmission affects the measurement more than it seems to. For spindle assemblies, a flat-belt drive is preferred. V-belts and toothed belts introduce extra dynamic loads from geometric errors in the belt and pulleys, and those loads arrive at the supports right alongside the useful signal. Mount the drive pulley on the spindle's rear end, as close to the bearing assembly as possible, with minimal overhang. A pulley set out on a long overhang increases the dynamic-load moment on the spindle's supports.

• The motor is rigidly mounted to the bed or the foundation, not to the support's moving part.
• The motor, together with its mounted pulley, is balanced before installation on the machine, or in place after installation.
• Drive-pulley radial runout within 20 µm: the measurement system reads pulley runout as unbalance.
• The belt is tensioned so it doesn't slip: slipping produces speed jumps, and the synchronous filter's tuning and phase accuracy both depend on speed.
• Line filters sit on the VFD's input and output, either factory-made or homemade on ferrite rings.
• The machine is reliably grounded: without grounding, the VFD induces interference directly into the measurement channel.
• Run-up and coast-down happen with the supports locked, if a locking mechanism is provided.
• A removable drive or coast-down measurement is provided as a way to escape drive interference entirely.

Coast-down measurement is a legitimate technique for a soft-bearing rig. You spin the rotor above the running speed, disconnect the drive, and record amplitude and phase at the target rotation frequency with the motor off. Interference from the belt, pulley, and VFD disappears in the process. The trade-off is that the speed keeps falling continuously, and on low-speed rotors there may not be enough time left for synchronous averaging.

The Measurement System: Sensors, Marker, Two Channels

The measurement system has one job: precisely measure the amplitude and phase of the vibration's running-speed component at the rotor's rotation frequency. Everything else is a means to that end. The useful signal has to be pulled out of a mix of interference, so the signal chain runs, in sequence, through broadband filtering, amplification, integration, a narrowband tracking filter, analog-to-digital conversion, synchronous filtering, and harmonic analysis.

Sensible bandpass-filter limits for a balancing instrument are 2–3 Hz on the low end and 50–100 Hz on the high end. Filtering the low end suppresses low-frequency amplifier noise; filtering the high end removes combination frequencies and resonances of individual machine components. Synchronous filtering works as averaging across revolutions: the useful signal's energy grows in proportion to the square of the number of averaging cycles, while the noise energy grows only in proportion to their number. The cost is that at low speed the measurement takes time: at 120 rpm and 64 averaging cycles, a single reading takes more than 30 seconds.

Two channels at once aren't a convenience — they're needed because a two-plane problem is solved as a system of equations across both supports at once. Measure the supports one after the other, and you get two readings taken in different states of the system, and the influence coefficients end up calculated from inconsistent data.

• What the measurement core's software gives you: correction calculation in one and two planes, influence coefficients saved for a specific rotor type.
• The 1x running-speed component with phase, separate from overall vibration, the FFT spectrum, and a polar diagram for checking that you're actually fighting unbalance.
• A target residual vibration value and a within-tolerance flag, plus tolerance calculation against grades G.
• Fixed positions: the software gives a position number and a mass instead of an angle, which removes the operator's most common mistake with the reference direction.
• Splitting the weight between two adjacent positions, and calculating drilling parameters when metal is removed instead of added.
• A measurement archive and report printing: without this a rig gives you no traceability, and you can't pull up the history for a specific part.
• Location-eccentricity compensation using the rotor-flip method: it subtracts the arbor's or spindle's contribution from the result.

The Balanset-1A's measurement band per the manual is 5–200 Hz for vibration velocity RMS, with a running-speed-component range of 0.02–80 mm/s. Assessing machine condition per the ISO 20816 series usually requires a broadband measurement in the 10–1000 Hz band. These are different things, and if your acceptance criteria are tied to the second band, check applicability in advance. Confirm the applicable part and edition of the standard separately.

