Replies

1. 
   tailsorpins | May 18, 2005 09:25pm | #1

   Real Forstner bits, with the continuous rim (and recent ones with a chip slot only in the rim, but not the saw-tooth wannabe's), are best sharpened only on the inside bevel, using a scraping motion with one edge of the point of a triangular file.  The file can be prepared by grinding to three "safe" (smooth) surfaces, meeting the other surfaces in a knife-like edge (sharp).  Use it to scrape the inside to restore the sharp rim, and on the smallest ones, it is used to restore the cutting edge, again, only on the beveled back side.  The cutter of larger bits may be sharpened with a small flat file.  Do not remove material from the outside of the rim, nor the forward face of the cutter .... other than just enough to remove a burr & smooth the surface.  The working edge of an old babbit bearing scraper works quite well.

   The original manufacturer (now Convalco) offered a sharpening service at one time.  You can see them at http://www.convalco.com/.  If your bit is one of theirs, they will recondition it for $10, but don't try to slip a Snell or B & S or BSI one in on them!  They have dropped their brace-shank line of Forstners, but the 60 series machine bits seem to still be offered.  You can pick up the brace shank versions occasionally on Ebay.   Wouldn't be without my Forstners!

   Good Luck!

   John in Texas

2. 
   mike4244 | May 18, 2005 11:20pm | #2

   Plan B, use a dremel tool with a tapered stone, works fine.Go lightly,reduce speed on dremel to 50% and hone the inside of the rim.

   mike

1. 
   silver77 | May 19, 2005 07:28pm | #3

   John in Texas and Mike,

   Thank-you...

   my inclination is to try the dremel first...sounds good...appreciate the tips...

   silver

3. 
   wnr | May 19, 2005 07:39pm | #4

   Definitely try the Dremel to sharpen the bits. I use an oval shaped stone that leaves a hollow ground edge. Just go slow and easy. A straight or conical stone tip will give a good edge to the interior flats.

    

1. 
   silver77 | May 21, 2005 07:09am | #6

   I dropped one off at a machine shop today...for what he wanted to sharpen 3 , I could buy a new set. He told me my saw guy ground the flats too low so it's toast...so I did buy a new one.

   The tapered dremel is giving me an idea...why can't I make a tapered wood dowel, take some scary sharp sandpaper starting at 600 and going to 1200...and hold it on the inside of the rim as the bit rotates slowly on the drill press?

   silver  

1. 
   nikkiwood | May 21, 2005 09:31am | #7

   RE: the Dremel for sharpening. I was talking to my tool guy recently, trying to pick out a conical shaped grinding stone for touching up some spade bits. He turned me to a tiny, conical shaped tungsten carbide bit (made by Dremel), that worked really slick. I haven't tried it yet on a Forstner, but I think it might work better than the stone.********************************************************
   "I would never die for my beliefs because I might be wrong."
   -- Bertrand Russell

1. 
   silver77 | May 21, 2005 04:59pm | #9

   a tiny conical bit...for speed bits...now there's an idea...I use a bastard file...not fond of sharpening...I'll try your way.

   thanks,

   silver  

2. 
   MarkRD | May 21, 2005 04:49pm | #8

   I just looked in my copy of Leonard Lee's Complete guide to sharpening...Are your forstners the saw-tooth kind?
   He sharpens the leading edge of each tooth with a triangular file. (the leading surface of the tooth) If the bit needs major work, he chuckes in a drill press, he joints the face of the bit on a bench stone so all the teeth are the same height before sharpening the teeth.There is about 5 paragraphs of detail for recovering a really bad bit...Mark

   Measure it with a micrometer, mark it with chalk, cut it with an ax.

   View Image

1. 
   silver77 | May 21, 2005 05:06pm | #10

   Leonard Lee eh...the guy's the quientessential canadian enterpreneur...a bit of a genius...sure found several lucrative markets to exploit...woodworking, gardening,hardware,books.

   that book is on my list...does he make sharpening fast, quick and easy?? Those are my parameters. I don't like to sharpen...I even send out my chisels most of the time...I look at it as cheap help...

   anyway,my bits are the rim type with flat cutting edges...  

   thanks for the info-

   silver

3. 
   wnr | May 21, 2005 10:16pm | #11

   Re holding sandpaper to even a very slow turning bit ......

   sounds scary to me!

   I feel in control sharpening the bits held in a vise and bringing the Dremel tool to the bit. it works for me.

    

1. 
   MarkRD | May 21, 2005 10:42pm | #12

   I would hand turn the bit by grabbing the chuck after locking the bid down against the bench stone...Mark

   Measure it with a micrometer, mark it with chalk, cut it with an ax.

   View Image

4. 
   WillGeorge | May 22, 2005 10:07pm | #14

   Just me..  I use them TOOLSHOP forstner bits  Cheep.. They work well and if I need to sharpen one I just get a new set of them!

   Well, I'm cheep but they work OK!

4. 
   WillGeorge | May 19, 2005 07:44pm | #5

   Does anyone know an easy way to sharpen forstner bits?

    I get a new set of them!

5. 
   lwj2 | May 22, 2005 08:43pm | #13

   Talk to the industrial tool suppliers and ask them who they recommend for sharpening.

   Jamison's (my local folks) sharpen my Forstner bits for about five bucks each, as I recall.

   Jamison's Sharpening Inc
   (540) 989-2744
   5630 Grandin Road Ext
   Roanoke, VA 24018

   Leon Jester