Drilling Hardened Steel?

[EZ Cad Blades]

I worked for several years as a tool and die machinist. Often times someone, invariably, would "finish" a part and send it through Heat Treat, only to find after getting it back that they had missed a dowel hole or some such. I can tell you (IMHO) the absolute best way (I've used the carbide bits also, both solid and masonry) to cut a hole in hardened knife steel (or any other that I have encountered) is to use a 4 flute solid carbide BALL end mill running between 500-700 RPM, NO COOLANT and LIGHT, SLIGHTLY firm pressure pulling down on the quill (this will allow the metal to heat up and "plasticise", hence NO COOLANT). Now I work on the selling side of the same industry. If you want someone who will verify the kind of results I'm talking about, and whose word you would probably trust, call Texas Knifemaker's Supply and ask Lance Reid. I ran a test for him to show him how well it worked. I am pretty sure he would verify to you that I was able to cut simply and quickly through a pre-ground, hardened knife blank. Before starting the test I noticed his machine had a little run out and pointed that out to him. I was still confident that I would be able to cut the hole, so I let him know that I might break the bit in the radiused flute area if I wasn't REALLY careful, but the bit would still cut. It did break as I suspected it might, but still cut a clean hole and he wanted to see it again and to show Jim Lemcke (TKS's Owner for any who don't know Jim). Even with the broken flute I was still able to cut more holes to show Jim. These are really great folks to deal with as I am sure most of you will agree. Anyway, this is an option that works great. And, if your machine doesn't have much run out (I almost always did this process in a drill press, which people have always said regarding using and end mill in, is a "no-no") you should have no problem getting good results. Hope this helps some of you.

Larry

 

[gusval]

good tip
thank you

I worked for several years as a tool and die machinist. Often times someone, invariably, would "finish" a part and send it through Heat Treat, only to find after getting it back that they had missed a dowel hole or some such. I can tell you (IMHO) the absolute best way (I've used the carbide bits also, both solid and masonry) to cut a hole in hardened knife steel (or any other that I have encountered) is to use a 4 flute solid carbide BALL end mill running between 500-700 RPM, NO COOLANT and LIGHT, SLIGHTLY firm pressure pulling down on the quill (this will allow the metal to heat up and "plasticise", hence NO COOLANT). Now I work on the selling side of the same industry. If you want someone who will verify the kind of results I'm talking about, and whose word you would probably trust, call Texas Knifemaker's Supply and ask Lance Reid. I ran a test for him to show him how well it worked. I am pretty sure he would verify to you that I was able to cut simply and quickly through a pre-ground, hardened knife blank. Before starting the test I noticed his machine had a little run out and pointed that out to him. I was still confident that I would be able to cut the hole, so I let him know that I might break the bit in the radiused flute area if I wasn't REALLY careful, but the bit would still cut. It did break as I suspected it might, but still cut a clean hole and he wanted to see it again and to show Jim Lemcke (TKS's Owner for any who don't know Jim). Even with the broken flute I was still able to cut more holes to show Jim. These are really great folks to deal with as I am sure most of you will agree. Anyway, this is an option that works great. And, if your machine doesn't have much run out (I almost always did this process in a drill press, which people have always said regarding using and end mill in, is a "no-no") you should have no problem getting good results. Hope this helps some of you.

Larry