The Talking Machine Forum — For All Antique Phonographs & Recordings

For those of you that do machine work here is a useful wall chart that may help when selecting drill bit sizes.
Lots of information in one easy to use chart including fractional, wire size and lettered bits.
Also, the tap drill sizes are listed for common threads.
I hope the resolution is high enough that you can print it out for your bench or wall. The original metal chart is 17” x 25”
Sorry, no metric sizes.

Mark

Let’s twist (drill) again, like we did last summer.

I love those charts. Have them hanging all around my shop. My favorite shows optional tap drill sizes for any given thread, along with a percentage of thread engagement resulting from each drill size. Good to know, when tapping very tough material where full thread engagement may end up with a broken tap.

Jerry,

Thanks for your comments. The Cleveland chart only lists the typical 75% thread engagement in the table on the right. I have to look up the others in the handbook. Would love to see some photos of your wall chart collection.

Mark

Here you go...