MNM 250 lb × 0.02 lb S-Type Tension/Compression Scale Guide
- pete8781
- Jul 30
- 4 min read
Need help choosing fixtures or confirming the right capacity? Call MNM Scales at (832) 290-3120 or email mnmscales@yahoo.com.
The MNM 250 lb × 0.02 lb S-type tension/compression scale is a compact force-measurement package for users who need substantially finer displayed increments than a typical heavy-duty crane scale. MNM lists the system as calibrated and ready to use, with an alloy-steel S-type load cell, digital indicator, rechargeable battery/power supply and two eye bolts. The 250 lb range is useful for pull tests, spring checks, small actuators, cable tension, fixture qualification, assembly-force measurements and other jobs where 500 lb, 1,000 lb or multi-ton systems sacrifice too much resolution.
What Comes with the 250 lb Force Scale
MNM’s product listing specifies one alloy-steel S-type load cell, one digital indicator with a built-in rechargeable battery and power supply, and two eye bolts. The system is listed as calibrated and ready to use. The product page notes that the photo is a general picture and that MNM supplies this family with different indicator models/brands, so the exact indicator face and menu structure can vary. That is why the most useful buying question is not simply “what does the picture look like?” but “does this package provide the capacity, readability, hold functions, output and mounting arrangement needed for my test?”
Published Specifications
Specification | MNM listing Capacity | 250 lb Displayed increment | 0.02 lb Measurement direction | Tension and compression Load cell | Alloy-steel S-type Included hardware | Two eye bolts Power | 6 V rechargeable battery / power supply listed Display | 6-digit, approximately 1-inch LED; listing also references LED or LCD variants Units | lb / kg selectable Functions | Zero, gross/net, accumulation, printing, counting, check weighing, auto-hold Communication | RS-232 output Indicator excitation/load-cell support | Listing says drives up to eight 350-ohm load cells Indicator performance statement | 6000e, max 30,000d; 0.3 µV/e resolution Mounting | Desktop, wall, column or adjustable angle
Why 0.02 lb Increments Matter
At 250 lb full scale, a 0.02 lb display increment gives 12,500 displayed steps across the range. That is useful when a test needs to distinguish relatively small changes—for example, spring-force variation, cable pretension, clamp force or breakaway force. The last displayed digit should not be confused with guaranteed total system accuracy. Real uncertainty also includes load-cell nonlinearity, repeatability, temperature, fixture alignment, calibration and the quality of the reference used to verify the system. Still, fine resolution is valuable because it allows the operator to see changes that a 0.1 lb or 0.5 lb display would round away.
Best Uses for a 250 lb S-Type Scale
Spring testing: measure extension or compression force at defined travel positions. Cable, wire and cord pull testing: check pretension, pull force, connector retention or assembly consistency. Small actuator and solenoid testing: verify push/pull force through a guided fixture. Clamp and latch testing: quantify closing, holding, release or breakaway force. Packaging and closure development: measure strap tension, pull tabs, handles and retention features when the fixture keeps force axial. Manufacturing quality control: compare a known-good component to production samples using the same test geometry. R&D test stands: integrate a simple S-type sensor into a benchtop frame for prototypes, fixtures and process-development measurements.
Tension Setup: Keep the Force Axial
S-type cells work best when the upper and lower fixtures share one centerline. Side load and twisting can change the signal and stress the central sensing web. Eye bolts are convenient, but eye-to-eye geometry alone does not automatically create a perfect test. Where movement or angular variation is expected, appropriately rated rod ends, clevises or flexible alignment hardware can help keep the applied force through the sensor axis. Do not use the load-cell cable as a restraint, and do not let a test fixture rotate the sensor body while the threaded ends are loaded.
Compression Setup
The listing describes the system for tension and compression, but compression fixtures must still be designed correctly. Use adapters that transfer force through the S-cell’s intended threaded interfaces without creating side load or bending. Guide the moving part independently if needed, but make sure the guide does not bypass force around the sensor. Start at a low force and confirm the displayed sign/direction and zero return before moving toward the full working range.
Peak Hold, Auto-Hold and RS-232
Peak hold is useful for a pull test, breakaway test or latch-release test where the highest force may appear only briefly. Auto-hold is more convenient when a stable result needs to remain visible after the operator releases a part. RS-232 can be valuable for logging measurements, printing records or integrating the indicator with a computer, but confirm the exact communication settings and cable pinout for the indicator supplied with your package because MNM notes that indicator models can vary within this product family.
Troubleshooting
Reading changes when the fixture is touched: look for cable pull, loose hardware or side load. Zero does not return after unloading: inspect for retained fixture preload, bent hardware or an overload before re-zeroing. Repeated tests differ: use the same loading speed, grip location, travel point and preload each time. Peak reading is much higher than expected: the test may include impact, snap-through or sudden breakaway rather than steady force. Fine last digit wanders: reduce vibration, drafts, electrical noise and mechanical friction, then judge whether the variation is meaningful relative to the test tolerance.
FAQ
Is this a crane scale? MNM markets it in its crane/tension category, but the package is best understood as an S-type force scale; suspended-load use still requires independently rated rigging and safe procedures. Is 0.02 lb the total accuracy? It is the published scale increment/readout description; total measurement uncertainty depends on calibration and test conditions. Can it measure compression? Yes, the listing explicitly states tension and compression. Does it include peak hold? The listing identifies peak hold and auto-hold functionality. Can I connect it to a computer? The listing specifies RS-232 output. Is the product photo exact? MNM explicitly says it is a general picture, so exact indicator appearance may vary. Who should choose 250 lb instead of a larger model? Users whose maximum test force stays comfortably below 250 lb and who benefit from finer displayed increments.
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