Drilling 1/2" holes in 1/4" HRS plate

I'm not familiar with your drill press, but I have an old Buffalo benchtop drill press that I use... the slowest RPM mine will turn is a little over 500 RPM if I'm remembering correctly.

It drills pretty well up to about 3/8 inch... and I have drilled quite a few 1/2 inch holes, but I end up sharpening the drill often... 500 RPM is simply too fast, IMO.

A while back, I tried a 5/8 drill in some 3/8 mild steel... I never did get the hole drilled, I ended up chucking the part in a 4 jaw chuck on my lathe to drill that hole...

So... now I'm keeping my eye on Craigslist for a floor model drill press (at a good price) that will turn a good bit slower than 500 RPM...

-Bear
 
Your old Buffalo is likely a lot tighter than any new Chinese or Taiwanese DP. These DP have a secondary step down shaft, even then they are pretty fast. Maybe think about one for your Buffalo.
 
3/8 to 1/2 inch shouldn t be that difficult. I wonder if the drills you are using or purchased have the proper clearance angles. Also once a drill has been heated the way you describe you may have taken what heat treatment the drill may have had. Thinning the web is crucial to relieve pressure. Do some peck drilling rather than just plunge. As things heat up it also becomes more difficult. Walk away for awhile it will help. As soon as your drill shows any sign that it has lost it s initial charm. Don t wait until it won t work anymore. Touch it up so there is lees grinding less heat and much easier for you to maintain proper geometry. Don t take for granted the drill was manufactured properly. I Always take the time to go over them before use and you will be surprised what you will find. Drill doctor junk. I have a Tormek t8 with the ds 22 jig for grinding drills. A four facet grind. Bar none better than any drill you can buy at your common store. People pay for that grind. Speeds and feeds!
 
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