Description
Some 20 mm nuts need only modest torque, yet they sit where a socket cannot go. The Snap-on QJXM20A box end head covers that case on a light J-shank body. Its closed 12-point ring wraps the nut, so the wrench pulls through a full grip rather than two flats.
Ring size and shank of the QJXM20A
- Opening: 20 mm, 12-point closed ring.
- Shank: J (0.425 in), the smallest Snap-on shank.
- Outside diameter: 30 mm.
- Head depth: 13 mm.
- Fastener center to retaining pin: 2.50 in, the QJXM series figure.
These values come from Snap-on’s UK torque brochure, and they match the Lost in HCM listing.
Why the Snap-on QJXM20A box end head pairs a big ring with a small shank
Most J heads serve small fasteners, so a 20 mm ring sits near the top of the J range. The ring is large, but the J shank still sets the load path. In practice, the J bodies on SMK Vietnam stop at about 75 ft-lb. That suits 20 mm nuts with low specs, such as cover nuts, adjuster locknuts and soft gasket joints. However, a high-strength bolt of this size usually needs more. For those joints, Snap-on also lists the QYXM20A in Y shank and the QXXM20A in X shank.
Which J bodies pair with the QJXM20A
- QC2I75 adjustable body, 5-75 ft-lb, for mixed jobs on one bench.
- QD2IN100A dual-scale body, 20-100 N·m (16.6-71.9 ft-lb).
- QD2IN50A dual-scale body, 10-50 N·m, for lighter values.
- CTECH1J240A ControlTech body, 1-20 ft-lb, with a digital readout.
With the QD bodies, there is no length math to do. The QJXM20A sits at the 2.50 in spacing those bodies expect. Snap-on sources disagree on the head rating, though, so ask Lost in HCM to confirm it before you set a value.
Measure the nut first
A 20 mm opening falls between the 19 mm and 21-22 mm sizes found on many metric machines. So check each nut across its flats with a caliper before you order the QJXM20A. A ring one size too big will slip and round the corners. Also check the space around the joint, because the ring is 30 mm across and 13 mm deep.
Keeping a 20 mm J head in shape
Wipe the ring and shank of the Snap-on QJXM20A box end head after each shift, then store the head in a slotted tray. Next, look for wear at the ring points and at the pin hole. Finally, keep the body on its calibration cycle, since Snap-on notes that periodic recalibration keeps a torque wrench accurate.
Quote request: Snap-on QJXM20A box end head
SMK Vietnam lists this head for our partner Lost in HCM, which supplies it and sends the quote. Tell Lost in HCM your body model and target torque, so it can confirm the match. Then request a QJXM20A quote from Lost in HCM. For other sizes, browse our torque wrench heads and adaptors, or contact SMK Vietnam with questions.
Before you order the QJXM20A
Can the QJXM20A handle a 100 ft-lb joint?
Not on a J body. The J bodies on SMK Vietnam top out near 75 ft-lb, so look at a Y-shank 20 mm head such as the QYXM20A.
How big is the ring?
Snap-on lists a 30 mm outside diameter and a 13 mm head depth.
Why is no torque rating shown?
Snap-on’s own documents give different maximum values for this head. Lost in HCM can confirm the current figure with your quote.
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