CBN 280g fro chisel sharpening

[Meredith]

Hi Guys, I am a professional sharpener in Australia. My sharpening business offers sharpening services on Knives, all scissors types, Animal Clipper blades, and much to my angst chisels.  I have a Tormek, however i find it much too slow to sharpen chisels on to continue to offer this service. My options are to buy a 280g CBN wheel or sell the machine. As i am in Australia the CBN wheel options are limited and importing a CBN from America is too cost prohibitive.   Is a 280 grit CBN suitable for chisel sharpening?
Thanks Meredith

[Ken S]

Welcome to the forum, Meredith.

Before offering an opinion whether to purchase another grinding wheel or sell your Tormek, I would like to do some fact finding.

What is the starting condition of the chisels you are sharpening? Chisels are often abused. Sharpening a dull chisel is one thing. Repairing a chisel with substantial nicks is another matter, and should be priced accordingly. A sharpener can reasonably charge more to regrind a knife with a broken tip. Why shouldn't a chisel with a broken edge be more expensive to regrind?

I originally purchased my Tormek to sharpen chisels. I have never thought of chisels as being slow sharpening. One of the differences I notice between CBN and matrix (the Original) wheels is that CBN keeps on cutting, whereas the Original wheel will slow down without some attention. I am a devout believer in keeping the grinding wheel regularly trued and dressed. A freshly trued wheel will cut the most efficiently. If you become fluent with using the TT-50 truing tool, frequent light truing takes very little time.

Chisels really require using the stone grader, both to keep the coarse grading refresher and to obtain a true 1000 grit. Don't skimp on frequency or time with the stone grader.

Chisels should be a good source of revenue for a sharpener. Sharpening them should be profitable. I hope you will stick with this long enough to solve the problem. Please do not hesitate to share more information and/or ask more questions.

Ken

[GKC]

Hi Meredith:

1. Like Ken, I find chisel sharpening on the Tormek standard SG wheel to be quite fast enough as long as the stone is kept coarse with the grader, but...

2. The Tormek diamond wheels should speed this up; and

3. It sounds like you should get in touch with Wootz, who, in addition to various stone wheels, uses 10" and 8" CBN wheels in his (also Australian) commercial sharpening business.  He posts to this forum often, and his website is very informative.  He has a page about the wheels he uses, and he doesn't seem to be stopped by the costs of getting the CBN wheels from America:

http://knifegrinders.com.au/05Equipment.htm

Gord

[RickKrung]

Wootz also posts a lot of great info on knife sharpening on the BESS Exchange.  As a professional sharpener, if you are not already following the BESS Exchange, I think you ought to, at least for knife sharpening.

Rick

[RichColvin]

Meredith,

Leonard Lee's book, The Complete Guide to Sharpening, is a great resource.  Chapter 8 deals with knives and also the froe chisel.  I looked at my copy, and he didn't get into the grind surface needed for a froe chisel; however I agree with others that the SG stone should be sufficient.  Most carving tools are high carbon steel, and the SG grindstone is excellent for such steels (it's what I use for my carving tools).

My underlying presumption is that these tools are being used for splitting out wall or roof shingles.  If that is the case, and knowing that the key purpose of the tool is to split the wood along the grain, having too sharp an edge may be problematic.  If the user lets the blade tilt enough, it could grab into the sides of the fibres as it cuts.

Mr. Lee even recommended a convex grind; however that may not be too much of an issue as the amount of convexness in the grind from the Tormek will probably not matter for this purpose.

Kind regards,
Rich