Sources: Balanset-1A operation manual · Balanset-1A manufacturer specification · ISO 20816-1:2016

Arbors, Location, and Eccentricity Compensation

Your rig's accuracy comes down to rotor location, not electronics. If the arbor has eccentricity, the rotor sits on it with an axis offset, and the measurement system will honestly show that eccentricity as unbalance. You'll balance the part together with the arbor's error, take it off the rig, put it in the machine, and get vibration.

The same goes for the spindle. Its radial and face runout carries straight into the result. A guideline tolerance: no more than 5 µm on both parameters, if you want to skip an extra 180° rotor flip. For mid-sized machines, hold the bearing assemblies' alignment within 10–15 µm.

There's a standard technique against eccentricity: balancing with a rotor flip, which measurement systems call eccentricity compensation. The idea is simple. You take a reading, flip the rotor on the arbor 180°, and take a second reading. The rotor's own unbalance rotates along with the flip, while the arbor's eccentricity stays put. The vector difference lets you separate the two contributions and subtract the location error from the result.

• The arbor has minimal runout and is itself balanced in two planes, to a grade 1–2 steps tighter than the part.
• The part's fit on the arbor is repeatable: a taper, a shoulder, a stop — not "by eye, hand-tight."
• The part's clamping is torque-specified: different torque means a different fit and a different result.
• The marker on the rotor or spindle is tied to the machine's angular-scale zero.
• For parts with a tight residual-unbalance requirement, an eccentricity-compensation mode is provided, not just a direct reading.
• The correction planes are accessible with the rotor stopped, without removing the part from the arbor, or every iteration breaks the location.
• The weight-mounting radius is marked and recorded: mount the correction at the same radius as the trial weight.

A practical limit. If the arbor's runout accounts for a noticeable share of the required residual unbalance, no measurement system will save you: you'll be capped by the tooling. Work out this figure before building the rig, because it determines what accuracy grade is even achievable with your construction.

Rig Acceptance: Geometry and Dynamics, Step by Step

A homemade rig is a one-off piece of equipment with no production documentation. That's why it needs a thorough check at commissioning, and the order here matters: geometry first, then dynamics, then the measurement channel, and only after that, accuracy on a reference rotor. Checking accuracy before the geometry is set is pointless.

For tools you'll need a machinist's level (spirit or electronic), a straightedge, a stand with a dial indicator, a measuring bridge, a reference arbor, and a force gauge. All of this is available to any repair shop.

1. 1

   Installation and leveling

   Anchor the bed into the foundation, or set it on vibration isolators. Level it in the longitudinal and transverse directions, taking readings at points evenly spaced along the bed's length.

2. 2

   Ways

   Check the ways' straightness with a straightedge and indicator, or with a level advanced in steps equal to its base length. The deviation equals the largest algebraic difference between readings across all sections. Separately check for twist using a level set crosswise on the ways.

3. 3

   Spindles and pulleys

   Measure the radial and face runout of the drive and driven spindles with a dial indicator, on the cylindrical and face surfaces of the locating washer. Then measure the drive pulley's radial runout.

4. 4

   Rollers

   Check each roller's radial runout on its cylindrical surface. While you're at it, look for nicks and raceway damage, which can appear both during manufacturing and in service.

5. 5

   Support alignment

   Set the reference arbor into the bearing assemblies of the front and rear supports. Locate the bridge with the indicator stand against the flat and side surfaces of the ways, and roll it back and forth between the supports. Take measurements in two mutually perpendicular planes, vertical and horizontal.

6. 6

   Natural frequencies

   Use the impact method to determine the natural frequencies of every support in the transverse and axial directions, and of the bed too if needed. Check that the supports' frequencies are close to each other.

7. 7

   Coast-down

   Spin the rotor up and record the 1x amplitude and phase on coast-down. Confirm that within the assigned working range there's neither an amplitude spike nor a phase reversal. Only after that, fix the working speed in the instructions.

8. 8

   Measurement channel

   Record the time trace on both vibration channels and the phase-angle channel. The sine waves should be clean, and their period should match the marker pulse rate.

9. 9

   Stability

   Take three readings in a row on the same rotor without stopping and compare them: the speed shouldn't deviate from the average by more than 1–2 rpm, the running-speed-component magnitude by more than 5%, or the phase by more than 1–2°.

