Drilling hard steel

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jonathan01

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I am trying to drill hole out from 0.310 to 0.3125. I drilled about 6 holes like that , and the drill bit is brunt. Now, as soon as I start drilling, the drill bit starts smoking. What speed and feed should I be drilling at. I am not sure what steel I am trying to drill, it may be spring steel, it does not rust though. I know I am probally trying to feed it too fast .

Also, I don't have my coolant working right now. I put a little bit of coolant on now by hand, but it is probally more of a lubicant right now them a coolant. So that I is probally also some of my problem.

Thanks
 
Your description sounds like your drilling stainless. Stainless like low rpms like under 300 rpm and plenty of lube. Maybe some of you fellas can explain why SS can be so hard to drill.
Dan


Master of unfinished projects
 
Stainless is a pig because it work hardens. If you have been spinning in the same hole with that drill bit, you have likely work hardened the material which will now be much harder to drill.

Paul.
 
You can get straight flute carbide drills from MSC. They will drill spring steel. I have used them for many years drilling 1095 spring steel saw blades. We made many,many saws for Williamsburg's Historic Area craftsmen when I was toolmaker there. I don't know if these carbide drills come in the exact diameters you need,though. I have drilled many a hole where the diameter was not critical,using carbide tipped masonry drills. Ran them at 2000 rpm dry. They de-temper the hardened steel and scoop it out. They will even drill holes in files. You have to be careful to not let them get too hot,or their brazed on tips will melt the brazing and fall off. I even drill 1/16" thick HSS full hard power hack saw blades with them,though I need to re sharpen the drill with a diamond wheel for each hole. If I don't,the pressure and heat pops the HSS saw blade in half.

You could likely just use carbide end mills to drill. Clamp the work securely,as the end mills want to cut side ways. They make "drill mill" end mills that have drill like tips. Still need secure clamping. Make sure you get CENTER CUTTING end mills. Peck drill with them.
 
Samthedog hit the nail on the head. I used to work with a lot of 316 stainless, which can be a real bear if using HSS bits. The trick as mentioned is low RPMs, plenty of lube, and plenty of pressure. Once you start drilling you need to apply pressure and do not let up until the hole is done. I prefer to use a drill press for the higher pressure and better control. Luckily, when the material does work harden, it usually is not a very thick spot, so you can usually get the drilling going again if you have a good sharp bit and can apply plenty of pressure at VERY slow speeds.

Carbide or cobalt bits work much better, but they come at a price.
 
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I think it is spring steel, but it may not be. I guess it could be hardened stainless. What ever it is even in salt water it doesn't rust. I am drilling some 17-4 ph SS right now, and the cheap center drills that I have are a little hard to start sometimes. Besides that though the 17-4 drills fairly easy.

I messed up in my first post about the hole I am trying to drill. What I have is a 5/16" hole that is 1" deep, and I am trying to deepen it to 1.5".

I am drilling it in a lathe, with just some HSS Norseman 135 degree drill bits.
 
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george wilson said:
You can get straight flute carbide drills from MSC. They will drill spring steel. I have used them for many years drilling 1095 spring steel saw blades. We made many,many saws for Williamsburg's Historic Area craftsmen when I was toolmaker there. I don't know if these carbide drills come in the exact diameters you need,though. I have drilled many a hole where the diameter was not critical,using carbide tipped masonry drills. Ran them at 2000 rpm dry. They de-temper the hardened steel and scoop it out. They will even drill holes in files. You have to be careful to not let them get too hot,or their brazed on tips will melt the brazing and fall off. I even drill 1/16" thick HSS full hard power hack saw blades with them,though I need to re sharpen the drill with a diamond wheel for each hole. If I don't,the pressure and heat pops the HSS saw blade in half.

You could likely just use carbide end mills to drill. Clamp the work securely,as the end mills want to cut side ways. They make "drill mill" end mills that have drill like tips. Still need secure clamping. Make sure you get CENTER CUTTING end mills. Peck drill with them.
Click to expand...

I will look into these options some more. I need to deepen a 5/16 hole from 1" to 1.5" deep. I am clamping the work in a 3 jaw chuck in the lathe, and drill with the tailstock.
 
Thursday I looked at rebuilding a tap flute grinding machine for this MN based drill bit company. On there web site they have trouble shooting.
I would wonder where your drill bit came from. You will discover that it pays to buy expensive drills and taps and not the cheap ones. Those cheap ones might be OK on wood, but not for steel. n drill bits and taps, you get what you pay for.
http://vikingdrill.com/
 
Most of the equipment i work on has stainless steel as the basic building material.
it is a difficult material to drill especially if already work hardened.
i will echo others' suggestions... low feed rate, but a lot of down force,low speed, and lots of bacon grease.
if you are lucky, sometimes you can use a slightly larger to get through work hardened areas.
for example you are drilling a half inch hole and your HSS 1/8" bit isn't cutting anymore and turning blue, ditch the HSS 1/8" bit, get a 5/32" Cobalt Bit or Carbide , lube up with your favorite brand of bacon grease and off to the races!!
i have used this technique repeatedly. works like a charm . Fresh or recently resharpened bits are best for stainless
i hope the info helps!!
 
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