You need something much better than a conventional screw for many applications or the nuts and bolts you come across. One type that is being used more frequently is the Torx screw drive that offers many benefits.
Torx screws have a 6-point star-shaped design and are used in a variety of applications. Hexalobular internal is the official generic term, which is standardized by the International Organization for Standardization as ISO 10664. Torx bits are similar to star bits, although the names are used differently by many individuals.
Improved head profiles include Torx Plus, Torx Paralobe, and Torx Ttap. Camcar Textron, the firm that invented the first screw-drive in 1967, developed these.
Automobiles, motorcycles, bicycle brake systems, and often use Torx screws show up more in electronics, computers, and consumer electronics. There are often many tamper-resistant versions where bolts are exposed, yet not easy to tamper with. (Read Socket Size Chart)
In our guide, you can learn the difference between star and torx, and also, you can know how many sizes of torx bits are there and which Torx bits sizes you will need most often.
What size do Torx bits come in?
| Size | Point-to-point distance | Point-to-point distance | Standard fastener selection | Standard fastener selection |
|---|---|---|---|---|
| (in) | (mm) | SAE | Metric | |
| E4 | 0.15 | 3.8 | #6 | M3 |
| E5 | 0.19 | 4.7 | #8 | M4 |
| E6 | 0.22 | 5.6 | #10 | M5 |
| E7 | 0.24 | 6.1 | ||
| E8 | 0.29 | 7.4 | 1/4" | M6 & M7 |
| E10 | 0.37 | 9.3 | 5/16" | M8 |
| E12 | 0.44 | 11.1 | 3/8" | M10 & M11 |
| E14 | 0.50 | 12.8 | 7/16" | M12 |
| E16 | 0.58 | 14.7 | 1/2" | |
| E18 | 0.65 | 16.6 | 9/16" | M14 |
| E20 | 0.72 | 18.4 | 5/8" | M16 |
| E24 | 0.87 | 22.1 | 3/4" | M18 & M20 |
| E28 | 7/8" | M22 | ||
| E32 | 1" | M24 & M27 | ||
| E36 | 1-1/8" | M30 | ||
| E40 | 1-1/4" | M33 | ||
| E44 | 1-3/8” | M36 |
What Size Star Bits are There?
A popular generic name for the drive is a star, as in star screwdriver or star bits.
If it comes with 6 points, it is a Torx screw; if you see 6 points plus a center pin in Torx, these are the tamper-resistant Torx or the Torx tamper-proof screw.
If there are six rounded points, then these are the Torx Plus screws.
Torx head sizes are identified using the capital letter “T” followed by a number ranging from T1 to T100.
Some manufacturer’s head sizes are abbreviated using “TX” or “Tx” before the number. The smaller the number, the smaller the point-to-point dimension of the screw head.
The more common sizes you will find in use are T10, T15, and T25, while T35 and T47 are most often used in specialist circumstances.
You can only use the proper Torx wrench sizes and the right torque bit sizes that match when using these. If you used smaller E Torx socket sizes for your driver, you could damage the driver or the screw on a larger head size.
The same Torx drivers are often used to drive SAE, metric, and other thread system fasteners, thus reducing the number of bit sizes any person would need to carry.
External variants of E Torx sizes are identified using the capital letter “E” and a number from E4 to E44.
The “E” numbers differ from the “T” numbers of the same size: for example, an E4 Torx socket will fit a T20 head.
While there is no difference between torque bits sizes and star bits sizes, you can get a variation between manufacturers. (Read Light Bulb Base Size Chart)
Here is the star bit sizes chart for Chapman; however, they fit Torx screws, and the key difference being the material they are made from has a breaking point before you could damage your screw.
| Part # | Diameter | Working Torque | Breaking Torque |
|---|---|---|---|
| S6 | .066" | 5" lbs | 6.5" lbs |
| S8 | .090" | 12" lbs | 16" lbs |
| S10 | .107" | 20" lbs | 45" lbs |
| S15 | .128" | 34" lbs | 68" lbs |
| S20 | .151" | 56" lbs | 108" lbs |
| S25 | .173" | 84" lbs | 168" lbs |
| T27 | .195" | 119" lbs | 200" lbs |
| S30 | .216" | 166" lbs | 200" lbs |
| S40 | .260" | 200” lbs |
If you do not use a Chapman driver, you will need to refer to the above sizing chart for Torx screwdriver bit sizes as the ones here come under different indicators. The Torx screw sizes would be the same, and the only difference is the snap ring on the Chapman Torx heads of the drivers.
