Description
A 12 mm hex sits between the common ISO sizes, so it often catches buyers out. Many Japanese-built machines and vehicles use it on M8 bolts with a reduced hex. The Snap-on QJXM12A box end head fits that size with a closed 12-point ring. It runs on the J shank, which is the only shank Snap-on lists at 12 mm.
One shank only at 12 mm
Snap-on’s UK brochure places the QJXM12A in the J column alone. Y rings start at 14 mm, so a Y or X body has no box end ring for this hex. The partner listing names a Y shank for this part, however. Because the two sources clash, confirm the shank with Lost in HCM before you order.
| Opening | 12 mm, 12-point |
|---|---|
| Outside diameter | 18 mm |
| Head depth | 8 mm |
| Pin to fastener center | 2.50 in (QJXM series) |
Low-range J bodies for the Snap-on QJXM12A box end head
Small bolts usually take small numbers, so pick a body whose scale starts low.
- QC1P300 preset, 60-300 in-lb, for one value at a bench.
- QD2IN50A dual scale, 10-50 N·m, the smallest QD body.
- CTECH1J240A ControlTech, 12-240 in-lb, which also stores up to 1,500 readings.
QC bodies hold their stated accuracy from 20% to 100% of full scale. So choose the body that puts your target inside that band. The two sources also disagree on the head’s maximum rating, and therefore Lost in HCM confirms it.
Machines that call for the Snap-on QJXM12A box end head
Look for it on Japanese motorcycles, outboard engines and compact machine tools. Some flange bolts with a reduced hex use it as well. In each case, the Snap-on QJXM12A box end head reaches into narrow spots, because the ring is only 18 mm wide. As a rule, measure the flats before you buy, since 12 mm and 13 mm look alike.
How to order the 12 mm ring
SMK Vietnam lists the QJXM12A for Lost in HCM, which supplies the part and writes the quote. Give your body model and target value. After that, request a quote from Lost in HCM. Browse torque wrench heads and adaptors for the 13 mm ring, or contact SMK Vietnam.
QJXM12A: quick answers
Is a 12 mm ring right for a standard ISO M8 bolt?
No. ISO and DIN M8 bolts use a 13 mm hex, so pick the QJXM13A instead.
How much space does the 12 mm ring need?
About 9 mm from the bolt center, half of its 18 mm width.
Is there a Y-shank 12 mm box end ring?
Not in Snap-on’s brochure, which lists 12 mm under J only.
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