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Help! Shaping the bevel with a grinder question.

2K views 13 replies 9 participants last post by  AlanWS 
#1 · (Edited by Moderator)
I picked up a never been used grinder with new stones at a garage sale. My plan was to use it to restore the correct bevel on old plane blades and chisels. I had thought to put 6 inch norton 3x grinding stones on it. This grinder runs at 3400 rpm. The woodcraft guy I talked to convinced me that this is a bad idea and I should just continue with scary sharp with say P150 to correct the bevel. Is it really a bad idea? How should I use this grinder? (I only have a couple of days while I am near a woodcraft store.)
 
#2 ·
I use a normal grinder for re-establishing bevels on my irons. Eventually I'd like to get a slow speed grinder, but if you are careful I don't think it's a big deal. I use a Norton White wheel which are made for cutting tools on my older Craftsman grinder, and I just keep a dish of water next to me, and only grind for 3 or 4 seconds at a time, making sure that the metal doesn't start bluing. Also just dip it in the water after every few seconds of grinding. So yeah I don't think it's a big deal as long as you take it slow.

I'm sure there's many varying opinions on that but to each their own, why not utilize what you've got.
 
#6 ·
Thanks you all for the responses. Grinding as you can tell is a new science to me. Thanks for the article it was very helpful.

My original plan was to replace the original wheels a 46 grit and and a 80 grit 3x norton 3x wheel. I understand that these wheels will ensure that the blade being sharpened will remain cooler than with standard stones.

The woodcraft store in Milwaukee where I am (on vacation) has only one 6 inch norton 3x wheel and it is 80 grit. So I'll have to order the other or convince my wife to stop at the woodcraft in Appleton on the way home.

They are not cheap though.

I guess the original wheels are 36 and 60 grit ... that seems standard. Am I to understand that you guys are implying that I should learn to use the original wheels and not bother getting the norton 3x wheels?

I did buy a 120 grit diamond wheel dressing tool. Should I instead get the 46 grit one?
 
#7 ·
I put the white wheel on mine just as insurance. If you go slow, keep the wheel dressed and wet and go slow.

I don't know much about metallurgy, but I know the newer Stanley cutters burn faster than the old ones. The old wood plane cutters don't burn much usually.

I tend to be impatient so I will grind a few minutes then set it down and come back to it.
 
#8 ·
I think they are saying to learn to use the high speed grinder with the wheels you want instead of trading it for a low speed grinder or the scary sharp method as the Woodcraft store employee suggested. Scary sharp is a good method but if you are removing a lot of material to get the correct angle it takes forever and most people don't want to spend the day doing that. Learn to grind your chisels without burning them. I think what Don W is talking about (not turning blue as easily) indicates the new chisels are softer in the beginning than the old chisels. That would also mean they don't stay sharp as long with use as the old chisels. Instead of trying to make them Rc 56, they are making them Rc 48 and telling you these are the same fine quality. The Rockwell C scale go to 60 I believe. When you get into the mid 50 range it is difficult to go further. That was our experience when we were manufacturing oil field equipment. Take you chisels or plane irons and grind a bit then cool in water. Grind and cool. That prevents the blue from over heating. When you heat something and allow it too cool slowly you are annealing it. That means you just made it softer. Don't do that.
 
#9 ·
I agree that you should learn to use the grinder, but I wouldn't hesitate to "upgrade" one of the wheels to a white Norton as linked above. I would use the gray wheel to get edges back to square and the white Norton to establish the bevel. I would also suggest that you do two things. First, build/buy a tool rest so you get the same angle consistently. Second, look for some junk planes/chisels at garage sales and use them to practice. Even the cheap Buck Bros. plane irons from HD would be good for that.
 
#10 ·
All of the above responses are great.

One other technique that I have learned when grinding a plane iron bevel on a hi speed grinder is to dress your wheel with a slight convex curve. As you move the iron across the wheel you are making contact at only one point, rather than a wide portion of the edge. This has two benefits: The risk of overheating the iron is lessened, and it seems to be an easier way to control the consistency of the grind. Like everything else, it takes practice.
 
#11 · (Edited by Moderator)
Thanks for clearing some of this up for me. So my plan is now to get a norton white 150 grit wheel and replace the coarsest original wheel with it. Thus I will have on the grinder a 60 grit and a 150 grit wheel on the grinder. These I will use for the initial shaping of the blades and bevels with frequent quenching in water. Once shaped I will continue the sharpening with a P320, P600,P1500,P200 scary sharp system.

7footer in a PM pointed out that for some reason it is cheaper to buy a norton white wheel from sharpening.com than from Amazon.com. Indeed it is and the woodcraft store did not have one. Unfortunately the day before when I bought the diamond dresser, they gave me this mystery coupon that had to be opened at the store this friday or saturday. So I just had to go back and find out what it would be. I received 20% off a single item and entry in a second drawing. I bought a 1" x 6 TPI wood threading kit instead of a norton wheel. I'll order the wheel from sharpening.com

So thats the state of sharpening for me. I went from know what I wanted to very confused and you guys straightened me out. So I thank you.
 
#12 ·
Once you hollow grind, you can go straight to 2000. I hollow grind, then go straight to my hard Arkansas stone. It works well.

You will also find it easier to free hand the hollow grind.
 
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