Choosing screw and bolt heads
Choose the head by how it must sit on your part and what will turn it.
Flush or raised
- Flush: a countersunk head sits level with the surface. Your part needs a countersunk hole. The tapered head wedges into the hole, so in plastic parts use it only where flush is needed and do not over-tighten.
- Raised: pan and hexagon heads sit on top of the surface and press on a wider area, which suits plastic parts. A socket head is raised but narrow.
- Washers: a flat washer under a raised head spreads the load further.
Head types
Hexagon head
Turned with a spanner or socket. Good for firm clamping and easy removal. Shop hexagon head
Socket hex head
Round head with a hex key drive inside. Compact, so it suits tight spaces. Add a washer on plastic parts, as the head is narrow. Shop socket hex head
Cross pan head
Low rounded head with a cross drive. Wide underside, so it suits plastic parts. Shop cross pan head
Cross countersunk head
Sits flush with a cross drive. Use where nothing may stick out. Shop cross countersunk head
Slotted pan head
Low rounded head with a single slot. The slot is easy to slip out of, so keep to light loads. Shop slotted pan head
Slotted countersunk head
Sits flush with a single slot. Shop slotted countersunk head
Grub and set screws
No head: the screw sits below or level with the surface. Used to hold one part against another. Shop grub and set screws
Slotted knurled thumb screws
Ridged head you can turn by hand, with a slot for a screwdriver. Suits covers and settings you adjust often. Shop thumb screws
Butterfly screws and butterfly nuts
Wings for tightening by hand, without tools. Suits panels you take off often. Shop butterfly screws · Shop butterfly nuts
Quick chooser
- No tools: butterfly or thumb screws.
- Must sit flush: countersunk head, tightened gently.
- Tight space: socket hex head.
- Firm clamping: hexagon head with a washer, tightened until snug.
- Hidden: grub or set screw.
With plastic parts
Tighten plastic screws until snug, not as hard as metal ones. Check the material guide for your plastic before choosing.
If you are unsure
See Find products by picture, or send us a photograph and any dimensions. Shop all nuts and bolts by head