CBN grit size vs abrasive wheel grit size

[Mark Jundanian]

@David Wrate , when your new grinder arrives make sure that it can run with guards removed. Reason being that your future CBN wheels may be wider than what your guards will accommodate. Fortunately, while friable wheels need guards, CBN wheels don't.

 

[David Wrate]

@David Wrate , when your new grinder arrives make sure that it can run with guards removed. Reason being that your future CBN wheels may be wider than what your guards will accommodate. Fortunately, while friable wheels need guards, CBN wheels don't.

Thanks Mark, it should be here today. My jig from Don Geiger arrives tomorrow and my 180gr CBN wheel arrive Oct 3.
Do some grinder have safety features which prevent operation without guards?

 

[robo hippy]

I think any grinder can operate without guards. With the Baldor grinders, you have to keep the inside one on because it is the seal for the internal workings. Outside grinder guards can pretty much all come off. You may need to work on the inside guard. My Rikon grinders had screw holes that protruded to the inside of the housing and the CBN wheels would rub against it. They can be pounded down flat, or ground off, or you can shim the wheel out a bit. Some times the shaft can be a bit short for getting the 1 1/2 inch wide wheels on. With my Baldor grinders, I had a 5/8 thick washer machined to space the wheel away from the housing so I could tighten up the nut enough to secure the wheel. Store bought washers are not machined so they can induce wobble. Also, the nuts that come with the grinders are not machined either. That is the purpose of the 'helical' washers from Ken Rizza. One concave, one convex so when you tighten the nut up, they 'adjust' and you get a 'flat' seating. I haven't tried it yet, but I think it might be possible to chuck up the hex nut and you can turn it down to 'close' to dead flat. M2 HSS will easily handle soft steel nuts.

robo hippy

 

[David Wrate]

I think any grinder can operate without guards. With the Baldor grinders, you have to keep the inside one on because it is the seal for the internal workings. Outside grinder guards can pretty much all come off. You may need to work on the inside guard. My Rikon grinders had screw holes that protruded to the inside of the housing and the CBN wheels would rub against it. They can be pounded down flat, or ground off, or you can shim the wheel out a bit. Some times the shaft can be a bit short for getting the 1 1/2 inch wide wheels on. With my Baldor grinders, I had a 5/8 thick washer machined to space the wheel away from the housing so I could tighten up the nut enough to secure the wheel. Store bought washers are not machined so they can induce wobble. Also, the nuts that come with the grinders are not machined either. That is the purpose of the 'helical' washers from Ken Rizza. One concave, one convex so when you tighten the nut up, they 'adjust' and you get a 'flat' seating. I haven't tried it yet, but I think it might be possible to chuck up the hex nut and you can turn it down to 'close' to dead flat. M2 HSS will easily handle soft steel nuts.

robo hippy

Thanks Reed, I have a metal lathe so it's easy for me to turn the nut faces perpendicular to the axis. I'm hoping for a good example out of the box!

 

[Mark Jundanian]

Do some grinder have safety features which prevent operation without guards?

My concern was more in line with Robo's comments. I doubt there will be any problem, but if there was one, now would be a good time to find it.

 

[Brian Gustin]

@David Wrate , when your new grinder arrives make sure that it can run with guards removed. Reason being that your future CBN wheels may be wider than what your guards will accommodate. Fortunately, while friable wheels need guards, CBN wheels don't.

For @David Wrate 's benefit , Mine is a 1/2 H.P. Rikon (which I believe is what he is getting) and I can verify that it will run fine with both inner and outer guards removed (In fact the wide wheel I got used on these forums will not fit my grinder without removing the inner guard) It has worked just fine for me, the wide CBN on the right side (with wolverine & varigrind) and original white wheel on the left (of course, guards all in place! I'm not that dumb, despite my looks... Set up with the wolverine platform which I use for platform grinds) - No trouble at all - Like I said I always give the CBN wheel a spin by hand in direction of grinder rotation before turning on the grinder, which helps it get up to speed faster. Just need to be aware it can take a while to coast down to a stop, so if your grinder is going to be in a spot where it might be easy to bump into it, might keep yourself a piece of scrap wood handy as a stop stick (hold against the side of wheel) once done sharpening...

 

[David Wrate]

For @David Wrate 's benefit , Mine is a 1/2 H.P. Rikon (which I believe is what he is getting) and I can verify that it will run fine with both inner and outer guards removed (In fact the wide wheel I got used on these forums will not fit my grinder without removing the inner guard) It has worked just fine for me, the wide CBN on the right side (with wolverine & varigrind) and original white wheel on the left (of course, guards all in place! I'm not that dumb, despite my looks... Set up with the wolverine platform which I use for platform grinds) - No trouble at all - Like I said I always give the CBN wheel a spin by hand in direction of grinder rotation before turning on the grinder, which helps it get up to speed faster. Just need to be aware it can take a while to coast down to a stop, so if your grinder is going to be in a spot where it might be easy to bump into it, might keep yourself a piece of scrap wood handy as a stop stick (hold against the side of wheel) once done sharpening...

