Mr. Frazier.

Yes, they change very rapidly when a tool is used to cut a hard object.

Mr. Eisenberg.

Could you elaborate on what you mean by "very rapidly"?

Mr. Frazier.

Well, for instance, when using a pry bar, for example, one insertion of a pry bar into the hard insulation of a safe, with pressure applied to it can change the entire blade of the tool to the extent that you could not identify a succession of marks, because of the abrasion by the insulation. But that same tool, used to mark a soft steel or brass or copper, could make mark after mark without changing, or only a small portion of it may change with each impression. Or it may gradually change over a period of time.

Mr. Eisenberg.

Now, is the metal in the bolt face a hard metal or a soft metal?

Mr. Frazier.

I would say it was hard metal----

Mr. Eisenberg.

Well---

Mr. Frazier.

With reference to copper or other softer metals---it is a steel. I could not say how hard it actually is.

Mr. Eisenberg.

What will the effect of the metal used in the bolt face be upon the tool which is used to finish it off, cut it and finish it off?

Mr. Frazier.

The tool will gradually wear out.

Mr. Eisenberg.

Well, will the tool leave different marks on the end of the bolt face from one bolt to the very next bolt face?

Mr. Frazier.

Oh, yes; that very often happens. The tool is worn out or the small cuttings get underneath the edge, between the tool, and nick the edge of the tool, so that the tool will gradually change over a period of time. The cutting edge the amount of change depends upon the amount of wear, the heat involved, and the hardness of the metal--the relative hardness of the metal.

Mr. Eisenberg.

Will that particular change be noticed invariably in two consecutive bolt faces?

Mr. Frazier.

No, sir.

Mr. Eisenberg.

So what is the genesis of the difference in the two consecutive bolt faces as they come from the manufacturer?

Mr. Frazier.

The change, as I said, depends on the bolt you are using. It does not always take place, because some bolts are made of a very soft metal, and they will not necessarily change a machining tool to that extent.

Mr. Eisenberg.

But the markings, you said, would be different on two consecutive bolt faces?

Mr. Frazier.

Oh, yes.

Mr. Eisenberg.

And if the tool is not changed, what is the origin of the difference between the markings?

Mr. Frazier.

There are other accidental markings placed there during the machining operation.

Mr. Eisenberg.

Could you describe that?

Mr. Frazier.

For instance, as the blade of a milling machine travels around a surface, it takes off actually a dust--it is not actually a piece of metal--it scrapes a little steel off in the form of a duster a very fine powder or chip-that tooth leaves a certain pattern of marks-that edge. That milling cutter may have a dozen of these edges on its surface, and each one takes a little more. Gradually you wear the metal down, you tear it out actually until you are at the proper depth. Those little pieces of metal, as they are traveling around, can also scratch the face of the bolt-unless they are washed away. So that you may have accidental marks from that source, just in the machining operation.
Now, there are two types of marks produced in a cutting operation. One, from the nicks along the cutting edge of the tool, which are produced by a circular operating tool--which produce very fine scratches in a circular pattern. Each time the tool goes around, it erases those marks that were there before. And when the tool is finally lifted out, you have a series of marks which go around the surface which has been machined, and you will find that that pattern of marks, as this tool goes around, will change. In one area, it will be one set of marks--and as you visually examine the surface of the metal, these very