What is the Difference Between Torx Bits and Star Bits?
Star, as in star screwdriver or star bits, is a popular generic name for the drive. It is a Torx screw if it contains six points, and a Torx tamper-proof screw has six points plus a center pin.
It is a Torx Plus screw if it has six rounded points.
Torx head bits are licensed products with part printing that producers must follow. The Chapman star bits are a step up from the official Torx bits. The star bits’ working ends are precision machined to accommodate Torx screws, but the shanks are the classic Chapman length and knurled end.
The quality bits match the average length of slightly over one” and feature a ball detent to hold it into our tools, and the working end that fits into the Torx screw is a precision quality machined. The signature knurled end allows for careful finger tightening of the fastener.
You can find the largest Torx size matches T socket sizes of Torx T40 with the S40 E Socket Sizes. Star socket sizes are no different, besides the quality and the material used by some manufacturers to create their drivers.
How Do I Know What Size Torx I Need?
Torx-head bits and screwdrivers from Textron are intended to work with Torx-head screws specifically. Six-point splines are used in the bits, and their sizes are quantified in “T-sizes.” If you come across a Torx bit that is mislabelled or does not have a T-size on it, you can use a ruler and a Textron chart to figure out the precise T-size.
- Line up the ruler on the star-shaped screw tip to measure from one point to the point directly opposite.
- Examine the markings on the ruler and write them down.
- Compare the measurement with the “P to P” (point to point) column in our chart to whatever size you need to determine which Torx bits exact T-size meet the measurement. You can measure in inches or millimeters for convenience.
You will find many various Torx drives from multiple manufacturers, yet many are cross-compatible as they meet the Torx standards. However, they may use a different grading or numbering for their tools.
Torx is the trademark and was developed to stop the cam out commonly found with Philips screws. The Torx features a distinct, 6-point star-shaped pattern and is often called a ‘star screw,’ which requires a ‘star screwdriver’ with a ‘star bit.’
Torx screws are used in vehicles, motorcycles, computer systems, hard disk drives, and consumer electronics, where they are more secure than regular flat-head or cross-head screws. It also delivers a higher torque transmission so screws and bolts can be tightened securely without as much worry as cam-out.
Torx Tools
The most important thing to remember about Torx screwdrivers is that they must be the same size as the Torx screws. So you’ll need a T15 Torx screwdriver if you’re working with T15 Torx screws.
Security six-lobe screws, tamper-proof Torx, six-lobe pin Torx, Torx TR, Torx pin, and star pin drive screws are all names for Torx screws. Security that cannot be tampered with Torx screws is more secure than standard Torx screws because they require a specialized security Torx screwdriver to loosen them.
Security Torx Screwdrivers
Due to the additional center pin in the socket head, standard 6 point Torx screwdrivers will not mate with security Torx screws. To utilize security Torx screws, you will need special tools that can fit the extra security pin.
Torx Plus 5 Point Screw Head
Torx Plus was released in 1990 as a successor to the original Torx heads design. This design improved on the original by allowing more torque to be applied while reducing wear.
The release of the tamper-resistant Torx Plus variation, sometimes known as Torx Plus Security or Torx Plus TR, was a further advancement (tamper-resistant). A five-point star-shaped head socket with a center pin is used in this form. (Find the Best Workbench)
A pentalobular socket is defined as a five-point or five-lobed socket design. The new design adds an extra layer of security and necessitates the use of specific tools that are compatible with the 5-point star socket and central security pin.