Thanks Brian, your setup is exactly what I was planning to do to I save up for the second 80 gr CBN wheel. Though if the bonded wheel works fine for roughing/shaping then I may leave well enough alone and put those dollars into other tooling.

 

[David Wrate]

The grinder has landed. Along with Don’s kit.

 

[Brian Gustin]

The grinder has landed. Along with Don’s kit.

Hmm paint it white and blue, you got a Rikon.

 

[David Wrate]

Hmm paint it white and blue, you got a Rikon.

I’m confident it’s the same grinder. With a lamp of course.

 

[Don Wattenhofer]

For grinders, I consider the 1/2 hp Rikon to be underpowered

The 1/2 HP grinders have enough power to grind just about anything however the Rikon grinders have very poor starting torque so they are very slow starting but once it gets up to speed there is no lack of power. When I purchased my Rikon with the CBN wheels I looked at the HP rating on my old grinders with the with the centrifugal starting switch rated at1/2 & 3/4 HP, which was the setup on all of the single phase grinders that I had seen in the past, I just expected that the Rikon at 1/2HP would be more then enough, so there I go making stupid assumptions.

 

[David Wrate]

I'll hijack my own thread with a shot of my freshly ground bowl gouge.
Please ignore the other grinding atrocity...I'm so ashamed

 

[robo hippy]

First thing I did with my 1 hp Rikon grinders was to remove the lamp. Totally worthless. Same with the tool rests that come with them and the deflector shields, though those may have some worth if you are using standard wheels.

One side matter and that is metal dust collection. The metal dust, maybe more so from the CBN wheels, will float around in the shop like wood dust does. Some use magnets and that gets a fair portion of the dust. We need some sort of dust hood for our grinders. One friend commented that some of the more modern metals have nasty stuff in them that we should not be inhaling.

robo hippy

 

[David Wrate]

First thing I did with my 1 hp Rikon grinders was to remove the lamp. Totally worthless. Same with the tool rests that come with them and the deflector shields, though those may have some worth if you are using standard wheels.

One side matter and that is metal dust collection. The metal dust, maybe more so from the CBN wheels, will float around in the shop like wood dust does. Some use magnets and that gets a fair portion of the dust. We need some sort of dust hood for our grinders. One friend commented that some of the more modern metals have nasty stuff in them that we should not be inhaling.

robo hippy

I have metal collection set up for my 2x42 belt grinder. I'm hoping to adapt it to the bench grinder. I can hardly wait for the CBN wheels to arrive as I absolutely hate the mess from dressing the wheels.

 

[Dean Center]

The grinder has landed. Along with Don’s kit.
View attachment 46998

Amazing they could get the new name plate on so soon after Charles' ascension.

 

[robo hippy]

David, what kind of metal dust collection do you have? I have seen some, but most seem to be designed for big machine shops and not the home shops. Don't want sparks in the wood dust collection system...

robo hippy

 

[David Wrate]

David, what kind of metal dust collection do you have? I have seen some, but most seem to be designed for big machine shops and not the home shops. Don't want sparks in the wood dust collection system...

robo hippy

I use a dedicated shop vac with a Hepa filter. I used to have a separator before the vac but found it didn't really do anything except reduce suction. I'm fortunate that my belt grinder has ports for collection but I need to figure out how a way to adapt the setup for the 8" grinder.

 

[hockenbery]

I need to figure out how a way to adapt the setup for the 8" grinder.

Check this out….. might give you a solution

How to make custom PVC fittings on your Lathe

I wanted to place my noisy shop vac in another room, so I made a thru-the-wall adapter. Requirements: Heat gun. Slow speed lathe Cone revolving center Turn a slightly tapered cylinder to the inner diameter that will fit your hose. And watch: View: https://youtu.be/kijxdluULgQ

www.aawforum.org

 

[Mark Jundanian]

I need to figure out how a way to adapt the setup for the 8" grinder.

I have a dedicated vac set up too. I used std PVC pipe to make the ducts. Mine is very simple.





The Tormek bars are displayed, but I also use Varigrind and plarforms.

 

[David Wrate]

I have a dedicated vac set up too. I used std PVC pipe to make the ducts. Mine is very simple.

View attachment 47020
View attachment 47019
View attachment 47021

The Tormek bars are displayed, but I also use Varigrind and plarforms.

That's awesome Mark, thank you for the inspiration!

 

[Tom Gall]

David - below is my comment from a thread in March 2021- "More on Grinders". The main point here is the Lee Valley Veritas dust chute in the link.

