Description
ISO 4032 gives M12 an 18 mm hex, and M12 is one of the busiest sizes on heavy frames and machine bases. When those bolts carry a high property class, however, the torque spec climbs fast. The Snap-on QXXM18A box end head meets that need on the X (0.735 in) shank. Its closed ring grips all six corners, so it resists slipping at high load. In addition, the Snap-on QXXM18A box end head comes with a published rating.
Rating of the Snap-on QXXM18A box end head
Snap-on’s UK brochure rates this ring at 2,690 in-lb. That equals about 224 ft-lb, or 304 N·m, and the partner listing gives the same 224 ft-lb. At 18 mm, the brochure also lists a J ring and a Y ring. However, the X version carries the highest limit of the three. So it suits M12 joints that the lighter shanks cannot reach.
X bodies and where to cap them
- QD3IN350A: 70-350 N·m (59-251 ft-lb) on a 23 in tube. Cap it at 224 ft-lb.
- QC4P300 preset: 60-300 ft-lb on a 27 in tube. Lock the preset at or below the ring limit.
- CTECH3X250A: 12.5-250 ft-lb, with a built-in factor for head length.
Notice that every X body here also reads past 224 ft-lb at the top. For that reason, write the cap on the tool tag, so nobody sets a higher value by mistake with the QXXM18A.
QXXM18A size and reach
| Opening | 18 mm, 12-point, closed |
|---|---|
| Shank | X (0.735 in) |
| Outside diameter | 27 mm |
| Head depth | 12 mm |
| Pin to fastener center | 4.50 in (QXXM series) |
As for space, the 27 mm width means about 13.5 mm of side room from the bolt center. Meanwhile, the 4.50 in reach lets a long X handle work deep inside a frame. Because that reach adds length, ask Lost in HCM whether a click body needs a setting change.
Quoting the 18 mm X ring
SMK Vietnam lists the QXXM18A for its partner, and Lost in HCM supplies it and prices the order. Give them your X body and the M12 spec when you request a quote from Lost in HCM. For other sizes, visit torque wrench heads and adaptors, or contact SMK Vietnam with a question.
Before you set an X body on the QXXM18A
Which X body stays inside the QXXM18A limit on its own?
None of the three listed here stops below 224 ft-lb. So set each one at or under that value.
Is 18 mm the right ring for DIN M12 bolts?
No. DIN hex hardware in M12 measures 19 mm across the flats, so it needs a 19 mm ring. This one matches ISO M12 parts.
How far does the X ring hold the bolt from the pin?
4.50 in for the QXXM series, compared with 3.00 in for a Y ring.
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