Tuesday, January 26, 2016

Cars & Books, In The Singular

Photo From Here
Is that pretty or what? Jaguar C-Type. What smooth lines.

I needed a tap drill chart for down the basement. I've got several little plastic pocket cards out in the shop but I thought I'd check my library and see what I had.  Glad I did. I had forgotten about this one. Besides the de rigueur tap drill chart and decimal equivalents, lots of tips and kinks for machinists. It's a 1924 printing and still in excellent condition for a discard from the Fall River, Massachusetts library

Fall River library
Don't know how the book got here to the Mid-West or even where I picked it up from anymore. Probably too nice to leave down the basement, however. Maybe make it a bedtime reader and leave it on the nightstand. 


Surly said...

For most vee threads - subtract the pitch from the major dia. to get your tap drill dia.
For general shop work, it'll get you a tap drill size very close to 75 percent of full thread just like the Starrett chart.
20tpi = .050"
.250-.050 =.200
Starrett chart = .201

Shop Teacher Bob said...

Thanks - both easy and handy to know. Most of the common fractional sizes I work with I know off the top of my head but I'm working with screw sizes on my basement project with some oddball stuff like a 6-40 thread. Probably quicker and less chance of me making an error if I just look at the chart. No guarantee there either, though.