Karl, just went to the shop to check on your concerns. As stated above, I have my grinder plugged in separately, but it works with no problems with two lights when plugged into the same power strip. With the added small ShopVac there is a slight delay, but I also have a plug in switched outlet (from an old track light set up) to turn on/off the noisy vac if not needed.

Re: the collector you can easily make something to adapt. I use a Veritas Magnetic Dust Chute (Lee Valley) which is mounted just below the wheel(s). My current stand is metal so no problem. Previously I screwed a piece of metal (mending plates in my case) to the wood stand under each wheel....easy to move when needed. Bought mine in 1998 for under $20 - a little more now. https://www.leevalley.com/en-us/sho...0041-veritas-magnetic-dust-chute?item=05J2110

 

[Mark Jundanian]

That's awesome Mark, thank you for the inspiration!

I got the idea from a tip in AWT that was published by another member. So I take no credit.

 

[robo hippy]

The concern with collecting metal dust is sparks igniting with all the air moving around them. At least with a shop vac, it would be easy to run outside with it. As for the single port, that might get most of the dust. My Baldor grinders have a port on them that is on the bottom of the main wheel guard. I would want some thing that pretty much covers 90% of the wheel, and a filter far enough back from the grinder so that any sparks will be out by the time they get there.

robo hippy

 

[David Wrate]

The concern with collecting metal dust is sparks igniting with all the air moving around them. At least with a shop vac, it would be easy to run outside with it. As for the single port, that might get most of the dust. My Baldor grinders have a port on them that is on the bottom of the main wheel guard. I would want some thing that pretty much covers 90% of the wheel, and a filter far enough back from the grinder so that any sparks will be out by the time they get there.

robo hippy

I have about six ft of hose before it hits the steel canister of my shop vac. I have been doing it like this for about five years and have never had the slightest worry about fire. I don't use the vac for anything except this so there is no sawdust or other flammable debris in the canister.

 

[Greg Carles]

I have about six ft of hose before it hits the steel canister of my shop vac. I have been doing it like this for about five years and have never had the slightest worry about fire. I don't use the vac for anything except this so there is no sawdust or other flammable debris in the canister.

Any chance of some pics of this set up? Sounds interesting....

 

[David Wrate]

Any chance of some pics of this set up? Sounds interesting....

I can shoot something this afternoon. It's ultra basic, essentially my shop vac is connected to the port on the belt grinder or to a small adapter.

 

[Mike Novak]

If worried about fire, they make fireproof vacuums. Search for pellet vacuum or ash vacuum on Amazon. I used to have one. All steel including the hoses.

 

[David Wrate]

My 180 grit CBN wheel arrived today.
What a dream that is compared to bonded wheels. Absolutely smooth.
Sharpening is no longer a nerve wracking experience!

 

[Neil S]

One friend commented that some of the more modern metals have nasty stuff in them that we should not be inhaling.

robo hippy

Yes, cobalt, chromium, molybdenum and vanadium to name just a few.

I ran some particle counter (PM2.5μ) tests and and the fine (invisible) metal dust does remain suspended in the air for some time, but it doesn't remain in suspension for as long as fine wood dust or travel as far...

.....
While grinding .................... 3mins after grinding​

However, standing in front of the grinder will have the highest concentrations.

I use a series of magnets in a container below the wheel to capture some of the swarf...

​

As mentioned by Reed, the swarf is prone to catching 'alight' if it is allowed to build up and stand out too far from the magnets. But, the excitement is brief once the grinder is turned off and the air stream around the wheel drops.

I also have a few sentinel magnets placed at intervals away from the grinding station. I also keep an eye on the particle counter that I always have running whenever I'm in the workshop to monitor fine wood dust levels, which also reads the fine metal dust levels.

I experimented with extraction using a dedicated vac but found no benefit from that. I would not consider using my dust extraction system for the metal dust extraction because of the fire risk unless I added a wet pre-separator to that...

​

I also wear a positive air pressure respirator while grinding to minimise the risk from the heavy metals.

 

[David Wrate]

Yes, cobalt, chromium, molybdenum and vanadium to name just a few.

I ran some particle counter (PM2.5μ) tests and and the fine (invisible) metal dust does remain suspended in the air for some time, but it doesn't remain in suspension for as long as fine wood dust or travel as far...

View attachment 47101 ..... View attachment 47102
While grinding .................... 3mins after grinding​

However, standing in front of the grinder will have the highest concentrations.

I use a series of magnets in a container below the wheel to capture some of the swarf...

View attachment 47100​

As mentioned by Reed, the swarf is prone to catching 'alight' if it is allowed to build up and stand out too far from the magnets. But, the excitement is brief once the grinder is turned off and the air stream around the wheel drops.

I also have a few sentinel magnets placed at intervals away from the grinding station. I also keep an eye on the particle counter that I always have running whenever I'm in the workshop to monitor fine wood dust levels, which also reads the fine metal dust levels.

