Reddit mentions of Machinery's Handbook, Pocket Companion

https://www.amazon.com/dp/0831130954/ref=cm_sw_r_cp_awdb_ubmlzbACY25EK

Prob be able to find one used. This has a thorough (though basic) primer and equations on gears and threads that should help you.

i feel like i am being trolled by this post but i'll give you the benefit of the doubt

• you are supposed to put the drills directly in the collets. you're looking for jobber and stub twist drills. good quality hss is ridiculously cheap, don't fuck around with the chinesium from home depot.
  
• er11 collets are also super cheap
  
• 2000 rpm is going to be fine for drilling most plastics up to about 1" dia, and most aluminums up to about 3/4" dia, and graphite up to about 11/32" dia
  
• most of your inevitable questions can be answered in the machinery's handbook pocket companion
  
  
  finally, CONCENTRICITY IS IMPORTANT TO ACCURATE HOLE SIZES. those garbage chucks you bought from amazon are meant for hand drills and will probably have 5-20 thou runout, which is a big deal if you need your hole to be 125 thou.
  
  the more things you have between the tool that's going to cut the workpiece and the spindle, the more inaccuracy you're going to have.
  
  if you cheap out on everything (where not cheaping out is still cheap), don't come back here asking why all your holes are fucked up.