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What Is a Star Screwdriver?

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  • Written By: Anna B. Smith
  • Edited By: O. Wallace
  • Last Modified Date: 12 November 2016
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A star screwdriver is a handheld tool with a six sided, star shaped bit. It is designed to interact specifically with star screw heads that are sized to match corresponding bits exactly. This type of screwdriver prevents cam out during use, while creating an ideal amount of torque between screws and the project work area.

This type of driver was invented by the company Textron. This company also performs work in the automotive, aviation, and software industries through a variety of smaller businesses. It was patented under the name Torx® for its ability to achieve perfect torque without slipping, though most individuals refer to this design as a star based on its visual appearance.

The primary benefit of using a star screwdriver is that it resists the urge to cam out during use. The term cam out is used to refer to the action created when a screwdriver or drill bit pops out of the screw head indentations while turning. Some driver heads, such as the Philips head, are designed to cam out intentionally to prevent the user from damaging the screw head or bit once the maximum amount of torque needed has been reached between a screw and a stationary object. Consequently, as the bit rotates in the head when using a power drill, it can strip and wear down the grooves in the screw, making it impossible to back it out later if necessary.

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The unique design of the star screwdriver features a six pointed star shape at the tip. This tip fits precisely into a similarly sized screw head. Sizes are designated by the letter T followed by a number, where larger numbers correspond to bigger drivers. As the driver turns, each point of the star bites against the solid surface of the screw head, preventing slippage or camming out. The driver consistently provides the same amount of torque to each screw to which it is applied, stopping when maximum torque has been reached.

The star screwdriver and screw head were initially created for precision work on computer equipment and sensitive avionics controls. It then became popularized in the automotive and construction industries as well. Tamper resistant versions of this style of head are also available to provide an added level of security on some devices due to the difficulty of obtaining the specific matching driver. These star heads often include a circular post cut out that requires a specialty bit, or use a five sided rather than six sided design.

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indemnifyme
Post 3

It's interesting that there are secured versions of star shaped screwdrivers available. I suppose it makes sense from a security standpoint, but I think it's kind of inefficient. After all, you can probably only use the secured version on one specific thing instead of for multiple projects.

I suppose it would be easy to pick out this star screwdriver from the rest of your toolkit though. If most star screwdrivers have 6 sides and tamper resistant screwdrivers have 5, you could probably find it right away if you needed it.

ceilingcat
Post 2

@Azuza - Keep in mind that a star tip screwdriver needs to be used with certain kinds of screws. I don't know if I would bother buying a star screwdriver unless you're planning on using it for a specific project.

Still though, the star screwdriver is a pretty cool invention. And it makes a lot of sense that a screwdriver that doesn't slip was invented to work on computers. When you're doing a project with wood or metal, if your screwdriver slips and hits what you're working on, it's probably not going to be a big deal. But with a computer you could definitely damage something if you slip.

Azuza
Post 1

I clicked on this article so I could learn more about the Torx screwdriver, but I ended up learning a new term too: cam out. I've never heard that term before! Granted, I don't do much home improvement work, but I do use screwdrivers sometimes.

And I have definitely had a Philips head screwdriver cam out on me before. I never knew it did that to protect the screw! I guess next time I'm using a screwdriver (unless it's a Torx screwdriver of course) I'll know that means I should ease up a little bit.

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