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CBN Wheel for a (very)old ABA Surface Grinder?

Kevin Wilkins

Cast Iron
Joined
Aug 19, 2003
Location
Berlin, Germany
I've been wanting to upgrade my surface grinding capabilities and since I won't be getting a new machine! I guess that means working with the one I have.

It's an ABA manual machine made in 1942 and still in good shape but does not have a coolant system. (Maybe I need to install one?) Right now I manualy spray water whille grinding.

I use the grinder for finish surface grinding hardened knife blades usually made from highly alloyed carbon or stainless steels. Hardness is typically around HRC 58 - 61.

Once in a while I would like to be able to surface grind annealed steel stock also.

I have a bunch of corund wheels however I mostly only use a white, medium grained stone.

A dealer has suggested what I need is a CBN wheel for the machine. Those are pretty darn expensive. Dealer says I can grind dry with the CBN wheel. Is that so?

Also I would only be able to do the hardened steel with CBN and would still need corund wheels for anything else. Since I only have one flange set for the machine, I would have to draw the flange and have new ones made too ... more expenses.

Do you guys think the CBN setu would be worth it for me? Or should I perhaps try another sort of stone wheel? I've heard the "green ones" are good??

Any thoughts or tips would be appreciated!
 
Corundum is a naturally occurring Aluminum oxide. Your white wheel is also aluminum oxide. Pure Aluminum oxide is white, as you can see it can be impure or colored.
While you can grind dry with CBN you will still have heat. If your workpiece metallurgy and tolerances permit then yes you can grind dry.
Wheel adaptors are available from Wm Sopko & Sons. By 1942 these were fairly standardized and they should be able to supply or if you know your taper and rotation, E bay.
Green wheels are near pure Silicon Carbide, used for roughing Tungsten carbide tools. Way too soft and expensive for your purposes.
Does Germany use the same wheel classification system as the U.S.? If so then I would recommend Norton 38A or equivalent, H or I hardness. For the CBN there is a bunch of variables such as bond type and percentage of CBN. I would talk with someone doing similar work and a knowledgeable rep before spending big bucks.

Cash, can you help on the CBN?
 
Wow, the contack to Sopko is fantastic! I think therre's a good chance I can get a new adapter flange from them. I'll print out their data sheet and measure my taper tomowwor in the shop.

I'll also check the hardness etc of the wheel I've been getting the best results with and let you know.

I really appreciate your help!
 
Kevin,

You have a number of different options when grinding hardened tool steel (52 Rc and up). It all depends on your application and how much stock you are removing, what your desired finish is, if you are holding a form or radius, and if you are set up to run coolant.

If you could give me the specifics I would be glad to help you out.

#1 NORTON QUANTUM

Norton has come out with a "bright green" ceramic wheel. This wheel is new to the market and has been around approximately 2 years. It is an upgrade over the original blue ceramic (3SG / 5SG). The SG wheels were the industry standard as the "best" grinding wheels for the last 35 years. This new technology is recommended for hard to grind materials and heavy stock removal. (So if you have a good bit of stock to remove, this may be an option.)

#2 CBN

CBN, or "Borazon" wheels are best when trying to hold a form or some type of radius. They do have a high initial cost, but last significantly longer than any bonded/conventional wheel. They are preferred for any high volume / production job where there are big lots / large runs of the same part.

#3 SILICON CARBIDE

As started in another reply, S/C wheels tend to be rather expensive for what you are trying to do. Also, the availability is not as extensive as you would like to see. S/C is typically best for grinding carbide, copper, etc. If this was a wheel you had around in the shop, you may be able to get by using it, but it is not preferred based on what I know right now.

#4 RUBY CORE WHEELS

FTI (Fantastic Tool) makes a Ruby Core Wheel. I believe it can be made in either Diamond or Borazon - but it is BEST for DRY grinding. It hangs itself on it's LOW COEFFICIENT OF EXPANSION. The famous "ruby core" does not expand as much as other cores would when grinding.

Please let me know the rest of the specifics and I would be glad to point you in the right direction.

The Grind Zone
 
I would for sure not mess with CBM on your old machine. If your infeed is not super precise and you feed too hard you will damage your very expensive wheel.

