Rikon Grinder, CBN Wheel Types, Grit Choices

[Allen Mattsen]

So I'm setting up a sharpening station for lathe/turning tools and have a few questions:

1) Rikon 1HP slow speed grinder or the 1/2HP model for running 1 or 2 CBN wheels?

2) Which wheel(s) to start with and what grit? I want to use for maintaining some chisels, etc., secondarily, so was thinking of the "Mega Square" wheel as the first one - at 180 grit. Follow that up with 350 or 600 and what type (model) for the second wheel? Is the 4-in-1 or Radius Edge a better choice for the lower grit wheel? Is 180 the best grit to be the lower grit of the two? Which wheel type is better for the lower and higher grits and why?

I don't plan to to a lot of tool shaping or restoration. Maybe a chipped chisel or re-bevel a plane blade here or there. Mainly this setup is for turning tools so I want that to be the primary driver of the choices I make but need to hear from some experienced folks first. I plan to also call Ken at woodturnerswonders early this week to see what he says.

Thanks in advance. I'm new at this and don't want to waste money and hope to get the desired results for the long term the first time.

[John K Jordan]

So I'm setting up a sharpening station for lathe/turning tools and have a few questions:

1) Rikon 1HP slow speed grinder or the 1/2HP model for running 1 or 2 CBN wheels?

2) Which wheel(s) to start with and what grit? I want to use for maintaining some chisels, etc., secondarily, so was thinking of the "Mega Square" wheel as the first one - at 180 grit. Follow that up with 350 or 600 and what type (model) for the second wheel? Is the 4-in-1 or Radius Edge a better choice for the lower grit wheel? Is 180 the best grit to be the lower grit of the two? Which wheel type is better for the lower and higher grits and why?

I don't plan to to a lot of tool shaping or restoration. Maybe a chipped chisel or re-bevel a plane blade here or there. Mainly this setup is for turning tools so I want that to be the primary driver of the choices I make but need to hear from some experienced folks first. I plan to also call Ken at woodturnerswonders early this week to see what he says.

Thanks in advance. I'm new at this and don't want to waste money and hope to get the desired results for the long term the first time.

There's been a lot of discussion about this so you might find some useful discussion with a search. Otherwise, some quick opinions:

Based on my experience the Rikon 1/2hp will work fine with aluminum CBN wheels; steel wheels might be a bit heavy. The 1hp works well and I recommend it if you have the coin (although the light they put on it is worse then useless). I use one of each plus a 3/4hp grinder.
I prefer a square edged wheel since it gives more useful sharpening area AND better allows grinding and sharpening custom tools. There aren't too many reasons to buy one with the radii - the biggest one is to sharpen long hollowing tools that have non-removable bits with curved tips.
Unlike your plan, I do a fair amount of heavy tool shaping so I have a 60 grit CBN. People who do less shaping will probably be happy with the 180. Ken Rizza will tell you what the top sellers are. For skews, scrapers, and bowl gouges I use a 600 grit, honing the edge after sharpening.
For my spindle gouges I use a 1200 grit CBN on a Tormek but I'm probably pickier than might be reasonable.

JKJ

[roger wiegand]

Definitely budget for a decent light for your grinder. I have and like the 1 hp machine, it seems adequate in every way. I have two 180 grit wheels on it, one set up with the varigrind for my bowl gouge the other with the platform for everything else. I hone frequently with a 600 grit diamond hone, takes about 10 seconds from the 180 grit finish by hand, so I've never felt a need for a finer grit. I'd like to have a much coarser grit for the occasional re-shaping of tools. I get by without it. I'm doing OK with sharpening hollowing bits on the square corner.

[Frederick Skelly]

I have the 1/2 hp Rikon with a white wheel on one side and a 120 grit cbn on the other. I think 2 cbn wheels might be a strain on it.

