Here we have given the tool size only for metric thread bolts.
Allen key sizes for metric screws.
The m3 and m4 nominal screw sizes have two drilled holes spaced 180 degrees apart.
The tool is usually formed of a single piece of hexagonal rod of hard steel with blunt ends that are meant to fit snugly into the screw s socket bent in an l shape with unequal arms the tool is usually held and twisted by the long arm creating a large torque at the.
For example for an m8 socket head cap screw we need at least 32 8 head size 40mm clearance above the screw for easy accessibility.
While these metric allen key sizes do exist they rarely appear in your basic allen wrench sets.
In the united states larger metric half sizes like 6 5 mm aren t standard in most hex key sets.
However the 1 4 sae hex wrench will likely work in place of a 6 5 mm wrench.
Hold on to it or post it somewhere in the garage where you can hold up the key or socket screw head to the physical picture this can help you to determine which size of allen wrench you need or have on hand.
We have given a table for your easy selection of proper size of tools.
Their purpose is largely to serve specialized applications where size constraints and strength requirements need to be met.
Lastly there s one other added benefit to having both sae metric hex keys.
Drilled head metric hexagon socket head cap screws normally are not available in screw sizes smaller than m3 nor larger than m36.
Screw diameter drive size.
Refer the following table for metric allen key sizes and dimensions for corresponding socket head cap screw based on iso 4762 din 912 standards.
These sizes are 1 mm 1 25 mm 3 5 mm 4 5 mm 5 5 mm 7 mm.
Less common metric sizes.
2 we use allen key or hex key allen keys or hex keys two are same but name is different in different countries for allen bolts csk bolts button head bolts and grub screw set screw.
Substituting uncommon hex sizes.
Hex key and torn key sets provide multiple head sizes so they can be used with a range of fasteners.
An allen key size chart often comes with furniture you need to build on your own such as baby cribs outdoor swings or computer desks.
A hex key allen wrench or allen key is a simple tool used to drive bolts and screws with hexagonal sockets in their heads.
Metric tools for hex head bolts and socket heads diameter 1 4 5 16 3 8 7 16 1 2 9 16 5 8 3 4 7 8 1 1 8 1 1 4 1 3 8 1 1 2 1 3 4 wrench size 7 16 1 2 9 16 5 8 3 4 13 16 15 16 1 1 8 1 5 16 1 1 2 1 11 16 hex key size 3 16 1 4 5 16 3 8 3 8 7 16 diameter m16 mio m12 m14 m16 m18 m20 m22 m24 m30 wrench size 7 mm 8mm 10mm 13mm 17mm 19mm 22mm 24mm 27mm.
Torx keys are used for fasteners having a head with a 6 point star or asterisk shaped socket and are frequently used in computers and electronics.