I have not had any luck with CBM in our shop surface grinding.

Like the grind zone said look to either Norton Quantum or SG.

I still have mixed results on quantum. Norton is really pushing it since it is new. I have had no success on segments with it when comparing to SG. SG still beats it hands down for Blanchard style grinding.

Surface grinding is better with quyantum but due to the higher cost of the quantum I think at the end of the day SG may still be as good if not still a bit better.
 
I would for sure not mess with CBM on your old machine. If your infeed is not super precise and you feed too hard you will damage your very expensive wheel.

I have not had any luck with CBM in our shop surface grinding.

Like the grind zone said look to either Norton Quantum or SG.

I still have mixed results on quantum. Norton is really pushing it since it is new. I have had no success on segments with it when comparing to SG. SG still beats it hands down for Blanchard style grinding.

Surface grinding is better with quyantum but due to the higher cost of the quantum I think at the end of the day SG may still be as good if not still a bit better.
 
I would for sure not mess with CBM on your old machine. If your infeed is not super precise and you feed too hard you will damage your very expensive wheel.

I have not had any luck with CBM in our shop surface grinding.

Like the grind zone said look to either Norton Quantum or SG.

I still have mixed results on quantum. Norton is really pushing it since it is new. I have had no success on segments with it when comparing to SG. SG still beats it hands down for Blanchard style grinding.

Surface grinding is better with quyantum but due to the higher cost of the quantum I think at the end of the day SG may still be as good if not still a bit better.
 
Hey Guys, thanks so much for the replies!

Here are a few pics of the machine below.

On the good side: I went through everything today and discovered I did indeed have a few more adapters which is great.

I called Sopko in the USA and they were very helpful. They do not have any adapters for my machine in any case and making them would be around $400 each. But it looks like I'm OK with what I have there anyway.

There is a company in Germany who have taken over the old ABA Werk and I'll call them tomorrow. Maybe they can help as I could use another screw that pulls the stone and adapter off the taper. I only have one of those.

My grinding wheels are 20mm wide and have a 50mm center bore. Outside diameter is 220mm.

I'm not sure if Norton even sells grinding wheels in Germany anymore. The Quantum does look like a great choice. Any ideas on how much they cost and if they come in my size? ;-)

I think I'll pass on a $1000 CBN wheel. I reckon I'd be better off putting the fúnds into some sort of cooling pump system.

What I do with the machines is surface grind folding knife blades mostly after heat treat taking off around 0.01mm per pass maximum with a total material removal of maybe 0.10mm.

I never do any profile grinding at all. Just try and get things flat.

Sometimes I try and do steel in the annealed state which is usually not very great with my lack of grinding knowledge and results in burn marks.

The wheel I have the best results with so far is the one marked K8 V20 46.

I am really ignorant when it comes to grinding so thanks for bearing with me!
 

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Your wheel is:
46 grit
"K" hardness
"8" structure ( amount of open space in the wheel
"V" = vitrified bond
The "20" is a manufacturers code, could mean anything

I suspect that if you tried an "I" or "J" hardness you would be even happier.
 
Cbn

Also keep in mind that CBN requires a wheel dresser designed for CBN and diamond wheels (a brake controlled dresser, or something similar, that uses a grinding wheel spinning at a slower SFM than the wheel to be dressed).

Once you get a CBN wheel dressed, you will not want to remove it from the hub, especially it fits a little loose. It can take a while to dress a CBN or diamond wheel.

I liked CBN for the more difficult to grind materials like CPM-10V, otherwise I preferred Norton's ceramic abrasives.

Bill
 
Boy, sorry for messing up this thread with 3 replies.

When we did mess with CBN we would true it by grinding a mild part of steel. Then dress it by using a white al oxide stick.

This is how we true and dress our diamond wheels for carbide grinding on our surface grinder all the time.

If you will switch between CBN and standard wheels getting a dedicated adapter for the CBN is the way to go.

Sopko is the way to go. Very helpful and great service.
 
If you true or dress a resin bond CBN or diamond wheel with a piece of steel you'll most likely not be impressed by the performance.

Even after you stick it to open it up the exposed grains will be dulled and you won't get the desired "tails" of bond supporting the grains.

