Fastener Head Type Survey

Looking to see what the general consensus is on what most teams use for fasteners. If you have a certain preference for a certain application or use a different head style, share down below.

  • I exclusively use hex-head screws
  • I exclusively use socket-head screws
  • I use a mix of both hex-head and socket-head screws

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HEX HEAD: Hex profile on the outside
SOCKET HEAD: Hex profile on the inside for allen wrench, etc.

What are the pros and cons of each head type, in the context of your build environment?

By hex you mean button-head hex, right?

I think socket should be used everywhere it can and just use button heads where it is necessary for the low-profile. The larger hex size of the socket head’s makes them easier to remove and less likely for freshmen to strip. I don’t know of a real disadvantage of socket heads other than the size.

In my experience button head hex screws are more prone to stripping than socket heads. Especially when inexperienced team members try to over tighten bolts. The pros of socket head hex screws are they have a lower profile than socket heads.

Socket Head hex screws protrude more but you don’t have to worry about them stripping as much. Our default is socket heads but depending on the application and design sometimes hex heads are necessary.

Edit: I misinterpreted the question. We generally don’t use hex head screws except for specific applications. Thank you @CarlosGJ and @cadandcookies for the clarification.

Actually I think this needs some clarification. I interpreted “socket-head screws” to mean both button-head hex cap screws and socket-head hex cap screws, and “hex-head screws” to refer to external-hex heads.


I interpreted hex head the same way McMaster-Carr does.

Button heads are just a different type of socket heads.


I guess we’re not allowed to use Phillips head screws. Darn.

And there is a distinct difference between button head and normal socket head screws: the button head has too small of a hex for the thread size, so the hex is prone to stripping out.

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We use way too many kinds of fasteners…

One day we’ll learn to standardize :slight_smile:

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We use exclusively slotted head screws. If the robot can’t be fully disassembled with a quarter, it shouldn’t be on the field.


Where are rivets and welds?
They’re fasteners too right?

You mean bolts?



Gimme the epoxy and I’ll show you a fastener…


Generally anything M5 (~#10) and below is socket head and anything M6 (~1/4") and above is hex head. We try not to use much M6+ because they add often unnecessary weight, but we will use them where needed.

If I had to give a real engineering reason for this choice, I’d say the socket head bolts are easier to use (especially when access is limited) while the hex head provides more torque for larger fasteners. But the real reason is probably a lot closer to “this is what’s easy to get from a local hardware store so it’s what we use.”

Don’t forget Velcro. And shrink tube.

And duct tape.

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As a general guide. There are Pan and Flat Allen/Torx/Hex type screws of course. I prefer to use the term ‘Socket Head Cap Screw’ or ‘Button Heat Cap Screw’ instead of ‘Hex’ because some people (rightfully) call Allen drives hex drives. And differentiating between ‘hex drive’ and ‘hex head’ is just too ■■■■ tedious.

We use SHCS most frequently. The tools are convenient, smaller than sockets, and generally more available in the 10-32 size we’ve standardized to as compared to Hex Head bolts/screws.


Button Head Cap Screws by choice although we’re making much more use of pop rivets now that we have a cordless riveter. I’ve never had a student strip one. Bumper work requires round or flat head wood screws and occasionally we use a flat head machine screw. They’re all Robertson which are far superior to Phillips or Slot.


Same. 1293 has used them for years, though I think we’re finally to the point that we’ll start ordering SHCS as supplies run out. Thank freakin’ goodness.

We also use a fair number of hex head screws, especially when we utilize things like Peanut and Walnut.

We tend to use hex cap machine screws for most tasks, but we do use other types as necessary. In very large bolts, it’s always hex heads. If we need low profile it may be a flat or pan head (usually phillips) machine screw or it may be a carriage bolt. Everything depends on the needs of the particular application.

Two things I’ve learned to never joke about with a Canadian engineer; the superiority of Robertson drive and the Avro Arrow.


Quick protip: 1/4-20 BHCS and 10-32 SHCS both use 5/32 allens so you can standardize tools with two different hardware sizes.