Hello All,

I need to drill 8 1" holes in 1/4" 304 SS plate. They position needs to be pretty good (within a couple thou) but the size can be +- 0.020"

I want to do them quickly, but with a fairly nice finish (EG, no huge burrs, burn marks around hole)

I've got a Haas VF-2 to do them with.

I was thinking a indexible drill of some sort. (I need to drill 8 holes per plate, 125 plates in total so 1000 holes)

Would a CoroDrill 880 with stainless inserts be good?

Would it be quicker to get a ~1/2" carbide drill, drive it through, then finish to size with a ~1/2" carb end mill meant for stainless?

I've got a large budget for tooling for this job. (All of my tooling up to this point is for Alum)

Thanks!

(Anyone want to recomend any Feed/Speed as well?)

PS, I do not have through spindle coolant.

I would use a 7/8" RotoBrute cutter and then interpolate with a 3/8 TiAln coated 4-flute Carbide.
RotoBrute is an aggressive carbide tipped "annular type" cutter.

Do you have through spindle coolant? You may have trouble with 304 and the indexable without it. I would reccomend drilling with a good HSS drill like OSG Exgold to .5 diameter or so. Then plunge with a 1.0 endmill to remove the remaining material. Annular cuuter will work but they are slow.

I use the corodrill 880 in 316/304 a lot at work and its a great drill. You'll get a pretty decent surface finish if everything is good an rigid, but you will have to debur the top and bottom of the hole. Or get a chamfer / back chamfer tool if possible. For only 1/4" thick material, you should be fine if you have good flood coolant pressure. We run the drill at the recommended specs. You should be able to drill 8 - 1" holes in a minute or so. Overall a good drill, we've had good luck with them

Do not confuse a RotoBrute type tool with a typical annular cutter.
These tools are extremely fast cutting.

If you make all your holes +.020 dia you can also open up on your positional tolerance.
Not what I would shoot for, but it is theoretically true.

Drill it undersize and end mill it in to size. That size I would def. use an insert drill. A good insert drill will hold the size but it may not give you a good finish and may leave a good sized burr. I've always had good luck with Seco and Ingersoll drills. Don't worry about the throught spindle coolant. I've run many many of these drills with regular coolant at regular pressure.

Wonder what we did before we had 2000psi thru spindle coolant?

:cheers: