Are all center drills the same? Frustrated here...

Take a look @ Stefan Gotteswinter's video on center drilling. Excellent description of how and why.
About the "runout" on the tip of a center drill, I think what is being indicated is the back clearance not runout.
 
With apologies to the 40 preceding posts regarding possible redundancy, here are my observations.

If there is runout in either the center drill or the setup, a center drill will orbit around the true spindle axis. If you push forcibly, it will start off the true spindle axis as play in the spindle allows. When the main cutting edge contacts the work , it will tend to run true and snap the tip. With the larger center drills, they just carve a new spot but smaller ones will break the tip. I was using 0000 and 00000 center drills with tips of .015" and .010" and breaking them regularly. A solution is to make light first contact and allow the center drill to find the true spindle axis. Once it has done so, as evidenced by the lack of wobble in the tip, you can proceed with the main cut.

If the broken tip leaves a stub, the tip can be reground to make a spotting drill

As to brand, all my larger center drills are house brand from Travers or MSC. with the exception of two Malcus No. 7's picked up at a hamfest. The 0000 and 00000 were purchased from Small Parts Inc. , no longer in business, and of unknown brand but likely to be German made.

Edit: corrected tip size of 0000 and 00000 center drills.
 
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RJSakowski said:
With apologies to the 40 preceding posts regarding possible redundancy, here are my observations.

If there is runout in either the center drill or the setup, a center drill will orbit around the true spindle axis. If you push forcibly, it will start off the true spindle axis as play in the spindle allows. When the main cutting edge contacts the work , it will tend to run true and snap the tip. With the larger center drills, they just carve a new spot but smaller ones will break the tip. I was using 0000 and 00000 center drills with tips of .010" and .005" and breaking them regularly. A solution is to make light first contact and allow the center drill to find the true spindle axis. Once it has done so, as evidenced by the lack of wobble in the tip, you can proceed with the main cut.

If the broken tip leaves a stub, the tip can be reground to make a spotting drill

As to brand, all my larger center drills are house brand from Travers or MSC. with the exception of two Malcus No. 7's picked up at a hamfest. The 0000 and 00000 were purchased from Small Parts Inc. , no longer in business, and of unknown brand but likely to be German made.
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I haven't ordered from small parts in years, but I just looked them up, they are still in business according to the website.
 
woodchucker said:
I haven't ordered from small parts in years, but I just looked them up, they are still in business according to the website.
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The name/brand still exists but it isn't the same company. Amazon took them over when they went out of business. I ordered quite a bit from them around fifteen years ago and they were the go-to place for things like hypodermic tubing and small diameter stainless rod as well as precision tools. For the benefit pf those unfamiliar with SPI, here is their 2002 catalog. Nine pages in their index alone. Pick any material/part/tool at random and see what Amazon offers. http://bahrnet.dyndns.org:2980/webshare/BahrZ/Small Parts Inc 2002 Catalog 22.pdf
 
I think a spotting drill is just a very short stiff drill with no flutes. And you can grind any starting point on it you want. The more the point is split the less it wants to run out. I grind my own and it only takes a few minutes to do so. And broken center drills work great to make spotting drills. I can’t see why drills are made with a 118 point . Why not a 120 point ? I mostly use split point drills and if I don’t have a split point drill I grind it too a split point. And I grind 118 point drills to split point . And 99 percent of my drills start out as Harbor Freight drills. I buy them planning to sharpen them before I use them. This is for a home machine shop where most of us use the easy to cut materials like 12l14 and the like. When most of what I drilled was tough stainless or Inconel and that type material then I shopped for the better high priced drills and carbide drills.
Jimsehr
 
Jimsehr said:
I think a spotting drill is just a very short stiff drill with no flutes. And you can grind any starting point on it you want. The more the point is split the less it wants to run out. I grind my own and it only takes a few minutes to do so. And broken center drills work great to make spotting drills. I can’t see why drills are made with a 118 point . Why not a 120 point ? I mostly use split point drills and if I don’t have a split point drill I grind it too a split point. And I grind 118 point drills to split point . And 99 percent of my drills start out as Harbor Freight drills. I buy them planning to sharpen them before I use them. This is for a home machine shop where most of us use the easy to cut materials like 12l14 and the like. When most of what I drilled was tough stainless or Inconel and that type material then I shopped for the better high priced drills and carbide drills.
Jimsehr
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I have a friend he's been a machinist for over 50 years, says he doesn't like split points... Not sure why, I don't remember what he told me..
 
woodchucker said:
I have a friend he's been a machinist for over 50 years, says he doesn't like split points... Not sure why, I don't remember what he told me..
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One reason , they are harder to re-sharpen correctly by hand .
 
Learned something new... now I need to buy some spotting drill bits... I have been using (and some times breaking) my center drill bits for everything...
 
mmcmdl said:
One reason , they are harder to re-sharpen correctly by hand .
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It’s hard to sharpen any drill . Even with a drill grinding machine. Till you learn how.
All most all the newest fancy drills that I’ve seen have a split point.
I have been hand grinding drills since 1953 . That is getting close to 70 years.

Jimsehr
 
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