[Allen Mattsen]

This is exactly the stuff I hope to hear so far. I search and read tons of older threads but seemed there wasn't anything recent. Seems 180 is the first wheel to get, but still have to sort out the wheel type/model. I wonder which profile is best for honing things like parting tools and scrapers compared with rounded or fluted tools if I indeed get 2 different wheels. Also seems many complain about the smaller grinding surface area of one of the wheels - It's tricky 😅

[David Walser]

...Also seems many complain about the smaller grinding surface area of one of the wheels - It's tricky 

Yes, it's tricky. But, then again, it's not. CBN wheels are so vastly superior to the A/O wheels we used before, just about any of them will be a noticeable improvement. Kinda a like switching from a horse and cart to a modern car or truck. Lots of different cars and trucks to choose from, but any one of them will be a vast improvement over your single horse powered vehicle. So, jump in!

If I had it to do over again, I'd get the mega square wheels with a 1hp Rikon grinder. I bought the Spartan wheels in 180 and 600 grits. (I also got the 1hp grinder, when CSUSA was running a sale.) They work fine. However, the Spartan wheels are narrower. You'll need spacers to get them to fit if you're running without the guards. I just don't like the look of the spacers.

[John K Jordan]

This is exactly the stuff I hope to hear so far. type/model....

I didn’t see if it was mentioned but I think the spherical washers that Ken Rizza sells are worth using. They can eliminate any slight wobble you might get if the stock washers/nuts are not perfect. Quite inexpensive; I use them on all my CBN wheels.

[Reed Gray]

The Rikon grinders do go on sale once in a while. I prefer bigger and heavier tools because I can abuse them more, so I would suggest going with the 1 hp Rikon. It has plenty of power to spin my steel wheels from D Way. I removed the light on my Rikon. It is just about as worthless as the grinder platforms that come with any grinder. I also take the rubber feet off, and bolt them to plywood bases. That comes in handy if you are traveling. I prefer to have my own grinder when I demo.

For wheels, if you are getting one, get the 180. If you are getting 2, then go with the 600. Very little difference between the 320 and the 600. I use the 180 for 90% of my sharpening. The 600 grit doesn't hold up to the heavy roughing I do, but is excellent for fine finish cuts, and for the skew edge, but the skew still needs to be honed on a leather wheel or strop. The helical washers do work. They are needed because the nuts on most grinders are not 'precision' machined and can cause wobble in your wheels. I do have a belt sander with a 36 grit belt for shaping, but old coarse wheels that come with the grinders can be okay for that job. I have one set of wheels with the radius edges and don't like them. I don't do much hollowing, and they were specifically designed for the small hollowing tips. Never used any side grind options.

robo hippy

[William C Rogers]

I’m using the 1/2 hp Rikon. I have one steel CBN and one aluminum. The grinder works, but takes longer to start up. A 3/4 - 1 hp grinder is a better option, but more $$. My recommendation is a 180 if just one CBN wheel and if a second CBN wheel I would go with a 80 grit. I don’t see a need for a finer grit especially just starting out.

[Allen Mattsen]

So I spoke with someone at W.Wonders and it was suggested I go 4-in-1 or Radius Edge for the lower grit (180) and Mega Square for the finer grit. As far as 350 vs 600 on the [ ] wheel / finer grit I'm told it depends on the steel it's interacting with. Low to mid-range tools such as Sorby, Benjamin's Best / PSI work better on the 350 and the higher end tools (Thompson, Carter n Sons, etc) better on the 600. Interesting stuff. She said the 600 grit wheel can clog easier with lower end steel but they have also recently added a product to keep the wheels from clogging, which I hadn't yet read or seen. Having not shelled out for high end tools (yet) perhaps 350 is the way to go on the finer grit. I used diamond stones for my hand tools, so it's hard for me to accept going 350 over 600 any way you slice it, but this is a new world to me.

[John K Jordan]

So I spoke with someone at W.Wonders and it was suggested I go 4-in-1 or Radius Edge for the lower grit (180) and Mega Square for the finer grit. As far as 350 vs 600 on the [ ] wheel / finer grit I'm told it depends on the steel it's interacting with. Low to mid-range tools such as Sorby, Benjamin's Best / PSI work better on the 350 and the higher end tools (Thompson, Carter n Sons, etc) better on the 600. Interesting stuff. She said the 600 grit wheel can clog easier with lower end steel but they have also recently added a product to keep the wheels from clogging, which I hadn't yet read or seen. Having not shelled out for high end tools (yet) perhaps 350 is the way to go on the finer grit. I used diamond stones for my hand tools, so it's hard for me to accept going 350 over 600 any way you slice it, but this is a new world to me.

