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Dale Lusby
01-05-2011, 12:01 AM
Recently I picked up a carbide tool grinder with diamond wheels. My understanding is that you are not suppposed to grind steel on a diamond wheel so what do you do when the carbide has been ground a few times and is flush with the steel? Do I first have to grind back the steel on a regular grinder and then sharpen the carbide? Also how important is it to use water or coolant when grinding on the carbide grinder? It has the water pots on top and trays underneath. Is water ok or should I have it setup with coolant?

Here is a picture of the new grinder. It doesn't have a tag so if anyone knows the make/model I would greatly appreciate the information. It runs smooth and seems to be of excellent quality.


Unloaded and as received
http://i279.photobucket.com/albums/kk138/dlusby22/2010-12-01_14-46-10_863.jpg

http://i279.photobucket.com/albums/kk138/dlusby22/2010-12-02_21-07-05_31.jpg

At home next to Baldor grinder
http://i279.photobucket.com/albums/kk138/dlusby22/2010-12-02_21-07-28_70.jpg


Thanks!

squirrel
01-05-2011, 12:06 AM
Don't worry about grinding steel and water is fine. The grinder might be an early Baldor.

lazlo
01-05-2011, 12:22 AM
Don't worry about grinding steel and water is fine. The grinder might be an early Baldor.

I'm pretty sure that's right -- it's an older Baldor 500 that's been attacked with a grey can of Rustoleum. Very nice grinder.

tdmidget
01-05-2011, 12:31 AM
Don't worry about grinding steel and water is fine. The grinder might be an early Baldor.

No you DON'T grind steel with diamond if it can be avoided, unless you just like to buy diamond wheels. At the temperatures at the grinding zone the carbon in the diamonds will dissolve in the steel. Grind as much of the steel away with an aluminum oxide wheel and the grind the carbide. Or use insert tooling.
You will have much better luck cooling with soluble oils or Kerosene. But is not necessary. Carbide will stand a lot of heat, but thermal shocks may cause cracks. many microscopic and ruin the tool.

Dale Lusby
01-05-2011, 12:34 AM
Thanks for the info. Being that I grew up in Ft Smith, AR (home of Baldor) I sure love my Baldor grinders and motors:)

As to setting up the water for coolant does it need to be a stream or a fast drip?

Would it have come with a stand like this or would it have been made afterward? Sure is heavy. It is 3 phase but the previous gentleman put a static converter on it. Seems to run fine as is but I do have 3 phase power off of a rotary converter. Would it make sense to switch to this or leave as is (meaning will it do any damage to grinder motor to run on static converter over time?)

You are correct about it not having the best paint job. The paint seems to be of decent industrial quality but whoever painted it never learned to "stay between the lines". Of course I like nicely painted machinery but I love nice running machinery with good or bad paint jobs much better:D

bborr01
01-05-2011, 01:14 AM
I spent some time working in a cutter grinding department grinding carbide form tools for screw machines.

I ran two surface grinders at the same time. Manually feeding a aluminum oxide wheel to relieve the steel and silver solder from under the carbide.

The other grinder slowly grinding the carbide sharp with coolant on it.

Always relieve the steel before grinding with a diamond wheel. Unless you just like buying diamond wheels.:eek:

Brian

PixMan
01-05-2011, 07:04 AM
I'm in agreement with Brian and tdmidget that you never grind away the supporting steel with the diamond wheels.

I used to grind a lot of Micro 100 brazed carbide tools for CNC swiss machines and it really ticked me off when I'd see coworkers rounding off the sharp corners of the diamond wheels by grinding steel. I needed those sharp corners to make fine form tools!

The Agathon tool grinders I used were filled with cutting oil for grinding. It seems to work best, but is quite messy.

ega
01-05-2011, 09:54 AM
Am I right in thinking that it's OK to do so with a CBN wheel?

