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Major Changes to a Grind

Dave Fritz

Dave Fritz

Joined
Jul 24, 2008
Messages
729
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Location
Montfort, Wisconsin
How do you make major changes to the grind on your tools? Do you use your normal grinding wheels or something else? The post about negative rake scrapers encouraged me into making some changes and I'd love to find a quicker way than my 80 grit CBN wheel.
 
I use either course grinding wheel I have on a 40 year old Craftsman grinder, or a course sanding belt on my 2" strip sander. I ground my large negative rake scraper over a 2 day period using my 180 grit CBN wheel. I would grind it until it got fairly hot and then go do something else in the shop. Every time I thought about it I would hit the CBN wheel again. Don't know how many trips it took but I was surprised that it would remove a fair amount of metal. So what I'm saying is it's doable on almost anything if you have patience.
 
Well, I cheat, I have a 1 1/2 hp belt sander with a 36 grit belt. Still, some times I will take an angle grinder and a cut off wheel if I am taking a square blank and turning it into a 1/4 round nose swept back scraper. They will go through M42 fairly quickly. Most saw sharpening services will have very coarse grit wheels and belts for major reshaping, which would be handy for several tools at once, then all you have to do is touch it up. If you saved some of the wheels that came with your grinder or grinders, some times they are in the 36 to 60 grit range.

robo hippy
 
Just a caution. Belt sanders and disc sanders are really good at removing steel. So good that it is easy to remove too much. Go slow....

For reshaping I haven an 80 grit CBN that’s is Good for medium reshaping and a 60 grit aluminum oxide that works quicker for big jobs but it is on a grinder that needs to be moved to use.
 
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I have both CBN wheels and course gray wheels and tried both to reshape a square scraper. The 80 grit CBN did a better job than the gray wheels.
 
I sometimes wish I had a small belt sander just for the purpose of regrinding my tools quickly. I don't regrind my lathe tools often enough to justify the cost and space for another bench or stationary tool (if I start talking about bench chisels and plane irons, I'm almost there. I do those by hand on a stone and it is extremely time consuming). Like Don said an 80 grit CBN wheel cuts fast and is pretty quick to reshape.
 
I have a 12" disk sander. I use an 80 grit disk, angle the table to the edge I want. I just got 2 of Thompson's 1/2" scrapers. They come with a square edge. I reshaped them in 5 minutes than made several pases on my CBN wheels to give me a great burr.
 
One of my friends uses a 46 grit on his Tormek. He said it is great for reshaping.

Rich
 
I purchased a 1" strip.sander from Lee Valley. Changing belts is a snap. I keep.a 600 grit on it for touching up my skew but change it to a 60 grit when new turners come.over with tools that need reshaping.
 
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