I experimented with extraction using a dedicated vac but found no benefit from that. I would not consider using my dust extraction system for the metal dust extraction because of the fire risk unless I added a wet pre-separator to that...

View attachment 47103​

I also wear a positive air pressure respirator while grinding to minimise the risk from the heavy metals.

Thanks for the reminder in the magnets!

 

[Lewis Elliott]

Learning is fundamental in woodturning and you can learn to grind your tools with a lighter touch even using a 3400 rpm grinder as long as you keep the stone flat. For me I have a dedicated grinder for me that no one else uses ever. My Vector Grind Fixture is never moved so when a tool needs sharpening it is just a very light pass on the 180 grit CBN which I doubt that it removes more than .005 off the length of the tool. And since the only tools ground on said grinder are Thompson tools (which stay sharper longer) I do not foresee any of my tools wearing out. There are 3 other grinders available to students and hands on participants. Sharpening in Woodturning is an art unto itself and the better learned the better your woodturning outcome will be!

Hello Bill. I don't mean to break in to your thread, but I have a question that I asked of another member, but didn't know about this thread. Will a 3/4" bowl gouge fit the Vector Grind Fixture? Also, what is the largest size bowl/spindle gouge that will fit? Please let me know.

 

[Darryl Fective]

I can't be the only one, but how do you tighten the nuts holding the wheels on? No spindle lock on my grinder and trying to use the other wheel just loosens that side. Both of mine seem to be just barely over hand-tight.

I have a Rikon with a 180 that I've had for a while and I just bought a 350 for the other side. (plus a Wolverine setup with Robo Rest)

 

[Lewis Elliott]

Learning is fundamental in woodturning and you can learn to grind your tools with a lighter touch even using a 3400 rpm grinder as long as you keep the stone flat. For me I have a dedicated grinder for me that no one else uses ever. My Vector Grind Fixture is never moved so when a tool needs sharpening it is just a very light pass on the 180 grit CBN which I doubt that it removes more than .005 off the length of the tool. And since the only tools ground on said grinder are Thompson tools (which stay sharper longer) I do not foresee any of my tools wearing out. There are 3 other grinders available to students and hands on participants. Sharpening in Woodturning is an art unto itself and the better learned the better your woodturning outcome will be!

Good input on the 3400 rpm grinder, which is what I will be using (1 HP 8" Jet) along with a CBN wheel and a friable wheel which I may replace with a second CBN later (along with the wolverine flattening device for the friable wheel). I have a slow speed 1 HP 8" Delta that I use for my carbon steel woodworking chisels and plane irons, in my hand tool shop, to get an initial straight edge when needed for re-sharpening, and for blades/irons that won't fit in any jig to supplement manual sharpening when no other way exists. I have a high speed 6" Baldor that I move around for sharpening garden tools, and re-habing screw drivers and other general grinding tasks.

 

[Tom Gall]

I can't be the only one, but how do you tighten the nuts holding the wheels on? No spindle lock on my grinder and trying to use the other wheel just loosens that side. Both of mine seem to be just barely over hand-tight.

I have a Rikon with a 180 that I've had for a while and I just bought a 350 for the other side. (plus a Wolverine setup with Robo Rest)

Not really necessary (or advisable) to "tighten" the nuts - snug is good enough. They will self tighten when the grinder is turned on. I find it best to put a wedge of sorts (or if you can hold it) between the wheel and the frame/stand/whatever - then loosen or tighten the nut.

 

[Brian Gustin]

I can't be the only one, but how do you tighten the nuts holding the wheels on? No spindle lock on my grinder and trying to use the other wheel just loosens that side. Both of mine seem to be just barely over hand-tight.

I have a Rikon with a 180 that I've had for a while and I just bought a 350 for the other side. (plus a Wolverine setup with Robo Rest)

I'll second Tom's comment - Just snug is good enough - tight as you can get it while holding the other wheel (not the opposing nut) would be plenty tight enough. Just make sure your flanges and/or washers or spacers are nice and clean and flat and dry (as well as the wheel where flanges touch it) , threads are clean, maybe a drop of oil on threads (one single drop of light machine oil will do) spin on the nut snug it up finger tight then hold the wheel and use wrench on the nut.. Does not need a lot of torque to be tight.

They'll seem FAR tighter when you go to remove the nuts.

 

[Darryn Achall]

I can't be the only one, but how do you tighten the nuts holding the wheels on? No spindle lock on my grinder and trying to use the other wheel just loosens that side. Both of mine seem to be just barely over hand-tight.

I have a Rikon with a 180 that I've had for a while and I just bought a 350 for the other side. (plus a Wolverine setup with Robo Rest)

I wedge a piece of wood into the wheel and tighten up the nuts with a wrench.