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[What are typical grinding lubricants?]

I remember using oils for keeping cutting tools cool and working efficiently (e.g., on drills, milling machines, and metal lathes).  I could not remember using oils for this purpose, so I asked Claude.ai.  Whilst AIs are not always right, Claude does seem quite good.  

Question:  What are typical grinding lubricants?

There was a long iteration of options provided, based on, 

• Material being ground (steel, carbide, ceramic, aluminum)
• Wheel type (CBN, diamond, aluminum oxide)
• Precision requirements
• Environmental/health regulations

But it was summarized as:

For most general-purpose surface or cylindrical grinding, water-soluble synthetic or semi-synthetic fluids are the go-to choice due to their cooling efficiency and cleanliness.

I followed this up with the question:
What is most commonly used for aluminum oxide grinding wheels?

For aluminum oxide grinding wheels specifically, the choice depends on the application, but here's the breakdown:

Most Common: Water-Based Synthetics & Semi-Synthetics
These are the dominant choice for aluminum oxide wheels because:

• Aluminum oxide generates significant heat — water-based fluids excel at cooling
• They keep the wheel from "loading up" (pores clogging with swarf)
• Good for ferrous metals, which are the typical workpiece material paired with Al₂O₃ wheels
• Easy to maintain and cost-effective

By Application
General surface/cylindrical grinding (most common use case)

• Synthetic or semi-synthetic water-based fluids are standard
• Concentration typically 3–8% in water

Precision grinding (tool & cutter, OD grinding)

• Semi-synthetic fluids for the balance of cooling + lubrication
• Sometimes light sulfurized mineral oil for very fine finishes on steel

Heavy stock removal

• Soluble oil emulsions — the oil content helps with lubrication under higher loads

Light/bench grinding

• Often run dry, or with a wax stick touched to the wheel periodically

What to Avoid with Al₂O₃ Wheels

• Straight heavy oils — poor cooling, can cause thermal cracking in the wheel bond
• Alkaline fluids with high pH — can degrade certain wheel bonds over time

So, I think we are good with water.

[Primary Facets]

Dan Heil contacted me by eMail and noted,

You can grind a SPA by setting the (DBS-22 clearance angle) to 90 degrees.

I tried it and that indeed worked ... exceptionally well!  Here is the resulting grind on a ½" drill bit.

This is a really big find by Dan as SPAs are really good on larger drill bits, and as noted on GadgetBuilder,

Secondary Point Angles ... extend drill life, improve hole finish and minimize the exit burr on through-drilled holes.

You can also see that the secondary facets are quite a bit rougher than the primary facets. This is due to using a different grinding wheel, making this a faster process

Primary Facets	Started with DC-250 diamond course grinding wheel (drill was in bad shape) Finished with DF-250 diamond fine grinding wheel
Secondary Facets	Used DC-250 diamond course grinding wheel
SPAs	Used DF-250 diamond fine grinding wheel

Ken once told me that grindstones are like brake shoes:  both are meant to be worn down through use.

I have the MB-100 which is quite similar to the MB-102.  That said, I have no issues as you've noted.  But, I also do not use it often.

I've been turning for ~30 years and have never encountered a 35° bevel. 40° is the smallest I've ever seen. 

None-the-less, the settings for the SVD-186 are shown (https://sharpeninghandbook.info/WW-BowlGouge.html).  Based on 40° needing a projection of 75mm, and 45° needing 65mm, you would probably need the projection to be 85mm. 

But, the sharpie method will have to be used to figure this out.  

An article by Larrin, "How Chipping of Edges Happens at a Microscopic Level" (on Knife Steel Nerds), debunks the idea of coarse edges due to the increased propensity for chipping and faster dulling of the blade. As noted by Dr. Vadim Kraichuk, "Meat plants are well aware that knives with coarse edges worsen product presentation and increase operators' fatigue and repetitive strain injuries. On the contrary, polished edges improve product quality through higher value cuts and increase throughput."

It is a common, but quite bad, practice of drawing the newly sharpened knife edge through a piece of wood or some other media to "rip off" the remnants of the burr. When this is done, the ripped off metal builds up on the front of the slice, and you then drag the rest of the edge through this crud. This crud, together with breaking off of ledges of material along the edge, will roughen the edge and worsen sharpness.

The scanning electron microscope (SEM) images to the pictures lined show the burr on a knife in the 1st image, that was then "ripped off" by cutting cross-grain into a piece of redwood in the 2nd image - loss of the sharp edge is obvious.

https://sharpeninghandbook.info/GT-Knives-Ripped-Burr.html

Key take-away from these photos : don't skip the honing step.

Dr. Larrin Thomas' book, Knife Engineering: Steel, Heat Treating, and Geometry (2025), discusses burr removal quite well.

This is really good.

I bought the SVD-110 Tool Rest and have been using it with the DF 250 to sharpen mower blades and its quick and really precise, no truing and I use the marker method (most blades are coming up between 35° - 40°. 

If the blade is uneven, I use the KJ45 with no problem.

I would love to see a video or pics of this.  It sounds like a great approach. 

I found that with a dissecting microscope I can see the size and shape of the burr. Years ago I used this method to refine my knife-sharpening skills. I was able to check whether or not a burr went along the full length of the blade. I can see the size and shape of the burr and as others have mentioned it does indeed depend on the type of steel and the grinding direction, but it doesn't matter.

Nowadays I keep a piece of an old bath towel handy and run the surface of the blade across the towel. Moving the knife away from me with the cutting edge facing towards me. The burr will catch fine threads of the towel and with good light and a magnifier I can easily see them, telling me if there's a burr all along the edge. Then of course I sharpen the other side of the edge and do the same. Now I know the knife is sharp and needs only to have the burr removed.

The knife is usually either a kitchen knife or a pocket knife and is now sharp enough for everything that do with it. I know that other techniques can get an edge sharper than that, but I'm of the opinion that that effort is just for show because as soon as the knife is used it will not be any sharper than it is with my technique. I don't have expensive knives and I've never used anything other than the SG grindstone and the honing wheel with the Tormek honing compound.

I use the same technique to sharpen tools, and modify it slightly for a lawn mower blade.

Herman,

That's an interesting idea.  What magnification are you using?

Rich

Thank you Gerd.  I appreciate your kind words.

John,

I've cataloged all that, and more at:  https://sharpeninghandbook.info.

Rich

I saw that Tormek now has a new knife sharpening kit, the KSK-106 (https://tormek.com/en/products/kits/ksk-106-knife-sharpening-kit).  

Of interest to me is the new CU-8 Edge Loupe.  That part is not listed in the Tormek catalogue, but I am betting it is the same as the magnifying glass in the DBS-22 Drill Bit Sharpening Attachment.  Any thoughts from anyone else?

I agree about using the micro bevel.  It is a better practice anyway as it will use up less of your SJ grindstone.

Here's what I've compiled about micro bevels https://sharpeninghandbook.info/MicroBevels.html.

How do you envision these being used?

I use a machinist's hand file.  It works fine.