TECH NOTE 03 / Replacement verification
How to verify inline load cell replacement dimensions and wiring
Freeze the exact original order code, drawing revision, output variant and calibration record before comparing candidates.
Freeze the exact original order code, drawing revision, output variant and calibration record before comparing candidates.
Compare installed geometry and electrical functions independently; connector pin count is not a wiring definition.
Re-establish calibration and acceptance after changing any part of the measurement chain.
01 / ENGINEERING DECISION
Begin with the original item, not only the family name.
FUTEK LCM300 and Honeywell Model 31 identify families whose exact configuration matters. Photograph the label and connector, obtain the original order code and retain the drawing and calibration record used by the installed machine. Record whether the machine reads a raw bridge, a conditioned voltage/current or a digital protocol.
This guide provides a repeatable measurement and evidence worksheet. Use the replacement hub for the source-backed original-part lookup and candidate family; do not create a compatibility decision from this checklist alone.
| Gate | Required record | Release question |
|---|---|---|
| Identity | Original full code and revision | Are we comparing the installed version? |
| Mechanics | Two interfaces and mounted envelope | Does the accepted candidate drawing fit? |
| Electrical | Power, signal and pin functions | Can the actual input read it correctly? |
| Dynamics | Mass, stiffness, filtering and timing | Does the changed chain meet the application? |
| Calibration | Serial-linked scaling and acceptance | Has the installed result been rechecked? |
Supporting scope: FUTEK LCM300 drawing FI1534 ↗ · Honeywell Model 31 datasheet 008360, Issue 2 ↗
02 / ENGINEERING DECISION
Use dimensional facts only within the cited original drawing.
The cited LCM300 FI1534 drawing shows two external M6x1-6g threads, a 24.9 mm diameter and a 30.7 mm overall dimension for its listed metric configurations. Its FSH04530 row identifies 223 N. These facts describe that original drawing, not every historical LCM300 or a supplied MT-ILC part.
A 30.7 mm overall dimension is not the full installed machine stack. Mark the locating shoulders, usable stud engagement, locknut positions and connector clearance on the assembly. For Model 31, use the exact original range/termination drawing instead of borrowing a dimension from LCM300.
| Field | Original baseline | Candidate confirmation |
|---|---|---|
| Reference example | LCM300 / FI1534 / FSH04530 | Accepted MT-ILC drawing and revision required. |
| Original force row | 223 N as printed | Define working/peak force and desired range. |
| Original threaded ends | 2 × M6x1-6g external | Verify both genders, pitch and tolerance. |
| Original envelope | 24.9 mm OD / 30.7 mm overall | Compare locating features and full mounted stack. |
| Model 31 variant | Exact order code / range / termination | Obtain its actual original drawing; no shared dimension assumed. |
Supporting scope: FUTEK LCM300 drawing FI1534 ↗ · Honeywell Model 31 datasheet 008360, Issue 2 ↗
03 / ENGINEERING DECISION
Compare the same named features, not two numbers called height.
Honeywell’s Model 31 datasheet 008360 Issue 2 has a range-dependent mounting table. For its 1–5 kN group, Table 9 lists a 25.4 mm D dimension, a 13.21 mm H body dimension and a 9.7 mm C stud projection. The thread column includes 1/4-28 UNF or the specified M6 × 1 option. The H dimension is not the complete stud-to-stud length.
The LCM300 example and this Model 31 group are not capacity-matched candidates. Their purpose here is to show why named drawing features must be normalized before a fit decision. The Model 31 figures also distinguish cable terminations: the 10–50 N group shows the 6AM arrangement with a balance module. Retain the actual termination and module with the original electrical record.
| Original example | Named dimensions | Comparison boundary |
|---|---|---|
| LCM300 FI1534 / FSH04530, 223 N | OD 24.9 mm; body 12.7 mm; overall 30.7 mm | Use overall versus overall, body versus body. |
| Model 31 Issue 2, 1–5 kN table group | D 25.4 mm; H 13.21 mm; C 9.7 mm | H is the body dimension; include the appropriate stud and shoulder features. |
| Proposed replacement | Approved complete drawing required | Verify range, two threads, locating faces and mounted clearance separately. |
Supporting scope: Honeywell Model 31 datasheet 008360, Issue 2 ↗ · FUTEK LCM300 drawing FI1534 ↗
04 / ENGINEERING DECISION
Measure reference features before judging clearance.
Use the drawing’s datum and tolerance scheme. Record your measurement method and uncertainty if a narrow clearance is involved; a handheld measurement of a threaded peak is not a tolerance inspection. A source drawing and a candidate drawing should identify the same physical dimension before values are compared.
Inspect the cable exit and connector extraction space at the actual machine pose. A sensor that fits inside the nominal cylinder may prevent cable service, obstruct a locknut or change the effective rod length. Do not machine the candidate from a third-party drawing; ask for its approved interface document.
- Record the original label, installed orientation and wiring before disassembly.
- Measure or obtain shoulder-to-shoulder length, overall length, maximum envelope and wrench access.
- Confirm usable thread lengths and the mating fixture’s depth.
- Check tolerance accumulation, connector direction and cable bend clearance.
- Request an explicit drawing-by-drawing sign-off rather than a “same size” statement.
Supporting scope: PCB rod-end manual, 1381-01A ↗ · FUTEK LCM300 drawing FI1534 ↗
05 / ENGINEERING DECISION
Map electrical functions rather than copying four wire positions.
