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CBN Grinding Wheels

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jbolt

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#1
After my near catastrophic bench grinder incident I decided to try the CBN grinding wheels. I got my wheels from woodturnerswonders.com. I got the 80 grit and 350 grit 8" wheels based on their recommendation. The wheels are the 4 in 1 design with grit on part of the side and with 1/4" radius corners.

The wheels are absolutely beautiful.

At 1-1/4" wide they fit in the factory guards. I did have to make a 1/4" spacer to center the wheels in the guard.

20170721_181651.jpg
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All I can say about them is WOW! These things are awesome on HSS. As a test, I ground this 3/8" tool in about three minutes free hand. Not my best work but I wanted to see how well the wheels worked. I think I wet the tool twice. The 80 grit removes material like nobody's business with very little heat. Amazing.

20170721_181708.jpg
 
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#2
That is nice!
Now I have to buy a 8" grinder!
My 7" Baldor grinder will not take 8" wheels.:bawling:

EDIT: Wow! they are a little pricy! I'm sure they are well worth it in the long run.
 

dlane

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#3
How long do Cbn last, I thought cbn was for carbide grinding, do u dress them, are they diamond
 

jbolt

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Generally speaking CBN wheels are for grinding on harden steels only. Such as most tool steels. I found out the hard way trying to sharpen some carbide endmills using a CBN wheel, it don't work! Not to say they don't have something for carbide. So far, I've only been able to use diamond matrix grinding wheels for grinding carbide.
 

Kernbigo

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#6
diamond wheels are for carbide and cbn are for steel, i have used them to tread grind and od grind thread gages. One cut on a thread gage 3/8" 16 and one finish cut. .080 rough cut no burn.
 
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#7
That is nice!
Now I have to buy a 8" grinder!
My 7" Baldor grinder will not take 8" wheels.:bawling:

EDIT: Wow! they are a little pricy! I'm sure they are well worth it in the long run.
Yeap, not cheap.

I have a three of the 8" wheels from Woodturners Wonders. Turns out that their pricing is some of the best and the owner provides good customer service.

I use them to sharpen HSS woodturning tools and have also done some finish work on HSS tool bits for my metal lathe. A set are good assets in the shop. Must admit that most of my HSS toll bit grinding for my lathe is done on a KMG.
 

jbolt

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#8
Yes they are pricey but worth every penny in time saved.

I'm thrilled to death with these wheels. I have a pile of old cheap wood chisels left over from my construction business that were used(abused) for everything but their intended purpose. Kind of like flat bladed screw drivers. Some times the chisels would get roughly sharpened with a 4" angle grinder. It took too long on my 1800 rpm grinder so it was not worth my time. I would just buy another cheap one and throw the abused one in a box.

I recently needed a beater chisel to scrape some cement board so I gabbed one of the old abused ones out of the box and gave the CBN wheels a go instead of the angle grinder. Took less than 2 minutes to put a factory edge back on it and with very little heat. Theses wheels are amazing.
 

MarkM

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#9
Looking for something specifically for fast metal removal of tool steel. Specifically A8M if by chance. How would you rate it for metal removal of tool steel compared to your white aluminum oxide wheel for the tool steels you have used?
 
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#10
I don't see CBN for serious metal removal. I see it as a sharpening wheel.

My CBN wheels replaced the white and blue wheels that I had. They are far superior.

BTW, if you want metal removal, I suggest you get a belt sander. They cannot be beat for that. I use a belt sander and then go to the CBN.
 

MarkM

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#11
I agree with the belt sander as far as quick removal. I am just set up with jigs for both my water and dry wheel grinders for some of the work I do.
 
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#12
After my near catastrophic bench grinder incident I decided to try the CBN grinding wheels. I got my wheels from woodturnerswonders.com. I got the 80 grit and 350 grit 8" wheels based on their recommendation. The wheels are the 4 in 1 design with grit on part of the side and with 1/4" radius corners.

The wheels are absolutely beautiful.

At 1-1/4" wide they fit in the factory guards. I did have to make a 1/4" spacer to center the wheels in the guard.

View attachment 238118 View attachment 238119 View attachment 238120

All I can say about them is WOW! These things are awesome on HSS. As a test, I ground this 3/8" tool in about three minutes free hand. Not my best work but I wanted to see how well the wheels worked. I think I wet the tool twice. The 80 grit removes material like nobody's business with very little heat. Amazing.

View attachment 238121
Do you like the radius on the edges? I was looking at the mega square wheels. I also notice they are used on a slow (1725rpm) grinder. Are they suitable for high speed grinder? They have a good price on a 1 hp (1725 rpm) grinder with wheels.
 

woodchucker

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#13
Do you like the radius on the edges? I was looking at the mega square wheels. I also notice they are used on a slow (1725rpm) grinder. Are they suitable for high speed grinder? They have a good price on a 1 hp (1725 rpm) grinder with wheels.
I would agree the square edge would be more valuable, as you can cut chip breakers that way.
 

