Whitworth thread as per GOST .Table with dimensions and diameters.

Whitworth thread, its main features and characteristics

If you read the normative document GOST 6357-81, with a description of a cylindrical pipe inch thread, you can find the following information.Its main characteristic is the pitch and diameter.Under the diameter should be understood one of the definitions below:

1. Outer diameter - a unit that characterizes the distance between the opposite top points on the tops of the ridges of carving.
2. Inner diameter - a unit that characterizes the distance between the opposite lower points on the depressions threaded grooves.

Height is determined by finding the difference between the two diameters.

Step pipe version - is the distance between two neighboring depressions or two adjacent crests.It is always the same as the distance between the coils is stable.If this condition is not

met, pick up a nut or bolt by a screw connection is not possible.

Distinctions between metric and NPT

In fact, the differences between inch and metric threads are not so much.If we talk about the most visible, emit inch version on the background metric, it should be said about the form of the profile of the threaded flange.In appearance, he seems to be more acute.Thus, the upper thread profile angle is 55 degrees.

addition forms feature metric pipe option is the calculation from inch diameter size and stride.Thus, for the metric calculation occurs in millimeters, for a tube - in inches.However, the unit of measurement "inch" in this case does not correspond to the usual value of 2.54 cm. For pipe threads using a special, inch pipe, which is equal to 3,324 cm.

detailed table can be found in the above regulations.It placed as whole and fractional inches data.Thus, for example, with the thread designation ¾ equals approximately 25 mm.Moreover, the step itself is considered to be not in mm., And in the skin.Threads - is cut grooves on the inch-dimensional interval.

To determine the step, it is necessary to use the usual tools: comb, caliber, mechanical meter, etc.Therefore, survey will be based on the same rules in both metric and tube version.

And so, how to implement step boring:

1. Take a coupling or fitting with cut internal or external thread, knowing their options.
2. Screw the bolt into the thread.
3. If Bolt sat tight, then step and the diameter can be regarded as certain.If the bolt did not fit, try the following caliber.

rezbomerom When used, the process is much easier.You just have to attach the plate to the thread.If the profiles match, the thread is the same figure indicated on the instrument plate.

Using an ordinary caliper or micrometer, you will be able to determine only the outer diameter.

Whitworth thread, manual and mechanical method of cutting

Pipe and metric thread cut either on the outside or on the inside surface of the manually or mechanically.Let us consider each of them.

For manual cutting method, you will need tools like die (outdoor) and a tap (internal).

To perform threading by hand correctly, follow the following instructions based on your type of thread:

1. Fix the pipe in a vise, with a tap to be inserted in the knob, and plashkoderzhatel plate.
2. Put the plate on the tube and insert the tap.
3. Rotate the handle or knob plashkoderzhatelya, screw on the plate or screw in or tap on the pipe.
4. If necessary, repeat the procedure several times.

To make the mechanical cutting, follow these steps:

1. Clamp the tube in the chuck of the machine by placing the threaded scar in his support.
2. Turn on the machine and do a facet.
3. Adjust the speed of the slide.
4. Move to the surface of the cutter, and turn the screw feed.

Forming thread by using the tool gives a good and high-quality result (of course, if enough skill turner).

Sizes inch threads as per GOST

dimensions shown in the above pictures.