Metric screw and bolt assortment kits, M2 to M10

How we build a metric screw assortment kit

Each kit starts with a diameter and the four to eight lengths that daily maintenance calls for: M3 from 6 to 30 mm, M5 and M6 from 8 to 35 mm, M8 from 16 to 50 mm, flange bolts up to M10. We add a hex nut for every screw and a washer assortment to match, flat washers to spread the load and split lock washers to hold it under vibration, which is the stack a 3D printer frame, a treadmill rail or a dishwasher bracket was assembled with.

We cut socket head screws rather than Phillips pan head machine screws for one reason: a hex key cannot cam out, so the head survives being driven and removed many times. The screws are grade 12.9 alloy steel with black zinc, or 304 stainless steel for the kits marked stainless; the threads are rolled to the metric standard with an average error under 0.01 mm, so our nut runs on a bolt from any hardware store and the other way around. The flange bolt kit in M6, M8 and M10 is 8.8-grade with black oxide, the grade and finish a motorcycle fairing or a mower deck expects. We stop at M10; there is no M12 in the drawer yet.

The storage box is the part people write to us about. Thick fixed dividers keep sizes apart in a toolbox, the sticker on the lid mirrors the compartment map, and the custom hex key and tweezers ride inside the container, so the case is the whole toolkit for that size.