Load cells report force as an electrical signal. Gauges attached to a purposely shaped piece of metal detect the small amount it gives way under load, bridge circuitry expresses that as voltage, and a certificate earned against reference weights turns the voltage into pounds.
On a through-hole design, that shaped piece of metal is a ring — and the ring is where the whole engineering argument sits.
Picture the cross-section. There is a hole in the middle for something to pass through, an outside diameter defining how much room the sensor occupies, and between the two an annulus of material that carries the load and does the sensing. Those three dimensions are locked together. Open the bore up without changing anything else and the annulus narrows, leaving less metal to carry force. Push capacity higher and you need more annulus, not less. Keep the outside diameter fixed and you are choosing between a bigger hole and a bigger load rating, because you cannot have both from the same body.
Which is why through-hole cells arrive as families rather than single products. Each step up in outside diameter buys back annulus, and that annulus can then be spent either on a larger bore, a higher capacity, or some of each. A range spanning several outside diameters is really offering you a grid of bore-and-capacity combinations, and choosing well means understanding which of the three dimensions your application has already fixed for you.
Usually it is the bore, because something already exists that has to fit through it. That is the nature of the format — you are adding measurement to an assembly rather than designing one around a sensor. And as bores grow past the size of ordinary fasteners, the applications change character too: no longer just bolts and studs, but tie rods, hydraulic cylinder rods, ball screws, and shafts running through bearings. At that point you are measuring what a machine is actually doing rather than how tight somebody made a joint.
Material has to keep pace with the geometry. Heat-treated 17-4 PH stainless — a precipitation-hardening grade whose ageing process seeds strengthening particles throughout the metal without distorting a precision part — is what allows a generous hole and a serious load rating to coexist in a modest body.
Conventional electrically. Distinctive mechanically, in ways that matter more as the hole gets bigger.
Signal. The bridge runs on a supplied voltage, 10 VDC being standard here. Compression strains the ring, gauge resistances move, symmetry breaks, and millivolts emerge. Since the supply sets the scale, sensitivity is written as a ratio. Electronics amplify, filter and convert; the certificate translates. Depart from the calibration supply voltage and every reading departs proportionally.
A wide ring is easy to load badly. Scale makes this worse, not better. On a narrow annulus almost anything bearing on it covers most of it; widen that ring and a bearing surface can easily engage the inner portion while leaving the outer half untouched, at which point the number you get reflects contact geometry as much as applied force. What bears on each face should be sized against the sensor's own dimensions — hardware chosen to suit a fastener has no reason to suit a two-inch body, and the resulting error announces itself in no way whatsoever.
Nothing should touch the inside of the hole. The bore is empty space by design, and anything rubbing there contributes friction and sideways force that arrives at the gauges indistinguishable from the load you care about. Bigger holes are more forgiving in one sense and more treacherous in another: there is more room to play with, which makes people relax about it, yet a rod sitting comfortably centred on a cold bench may find the wall soon enough once the machine warms, the structure deflects, and vibration has spent a week nudging things sideways.
Rotating components need thinking about. Once bores are large enough for shafts rather than fasteners, a new question arises: the shaft turns and the sensor must not. The established approach is to let the load path run through the sensor axially while restraining the body against rotation — typically a bracket on the outer circumference — so thrust transfers properly without the cell spinning along with the machinery. Anything sliding or rubbing against the sensor face while under load is generating friction that will show up in your data.
Zeroing is a fork in the road. Assembly itself applies load to a captured sensor, so the moment you choose to establish zero determines which of two entirely different quantities you spend the rest of the installation measuring. Establish it while the assembly is still loose and the clamp you subsequently apply is what you read. Establish it once everything is torqued and that clamp vanishes from the record, leaving only whatever the machine adds afterward. Neither is wrong; ending up with the one you did not want is a genuinely common outcome.
Selecting from a through-hole range means working the grid rather than reading down a capacity column. Our application engineers do this constantly — describe what has to pass through and what surrounds it, and we can usually place you within a couple of minutes.