Carld
01-05-2011, 10:38 AM
Don't waste your time trying to use the water dripping on the grinding process. just don't force the grinding process and get the carbide to hot. Cooling it in a bucket of water is ok if you allow the cutter to cool a few seconds by blowing on it and then dunking it.

Don't plunge hot carbide into cold water. Grind the steel away before using the diamond wheel to dress the carbide.

davidwdyer
01-05-2011, 10:50 AM
I have to strongly disagree with Carld. It is not a waste of time to lubricate your diamond wheels. It is essential! If not, you will reduce your wheel life a LOT. It does not have to be soaking wet, but dry diamond will wear quickly.

My son and I make our living with diamond wheels. If you don't use them much, perhaps you won't notice the attrition without water or oil lube, but you will pay the price later. Oil may be better, but much messier.

You can even wet the wheel with a wet finger frequently if you don't want to make a drip system. Soaking is not absolutely necessary. However, it is easy to modify an aluminum baking pan to catch water and rig up some way to do it. Why not do it right and have something very useful for the rest of your life?

Besides affecting your diamond wheels, grinding steel will cause RUST quickly and therefore degrade you wheel.

Carld
01-05-2011, 11:03 AM
If your using a slow turning diamond wheel the water may work but a wheel turning at 1000 to 3000 rpm will never see the water from a drip bucket. The air flow and speed of the wheel will sling the water away from the surface before it can even touch the diamond surface.

If you think the water is getting to the surface of the diamond your living under a delusion.

If I want to "lube" the diamond wheel I use some special oil that is used on the Kwik-Way boring bar. A coolant mister may "lube" the surface if directly pointed to the area the cutter is being applied.

I didn't make my living using diamond wheels but I did make my living as a job shop machinist and have a lot of experience using cutter grinding under many conditions and dripping water directed at a high speed wheel never sees the area of contact of the cutter and wheel.

davidwdyer
01-05-2011, 11:11 AM
We have several grinders, all of which run at high speeds, perhaps not 3,000 but well over 1,000. The designs we use leave the wheel constantly wet.

Another idea would be to use a wet sponge in light contact with the wheel. At minimum this would keep a little lube available. Much better than nothing.

tdmidget
01-05-2011, 11:42 AM
Carl is right. While water may carry heat better anything else you first have to get it to the tool work interface. Water has too much surface tension to get there. That is why there are soluble oil coolants. It has less surface tension and is more likely to get to the places where the heat is generated. Oil has virtual no surface tension but does not carry heat well. Either will be slung off from a wheel with any significant surface speed.

noah katz
01-05-2011, 12:40 PM
Water would be flung off tangentially in the plane of the wheel so ieems to me if you apply it (or mist) to the wheel an inch or two above the work it would be carried straight down to it.

lazlo
01-05-2011, 12:44 PM
Dale, the wheel mounting plates have two hole patterns: one for the 6A1 diamond wheels, and another for the Type 35 plate-mounted AO wheels.

I have my grinder set-up with a diamond wheel on one end, and a 60-grit AO wheel on the other. That way you can grind carbide or HSS.

Black_Moons
01-05-2011, 01:22 PM
How about apply the water to the center of the wheel and let it sling towards the work? :) (Assuming a face wheel)

Carld
01-05-2011, 02:47 PM
That may work but the only effective way I have found is to use a mist directly on the spot the cutter touches the wheel. Anywhere else and the coolant is slung off the wheel and does no good. That causes to much mess for me.

For sharpening brazed carbide I finally decided to just dress the edge without forcing the cut and wait a few seconds and then cool it in a water bucket. I try to not load the motor down or get the cutter hot.

Now, the above only applies to sharpening brazed cutters, not grinding endmills, reamers, etc.

AiR_GuNNeR
01-05-2011, 03:48 PM
I cut back the hanlde to a disposable flux brush and pushed the copper tube coming out of the water pot into the handle. I had to tighten the crimp along the sides of the handle to make it more water tight, but the wanter now flows into the bristles throught the handle. The bristles are lightly running along the wheel and I can keep a watery sheen on the surface while I grind.

davidwdyer
01-05-2011, 04:44 PM
The cooling needed is not really for the carbide. It is needed to prolong the life of the wheel.

