JIS standard and commonly used hole dimensions

Today, we are going to discuss the "JIS standards and commonly used hole dimensions for pan firings and countersunksA note on the "What's the difference between the two? I'd like to note something I learned the other day while doing some research on the dimensions of a countersunk counterbore for countersunk screws.

About the firings, counterbores, and holes in the plates

The JIS standard for the dimensions of the firings and counterbores isJIS B 1017: Shape of countersunk hole for countersunk head screwThe "M" in the "M" is written in the "M" and the "M" is written in the "M",This countersunk hole shape is applicable to the following thread standardswill be.

*Hexagon socket countersunk bolts are not available.

In fact, with the pan-fir dimensions standardized in JIS, the screws pop out.

Many of the reasons why countersunk holes are used areOften keeps countersunk screws from popping outI think it is a good idea.　However,The dimensions of holes for countersunk screws differ from company to company, confusing novice designers.I think that the "I" in "I" is the same as the "I" in "I".

The following figure shows a combination of the holes specified in the JIS standard and the commonly sold "countersunk small screws with cross holes," which is actually a combination of the holes specified in the JIS standard.If JIS standard countersunk hole dimensions are used, the screws will pop out.

*Fine dimensions of screw heads may differ from manufacturer to manufacturer.Therefore, not all of them may exactly match the figure below. (Therefore, please check them only as a reference.)

Like this,With JIS standard countersunk hole dimensions, there is a difference in countersunk screw protrusion.The following is a summary of the results of the study.

Using the commonly used dish fir dimensions will not pop out 👈Use this!

Next, the commonly used reference dish fir and dish counterbore dimensions are shown in the figure.

Basically, use this.

The hole dimensions used in the figure below are the ones I often use. (reference(This is what happens when this countersunk hole is combined with a common "countersunk small screw with a cross-hole.

Everything is sunk in and no countersunk screws pop out. This is safe.

This is what happens when a hexagon socket countersunk bolt is inserted

Finally, a diagram with a hexagon socket countersunk bolt in the general countersunk hole dimensions is shown below.

Earlier, I summarized the applicable standards for countersunk holes, but the standards for hexagon socket countersunk bolts were not included there. In some places in mechanical systems, hexagon socket countersunk bolts are used instead of cross-hole countersunk bolts, so this is for that purpose of understanding.

I can use it without any problem.

summary

The table below shows JIS standards and common sizes.

Supplemental information: Points to keep in mind when indicating the firings and countertops on the drawings.

In drilling holes for countersunk screws, when holes are drilled according to JIS standards, general countersunk screws will pop out, but when they are drilled to general countersunk fir dimensions, they will not pop out. Looking at drills for drilling countersunk holes, we found that the dimensions of drills for countersunk screws are not the same for each company.

What should we, the designers, do?

We have received information from all of you, so let me summarize it in bullet points.

That's it.

For one-off requests, use the notes, and for mass production requests, include the dimensions of the firings and counterbores in the drawings.

That's it.