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A screw number such as 4-40 means that the screw size is 4 and there are 40 threads per inch. When drilling holes to be tapped, they should be a little larger than the minor diameter and less than the major diameter. The tap hole needs to be larger in harder materials such as steel or iron than in softer materials such as brass or aluminum.
A screw number such as 4-40 means that the screw size is 4 and there are 40 threads per inch. When drilling holes to be tapped, they should be a little larger than the minor diameter and less than the major diameter. The tap hole needs to be larger in harder materials such as steel or iron than in softer materials such as brass or aluminum.
Clearance holes are larger than the major diameter and they can be either a close fit or a larger free fit. For the washers we used the free fit.
Another useful tip is that there is a little knob for locking the micrometer.
When drilling I had to go slowly and back the drill bit out as needed. I am still not really sure when to back it out, but I did it for every washer I drilled. My best drill holes seemed to be in the last two washers. They did not have much material projecting after I was done.
Here is the [https://www.homedepot.com/catalog/pdfImages/70/70dee0f4-a6b8-4cfe-b38b-bec0aaa745db.pdf drill user manual].