lip on reduced shank drills

[cmv]

Bought a set of Enco reduced shank drill bits and they don't look "right" to me. Set was inexpensive & goes from 9/16 - 1" by 16ths. Most have a raised lip along the flute and it doesn't look right. the 13/16 looks like a "typical" drill bit and does not have this lip. All the others do. Don't know how well it will show up in my pictures so you can see what I'm talking about. In the 2nd picture you can see the 13/16 one doesn't have that lip but looks like it may have been there & ground away.

The 1" bit measures .925 on the flutes & 1.000 on the "lip" so I'm guessing it should be there. The 13/16 measures .8075 so it's .005 undersize.

I've never seen bits that weren't uniformly round. Does that raised fin serve some purpose? Does it limit the application? I typically use drill bits in a tailstock chuck to bore holes in 6061, 1018, 304, & 316. Also when using the mill as a drill press for the same materials. Everything else I have are (well, were before wearing off) TiN coated HSS, these are black oxide HSS.

 

[Tony Wells]

That's pretty normal for larger bits. Actually most bits have a little upset along the edge of the flute, but it's more pronounced on the larger sizes. That is, if I am seeing what I believe you are talking about.

 

[Bill Gruby]

As Tony said that's normal. All of my MT2 drills above 1/2 have it. Just use them as is although some of those you show are in need af a facelift. They look pretty rough.

"Billy G"

 

[pineyfolks]

I've bought the same set over 10 years ago. I needed them for a job on my bridgeport, I bought them because of the price , I figured they would last one job but they are still going strong. they look just like yours , not the best looking but they do drill ok.