Unstable readings almost always have one of two causes. Electrical: no grounding, no filters on the VFD, welding running on the same mains nearby. Mechanical: support or bed resonance, worn rollers and raceways, play in the spindle bearings, pulley runout, ovality or nicks on the rotor's own journals. A convenient way to tell them apart: drive interference disappears on coast-down, a mechanical defect stays.

Verifying Accuracy on a Reference Rotor

This is the step that homemade rigs skip most often, and it's exactly what separates a verified machine from an unverified one. The idea is to take a rotor with a known, small residual unbalance, introduce known trial unbalances into it, and see how consistently the machine finds them.

Ideally the reference rotor should be a certified standard, but in shop conditions a carefully balanced production part will do. The requirement on it: its residual unbalance shouldn't exceed ten times the minimum residual unbalance achievable on your machine. The test rotor's mass is taken as 0.2–0.3 of the maximum mass you're designing the rig for.

Verification runs in two stages. First, iterative convergence: the standard procedure with trial runs, followed by a few more cycles that drive the residual unbalance down to the limit of the machine's capability. In addition, the marker gets shifted by 60° and a verification reading is taken in the new angular coordinate system: this checks that the result doesn't depend on where the zero sits.

The second stage is walking a reference weight around the rotor. A weight of known mass is moved through a sequence of angles in 30° steps — 12 runs — or 60° steps for a shortened check. For each correction plane, calculate the average of the measured unbalance and the ratio of each reading to that average. The spread of these relative values is the honest characterization of your machine. As a guideline drawn from standard practice, a band of 0.88 to 1.12 is used.

1. 1

   Preparation

   Balance the reference rotor down to a state where its residual unbalance doesn't exceed ten times the minimum. Apply a marker aligned with the machine's scale zero.

2. 2

   Trial weight

   Calculate the trial weight's mass from the stated relative residual unbalance, the rotor's mass, and the mounting radius. Weigh the weight and enter the actual mass and radius into the software.

3. 3

   Iterations

   Run the standard procedure with setup runs, then several successive-convergence cycles. Log the initial and running residual unbalance values on a verification sheet.

4. 4

   Changing the zero

   Shift the marker by 60° and repeat the reading. The result shouldn't drift: if it does, look for location runout and errors in the angle reference.

5. 5

   Walking the weight around

   Mount the reference weight in sequence at 12 (or 6) angular positions and record the measured unbalance for both correction planes at each position.

6. 6

   Processing

   Calculate the average values and relative deviations, and plot a chart for each plane. A spread that falls outside the band means a defect remains somewhere in the machine — not that the tolerance in the data sheet needs to be loosened.

7. 7

   Eccentricity compensation

   Separately check the eccentricity-compensation chain: simulate the rotor flip by moving the reference weights 180°. Once this mode is working correctly, the residual unbalance should drop to a few percent of the reference unbalance introduced.

What to do if verification fails. Don't rewrite the tolerance in the data sheet until you've worked out the cause. The troubleshooting order runs opposite to the acceptance order: measurement channel and grounding first, then resonances, then roller and spindle runout, then location and the arbor, and only then the support construction itself.

Sources: ISO 21940-11:2016 · Balanset-1A operation manual

Long and Multi-Support Rotors

Two correction planes are enough for a rigid rotor that doesn't deform at the running speed. The geometric threshold is simple: at a length-to-diameter ratio up to about 0.5, the part behaves like a disc, and one plane is often enough. Above that ratio you need two, or couple unbalance will remain — a pair of forces that twists the rotor — and vibration at the second support won't go away.

From there it becomes a different problem. A composite shaft on three or four supports is balanced in three or four planes, and it has to be solved as a system of equations with three or four unknowns, using the influence coefficients of all the supports. Every trial run fills one column of the matrix: you mount a trial weight in one plane and record the response at all the supports at once. For three planes that's a minimum of four runs; for four planes, five.

A flexible rotor, one that changes shape while running, stands apart entirely. Here the two- and three-plane rigid-rotor scheme doesn't work at all, and modal methods are used instead. That's no longer a job for a homemade rig, and it's worth honestly labeling it as such.