The clogging will not happen with hardened High Speed steel, or even hardened tool steel unless you grind too aggressively and destroy the hardness (as I mention below). Loading up the wheel can happen with heavy grinding of mild steel.

I've sharpened all types of tools here, from the best to "low end" and the 350 vs 600 grit recommendation you were given sounds like nonsense to me. The difference in the edge when examined under the microscope is considerable. Most of my tools are Thompson but just the other day I sharpened all of a friend's tools which are about as low end as you can get. No problem with the 600 grit - but see the comment below about overheating the edge.

BTW, at first I bought 180 and 350 grit CBN with radiused edges and sold one and gave the other away. In my opinion (and for MY use) the 600 grit is far better - it gives a great edge and quick stropping makes the edge hair-shaving sharp. Of course, some of it depends on how and what you turn. I've already give my opinion on the radiused wheels. I'm wondering if they are pushing radiused wheels for some reason.

One possible thing - cheap or old tools that are hardened tool steel and NOT high speed steel can have their hardness damaged by overheating. If you generate enough heat to turn the edge blue you've destroyed the hardness there and must then grind past that zone to get to good steel. That's where a finer grit wheel might cause problems, especially for someone learning to sharpen. Since the 600 grit takes off less steel for the same pressure, someone who presses harder could overheat the edge where a coarser wheel will take off steel quicker with less pressure. This is only important for non-HSS tools which are best avoided. But there is little reason to buy new lathe tools that are not HSS. Even Benjamin's Best HSS tools are only about $10 each when bought in a set.

Hey, I know: get two grinders and a 60, 180, 350, and 600 and report back.

But I may tend to be excessive so you might want to listen to someone else. This is part of my sharpening setup.
I also have two other bench grinders and a second Tormek not shown here.
Sharpening_small2.jpg
I use conventional aluminum oxide wheels for mild steel.

JKJ

[Allen Mattsen]

Lots of 'flat' wheels there, John.
I appreciate all the feedback, good, bad, or otherwise. Some of us don't mind the real truth and there's no substitute for experience (and common sense) 😎

[tom lucas]

I purchased the 1 HP Rikon with 80 and 180 Mega CBNs. I wish I had purchased 180 and something finer like the 600 grit. The 80 is pretty handy for shaping though and useful if you buy "blank" stock to make your own scrapers. One day when/if I have room for a second grinder it'll have higher grit wheels. The 180 is adequate though. It raises a burr quickly, which is all you want on scrapers. My skews, for now, get refined on a Tormek, which is a slower process.

[William C Rogers]

I agree with what JKJ says, however I still recommend going with the 80 and 180 grits for a new turner. I do not have a 600 grit wheel for these reasons. True you do get a nice fine edge from 600 grit wheels, however this is really only good for a finish cut and won’t hold that edge IMO. Definitely not good for rough turning removing stock IMO. There are times I will sharpen my scrapers on the 80 grit because I want that aggressive bur from that grit wheel. I usually go straight from the grinder and don’t roll a bur on my scrapers. I can also use the 80 grit to reshape tools. I can get a very good surface on a finish cut using the 180 grit wheel, so fo MY turnings a 600 does not offer that much. The main use for the radius CBN Wheels is grinding the small hollow form bits.

[David Walser]

I agree with what JKJ says, however I still recommend going with the 80 and 180 grits for a new turner. I do not have a 600 grit wheel for these reasons. True you do get a nice fine edge from 600 grit wheels, however this is really only good for a finish cut and won’t hold that edge IMO. Definitely not good for rough turning removing stock IMO. There are times I will sharpen my scrapers on the 80 grit because I want that aggressive bur from that grit wheel. I usually go straight from the grinder and don’t roll a bur on my scrapers. I can also use the 80 grit to reshape tools. I can get a very good surface on a finish cut using the 180 grit wheel, so fo MY turnings a 600 does not offer that much. ...

