Spot drilling case hardened steel

[Zumba]

The problem is that the case hardening goes down as deep as .150". I tried a 3/8" carbide endmill on a piece of scrap and the flat that it created when going down that deep was too wide.

I think my only hope is to constantly resharpen the spotter dril. I will also use a collet instead of a drill chuck to minimize runout.

[lakeside]

what size hole are you drilling could you sprial down the .15 with a center cutting endmill undersize first.

[dertsap]

seco makes an insert type counterboring tool , they work unbeleavably well on some hardened stainless we do ,unsure of the exact hardness but it is tough material and an interupted cut as well and the tool stands up to it , we can do a lot of parts with one insert , unsure of numbers because those parts are in the production end of the shop ,i ve ran them a few odd times and it is an impressive tool

[SeaSchell]

Staright flute carbide drill, McMaster, MSC, etc. Coated $15.00 or so, Drill at high RPM, Dry with air blast, (not Chiller), Don't over pressure feed at start.

[Derek.C]

A diamond or ceramic tool would be the first tool of choice for myself. Or find a way to break through that case hardening first but it will have to be the entire drill dia otherwise you will have the same problem with your drill getting chewed up. Try a carbide or diamond burr to break thru . Also what is the material and depth of the case.

[HIGHtungsten]

DUde the answer is so simple. heat your steel up to red hot and let it cool down in sand for a day. this process will soften up the steel.

[stevelang]

cheap masonry bits can go thru case hardened easy.

this is an old post but may be useful to the future search, I read this somewhere and tried, it works great, use masonry drill bits after grinding a little spot with the dremel to get it started and to avoid wooble, it goes like butter, you have to use a drill press and apply some pressure, keep on cooling the bit with alcohol or water spray mist, stop before you go too deep because the masonry bits are not precise, take over drilling with a normal steel drill bit, each masonry bit will last only a couple dozen holes but at a couple of dollars or less each, it might be worth it.

[Newby2]

If you are using a 90 degree spotting drill, a drill doctor will not help
They only grind a 118 and 135 degree drill bit. On the other hand, I have one (drill doctor) that I use at work and the wheel on it works very nicely on solid carbide drills. I resharpen 135 deg. split point SC bits to use in a CNC lathe
Steve

[RICHARD ZASTROW]

Zumba, I like lakeside's idea. Mill a flat on the shaft that is as wide as the hole you will drill. That will cut thru some if not all of the case hardened material and give you a flat surface to start your drill point instead of the round top of the shaft.