Which 2 CBN wheel grits?

[3D Anvil]

So I'm thinking about turning my love of sharpening into a part-time business and considering what equipment I'd use in that capacity. I've ruled out belt grinders (but see below) because I don't want to have to worry about burned edges. I think I'm going to start out with a Tormek T-8 converted to run two CBN wheels. I reckon I need to be able to get a knife from dull to sharp in 1-2 minutes to make it worth my while. I'm wondering if I could get by with 400 as my coarse grit, which I'd follow up with something in 800-1200. Or if I had to go lower, to something like 200 grit, would 800 then be too big a jump? Or would 600 provide a good enough final finish (before stropping)?

To start, I'll probably use my KO belt grinder with leather belts for stropping/final finish. Eventually I may swap that out for a half-speed grinder with felt/paper wheels.

FYI, my experience is with bench stones, fixed angle systems (KME & Hapstone) and the aforementioned Work Sharp Ken Onion Belt Grinder and I'm just not sure how the grit ratings I'm familiar with would translate to CBN wheels on a Tormek.  Typically, for kitchen knives, I would reprofile on F80-150 stones, and for general sharpening I'll start at F240 or (Japan) 500 and finish up at F400-800 or (Japan)1000-2000. 

Thoughts? Comments? I realize that turning a hobby into a profession can suck the fun out of it, but I think I'm going to give it a go anyway. The total investment isn't so big that it would be a problem if I decide it's not my cup of tea.

[Ken S]

Adam,

I read your four posts. Based on them, I would suggest this for your next purchase:

https://sharpeningmadeeasy.com/video.htm

Steve Bottorff, the presenter, is a very experienced sharpener with many years of working farmers markets. He is also an excellent teacher.

My second suggestion would be to study the online classes. They have a wealth of information. Along with them, I also hold the Knife Grinders you tubes in high regard.

I would get some experience sharpening knives for myself, family and a few friends before thinking of starting a business. One to two minutes per knife seems very optimistic. What kind of knives are you planning to sharpen?

Back to your question about grits, grit size is only one factor. I have found that my 360 grit diamond wheel cuts more aggressively than my 220 grit SG. There is much to learn.

Keep us posted.

Ken

[cbwx34]

You can do a lot with just the stock setup... I'd try that before investing in CBN wheels, running two on the Tormek, etc.

I'd 2nd Ken's advice on getting SteveB's video.  Probably the most practical advice you can get in sharpening as a business.

[3D Anvil]

Thanks for the replies.  I will definitely order Steve's video -- looks great.  I've watched the Knife Grinders' videos and I have Dr. Kraichuk's deburring book.  It was actually one of his videos that gave me the idea of running two CBN wheels on one machine.

I get that it sounds presumptuous to start out with specialized Tormek setup, but the truth is that it's not really extravagant.  A base T-8 kit starts at around $800 with the standard alox wheel.  I would need to add additional jigs to that, plus a truing tool, so the price would go higher. 

What I'm considering for my initial purchase is the bare T-8 machine, the tool jigs kit, 2x CBN wheels, and the LA-20 (for the 2nd wheel shaft).  Total cost: $1,200.

If I was to go with the SG-250 option, I think the most economical route would be to purchase the Chef's Bundle for $1,030. 

So, only a difference of $170!  And the CBN option has the following advantages:

1.  Cuts faster;
2.  No need to regrade between grits;
3.  No need to true the wheel;
4.  No need to recalibrate based on shrinking wheel diameter;
5.  No need to deal with water;
6.  Can sharpen every kind of steel (and potentially even ceramic and tungsten).

The downsides I can think of are somewhat higher cost, dust, and noise.

In either case, I would certainly spend a good deal of time practicing with either system before taking on paid work.  I'm sure this sounds cocky, but I'm confident that I can get to where I need to be with a few months of practice.  I've been sharpening for 40 years with various systems and can regularly achieve BESS scores of +/- 100 with bench stones, fixed angle systems, or the Work Sharp Grinder.  I already have thousands of dollars in sharpening equipment, but my focus has been on high end knives and mirror finishes.

When I say I'd like to be able to get a knife sharp in under 2 minutes, that's my ultimate goal.  I know it might take years to get to that point.  But if I can get to maybe 5 minutes/knife to start, I think I can make a go of it. 

I apologize for thinking out loud here, and probably sounding like an ass.     Perhaps the best course would be to start out with the Chef's bundle, which I could upgrade to dual-CBN for about $200 more than I would have spent if I had started out with the all-CBN system....

