Description
Terminal blocks, DIN-rail parts and small motor covers often use M4 nuts, and ISO 4032 gives M4 a 7 mm hex. The Snap-on QJXM7A box end head fits that size with a closed 12-point ring on a J-shank (0.425 in) body. So a panel builder or an instrument tech can set a small, repeatable value on each nut. The ring wraps all six corners, which protects soft plated hardware.
QJXM7A limit and outline
Snap-on’s UK torque brochure rates this ring at 240 in-lb. That equals the partner figure of 20 ft-lb, or about 27.1 N·m. Its outline measures 11 mm across and 5 mm deep, and it sits 2.50 in from the retaining pin. In fact, it shares that outline with the 6 mm QJXM6A, so the two fit the same pockets.
A body that tops out at the Snap-on QJXM7A box end head limit
The ControlTech CTECH1J240A reads from 1.0 to 20.0 ft-lb, which is 12 to 240 in-lb. In other words, its full scale equals the ring rating. As a result, no setting on that body can overload the Snap-on QJXM7A box end head. It also keeps a time-stamped record of readings, which helps on audited lines.
Preset stations for M4 nuts
For one value repeated all shift, a preset J body keeps the number locked. For example, the QC1P60 covers 10-60 in-lb, and the QC1P100 covers 15-100 in-lb. The adjustable QC1I200 spans 40-200 in-lb, so it also stays below 240. However, the QC1P300 and the QD2IN50A both pass the ring limit. With either one, cap the setting before it drives the Snap-on QJXM7A box end head.
Checking the hex before you order the QJXM7A
DIN 934 also gives M4 a 7 mm hex, so European and ISO parts agree here. Still, some screws and spacers use their own hex sizes. Hold a caliper across the flats of one part from the job. If it reads 6 mm, the QJXM6A is the ring you need. If it reads 8 mm, which ISO gives to M5, choose the QJXM8A.
Panel shop orders: the Snap-on QJXM7A box end head
SMK Vietnam lists this ring for its partner Lost in HCM, which supplies it and sets the price. Request a quote from Lost in HCM with your J body and the in-lb target. Then compare other small rings under torque wrench heads and adaptors, or contact SMK Vietnam if you need help with a pairing.
M4 nut questions on the QJXM7A
Does the QJXM7A fit M4 nuts from ISO and DIN?
Yes. ISO 4032 and DIN 934 agree on 7 mm for M4.
Can a QC1P300 overload the QJXM7A?
It can, because its scale reaches 300 in-lb. So lock its preset at 240 in-lb or lower.
Why choose the QJXM7A over a socket for small nuts?
The ring stands only 5 mm tall, so it reaches nuts under covers and brackets. A socket stack often stands too high there.
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