countersinking question

[jdm61]

I know that the suppliers sell countersink bits for use on handle bolts, but I am going to be drilling and countersinking 416ss buttcap and using the female side of a Corby bolt to secure it. What is the best way to drill and countersink such a piece? I was playing around with my mini-mill, but it seems thatt he 4 flute 5/16 end mill cuts the hole too bit....I['m guessing because of tool chatter/woble when making the intial cut. I would like to drill the pilot and then countersink a hair under 1/8 into my 3/16 buttcapp material so that, if I choose, I can grind the head of the Corby bolt flush.

 

[RUJOCO]

Have you tried a 1/4" end mill to outsmart the chatter ? Or go to a piloted counterbore in the size you need. The counterbore pilot follows your predrilled guide hole, it's pretty acurate and stable in a drill press or mill. (unless they have alot of runout.)

 

[jdm61]

Have you tried a 1/4" end mill to outsmart the chatter ? Or go to a piloted counterbore in the size you need. The counterbore pilot follows your predrilled guide hole, it's pretty acurate and stable in a drill press or mill. (unless they have alot of runout.)

I have a set of indexing bits (?) that you use to start holes when drilling in the lathe. I will try those to start the hole, but they are pretty cine shaped so they may not help other than to get the smaller hole done right. If you are using 2 bits/end mills, should you drill the big hole first or do the small hole first