Measure the hole requirement first, and be generous. Whatever passes through needs to clear the bore under every condition the installation will see, not just at rest on the bench. Thermal expansion, deflection under load, and years of vibration all conspire to close clearances. Where a series offers several bores at your capacity, taking the next size up costs nothing in performance and buys margin against all three.
Check what the outside diameter has to fit inside. The counterbore, recess, or gap between a nut and a flange puts a hard ceiling on outside diameter, and in retrofit work that ceiling frequently decides the entire selection before any electrical specification enters the conversation. Measure the available space honestly, including whatever tooling has to reach in there.
Then find where bore and capacity intersect. With those two constraints established, the question becomes whether a body that fits your space can offer both the hole you need and the load rating you need. Often it can. Where it cannot, something has to give — a different mounting arrangement, a modified fixture, or a conversation with us about alternatives. Better to discover that at specification time than after machining.
Size capacity against assembly, not just service. The force a joint sees in normal operation is often far less than what a wrench and a long lever can generate during installation. Overload during assembly is a genuine failure mode on bolted-joint measurement, so check the safe overload rating against what somebody could plausibly apply, not merely what the design intends.
Treat the bearing surfaces as part of the order. They need hardness, flatness, and enough diameter to engage the sensor's full ring. Where an existing assembly cannot offer that from its own hardware, the washers required to fix it belong on the same purchase order as the sensor rather than being remembered on installation day.
Confirm environment and direction. Sealed gauges cope with dust, debris and the sort of moisture most facilities produce; directed wash-down or chemical exposure belongs in a conversation with us instead. The certificate you receive documents downward force and no other kind, which makes any pulling in your application a quotation-stage conversation. And rather than treating thermal movement as an unknown, run your expected swing through the published coefficients and get an actual number for it.
Finally, the readout. What the sensor reports to depends on what you intend to do with the number. Sometimes a regulated supply and a voltmeter genuinely suffice. Beyond that, either an amplifier signal conditioner module handing data to your acquisition system, or a digital display capable of alarms, analog output and logging in its own right. Machines carrying multiple cells are the strongest case for Cal-Teds plug and play, since each unit then arrives at the instrument carrying its own calibration.
Four measurements let us place you on the grid: the diameter of the component going through the middle, the room available around it, the forces you expect, and a fair description of the surroundings. Standard items are held in stock for prompt dispatch, and schools and universities receive discounted pricing.
THC Series Load Cell Applications.
The Transducer Techniques THC Series through-hole donut load cells, featuring multiple through-hole diameter options and constructed from heat-treated 17-4 PH stainless steel, have diverse applications across various industries where precise force measurement is critical.
- Industrial Automation: THC Series load cells are integrated into industrial automation systems for monitoring and controlling forces in robotic applications, material handling processes, and manufacturing operations.
- Robotics and Automation: These load cells are used in robotics and automation systems for force sensing applications, including robot end-effector force control, pick-and-place operations, and quality checks on assembly lines.
- Force and Torque Measurement: THC Series load cells are essential for precise force and torque measurement in research, testing, and quality control across various industries.
- Materials Testing: In materials testing laboratories, THC Series load cells are employed for various testing applications, including tensile and compressive testing of materials such as metals, plastics, ceramics, and composites.
- Automotive Testing: Automotive manufacturers and testing facilities use THC Series load cells for quality control and testing of vehicle components, such as suspension systems, steering mechanisms, and brake systems.
- Aerospace and Aircraft Testing: The aerospace industry relies on THC Series load cells for structural testing of aircraft components, flight control systems, and materials used in aircraft construction.
- Product Development: Engineers and researchers use THC Series load cells during product development and prototyping.
- Biomechanics and Medical Devices: In biomechanics research and medical device testing, THC Series load cells measure forces applied to the human body or medical devices during experiments and analysis.
