We specialize in small set screws.

Machine to make small set screws

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Our main mechanical equipment is Cam-type Automatic Lathes of Microcomputer Control modified in-house. The Cam-type automatic lathes modified so that screw threads can be machined chasing with a thread cutting tool.

Why is it possible to process small set screws with the "Cam-type automatic lathes of microcomputer control" ?

The reason is ...

Mr. Takashi SAIDA of founder our company was a factory manager at NOMURA SEIKI, an automatic lathe maker, and was in charge of mechanical design and manufacturing.

Under Mr. Takayuki NOMURA, the first president of NOMURA SEIKI, which was founded in 1959, the automatic lathe designed by Takashi SAIDA, who was 25 years old at the time, was a model called P-8.

The photo on the right is the P-8 being remodeled. (Click the photo to enlarge)

This P-8 is designed with a mechanical structure suitable for making "slotted set screws". When cutting off, the set screw is picked up by a pickup device called the "THUMAMI". After that, since the slot is machined with the "THUMAMI" in the same automatic lathe, it is possible to reliably machine the slot even for small set screws. If you watch the video below, I think you can understand it well.

Our microcomputer-controlled cam-type automatic lathe controls the spindle and camshaft, was enabled thread cutting with the thread cutting tool.

Since Takashi SAIDA designed the P-8, it was a machine that knew all about the structure, both good and bad. Since the founding of our company, we have repeatedly remodeled such P-8, and as a result, only about 40% of the mechanical parts remain as they were.

I will briefly explain the thread cutting process with the thread cutting tool. While the spindle of the automatic lathe makes one rotation, advance the spindle (material) by the amount of the lead of a screw (Note 1), and scrape off the thread valley with a thread cutting tool. Repeat this multiple times to form the screw.

(Note 1)
• Lead of a screw is the distance traveled when a screw is rotated one.
• Pitch of a screw is the distance between adjacent threads of a screw.
• Single-thread screw is lead = pitch x 1.
• Double-threaded screw is lead = pitch x 2.

In addition, there are peripheral devices for automatic lathes that have been modified in-house. All Cam-type automatic lathes and NC-type automatic lathes are equipped with a "Count Selector (CS)" that was also developed in-house. (Click the photo to enlarge)
This is a "time-series product sorting device" that sets the number of set screws that can fit in one can.
(Although it is a long sentence, "The story of the birth of the Count Selector" is here. If you like, please.)

In addition, the in-house developed "DELchip" that automatically discharges swarf (cutting chips) to the outside of the machine is attached to all automatic lathes, and the factory operates 24 hours a day, 7 days a week. (Click here for "The Story of the Birth of DELchip". If you don't mind, please.)

Of course, the automatic material supply device is attached to all cam-type automatic lathes, and this control unit is also manufactured in-house. If any trouble occurs in these, we will continue to modify it.

How to make small set screws

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The material used is a straight rod-shaped metal material with a length of 2 m or 2.5 m.

• Depending on the thickness of the screw, materials with diameters of 1.5 mm, 2.0 mm, 2.5 mm, etc. are used properly.
• We use brass, iron, stainless steel, aluminum, etc.
  The only materials for DELscrew are iron (free-cutting steel: SUM24L) and stainless steel (equivalent to SUS303), but we can also manufacture custom-made set screws with other materials.

Our screws are made by "chasing process in the thread cutting bite".

• When making screws by cutting, we usually use a thread cutting tool called the "thread cutting dies".
  We omit "thread cutting" and simply call "dies".
  We used it until around 1988.
  The photo on the right is a thread cutting dies for M1.4 x P0.3 that we used in the past.
• Thread cutting bite is a cutting tool, which is a triangular shape with a tip angle of 60 angle formed from the carbide tip that is even harder than a thread cutting dies.
  The thread valley angle (60) is the same as the thread angle (60).
  The photo on the right shows the shape of the basic thread cutting bite.

Rotate the material and shave off the valley of screw with a thread cutting bite.

• If the angle of a thread cutting bite is 60 angle, the angle of the thread valley will be 60 angle.
  At this time, the angle of the screw thread is also 60 angle.
• If the angle of a thread cutting bite is 55 angle, the angle of the thread valley will be 55 angle.
  At this time, the angle of the screw thread is also 55 angle.
• It seems a little strange that the angle of the valley and the angle of the mountain are the same, but it can be explained by the theorem that "the illusion angle is equal in two parallel lines".

The rotation of the material and the progress of a thread cutting bite are well matched to create a screw lead (spiral).

• To make an M2 x P0.4 screw, the thread cutting bite is advanced by 0.4 mm in the longitudinal direction while the material with a diameter of 2.0 mm is rotated one. This will create a screw with a lead of 0.4 mm.
• Lead of a screw is the distance traveled when a screw is rotated one.
• Pitch of a screw is the distance between adjacent threads of a screw.
• Single-thread screw (general screws) is lead = pitch x 1.
• Double-threaded screw (two entrances of the screw in one revolution) is lead = pitch x 2.
• The fountain pen cap uses double-threaded screw or triple-threaded screw.
• We can also manufacture double-threaded screws (we have a track record).
• We can also manufacture left-handed screws (we have a track record).

When a screw is made by the thread cutting bite, it is possible to suppress the variation in the outer diameter and effective diameter of the screw to 0.02 mm or less. In other words, since it is possible to manufacture screws with high precision, it is possible to manufacture screws that meet ISO Class 4h standards.

In addition, in order to cut a screw with the thread cutting bite, it is easy to make a screw with a pitch that is not in the ISO standard, a screw with thread angle of 90 angle , or a thick diameter screw.

Also, we are very good at making the slotted head screws that have only two threads. In addition, it is possible to fit incomplete threads within 0.5 threads.

On the other hand, if the length of the threaded part of the headed screw exceeds 2.5 times the nominal diameter of the screw, it cannot be manufactured.

However, with the slotted set screws, if the total length is shorter than two threads, it is difficult to process that slot.
On the contrary, it is possible to manufacture a long set screw with a total length exceeding 15 threads, but it takes a long time to manufacture, which is disadvantageous in terms of cost.