Interesting. When I first started turning, back in 2002, one article of faith common among the turning community was that a tool sharpened on and 80 grit wheel held its edge better than one sharpened on a 120 grit wheel. (Back then, aluminium oxide wheels were state of the art for turners.) The theory was the more 'ragged edge' from an 80 grit wheel acted like a serrated knife, allowing the tool to cut efficiently for a longer time. Many turners claimed they got a better cut and a longer lasting edge straight off the 80 grit wheel than they did after honing at 300 or 600 grit. We debated this question here on Sawmill Creek quite frequently.

Then, some people started examining this question with the aid of a microscope. Alan Lacer was one. He wrote an article in American Woodturner that included several magnified pictures of the edges produced by different sharpening media and with a magnified picture of the cut quality these pictures produced. Alan concluded a sharper tool left a better, cleaner, surface.

Another article was written by a university professor who set up a fairly rigorous experiment to test the hypothesis that a lower grit wheel produced a longer lasting edge. He used a jig to precisely sharpen each tool to the same bevel angle with different sharpening media. IIRC, he used an 80 grit wheel, a 120 grit wheel, honing to 600 grit, and a Tormek with its 1,000 grit wheel and leather strop. He tested skews, spindle gouges, and scrapers. His results were exactly opposite of the long-held article of faith. He found the higher the grit used the longer the edge lasted -- without exception. To perform the experiment, he used each tool to cut wood until the tool was too dull to cut efficiently. To measure this, he used a sensor to measure the force required to push the tool through the wood and established at what point a certain amount of force required yielded a poor surface on the wood. That was the 'dull' point. He then measured how many linear feet each tool could cut before reaching the dull point. As suggested, the tools sharpened on the Tormek turned more linear feet of wood before reaching the dull point than did those turned on an 80 grit wheel, with the others lining up in order of the grit used to sharpen them. He also looked at the bur left by the grinder that is used with scrapers (and is often left on when using other turning tools). He examined the bur both right after the grinder and after a few seconds of cutting. Frequently, the bur simply folded over the cutting edge -- dulling it almost as soon as the tool touched the wood. In his tests, he found such scrapers became 'sharper' after a little use. That is, they cut more cleanly once the bur from the grinder haw worn away. Honing the bur off (for both scrapers and 'regular' turning tools) and raising a bur for use with a scraper, produced better results that did using the bur from the grinder.

His explanation of why a 'sharper' tool remains sharper longer made sense to me. In essence, he said, suppose we measure sharpness on a scale of 1 - 10, with 10 being perfectly sharp and 1 being too dull to use as a butter knife. Assume also that on our scale, a tool comes off the grinder at a 7 when sharpened with 80 grit and at 9 when sharpened on the Tormek. Finally, assume when a tool reaches 4, it's too dull to use efficiently. The faith promoting rule was that the sharper edge of the Tormek sharpened tool was thinner, and more delicate, than the still sharp, but not as sharp, edge off of an 80 grit wheel. His examination found this not to be true. Sharpened at the same bevel angle, both edges are the same thickness. The difference is the smoothness of the surface. So, since the 'sharp' edge started at a 9 on our sharpness scale, it cuts better (and leaves a better surface) at first. It also produces more linear feet of work, because, starting out at a 9, it takes the edge longer to wear down to a 4. Bottom line: sharper tools both cut better and last longer.

My take aways from this study and from my personal experience: First, if you're using a tool that starts out at a 9 on the scale of sharpness, by the time it gets dulls to a 5 or 6 on the scale, it probably feels dull enough to touch up the edge. Thus, I don't know that 'extra sharp' tools mean fewer trips to the grinder (or pocket hone). I just think the tools cut much better -- giving you better control and leaving a better surface. Second, if you're used to turning with a tool right off the 80 grit wheel, you may have developed techniques that give you a decent cut even though the tool isn't quite as sharp as one sharpened with a finer grit. If you then start using a sharper tool, the techniques you developed may not work as well with the sharper edge -- leading you to incorrectly assume the tool has dulled more quickly. That is, the human element cannot be taken out of the equation. A more aggressive cut angle may allow a 'dull' tool to get a quality surface. that same aggressive cut angle may cause the sharper tool to take too big a bite, making it feel grabby or even dull.

As with most things, YMMV.