Sharpening Drills

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  #1  
Old 02-25-01, 07:12 PM
Bart Beaudin
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Question

I have several metal twist drills that need sharpeing. Up to now all I have done is go out and buy a new one when the old ones get dull. Do you have any tips for doing drill sharpening with a small table-top grinder?

Hope you can help.
 
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  #2  
Old 02-25-01, 07:56 PM
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Hi: Bart

An "Excellent Question" to a dull problem.
To which I have a "Sharp Answer."...

With a good eye and a steady hand, almost any steel drill bit can be sharpened on a belt sander or grinding wheel. However, practice does make perfect.

The first step is to view the bit closely from several angles prior to any grinding. Look at the center point with the bit facing upwards towards you.

Then hold the bit vertical, at eye level and notice the cutting edge. Rotate the bit while at eye level. Notice the back side has a sloping angle.

That sloping back angle from the center point and from the cutting edge backside is called the "relief angle" and must be closely maintained. So must the center point which is called a "Web."

TIP: Failure to maintain the web centered and the bit will wonder when first coming into contact with the item being drilled. Failure to not maintain the relief angle and the bit not cut well.

Once your aware of these angles, you can best sharpen any drill bit. Once your ready to start sharpening, follow the existing angle on the bit. You'll have to also rotate the bit in your hand while sharpening.

I suggest using a fine grit belt or grinding wheel and have a pot of cold water near by to cool the warmed bit. Do one side partially then the other but never any side completely at once. Continue sharpening each side a little until the bit is completely sharpened on both cutting edges.

Another suggestion is to make the task easier and just purchase any brand table top drill bit sharpening machine. They work fine for non commerical purposes. They'll sharpen any steel drill bit used for casual useages just fine.
 
  #3  
Old 02-25-01, 08:04 PM
Bart Beaudin
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Thumbs up Thanks for the Drill Sharpening Tips

Thanks for the drill sharpening tips! Now I will be able to save lots of $$$$.

Great instructions!
 
  #4  
Old 02-26-01, 03:27 PM
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Location: Lake Murray, SC USA
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Bart,

One way to help maintain the correct angle, is to use a C-clamp to clamp a large hex nut to the tool rest in front of your grinding wheel. Place any flat side of the hex nut, parallel to the face of the grinding wheel, which will make one side of the hex nut, approximately lined up with the angle of the cutting surface on the drill bit. Now place the drill bit flat on the tool rest, and flush against the angled side of the hex nut, and rotate the bit as you make contact with the grinding wheel. You can rotate and re-clamp the hex nut, if you need to adjust the cutting angle on the bit.
 
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