At the risk of incurring ridicule, I am including a picture of a latch up diamond grinder I made and now use for carbide. The thingy in the pan which looks like a nut burbles water up onto the wheel at the bottom. It is powered by a cheapo aquarium air pump. This gizmo is made for the purpose of wetting diamond grinding wheels. The entire wheel runs wet all the time since it has 3/4 turn to spread the water. The outer lip of the shield in the front should be closer to the wheel, almost touching to get less splash.

I think Airgunner's idea is a great one.

The "high tech" connector between the motor and the spindle was harmonically balanced by the putting the two hose clamp screws on opposites sides. ;)

Don't laugh, it works well.

http://www.johndyerco.com/Dad/Carbidegrinder1.jpg

This was a Chinese drill press motor which I replaced by a variable speed tread mill motor. Since it was doing nothing, I used it to replace another larger motor on the grinding set up. The first motor was larger and fit better.

http://www.johndyerco.com/Dad/Carbidegrinder2.jpg

The white powder is from its previous life grinding on rocks.

Tony Pratt
01-05-2011, 05:10 PM
[QUOTE=tdmidget]No you DON'T grind steel with diamond if it can be avoided, unless you just like to buy diamond wheels. At the temperatures at the grinding zone the carbon in the diamonds will dissolve in the steel. Grind as much of the steel away with an aluminum oxide wheel and the grind the carbide.
When grinding carbide does the carbon in the diamond not dissolve into the carbide?
Tony

Langanobob
01-07-2011, 11:32 AM
Here is a picture of the new grinder. It doesn't have a tag so if anyone knows the make/model I would greatly appreciate the information...

Thanks!

Dale,

I have an identical grinder and it's not a Baldor, it's a Rockwell Delta and I think they are as good or better than the Baldor's. At least equal. Sorry, don't know the model number but they're generally referred to as just "Delta Carbide Grinders". You can find confirmation by Googling.

You were fortunate to get it with not just one but two water pots. Mine came without a water pot and I'm adapting a non-original one.

Bob

tdmidget
01-07-2011, 11:53 AM
[QUOTE=tdmidget]No you DON'T grind steel with diamond if it can be avoided, unless you just like to buy diamond wheels. At the temperatures at the grinding zone the carbon in the diamonds will dissolve in the steel. Grind as much of the steel away with an aluminum oxide wheel and the grind the carbide.
When grinding carbide does the carbon in the diamond not dissolve into the carbide?
Tony

In short, No. The carbon does not enter the cobalt -tungsten carbide mix. It is not soluble on cobalt and the tungsten molecule is already hold as much carbon as it can.

john hobdeclipe
01-07-2011, 12:45 PM
Am I right in thinking that it's OK to do so with a CBN wheel?

That would work, but it's a waste of money. Use CBN wheels for hardened tool steels, like High Speed Steel. Much cheaper to use a relatively hard Aluminum Oxide wheel on the soft steel backing of your carbide tools.


In short, No. The carbon does not enter the cobalt -tungsten carbide mix. It is not soluble on cobalt and the tungsten molecule is already hold as much carbon as it can.

I think I recall Evan discussing this a year or two ago, and stating that iron has a great affinity for carbon, and that at the high temps encountered at the point of contact, the diamond (carbon) simply dissolved into the iron (steel.)

lazlo
01-07-2011, 01:03 PM
That would work, but it's a waste of money. Use CBN wheels for hardened tool steels, like High Speed Steel. Much cheaper to use a relatively hard Aluminum Oxide wheel on the soft steel backing of your carbide tools.