- Educational Laboratories: Educational institutions incorporate THC Series load cells into engineering and physics laboratories to teach students about force measurement principles and conduct experiments related to mechanics and materials science.
- Custom Machinery and Equipment: Manufacturers and research facilities integrate THC Series load cells into custom-built machinery and equipment designed for specialized testing and manufacturing processes that require precise force measurement.
The Transducer Techniques THC Series through-hole donut load cells, with their versatile design and multiple through-hole diameter options, are valuable tools across a wide range of industries and applications where accurate and reliable force measurement is crucial for safety, quality, and performance assessment.
Frequently Asked Questions
What are the six THC bore options?
The model suffix identifies the through hole: -P is 0.128 inches (nominally 1/8"), -Q is 0.193 inches (3/16"), -R is 0.266 inches (1/4"), -S is 0.391 inches (3/8"), -T is 0.532 inches (1/2"), and -V is 0.656 inches (5/8"). Six options is the widest bore selection we offer, and every one of them is available across every capacity in the series.
What capacities does the THC Series cover?
Eight: 250, 500, 1,000, 2,000, 3,000, 5,000, 7,500, and 10,000 lb. Combined with six bores, that produces forty-eight distinct configurations from a single series — and every one of them costs the same $695. Bore and capacity are therefore fully independent decisions here; you can order the largest hole at the lowest capacity, or the smallest hole at the highest, without any pricing consequence.
Can I really get any bore at any capacity?
Across this series, yes — all six bores are offered at all eight capacities. That's less obvious than it sounds, because bore and capacity genuinely compete for the same material: the sensing structure is the ring between the hole and the outside diameter, so a bigger hole leaves less metal to carry load. The 2.00 inch outside diameter is what makes the full grid possible, providing enough annulus that even the 5/8 inch bore leaves adequate material at 10,000 lb.
Why is the THC's outside diameter 2.00 inches?
Because that's what the bore range and capacity range together require. Through-hole cells are constrained by simple geometry — bore, outside diameter, and load rating all draw on the same cross-section of material. A 5/8 inch hole through a smaller body wouldn't leave enough ring to carry meaningful load. Two inches is the outside diameter that lets this series stretch from 1/8 inch bores up to 5/8 inch, and from 250 lb up to 10,000 lb, without compromising either end.
What can pass through a 5/8 inch bore that couldn't through a smaller one?
This is where the application space changes character. Below about 3/8 inch you're generally working with fasteners — bolts, studs, threaded rod. At 1/2 and 5/8 inch you can accommodate tie rods, hydraulic cylinder rods, ball screws, and shafts running through bearings. That shifts the measurement from "how tight is this joint" to "what force is this machine actually producing," which is a different and often more valuable question.
What accuracy does the THC Series offer?
Nonlinearity and hysteresis are each 0.25% of rated output, nonrepeatability is 0.1% of rated output, and zero balance is 1.0% of rated output. Those figures hold across the whole grid, so choosing a larger bore doesn't cost you measurement performance — the specification is the same whether you order a -P or a -V at any given capacity.
Are the THC's strain gauges sealed?
Yes, the bonded foil gauges are sealed for protection against most industrial environments, which suits a sensor likely to be installed in machinery and left there. Worth being clear on the boundary: this is environmental protection against dust, debris and moderate moisture rather than hermetic sealing, so heavy wash-down or genuinely corrosive service is a different specification. Describe your environment to us and we'll tell you honestly whether the THC is the right answer.
Is the THC compression only?
Standard calibration is compression, matching how donut cells are normally used — captured in an assembly and squeezed. Tension calibration is available as an option and should be specified when you order if your application pulls, since the load path differs between directions and a compression certificate describes compression alone.
How much does a THC deflect, and how does temperature affect it?
Deflection is 0.002 inches at rated output. Compensation runs 60° to 160°F with a safe range of −65° to 200°F; inside that band output drifts 0.005% of load per °F and zero drifts 0.01% of rated output per °F. The low deflection figure matters practically on a captured sensor — two thousandths of an inch is little enough that adding a THC to a clamped assembly doesn't meaningfully change how that assembly behaves.
