Reading a click wrench
The handle has a main scale along the tube and a second scale around the collar, the knurled grip you turn. Turning the collar one full turn moves its edge one main division. To read it, take the last main line the edge has passed (count on from a numbered line if that one has no number), then add the collar mark on the center line, times the value of one mark. A typical 3/8 in wrench has lines every 5 ft-lb and five 1 ft-lb marks on the collar:
50 line + collar 3 = 53 ft-lb
The usual slip is adding the collar to the next line up, the one the edge has not reached yet. Read this wrench
Setting newton meters on a ft-lb wrench
Dual-scale wrenches print the Nm values of the same main lines on the other side (13.6, 20.3, 27.1 and so on) and use the same collar, so each 1 ft-lb mark is 1.36 Nm. Spec 80 Nm: the last Nm line below it is 74.6, and 5.4 ÷ 1.36 is about 4 marks.
74.6 line + 4 marks × 1.36 = 80.04 Nm
Some wrenches add a second row of collar numbers already in Nm. Either way, round numbers like 80 Nm fall between marks, so you set the nearest one. Set 80 Nm yourself
Extensions and crowfoot adapters
An adapter on the drive that sticks out in line with the handle makes the lever longer, so the bolt gets more than the wrench reads. Set the wrench lower:
setting = torque wanted × L ÷ (L + E)
L is the length from the grip mark to the drive and E from the drive to the bolt. Pull at right angles to the handle. With the adapter at right angles to the handle, nothing changes, because the bolt is then as far from the line of your pull as the drive is; turned back under the handle, use L − E. Socket extensions straight down from the drive need no correction.
Tightening order
The sheets teach the generic patterns: a star on 5 bolts, a crisscross (straight across each time, working round the pattern) on wheels and flanges, and center outward on long parts like heads and covers, in two or three passes. Real jobs have their own numbered sequence, passes and specs. Always follow the manufacturer’s sequence and torque specs.
Questions
How do you read a click torque wrench?
Find the last main scale line the collar’s edge has passed, then add the collar number sitting on the center line. One full turn of the collar is one main division. On a typical 3/8 in wrench, the 50 line plus 3 on the collar is 53 ft-lb.
How do I set a torque wrench in newton meters?
Use the Nm side if your wrench has one: bring the collar edge to the last Nm line below the spec, then turn on by marks. On a ft-lb wrench each mark is 1.36 Nm, so 80 Nm is the 74.6 line plus 4 marks. With no Nm side, divide by 1.3558 and set the nearest ft-lb.
How do you read a beam or dial torque wrench?
Pull smoothly and read where the pointer sits while the fastener is turning. Beam scales read both ways from 0 in the middle; dials read round from 0 at the top, and an orange memory pointer keeps the peak after you let go. Count the small divisions on from the last number, in the row for your unit.
What is the torque wrench extension formula?
For an adapter that makes the wrench longer: wrench setting = torque wanted × L ÷ (L + E). L runs from the grip mark to the drive, E from the drive to the bolt. A 60 ft-lb spec with an 18 in wrench and a 3 in crowfoot: 60 × 18 ÷ 21 = 51.4 ft-lb.
Does a crowfoot at 90 degrees change the torque?
Not when you pull at right angles to the handle: the bolt is then as far from the line of your pull as the drive is. Turned back under the handle, the adapter shortens the lever, so use L − E. Socket extensions straight down from the drive need no correction.
How many inch-pounds are in a foot-pound?
12. Divide in-lb by 12 for ft-lb and multiply ft-lb by 12 for in-lb. One ft-lb is 1.3558 Nm (0.3048 m × 4.4482 N), and one Nm is 8.85 in-lb.
Should a click torque wrench be stored at zero?
Store it at its lowest marked setting, not below. Manuals for typical click wrenches say this takes tension off the spring, and warn against turning the handle past the lowest setting.
Practice drawings, drawn after typical wrenches; use your own wrench’s manual and the manufacturer’s specs on real work. Sources, read October 27, 2026: dual-range 3/8 in click wrench operator’s manual (PDF): main lines every 5 ft-lb, five 1 ft-lb collar marks, 1.36 Nm per mark, the 53 ft-lb and 80.0 Nm examples, storage; micrometer adjustable torque wrench instructions (PDF): main and thimble scales, metric thimble row; click torque wrench brochure (PDF): the ANSI standard allows 4% of reading error between 20% and 100% of wrench capacity; micrometer torque wrench operating instructions (PDF): TW = TE × L ÷ (L + E), in-line socket extensions need no adjustment; FAA-H-8083-30B Aviation Maintenance Technician Handbook General (PDF), chapter 7, figure 7-33: Tw = Te × A ÷ B and F × L = T with the force at 90°; bicycle click wrench instructions (PDF) and 5 to 25 Nm click wrench data sheet (PDF): Nm scales with 0.1 to 4 Nm divisions. dial torque wrench instructions (PDF): 0 at the top, full capacity at 180°, orange memory pointer; beam torque wrench manual and beam wrench listing: pointer at 0 in the center, reads clockwise or counterclockwise, 0 to 150 ft-lb in 5 ft-lb steps with an Nm scale. 1 ft-lb = 0.3048 m × 4.4482216152605 N exactly.