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[Primary Facets]

#11

Drill Bit Sharpening / Re: SPAs on Twist Drills

Last post by Rossy66 - May 20, 2026, 12:28:17 AM

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

That's really cool.

#12

Knife Sharpening / Re: SG-250 - Oil Better Suited...

Last post by Rossy66 - May 20, 2026, 12:26:32 AM

Has anyone tried using Tormek ACC with the SG? It has cooling properties like water, and also has anti rusting properties.

Ken

I noticed that when I started using ACC with my SG250, it stopped getting brown spots on it which I assume was some part of metal partial stuck to the wheel.

#13

General Tormek Questions / Re: Angle Master Degree Differ...

Last post by Rossy66 - May 20, 2026, 12:24:31 AM

The Anglemaster, being a Tormek product, is calibrated to the standard 250mm Tormek grinding wheels. If the oversize difference with CBN wheels bothers you, take a millimeter reading of their diameter and make a fine sharpie line. Your guess will be close enough.

Ken

Thanks

[What are typical grinding lubricants?]

#14

Knife Sharpening / Re: SG-250 - Oil Better Suited...

Last post by RichColvin - May 19, 2026, 11:27:06 PM

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.

#15

General Tormek Questions / Re: Angle Master Degree Differ...

Last post by Ken S - May 19, 2026, 11:22:02 PM

The Anglemaster, being a Tormek product, is calibrated to the standard 250mm Tormek grinding wheels. If the oversize difference with CBN wheels bothers you, take a millimeter reading of their diameter and make a fine sharpie line. Your guess will be close enough.

Ken

[Primary Facets]

#16

Drill Bit Sharpening / SPAs on Twist Drills

Last post by RichColvin - May 19, 2026, 10:56:27 PM

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

#17

General Tormek Questions / Angle Master Degree Difference

Last post by Rossy66 - May 19, 2026, 10:25:52 PM

I apologize if this is a stupid question but, I was wondering if anyone knows the degree difference on the angle master setting of 250mm to the middle scale of 10"?

I ask because I use 10" CBN wheels with my T8 and I am wondering if the difference between both numbers makes much of a difference in degrees also, why does the adjustable guide not point to the 10" mark?

Thanks

#18

Knife Sharpening / Re: SG-250 - Oil Better Suited...

Last post by John Hancock Sr - May 19, 2026, 03:12:24 AM

Still, from a physics standpoint, in a situation where a solid moves in relationship to another, the friction coefficient is the ratio of the tangential force to the normal force. If there is no friction, there is no tangential force applied to the material being cut, so no work being done and obviously no matter being removed.

The work being done can be measured by the material being removed (bonds being broken within the steel) and the generation of heat. You need to maximise the first and minimise the second. We want as little heat as possible and as much material removal as possible for maximum efficiency. This is achieved by ensuring that the relative MOHs hardness of the abrasive is higher than the steel, the abrasive keeps as sharp as possible (friability helps with this) and the surfaces slide past one another as smoothly as possible, which is done by lubrication. The lubricant also assists in removing any heat that may be generated by friction. Water and oil have both been traditionally used on sharpening stones.

#19

Knife Sharpening / Re: SG-250 - Oil Better Suited...

Last post by John Hancock Sr - May 19, 2026, 03:01:22 AM

Eventually found that my trusted ceramic stones just couldn't handle the harder steels, loads of work, glazing on the stones,

There are different ceramic compounds and they have differing harnesses. It really depends on the MOHs hardness of the ceramic in the stone.

#20

Knife Sharpening / Re: SG-250 - Oil Better Suited...

Last post by John Hancock Sr - May 19, 2026, 02:57:45 AM

Friction is nothing more than generating heat.

Indeed, the water actually acts as a lubricant as states by Tormek.