1/4-20 Thread Dimensions

May 18, 2024 Post a Comment

1/4-20 thread dimensions

So, a 1/4-20 screw has a 1/4" diameter (. 250") with 20 threads per inch.

What does a 1/4-20 thread mean?

The 1/4″ refers to the bolt diameter (in inches), the -20 refers to the threads per inch meaning that there are 20 threads per inch on this bolt, and the 2″ refers to the length (also in inches).

What pitch is a 1/4-20 thread?

Major Diameter (in)	Threads per inch (tpi)	Pitch (mm)
#12 - 24	24	1.058
1/4" - 20	20	1.270
5/16" - 18	18	1.411

What is a 1/4-20 UNC bolt?

As an example, a 1/4"-20UNC thread has a 1/4" major diameter, with 20 threads per inch (TPI) and is a UNC coarse pitch thread. Metric threads are normally described only with the use the outer diameter of the thread listed in millimeters like a M12.

What size is a 1/4 inch screw?

Screw Size	Inch Decimal	Nearest Fraction
#8	0.164 in.	5/32"
#10	0.190 in.	3/16"
#12	0.216 in.	7/32"
#14	0.250 in.	1/4"

How do I measure thread size?

Use a caliper to measure the nominal male or female thread press to crest diameter on the first

Are M6 and 1/4 the same?

6mm equal to 0.2362 inches. Your 6mm spinner will "work" on a 1/4" shaft, but you may have to ream out the hole a little to get it to slide on easily.

What do thread size numbers mean?

1. Thread sizes in inches are specified by diameter and threads per inch. For example, in the screw size 10-24, the first digit refers to the thread diameter, the and second digit is threads-per-inch (TPI). When the diameter smaller than 1/4”, the value is indicated by a number, like #1 or No. 1.

Is a #12 screw the same as 1 4?

The diameters listed in the chart below are in fractions of an inch, so the #12 is just shy of 1/4 inch. A more detailed table with thread count can be found below, along with tap drill sizes.

How do you read thread size UNC?

Threads in the UNC, UNF & UNEF designations have a fixed number of threads per inch (tpi) for a special diameter. For example, 5/16” UNC has 18 tpi, 5/16” UNF has 24 tpi, and 5/16” UNEF has 32 tpi.

What does UNC mean for threads?

UNC – Unified National Coarse Thread, comparable with the ISO metric thread. UNF – Unified National Fine Thread.

Are NC and UNC threads the same?

NC/UNC/UNJC These tap sets come with a combination of National Course (NC), United National Coarse threads (UNC), and UNJC taps. UNC threads allow for easy removal. UNJC threads are almost identical to UNC threads except that they have a larger root radius for improved thread strength.

Are #14 and 1/4 screws the same?

#14 is close to, but not exactly the same as, 1/4-inch.) The major diameter in Unified threads = 0.060″ + 0.013″ x (numbered diameter). So #2 has a major diameter of 0.086″. The odd numbers exist, but the even numbers are in far more common use.”

What is nominal thread size?

Thread sizes are given in nominal sizes, not in the actual measurement. The exact measurement is slightly below the named or nominal size. For example, a 6mm bolt may measure 5.8mm or 5.9mm, but it is called 6mm bolt. It is also common to use “M” before the bolt size, such as M6 for a 6mm bolt.

What size screw has a 1/4 head?

Bolt Diameter	Head and Wrench Size
Bolt Diameter	Hex Bolt - Lag Bolt - Square Bolt	Heavy Hex Bolt
1/4"	7/16" or 3/8"	-
5/16"	1/2"	-
3/8"	9/16"	-

Are threads measured from the inside or outside?

Step 2: Measure the diameter For male threads, measure the Outside Diameter (O.D). For female threads, measure the Inside Diameter (I.D).

Is thread measured to the outside diameter?

To determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI).

What is the basic major diameter of a thread?

The major diameter of a thread is the diameter of the imaginary co-axial cylinder that just touches the crest of an external thread or the root of an internal thread. The minor diameter is the diameter of an imaginary cylinder that just touches the roots of an external thread and (or) the crests of an internal thread.

Is M6 or 1/4 bigger?

Metric	Closest Inch
M6-1.0	1/4-28 (Larger)
M7-1.0	1/4-28 (Smaller)
M8-1.25	5/16-18 (Smaller)
M10-1.5	3/8-16 (Smaller)

Will a 1/4 inch bolt fit a 6mm hole?

The holes that are slightly large of 6mm are actually for 1/4" bolts. As they say, the bolts are 1-1/4" long. Typically this will be 1/4-20 unless there is an extraordinary need for strength. Since they are bolt-nut pairs, you may be able to substitute 6mm, but the 1-1/4" length will still be essential.