Blackstone SB-250 vs Diamond DC-250, DF-250 and DE-250

[rithram]

Hi

I have all three diamond wheels DC-250, DF-250 and DE-250 for a T8.
I also have the DBS-22.

I would like to know if there is a technical reason of acquiring the SB-250 for HSS or HM drills for example?

[Ken S]

Welcome to the forum, Ricky.

As the diamonds in the diamond wheels are harder than the silicon carbide ofthe SB-250 Blackstone, you probably don't need the blackstone. Both materials work better with light grinding pressure.

The SB was introduced several years before the diamond wheels. It was the first Tormek wheel designed for harder steels, including hss. It remains popular with woodturners and some knife sharpeners who want a longer lasting grinding wheel than the traditional SG. It appears to be somewhat eclipsed by the diamond wheels.

Ken

[RickKrung]

I'll say this in favor of the SB wheel for drill bits.  I have and use it for drill bits.  I have and have tried the diamond wheels for drill bits, but I don't use them much for drill bits.  Reason is, at least one of my diamond wheels is not actually flat across the outer surface.  As increasingly smaller depth cuts are take as the grinding reaches its final stages, the grinding action is not uniform across that diamond wheel, as though the surface is slightly concave (lower in the middle).  The grinding action remains the same all the way across the SB stone.  The latter will vary and change as the stone wears but I just don't seem to notice it the way I do with that diamond wheel.  The diamond wheel may be functionally flat and within specs.  It just "feels" wrong, if nothing else. 

I had hoped the diamond wheels, or more correctly the coarse diamond wheel (DC) would be significantly more aggressive and take of steel a lot faster than the SG or SB.  I was disappointed.  I have gone to other alternatives, such as a traditional grindstone mounted on the T8, running in a water bath, a Viel 1x42 belt grinder or a slow speed Rikon bench grinder.  The former has no issues with heat build up, the latter two do.  I still use all three diamond wheels, in succession after any of the faster alternatives, whether for drill bits, knives, plane blades, chisels, whatever. 

YMMV,

Rick

[rithram]

Hi Ken and Rick,

Thanks for your replies.

I had the same toughs that diamonds are obviously hard and should work.

When I sharpen knives I value the fact that I can easily progress from
DC -> DF  -> DE -> SJ -> paperwheel -> kangaroo strop with a result under 100 BESS.

Having the same diameter is something I really value,
but having to take care that I do not damage the diamond with that much pressure is something I really dislike.

Also I agree that the diamonds are not as aggressive as I had hoped.

I think I will for the shaping process get the BGM-100 Bench Grinding Mounting Set
and attach this a grinder for faster shaping and less likelihood of damaging the diamond wheels.
After the shaping process with the grinder I will continue the sharpening and polishing process with diamonds and japanese wheels.

Ricky