[brian257]

I have always used center drills in the past, but I am about to start a run of parts with a ton of smallish (6-32 tapped and clearance) holes and I am wondering if using a carbide NC spotting drill would be better. Having never used one before I would like some advice on if they would be better for this application than the center drills. In particular I want to know if they need to be peck drilled or can you just run them straight in without clearing chips which I assume would make them much faster than the center drills.

[okumamaster14]

We use the Iscar Cham Drills with Ø.5 insert to spot face are holes. Never had any problems with locations or drills running out plus they hold up for a long time. I have used it with a 6-32 also, worked fine. I only go .015-.025 depending on the Ø of the hole with and dwell for 1sec @ 8ipm and 1200rpm A-2 speed, with no peck.

[rcs60]

rpm and feed are dependent on the type of material IE. 12l14 steel i would use a spot drill at 4500 rpm and a 12. ipm feed and any dwell would be a factor for increased accuracy and how many times you want it to revolve at the end of the cut --rpm/60(seconds)/10(tenths of a sec) 4500/60/10= 7.5 revolution per .1 sec and a spot drill will save some time due to distance to be drilled- for a 6-32 a spot would be about .08 deep a #2 center drill would be about .160 deep
rcs60