Concerning the prick punch, I learned to scribe two intersecting lines at the hole location. Then you place a prick punch tip in one of the scribe lines and follow the scribe like a phonograph record groove until the tip drops into the intersecting scribe line. You can feel it. Then you hit with a hammer to make the prick mark. To be old school true, i would set the tip of a center punch in the prick punch mark and restrike heavily to center punch. If my drills were not center cutting, I would use a 1/8" bit or a #5 center drill and let it drop into and center up on the center punch mark and finally go into the hole with the final drill, letting it drop into the 1/8" hole or center drill mark.
I also learned that with larger drills that did not have a split point, things went much easier if I first drilled the hole with a small drill the diameter of the width of the chisle point on the larger drill. I was taught that about 80% of the force required was to push the center of the drill through the metal and to push that metal sideways into the flutes.
Learned something about drilling today
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Re: Learned something about drilling today
That's exactly what I do. It's not real precision, but the resulting holes are not visibly misaligned and it's adequate for assembly holes with free-fit clearance.jpfalt wrote:Concerning the prick punch, I learned to scribe two intersecting lines at the hole location. Then you place a prick punch tip in one of the scribe lines and follow the scribe like a phonograph record groove until the tip drops into the intersecting scribe line. You can feel it. Then you hit with a hammer to make the prick mark. To be old school true, i would set the tip of a center punch in the prick punch mark and restrike heavily to center punch. If my drills were not center cutting, I would use a 1/8" bit or a #5 center drill and let it drop into and center up on the center punch mark and finally go into the hole with the final drill, letting it drop into the 1/8" hole or center drill mark.
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Re: Learned something about drilling today
All--
As you might know, I am heavily involved in other matters at this time. However, I am very glad I took time to read this thread!!!
--Bill
As you might know, I am heavily involved in other matters at this time. However, I am very glad I took time to read this thread!!!
--Bill
You are what you write.