Single Point Load Cells

Corner compensation is trimmed against a specific platform size. The trimming corrects for a known worst-case offset, which is the distance from the load cell centre to the far corner of the rated deck.

Fit a larger platform and that distance grows. The moment grows with it, past what the flexures were trimmed to absorb, and corner readings begin to disagree with centre readings. Nothing breaks and nothing is overloaded, so the failure is quiet: the scale simply stops being accurate in a way that only shows up if you weigh the same object in two places on the deck.

This is why the platform dimension is quoted alongside the capacity, and why it is the first number to check when an existing scale reads inconsistently. The FAY is rated for platforms up to 24 by 24 inches; the smaller families are correspondingly smaller.

A four-load-cell platform needs a summing junction box, corner trimming in the field, and four cable runs. Each load cell reads its own share of the load and the box adds them, which means each corner has to be balanced against the others after installation.

A single point does all of that in the factory. One cable, no junction box, no field trimming, and a corner error already inside specification when it arrives. For a bench or retail scale that is a decisive simplification, and it is why almost every scale under about 500 kg is built this way.

The trade is size and capacity. Four beams spread the load across a structure and have no inherent platform limit, so above roughly 1,000 kg or beyond the rated deck size, four load cells is the sound answer and a single point is not.

The parallelogram needs to flex enough for the compensation to work, and it needs to do so repeatably over millions of cycles. Aluminium alloy has a lower modulus than steel, so for a given capacity the section can be more generous while still producing usable strain, which makes the part easier to machine accurately and easier to trim.

Every one of our single point families (FAK, FAS, FASB, FAV and FAY) is aluminium for exactly that reason, and all five carry the same ±0.03% figure for nonlinearity and hysteresis.

What aluminium does not do is survive washdown or corrosive process environments indefinitely. Where that is the requirement, a hermetically sealed stainless bending beam such as the BSH is the right part even though it gives up the single-load-cell simplicity.

They overlap deliberately, because the platform size and the capacity do not scale together. Stocked, FAK covers 10 to 30 kg for retail, postal and parts counting; FAS 30 to 50 kg; FASB 45 to 200 kg; FAV 100 to 500 kg; and FAY 250 to 1,000 kg.

The published series run wider than the stocked list: the FAS is specified from 10 kg, the FASB from 5 kg, the FAV from 60 kg. A capacity inside a series but outside the stocked list is a build, not a redesign. Lead time is the only thing that changes.

Where two families cover the same capacity, the deciding factor is the platform the load cell has to compensate for and the physical envelope you have to mount it in, not the rating.

All five families output 2.0 mV/V at rated capacity. At the usual 10 V excitation that is 20 mV of full-scale signal, and an indicator divides that span into displayed increments.

Asking the indicator for more divisions does not create information. It subdivides the same signal more finely, and past a point the added digits are noise rather than weight. If you need finer resolution the answer is a lower capacity load cell, so that the load you care about occupies more of the span.

On a load cell rated in kilograms, a cable that is tugged, clamped or routed under tension applies real force to the free end. It shows up as drift, as a zero that will not stay put, or as a reading that changes when the enclosure door is closed.

Route it with a service loop and strain-relieve it to the frame, never to the platform. Never shorten a load cell cable without recalibrating: the four-wire connection has no sense lines, so lead resistance is part of the calibrated system.

A mechanical stop under the platform is the cheapest insurance a bench scale can have, and the most commonly set wrong. The gap has to allow full rated deflection plus a margin, so that the stop only engages beyond rated load.

Set it too tight and the stop carries part of the working load, which makes the scale non-linear in a way no calibration will fix. Set it after the load cell is installed and the platform is on, with rated load applied, not on the bench.

No. The parallelogram is built for compression under a platform, and the compensation assumes load arriving downward onto the free end. For pulling or hanging loads use an S-beam or an inline threaded load cell.

None of these five families carries an NTEP certificate. If the reading has to be a legal weight, the SBS single-ended shear beam is certified under CoC 95-146 from 1,000 through 10,000 lb, and the BSS S-beam under CoC 97-028 from 250 through 2,500 lb.

The load cell will not be damaged and the scale will appear to work. What degrades is corner agreement: the same object will weigh differently at the centre and at the edges, by an amount that grows with the overhang. It is the most common cause of a scale that cannot be calibrated into specification.

Regularly. Capacity within an existing body, cable length, connector and corner trimming to a non-standard deck are all routine, and beyond that we build to print for OEM programmes.