# Thread: Want to find a formula for my drill feeds based on the size of my drill bit

1. ## Want to find a formula for my drill feeds based on the size of my drill bit

DRILL FEEDS

Hi there,

My drill size is 7mm and i want to work out my feed rate accurately. dose anybody have a formula or know how to work this out,, see chart..please help..it confusing me.

thks

karol byrne

 DRILL SIZEInch FEEDIns/Rev DRILL SIZEmm FEEDmm/Rev 1/16 – 3/32 .0015 – .003 1.6 – 3.0 0.04 – 0.075 1/8 – 5/32 .002 – .005 3.0 – 4.0 0.05 – 0.13 3/16 – 7/32 .003 – .006 4.0 – 5.5 0.075 – 0.15 1/4 – 5/16 .003 – .008 5.5 – 8.0 0.075 – 0.2 3/8 – 7/16 .005 – .010 8.0 – 11.0 0.13 – 0.25 1/2 – 9/16 .007 – .012 11.0 – 14.5 0.18 – 0.30 5/8 – 11/16 .009 – .014 14.5 – 17.5 0.23 – 0.36 3/4 – 13/16 .011 – .016 17.5 – 20.5 0.28 – 0.40 7/8 – 15/16 .012 – .018 20.5 – 24.0 0.30 – 0.45 1 – 1.1/8 .014 – .020 24.0 – 28.5 0.35 – 0.50 1.1/4 – 1.1/2 .016 – .022 28.5 – 38.0 0.40 – 0.55 Over 1.1/2 .020 – .025 Over 38.0 0.50 – 0.64

2. ## Re: Want to find a formula for my drill feeds based on the size of my drill bit

The "feed" does not depend on the diameter of the drill. It depends upon the "pitch", the distance between successive flutes, the feed per revolution. The table you give must be for a specific type of drill with a specific pitch that is not given.