You can also use a piece of molybdenum on a convention angle/radius dresser to put in forms.
See here: Process for truing grinding wheels - Google Patent Search
Same performance problems, the bond is just not opened up enough.

Sometimes we will use a piece of steel as a stick to intentionally dull the wheel. This slows the cutting action way down but helps eliminate edge chipping when grinding high positive cutting tools.

With the correct stone dressing should only take about 2-4 minutes on a new wheel and 30 seconds or so for a touch up using a brake dresser.

If you get a CBN wheel tell the supplier you want one on a "pay for performance" basis. If you don't like it send it back and don't pay for it. This is standard practice for me and over the years I've sent back at least 50 wheels with a note that basically says "This is junk".

Finding the right bond type, concentration, grit size, and hardness in a resin bond wheel can take a lot of trial and error. Get the wrong one and you will hate these types of wheels, get it right and you'll never go back. You need a good wheel person to work with.
Bob
 
X2 for comment by Carbide Bob.
We use a lot of CBN for hard A-2, D-2,M2, M4, 10V and 15V. It took a while to get the right combination, but in the end it is well worth it. Balance, Brake controlled truing device, then the white sticks. Leave it on the arbor, don't grind anything softer than 56 R/C. Lots of coolant, we get 16 RA finishes with no problem. We have to leave .015 - .020 per side for grinding after heat treat on some applications. Surface grind .003 -.004 per pass with no wheel wear with CBN (maybe .0001 after grinding for half a day). For slot grinding you can't beat it.
You MUST have a rigid setup, and a good magnet (or hold your part in a grinding vise). I don't think an old loose grinder is a good candidate.
 
I would agree brake controlled device is probably the best. We had one for one of our grinders we were trying to get CBN to work on. Still no luck.

SG has just been such a versatile product for us to use. I have 6 large grinders that all use the same wheel running several different products of hardened tool steel.

The biggest thing for us is having a vfd on each machine grinder spindle to adjust the speed for the job.

An old loose machine is for sure not the ideal set up for CBN.
 
My machine a "loose old machine" just because it's 69 years old!!??? I'll have you know that machine is just getting broken in!!

I'm gonna have to get some bumper stickers like "Old but Paid For" or "I'm not getting Older, I'm getting Better" for the "old" guy!! I could get some baseball caps with the same slogans and wear 'em myself! What goes for the machine goes for the operator. ;-)

I do think I will pass on the CBN wheel though. I'm glad I asked for opinions here.

I hope I can find a Norton dealer in Germany, if not I will try and order a wheel from the USA.
 
Nother quick update: I did locate Saint Gobain / Norton here in Germany and they're going to hook me up with a dealer as they only sell directly to customers who need a lot of wheels. When they guy asked me about my machine and how many wheels I needed to start I said, Second World War and -one-. Could almost hear that Dragnet music start up... not gonna make salesman of the year on my business I guess... oh well, hopefully I will hear from a dealer ...
 
Cash
If you are grinding a lot of hard tool steel, you really need to go CBN. It has been perfected over the last 5 years. Get an applications guy in from the manufacturer and have some pateince. It will be an unbelievable advantage when you get the right combination. We leave a CBN wheel mounted for each of our 6-12, 8-20,12 - 24, and16-32 surface grinders and our cylindrical. Most are 1/4 wide aluminum hub plated about 1/4 inch up each side. We use them for surface grinding and slot grinding (chop grinding, plunging down the side of the slot .0005 per pass). Once they are balanced, trued and dressed it's go time.
 
All my surface grinders have 20" wheels that are 4" wide. So CBN wheels this big get very $$$$.

Plus I am grinding all different grades of tool steel and different hardness and sometimes mild as well.

1 wheel does it all for me. A CBN could not do this variety.

I buy my 20" wheels 40 at a time.

Those are for my small machines. My big machiens take 6" wide wheels and have 40-50 h.p.
 
From the prices I've seen, even the little ones for my machine are around 600 Euros. For me, that's some dough.

I went carefully through all the wheels I have and found several ols but still new in packages from Norton marked 32A60 G12VBEP.

Does anyone know what materials these might be good to use on?

I hope I hear back from a Norton dealer...
 








 
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