TECH: helpful charts (for your shop)

Sooner or later you'll run into a thread that may not be listed on your chart for tap drill sizes, like 1/4-24. Heres a formula that works on all thread sizes and pitch's, the diameter of the bolt minus.974 divided by threads per inch. Take 1/4-20, .250 minus .974divided by 20=.201 or as its more commonly known a # 7 drill. Sometimes walkin over to the chart is a pain.

i think you need to specify your math

the calculation would not be:
(0.250 - 0.974) / 20

it is:
0.250 - 0.974 / 20

or, to be more obvious:
0.250 - (0.974 / 20)

Please excuse my ignorance

thats a cool trick homie, i was just trying to make sure everyone got it

http://www.imperialsupplies.com/pdf/...rqueCharts.pdf


Sorry, the PDF is too big to uplioad.

Originally Posted by GRHebard

heres a closeup of the starrett chart, it doesnt look too clear on the top post
heres a link to download the charts from starrett

Thanks for the link man

cool thanks!

they still send them out,although,they now manufacture in china too

Originally Posted by Millmech666

The only other ones I would HIGHLY recommend would be torque chart and cutting/feed speeds. Other than those Looks as tho ya have your bases covered! The 2 I use on a daily basis in the field, shop, and @ home are the conversion chart and the drill/tapchart. Those have proven to be invaluable. Starrett used to send those charts out free(pocket size and the wall posters). Not sure that they still do...