I'm not suggesting it, but there are a lot of folks who sharpen HSS on their diamond wheels, and they report that the diamond wheels are no worse for the wear. The sharpening wheel in the Darex drill grinders is diamond, for example, and commercial diamond sharpening hones are not uncommon.

It is true that carbon is highly soluble in iron at high temperatures, so it's primarily how much heat you generate and how much wear you're willing to accept.

tdmidget
01-07-2011, 01:27 PM
I'm not suggesting it, but there are a lot of folks who sharpen HSS on their diamond wheels, and they report that the diamond wheels are no worse for the wear. The sharpening wheel in the Darex drill grinders is diamond, for example, and commercial diamond sharpening hones are not uncommon.

It is true that carbon is highly soluble in iron at high temperatures, so it's primarily how much heat you generate and how much wear you're willing to accept.
I don't know for sure what the Darex Drill Doctor's wheel is but I have heard even knowlegeable people refer to all super abrasives as "diamonds". Regardless the Drill Doctor is a low surface speed and they sell a lot replacement wheels. Obviously diamond hand files are low speed unless you do a lot of methamphetamine.

lazlo
01-07-2011, 02:04 PM
Obviously diamond hand files are low speed unless you do a lot of methamphetamine.

I'm talking about commerical machines like the Glendo Accu-Finish, which uses diamond wheels and is meant for sharpening HSS:

http://www.accu-finish.com/seriestwo.html

http://www.accu-finish.com/images/001-610-1-1Wa.jpg

tdmidget
01-07-2011, 02:42 PM
If you read their description you will see it described as a low speed machine. So even on the periphery of the 8" wheel it is only 628sfm. Slow motion in the grinding world. And looks like they sell a lot of wheels too.

lazlo
01-07-2011, 02:53 PM
And looks like they sell a lot of wheels too.

LOL -- good point :)

My only point is that it's not going to strip the diamond surface off your wheel, if you do it. It'll definitely accelerate the wear, possibly a lot if you running the wheel faster.

PixMan
01-07-2011, 03:43 PM
The Darex drill grinders I've used were both equipped with CBN wheels, not diamond.

I am quite certain of this because when some boneheaded newbie tried to sharpen a solid carbide coolant-fed drill on one of the machines, the wheel was toast long before he was done.

lazlo
01-07-2011, 03:45 PM
The Darex drill grinders I've used were both equipped with CBN wheels, not diamond.

I was referring to my cheap Drill Doctor 750X, which works surprisingly well :) Someone quoted a FAQ on Darex's web page explaining why they used a diamond wheel on a drill sharpener. Don't remember the reasoning, but CBN wheels are more expensive than diamond wheels, especially when you're talking Chinese.

BadDog
01-07-2011, 08:18 PM
I bought my Baldor grinder with used (like new) wheels almost 2 years ago. The whole machine was "like new" except for accumulated coolant mess. The guy who had used it for several years and only spritzed the wheels with WD before each grind, reported not pre-clearancing the bits, seemed happy, and can't see any damage.

My local friend (Mr Mori) who helps me when I get myself into a jam has one just like it, and never uses coolant. He provides slightly "generous" clearance angles below the carbide using the standard AO wheels, then grinds the carbide without further concern about the small touch just below the carbide edge. End result is kinda like one flute of 4 facet ground drill bit. That's the approach I've adopted, and I have no noticeable damage to report.

I watched a fellow with a brand spanking new grinder get all worked up over clearancing the steel (on some bits I gave him, helping him get started) before grinding them. Actually got out a die grinder and ground it close under the carbide, maybe 0.010 or so back. He had read/heard all this and was so worked up over ruining his new Chinese wheels that he must have spent about 10 minutes on that one bit. <shrug> Not me, I got more interesting things to do.

And yes, I am pretty sure that's a Rockwell grinder pictured.

knedvecki
01-07-2011, 11:18 PM
We would use stoddard solvent or kerosene in our drip lubricant / coolant pots and have a silicon carbide wheel for rough grinding mounted on the side opposite the diamond wheel.