Dan_S

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#14

jbolt

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#15
Looking for something specifically for fast metal removal of tool steel. Specifically A8M if by chance. How would you rate it for metal removal of tool steel compared to your white aluminum oxide wheel for the tool steels you have used?
They are far superior to the stone wheels for material removal. I can't comment on how that compares to using a proper belt grinder as I don't have one. I have one stone wheel that comes close to the 80 grit CBN wheel but at the cost of excessive stone loss.
 

jbolt

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#16
Do you like the radius on the edges? I was looking at the mega square wheels. I also notice they are used on a slow (1725rpm) grinder. Are they suitable for high speed grinder? They have a good price on a 1 hp (1725 rpm) grinder with wheels.
I'm okay with the radius so far. I would be nice to have a wheel with a smaller radius. I considered the Mega-square wheels but they are 1.5" wide and would not fit in my guards. I'm not comfortable running a grinder without guards.
 

woodchucker

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#17
I'm okay with the radius so far. I would be nice to have a wheel with a smaller radius. I considered the Mega-square wheels but they are 1.5" wide and would not fit in my guards. I'm not comfortable running a grinder without guards.
There's no need for a guard to protect you from the wheel blowing up.. Those wheels don't blow up. If you are worried about touching the wheel, you could build some standoffs and then cover the slot with soft aluminum.
 

MarkM

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#18
Thanks jbolt for the reply regarding material removal. Can I ask about heat in the tool. More often then not I ll get some chipper knifes that have been hand ground with a hand grinder and alot of shape work to bring back to the recommended angle. There 5/8 thick and take some time. For now I rough it on a variable speed grinder at around 2200 rpm but have to be carefull with heating the blade and do it in stages and let it sit even with dunking and come back to,it before I finish it on the Tormek wet grinder. It would be great to be able to run the grinder ar it s 3600 rpm and remove the material without worrying about ruining the temper. The material a8m isn t hardened fully around 40 on the r c scale. A pain to grind as it clogs the wheel. Using a white aluminum oxide wheel how would you compare the cbn in this regard? Also is dust reduced as well with the cbn?
 
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#19
You shouldn't have any issues running a 8" CBN wheel at 3600 RPM. Max speed is higher than 3600 RPM. May occur a small balancing issue i the wheels were not properly balanced at the factory or using flanged washers that are out of wack.
 
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You shouldn't have any issues running a 8" CBN wheel at 3600 RPM. Max speed is higher than 3600 RPM. May occur a small balancing issue i the wheels were not properly balanced at the factory or using flanged washers that are out of wack.
They offer a 1hp grinder with wheels at a good price ($445). They set it up with their spherical washers ( available separate also). The only thing is, it is 1725 rpm. I wasn't sure about the speed using on HHS steel.
 
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Thanks jbolt for the reply regarding material removal. Can I ask about heat in the tool. More often then not I ll get some chipper knifes that have been hand ground with a hand grinder and alot of shape work to bring back to the recommended angle. There 5/8 thick and take some time. For now I rough it on a variable speed grinder at around 2200 rpm but have to be carefull with heating the blade and do it in stages and let it sit even with dunking and come back to,it before I finish it on the Tormek wet grinder. It would be great to be able to run the grinder ar it s 3600 rpm and remove the material without worrying about ruining the temper. The material a8m isn t hardened fully around 40 on the r c scale. A pain to grind as it clogs the wheel. Using a white aluminum oxide wheel how would you compare the cbn in this regard? Also is dust reduced as well with the cbn?
Mark, If the steel you use clogs your ceramic wheels, it will be an issue for the CBN.

It will likely clog the CBN and that can ruin the wheel. With a ceramic wheel you can level/grade it again if it gets clogged. With a CBN wheel the CBN is a coating so you have toasted it if you clog it badly.

CBN likes the hardness of RC54 steels and above. Here's a link that talks to that issue and defines the use of CBN and materials you should machine with it.
 

woodchucker

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#22
yep, no mild steels, only hard steels.
 

MarkM

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#23
What I Was referring to when run at 3600 was the heat. Right now around 2200 is where I Limit the speed due to heating of the a8m chipper knife too much. The grinder and wheels are very smooth. It s a hardened tool steel just not as much as normal. I may take a chance and try one.
 

jbolt

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#24
Thanks jbolt for the reply regarding material removal. Can I ask about heat in the tool. More often then not I ll get some chipper knifes that have been hand ground with a hand grinder and alot of shape work to bring back to the recommended angle. There 5/8 thick and take some time. For now I rough it on a variable speed grinder at around 2200 rpm but have to be carefull with heating the blade and do it in stages and let it sit even with dunking and come back to,it before I finish it on the Tormek wet grinder. It would be great to be able to run the grinder ar it s 3600 rpm and remove the material without worrying about ruining the temper. The material a8m isn t hardened fully around 40 on the r c scale. A pain to grind as it clogs the wheel. Using a white aluminum oxide wheel how would you compare the cbn in this regard? Also is dust reduced as well with the cbn?
All I have ground so far is tool steel lathe bits, drill bits, a bunch of old abused wood chisels and cleaned up the end of a cut bolt or screw. Compared to the AO wheels the heat generated and grinding time is significantly reduced.

As far as"dust" is concerned the only residue is the removed material. Also I'm not getting any debris buildup in/on the guards like with the AO wheels.

I can't comment on the steel your using since I have no experience with it on these wheels.
 

MarkM

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#25
Thanks jbolt. I think i am going to try one when the funds permit.
 

woodchucker

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#27
I would think the nylon center defeats the heat sinking that the aluminum hub does. There by creating a new issue (HEAT) which you didn't experience.
 

Dave Paine

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