How to cut a thread with a triangular file without a die

Do-it-yourselfers are often faced with the need to cut large threads at the end of a shaft, for which they do not have the appropriate die. If this problem is familiar to you, and turning to a turner is not an option, then you can cut the threads yourself. This is possible even using the simplest tool and machine.

What you will need:

Shaft;
calipers;
Bulgarian;
flat file;
triangular file;
thread gauge;
machine;
copy pen.

Thread cutting process without a die

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The end of the shaft blank must be ground to the required diameter. It can be determined from the table for cutting threads with a die from any mechanic's reference book.

You can process the workpiece using a homemade machine that will rotate it. Read how to do it here - https://home.washerhouse.com/en/8699-naiprostejshij-tokarnyj-stanok-dlja-metalloobrabotki-svoimi-rukami.html

The easiest way to grind off the excess diameter is with a grinder. At the end, the shaft is finished with a flat file. Diameter control is performed with a caliper.

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A bolt with a thread that needs to be cut is glued to the end of the workpiece. There must be a nut screwed onto it.

Next, you will need a triangular file, the angle of which just fits between the turns of the desired thread. It is clamped into a homemade holder that functions as a copying pen. Next, one face of the nut on the bolt is painted over.

Now you need to use the corner of a file in a copying pen to mark the thread on the workpiece. To do this, we cut it with a back-and-forth motion, moving only along the painted edge. As soon as the groove is identified, we turn the workpiece along with the nut. By moving only with emphasis on the painted edge, you can accurately copy the thread pitch from the glued bolt.

The thread can only be deepened with a file without a copying pen. When it is already quite expressive, it is better to remove the glued bolt.

After this, we place the file at the beginning of the thread, and start rotating the machine so that the tool moves to the end. We repeat this over and over again until the thread gauge shows the required thread depth.

If you end up with flaws in the height of the threads, you can carefully correct them with a flat file. After this, the nut will screw onto the shaft without any problems.