Thanks for all the great responses. My worry is not speed at all, in other words, slower is just fine. In fact, if 6 inch wheel size is not an issue when grinding thick Veritas bevel up plane irons due to deeper hollow than one would get with a 8 inch wheel, I will likely just go with a 6 inch size. Other than being faster, is there any inherent advantage for 8 inch grinders? It seems they are a lot more common among turners, I am not and don't plan to get into turning any time soon.
There are tools, Japanese chisels for one, that many experts suggest not hollow grinding. Some knowledgable users still hollow grind some of these tools particularly with 8 & 10 inch wheels. The lesser bevel may be preferred in these situations.
I thought about buying a grinder with a 6" wheel, but felt that the 8" would make better bevels on the drawknives, scorps, adzes and other green wood tools I use. I suspect someone will "do the math" and give you the actual numbers. Still, it just depends on the tools you use and what size bevel might benefit them. I was also thinking about getting a lathe for turning where the 8" grinder seems to be preferred.
Some useful numbers:
For hollow 1" long the difference between 6" and 8" wheel would be 0.005" (0.021" vs 0.016")
For hollow 1/2" long the difference between 6" and 8" wheel would be 0.0013" (0.00521" vs 0.00391")
So, from theoretical point of view I can conclude that 6 or 8 mostly different in speed of work and life span and money. In practice - I don't have any.
Last edited by Andrey Kharitonkin; 06-13-2016 at 10:04 AM.
I ended up with a slightly used 7" full speed (3600 rpm) Baldor at a great price. Now onto finding the right CBN wheel. It appears 180 grit is the one to start. I have been thinking of getting a 1.5" wide wheel with side grinding option (i.e., about 1" portion of the side coated in CBN) but have not yet found one.
Any recommendations? This will be used for plane irons and chisels for the most part. I don't do turning and no plans at the moment.
Frank
Contact Ken Rizza at Woodturners Wonders. He provided super service to me.
Apparently Ken has crowned wheels in now, as well as the straight wheels I use:
http://woodturnerswonders.com/collec...own-cbn-wheels
I have no difficulty with straight wheels since they are wide and grind so fast. However, if you are used to running the blade past a crowned face, then you may prefer the crowned wheel.
Get the 180 grit. I use it 90% of the time. I also have a 80 grit, which is intended for deep grinding.
Regards from Perth
Derek
I also have a 7-inch Baldor although mine is 1800 rpm. The only vendor I found selling 7-inch CBN wheels was D-Way Tools. I don't see any side grinding options in his list but you should contact Dave, the owner, to see what he can offer. I bought the 180 wheel and removed the outer half of the wheel guard and attached a magnet at the back of the inner half to collect metallic particles from grinding. I use my setup primarily for turning tools so it is equipped with the Wolverine system.
I suppose your side grind options might improve if you remove both halves of the wheel guards so you can then install an 8-inch wheel.
You can use wheels from 6" - 8" on a 7" machine. The guards are not necessary with these wheels.
Regards from Perth
Derek
I have one of the crowned CBN wheels, there was a bit of a learning curve for me, it is very fast and doesn't heat the tool much at all. The first couple tries ended with a bit of a scalloped edge that I had to true up on stones. Now that I've got the hang of it it is possible to grind cambers without rotating the blade, just by varying the pressure.
jim
Ancora Yacht Service
I can't help with the exact grit (I don't sharpen plane irons much), but I can also say Ken Rizza at Woodturners Wonders has treated me right. I have purchased and ordered 6 wheels from him now for myself and others, from 80 to 600 grit. I do like the 600 grit wheels but that may not matter if you finish your edge on a fine flat stone.
http://woodturnerswonders.com/collections/cbn-wheels
Oh, Ken also sells an inexpensive washer set that can help the wheel run perfectly true on some grinders.
For my sharpening (mostly turning tools) I prefer the flat wheel with the square corners (not radiused) and with the 1" side coating. Can you remove the wheel guards and use the 8" wheels on the 7" grinder? Most people run CBN wheels without the guards.
JKJ
Last edited by John K Jordan; 06-25-2016 at 9:59 AM.
I will contact D-Way and Ken Rizza at Woodturners Wonders to see what they recommend. I prefer 7" wheel to keep the surface speed a little lower compared to 8" wheel as my grinder spins at 3600 rpm.
Thanks!