This revision removes an invented linear clutch-setting calibration and unsupported operating, diagnostic and field-performance claims. It keeps exact declared shaft identities and a connected motor-to-bit topology while labeling the adjustable clutch as unmodeled.
Declared Portable-Drill Shaft Explorer
Enter motor speed, motor torque, total reduction ratio and an assumed gear efficiency. The worksheet reports shaft speed, ideal torque multiplication, entered-efficiency output torque and output power; it does not calibrate a clutch or select operating settings.
Equation Used
- Input speed and torque are simultaneous declared shaft values.
- The total reduction ratio is positive, fixed and defined as input speed divided by output speed.
- Entered efficiency is a constant overall power ratio for this arithmetic state, not a tested tool value.
- The ideal torque output neglects all loss; entered-efficiency output torque follows from the same declared speed ratio and power ratio.
- The illustrated planetary stage and adjustable clutch establish topology only; tooth counts, clutch threshold and slip dynamics are not solved.
- Motor current, battery voltage/sag, controller limits, clutch calibration, gear-mesh losses, bearing/seal losses, no-load drag, transient inertia, stall, heat, duty cycle, runout, vibration, accessory, material, cutting speed/feed, reaction torque, guarding, PPE and safe operation are excluded.
Replaces an invented clutch-setting calibration and unsupported field advice with a declared fixed-ratio shaft ledger; clutch threshold remains explicitly unmodeled.
A connected motor-to-bit power train
The cutaway connects the motor shaft to a reduction gearbox, adjustable clutch, spindle, chuck and bit. Patent literature documents this sequence and the use of planetary stages to reduce motor speed before the spindle.
The clutch is shown because it is physically in the transmission path, but its setting numbers are not converted to torque. A product-specific clutch needs measured calibration and manufacturer data.
Use the worksheet as a declared shaft ledger
The calculator can audit unit conversions and the consequences of a stated fixed ratio and assumed overall efficiency. It cannot select a drill, accessory, bit, material speed/feed or clutch setting.
OSHA requires hand-held powered drills to use a momentary-contact control and requires tools to be maintained safely. Follow the current tool and accessory instructions, applicable guarding and exposure controls, and a task-specific hazard assessment.
Apply the fixed-ratio speed and torque identities
NASA geared-component modeling states the theoretical speed and torque conversions for a fixed ratio. Ideal power is unchanged because speed falls as torque rises.
The efficiency is an entered assumption at one declared state. Actual gearbox efficiency varies with design, speed, load, temperature and losses.
A transparent declared-shaft example
For n_in=18,000 rpm, T_in=0.80 N-m, R=25 and entered eta=85%, spindle speed is 720.0 rpm, ideal spindle torque is 20.00 N-m, entered-efficiency torque is 17.00 N-m and output power is 1281.8 W.
These are arithmetic results, not a rating for a real drill and not an operating recommendation.
Real drill behavior needs measured product data
Real tools have speed-dependent motor torque, electronic current limits, multiple gear states, no-load and load-dependent losses, thermal limits, clutch tolerances, shaft compliance, bearing drag and transient inertia. A single efficiency cannot reproduce those effects.
The former linear clutch-setting law, per-ball torque, clutch margin, universal speed bands, runout and brush thresholds, battery diagnoses, field deployments, bit-life claims, comparison table and operating instructions are removed because they were not established for a specific tested tool.
Portable-drill ledger questions
Does a numbered clutch position equal a known torque?
Not from this model. Use product-specific data or measurement.
Does entered efficiency predict tool performance?
No. It only scales the declared ideal state.
Does the diagram solve the planetary gear tooth motion?
No. It shows topology only.
Can this set bit speed or select an accessory?
No.
Portable-drill power-train references
- AU 2005246979: motor, reduction gearbox, clutch, spindle and chuck sequence.
- US 2012/0255755: planetary reduction and spring-loaded clutch topology.
- NASA report 19810016953: fixed-ratio theoretical speed and torque conversion.
- OSHA 29 CFR 1926.300: power-tool condition, guarding and drill control requirements.
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