Can I get the THC with the plug-and-play TEDS option?
Yes, OPT-TEDS adds IEEE 1451.4 smart connector functionality, holding the unit's calibration data at the connector so a compatible instrument configures itself. With forty-eight configurations that look broadly similar once installed, and installations often running several cells at once, it's a practical safeguard against the right sensor being read with the wrong calibration.
Questions From The Field
How do I choose between the THA, THB and THC?
Work from the hole outward. The THA has a 1.00 inch body with bores to 3/16 inch and capacities to 500 lb — the choice when space is genuinely tight around a small fastener. The THB steps up to a 1.50 inch body, bores to 3/8 inch and 2,000 lb. The THC's 2.00 inch body reaches 5/8 inch bores and 10,000 lb. In practice the decision is made by whichever constraint is fixed: if the space around your fastener is limited, that caps your outside diameter and you work down; if a large rod has to pass through, that sets your minimum bore and you work up.
Can I use a THC to measure thrust on a rotating shaft?
Yes, and the larger bores make it practical — but the installation needs one specific provision. The sensor must not rotate with the shaft, so it needs restraining against rotation, typically with a bracket engaging the outer circumference, while axial thrust transfers through the sensor normally. The cell then sits in the load path between the thrust bearing and a stationary reaction surface. Anything rubbing or sliding against the sensor's face while loaded generates friction that appears in your data as force, so getting the restraint arrangement right is essential rather than optional.
My rod clears the bore on the bench but binds once the machine is running.
Clearance measured at rest and clearance under working conditions are different numbers. Thermal growth, deflection under load, and vibration walking a component off-centre can all close a gap that looked adequate during assembly. Because bore contact adds friction and side load the sensor cannot separate from real force, the fix is more clearance rather than better alignment alone — and since all six THC bores share identical specifications, moving up a size costs you nothing but a different part number.
What washers should I use on a 2.00 inch cell?
Hardened, flat, and sized against the sensor rather than against the fastener — this is the mistake that catches people most often on the larger through-hole bodies. A washer appropriate for a 3/8 inch bolt may bear on only the innermost portion of a two-inch cell's annular face, concentrating load where it wasn't intended and producing readings that depend on contact position. The bearing surface should cover the annulus properly on both faces.
Does choosing a larger bore reduce my accuracy?
No. The published specifications are identical across all six bores at any given capacity, so a -V performs the same as a -P at the same rating. What the bore choice affects is fit, not performance. Choose the hole your application genuinely needs, with margin, and let capacity be a separate decision — there's no accuracy penalty to trade off and no price difference either.
I'm retrofitting into an existing assembly. What do I need to check first?
Three dimensions, in this order. The diameter of whatever passes through, which sets your minimum bore. The clear space around it, which caps your outside diameter and may push you toward a smaller body in the range. And the available grip length, since the sensor plus its bearing washers has to fit into the joint without leaving the fastener short of thread engagement. That last one catches people out, so measure it before ordering rather than after.
Can I install several THCs on one machine and read them together?
Yes, and with forty-eight configurations available you can mix bores and capacities across the same installation to suit each location. Decide early whether you need each sensor read individually or a combined figure, because that determines how many channels you're buying. Where you need to know which specific point moved — usually the case on a machine with several load paths — individual channels are the only way to get that. The TEDS option is worth considering when several cells with different calibrations are in service simultaneously.
How often should a permanently installed THC be checked?
Set an interval and hold to it, because a sensor nobody looks at is exactly the one that quietly stops being trustworthy. Annual is a common baseline, with more frequent verification where the reading supports a safety function or a quality record, or where the sensor has seen overload or unusual conditions. A practical middle ground on installed cells is periodic verification in place — checking the unloaded zero against what was recorded at commissioning — between full calibrations, which is why recording that original zero is worth the moment it takes.