• A rig for a multi-support shaft requires longitudinal travel of the intermediate supports along the ways, and fixtures for adjusting the intermediate bearing assemblies in height.
• All the supports on a rig like this need to have close natural frequencies: a spread narrows the working speed window down to the worst support.
• A two-channel measurement system solves the problem for two planes. Three and four planes require a matching number of channels and a different calculation algorithm.
• A practical workaround for three planes on a two-channel system: break the problem down into stages by shaft section, though repeatability suffers, and the result needs to be checked with a verification run across all the supports.
• The classification of rotors into rigid and flexible, along with approaches to balancing flexible rotors, is described in the ISO 21940 series. Check the applicable part and edition separately.

Sources: ISO 21940-11:2016 · ISO 21940-12:2016

Safety and Common Mistakes in Homemade Rigs

A balancing rig is a machine with a spinning mass and removable weights bolted onto it. A correction weight flying off at running speed isn't a hypothetical risk. Build guarding and a work procedure into the design from the very first drawing, not after the first incident.

• Guarding around the entire rotating zone, with an interlock: the drive won't start with the guard open.
• An emergency stop within the operator's arm's reach, separate from the VFD's buttons.
• Software and mechanical limits on maximum speed, set for the heaviest and largest-diameter part.
• Mount trial and correction weights as securely as a permanent one: welding, a bolt, a pin — not putty and not tape.
• Sanity-check the trial weight's mass: it shouldn't create dangerous vibration, overload the supports, or touch any stationary parts.
• Securing the rotor on the arbor with torque control and an axial stop.
• Locking the supports during run-up and coast-down, if the running speed is above the suspension's resonance.
• Grounding the rotor and the machine, especially with non-metallic bearing assemblies.
• A separate procedure for coast-down: the operator doesn't approach the rotor until it's fully stopped, not "once it's nearly there."

What You Can Honestly Claim, and How AXILINE Can Help

Keep two claims separate. The first: "our rig delivers a repeatable result and is fit for internal control." You can confirm this yourself by passing acceptance testing on geometry, dynamics, and the reference-weight walk-around. The second: "our rig achieves accuracy grade X and we issue reports for external acceptance." This requires a verified procedure, a reference rotor, and agreement with whichever party accepts the report. Don't blur the two together in correspondence with a customer.

A separate note on what "within tolerance" means in the software. It means exactly one thing: the residual running-speed component has dropped below the target value you entered yourself. It's not confirmation of grade G per the ISO 21940 series, and it's not an assessment of the machine per the ISO 20816 series. Three criteria exist in parallel: residual 1x against your own setpoint, residual unbalance in g·mm/kg against grades G, and overall vibration velocity against the zones. Check the applicable part and edition of the standard separately in each case.

Balanset instruments are designed and manufactured by engineers who do their own on-site balancing with them. In practice that means questions like "where will the sensor land on a support like this," "will one plane be enough for this impeller," or "what speed window is left with a mass spread from 3 to 40 kg" get answered directly, not out of a catalog. We provide consulting support on choosing the measurement configuration, the sensor and marker mounting scheme, software setup, and training your operator.

Where to start the conversation. Send us the mass and diameter range for your rotors, their length-to-diameter ratio, the required accuracy grade, the planned speed, the drive type, and a sketch or photos of the intended support construction. That's enough for us to tell you whether the Balanset-1A OEM will fit your scheme as a standard application, where you'll be capped by the tooling, and what to check before you build. If your data shows a rig isn't needed, we'll say so: for machines already sitting on their foundation, on-site balancing in their own bearing housings remains the more honest choice.

A middle path people forget about. Start with on-site balancing of your own part range using a full Balanset-1A kit. You'll get figures on initial unbalance, on the number of planes needed, and on achievable residual values, you'll see the instrument working on your own parts, and only then decide whether to build a rig and what it should look like.

Sources: Balanset-1A operation manual · Balanset-1A manufacturer specification · ISO 21940-11:2016 · ISO 20816-1:2016

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