A four-pin connector does not establish a universal bridge pinout. Map excitation positive/negative and signal positive/negative from the exact original connector code and drawing view. Also identify shield/case connection, any sense wires, balance modules or calibration memory.
For the cited FUTEK CC19 drawing only, the printed functions are shown below. Treat this as a logical mapping, not a new front-view connector drawing. The drawing notes that key orientation varies; the mating view and connector revision still need verification. The map must not be assigned to Honeywell or a generic MT-ILC receptacle.
| Original pin | Function | Printed wire color |
|---|---|---|
| 1 | Excitation positive | Red |
| 2 | Excitation negative | Black |
| 3 | Signal negative | White |
| 4 | Signal positive | Green |
Supporting scope: FUTEK LCM300 drawing FI1534 ↗
06 / ENGINEERING DECISION
Worked example: equal mV/V does not mean equal millivolts.
Assume a linear bridge rated at 2 mV/V. At 10 V excitation its nominal full-range change is 20 mV; at 5 V it is 10 mV. A readout using an unchanged millivolt-to-force scale would misread the second case. An appropriately configured ratiometric input uses the excitation ratio instead, within its permitted input and common-mode limits.
The arithmetic does not authorize either excitation for a particular sensor. Check the sensor and input limits, then calibrate the actual sensor/cable/conditioner association. Preserve the old scaling record for comparison rather than silently reusing it.
| Assumed rated sensitivity | Excitation | Nominal full-range change |
|---|---|---|
| 2 mV/V | 10 V | 20 mV |
| 2 mV/V | 5 V | 10 mV |
| Ratio-based measurement | Actual excitation measured | 2 mV/V in either ideal case |
Supporting scope: NI-DAQmx: Bridge Sensor Scaling ↗
07 / ENGINEERING DECISION
Worked example: define a bidirectional analog scale explicitly.
For an assumed −500 N to +500 N range mapped to 0–10 V, zero force is 5 V and the slope is 0.01 V/N. A different 0–500 N mapping would put zero at 0 V and use 0.02 V/N. Both can be called “0–10 V output”, so the label alone is incomplete.
Confirm whether positive means tension or compression, how the output behaves outside the calibrated range, and whether the controller accepts the chosen zero. This is an example specification, not a claim that an arbitrary amplifier can implement that mapping.
| Force | Bidirectional −500 to +500 N → 0–10 V | Unidirectional 0–500 N → 0–10 V |
|---|---|---|
| −500 N | 0 V | Outside requested range |
| 0 N | 5 V | 0 V |
| +100 N | 6 V | 2 V |
| +500 N | 10 V | 10 V |
Supporting scope: NI-DAQmx: Bridge Sensor Scaling ↗
08 / ENGINEERING DECISION
Check the installed result after the change.
Replacement can change stiffness, mass, overload behavior, polarity, filtering and sample delay even when threads fit. Define the smallest useful force, allowed error and dynamic conditions for the machine; compare the complete installed chain against an appropriate reference.
A new serial number requires its own association with the conditioner and record. Zeroing an unloaded sensor removes an offset; it does not verify gain, hysteresis, off-axis effects or uncertainty. Use the relevant tension/compression points and an application acceptance cycle.
| Check | Evidence to retain |
|---|---|
| Zero / polarity | Unloaded condition and known small forces. |
| Gain / direction | Reference forces across the agreed range. |
| Reversal / mechanics | Loading-unloading and fixture movement. |
| Timing / filtering | Acquisition configuration and dynamic comparison. |
| Traceability | Reference identity, uncertainty and paired serials. |
Supporting scope: NIST: metrological traceability ↗ · FUTEK: load cell calibration variables ↗
09 / ENGINEERING DECISION
Attach one original-reference packet to the inquiry.
Send the full original code, label photo, drawing revision, connector/wiring document, calibration record and machine input definition. Add operating force, peak force, temperature and envelope restrictions. State which characteristics can change and which must remain mechanically or electrically compatible.
An MT-ILC-MM family review is a starting point for the external-thread originals discussed here. Approval requires the actual proposed drawing and measurement-chain evidence; published original dimensions or an FSH lookup are not a certified drop-in match.
Resolve the fit, signal and calibration questions.
Does the LCM300 family name uniquely identify its thread?
No. Use the exact item and drawing revision. The FI1534 metric drawing discussed here shows M6x1-6g external ends; historical or other variants require their own documents.
Can I use the CC19 table for every four-pin sensor?
No. It is specific to the cited original connector code and drawing. Obtain the mating view and the proposed sensor’s verified functional pin map.
Can the existing calibration certificate be reused?
A different sensor or conditioner changes the measurement chain. Retain the original for comparison and obtain the new serial-linked calibration and installed acceptance evidence.
Is matching a 0–10 V label enough?
No. Define force endpoints, zero voltage, polarity, output limits, power and input compatibility. Two 0–10 V mappings can assign different voltages to the same force.
Does an original 223 N model require a 500 N replacement?
No. Determine working force, peaks, resolution and the available approved ranges. A larger request range can change the useful signal and is not automatically an equivalent choice.
Can the replacement guide guarantee a price or delivery time?
No. The guide is a verification method. Price, availability, drawings and supplied specifications belong to the configuration-specific quotation.
ENGINEERING RFQ / SAMPLE REQUEST
Send the load case.
Define the interfaces.
Include both thread ends, working and peak force, available space and the signal your controller expects.
Company and university email domains are preferred. Prototype and research inquiries are welcome.
inquiry@inlineloadcell.com ↗