[Hannsi1957]

you will not be happy with 2 CBN Wheels. It is no different than when you use sandpaper. everything builds on each other. For example, if you take a CBN 80 to do the rough work (which I recommend) you will already have a problem with the 2nd wheels. if you take the logically following CBN 160 your cutting edge will be too rough. If you take the CBN 400 one step higher, you will overuse this wheel. So ultimately, either all CBN in order or continue to torment you with the normal Tormekstone over the rounds. your claim to grind a knife in 2 minutes you will not achieve. even if I have a well-preserved knife which I draw to re-sharpen only over CBN 400 and 1000 comes afterwards still the deburring. i need for such a knife rather 5-7 minutes than 2 minutes.
my colleague Hans-Heiner has posted a great video on Facebook in the Tormek Users group showing the efficiency of the CBN wheels. After the cbn 80 has made the edge, all the following wheels are pulled over only once and at the end there is a perfect cutting edge which is then deburred on a rockhard felt. results are always in the range between 90-150 Bess.

greetings Hanns

[3D Anvil]

I guess I'm not understanding why a CBN 80 -> 160 or 400 setup would be selected over the standard Tormek setup of 200 ->1000?  In other words, if I was to use CBN over the SG-250, wouldn't the logical comparison be CBN wheels in 200 and 1000 grits?

I think you are right that 5-7 minutes/knife would be very good speed using ordinary Tormek methodology.  The guy I'm looking at who is able to do it in about 1 minute has sharpened tens of thousands of knives and he does it freehand, which saves loads of time in clamping/measuring/adjusting.  And he's using a slow-speed grinder with felt wheel to deburr.  It would take a LOT of practice to get that good.

https://www.youtube.com/watch?v=MkfakpVOgoc

Anyway, I've ordered the T-8 Chef's Bundle, so I will start out learning on the SG-250 and take it from there.

[Hannsi1957]

don't compare grinding on the Tormek stone with grinding on CBN. if we are talking about mainstream knives with a hardness of 50-58 HRC you can achieve good results with the Tormek stone. however, your time requirement of 5 minutes will not work if you need to, for example, create a new cutting edge or remove any breakouts. Here we are talking about a 10 times longer time span, depending on the knife. if you want to save time, then use a belt grinder. the point of the tormek machine is that you can always create reproducible cutting edges, which has nothing to do with freehand grinding. of course, you can get a sharp edge freehand with some practice, but this is a completely different approach. i have had many discussions with colleagues who said they could grind freehand and then we looked at the grind in the goniometer or under the microscope. you will never get such a perfect grind freehand as with a knife guided on the tormek. i know that many will now say that this is possible. but no one has been able to prove it to me. The comparison between diamond or CBN wheels and the tormek stone is like when you have to travel 100 miles. one by car and the other by bike. both will arrive. the car is just more expensive, but also more comfortable.

regards Hanns

[Thoward]

Very good points Hanns. It should be understood that the finished product is much more important than the time it takes to complete the job. I've been sharpening professionally for over two decades and can testify that my most loyal customers are those whose knives were previously sharpened by "freehanders". What I've noticed is that the edges they produced, although initially appearing to be sharp (functionally), were actually very ugly (rough) under magnification. As with everything in life, the edge of your knife is only as good as it's weakest link, and in very little time the weaknesses dominate the users experience, particularly in knife demanding businesses such as restaurants. Simply put, a carefully sharpened knife (using a precise, repeatable angle) will stay sharp much longer than a "quick and dirty" freehand method. Thanks for sharing your knowledge and experience!

[3D Anvil]

Unfortunately, sometimes speed *does* matter, and it particularly matters if you're working at a farmer's or flea market and you're trying to turn around customers' knives while they peruse the wares.  No one is going to browse for 2-3 hours while I mess around trying to get a paring knife to split atoms. 

[BeSharp]

While I can now do even very dull knives in 5 minutes following Vadim's two-machine/ 4 wheel setup, at the farmers market I tell people to come back between .5 hour to 1.5 hours, depending on my backlog (my market runs 10am - 2 pm, and I'm usually "sold out" by 12 noon). Steve Bottorff was offered a free booth at his farmers market because that market's management found out that having people hanging around to pick up their sharpening increased other vendors' sales!

2 hours is getting borderline, but I use that to encourage people to pick up at my shop that's close by. After all, I can only do so much in four hours. For me, the market is to encourage people to come to my shop, so that one day I'll grow out of the market.

Since I no longer take everything to the market, I do these only at the shop: serrated knives, Japanese knives, supersteels (i.e. Miyabi, Shun), folders (lots of Benchmade). But people don't mind coming to the shop as I explain that there I can take extra care and use the correct equipment.