What size drill,

[gull wing]

bit do I use before the 1/4" dia. ream?

 

[Stacy E. Apelt - Bladesmith]

It depends on a lot of variables. The reamer type,the hole tolerances, the material being reamed, etc. Here is a good link, http://www.yankeereamer.com/Tech_Info/tech_info.html
For a ball park, go .01 below the reamer size, thus .240 would be a good guess.

 

[A C Richards]

I use a B drill. Stacy's .01 under is good, you can go to .015 but not much smaller. if your drills are sharpened properly and do not drill an over size hole it should not be a problem.. I used an improperly sharpened drill bit without checking once and the reamer did not even touch the hole.

Chuck

 

[gull wing]

Thank you!