Replies

1. 
   JohnWW | Nov 23, 2005 05:02pm | #1

   The simplest solution is to do nothing.  The overheated area will probably dull faster when you use the chisel, but will eventually be ground away as you resharpen the chisel.  After a few sharpenings the damaged steel will be gone. 

   You didn't say why the chisel burned but a common cause is a dull wheel.  If you don't have one, buy a grinding wheel dressing tool.  The simplest dressing tool to use is a star wheel type and they work well on ordinary grinding wheels.

   John W.

2. 
   lwilliams | Nov 23, 2005 05:35pm | #2

   How do you know you over heated it? What type of steel is involved?

1. 
   smbevma | Nov 23, 2005 05:43pm | #3

   It turned blue. I always was told that was a sign of overheating.

1. 
   lwilliams | Nov 23, 2005 07:53pm | #4

   If your gouge is made of high speed steel, like most modern turning tools, you didn't do any damage. High speed steel has a higher "red hardness" than plain carbon steel which means it can withstand higher temperatures.If the color you got was in the blue range, light purple to light blue, you reached temperatures of 530º to 640º. High speed steel is tempered to around 1150º for a Rockwell hardness of 62. From what you've said, my guess is that you were around half the temperature that would have been required to change the hardness of the gouge.If the darker color bothers you stone just the color off and forget it.

1. 
   smbevma | Nov 23, 2005 08:10pm | #5

   thanks, they are high speed steel. Sounds like I'm worrying over nothing.

    

    

3. 
   alanplanesaw | Nov 25, 2005 07:21pm | #6

   I have always heard you want a grinder wheel turning under 2,000 rpm to minimize the risk of overheating.  Mine does 1,750 and I still don't keep the steel on the stone for very long.

   Alan - planesaw 

1. 
   Machinist60 | Nov 29, 2005 04:14am | #7

   Safest grinding for woodworking tools is done on a 1" belt sander with proper belts as available from Lee Valley, they run very cool and and you can see what you are doing as the edge faces up toward you as the belt travels down.  If a wheel is to be used, the best you can do is get a 1725 rpm grinder with a 6" wheel with an open and friable bond such as Norton makes and available at Lee Valley.  Use the smaller wheel to keep the peripheral speed down.  This is important for high carbon steel edges, not so for HSS.  The grey and white wheels from China are only good for boat anchors and grinding the heads off bolts and rivets.

   John Wilson.

1. 
   alanplanesaw | Nov 29, 2005 05:21am | #8

   Thanks for the detail info with explanation.  Best way to learn.

   Alan - planesaw