Verdict on the SG-250 Blackstone silicon Wheel

[Jeff Farris]

Good field work, Rob.

In his excellent book on sharpening, Ron Hock makes the comment that he uses carbon knives in his kitchen.  He states he hasn't needed to use more than a steel on them in years of use.  Interesting that someone of his knowledge and experience hasn't bought into the marketing nonsense of needing knives which won't stain when cutting onions.

Ken

Ken,

It isn't as much "marketing nonsense" as bureaucratic nonsense. Stainless blades and plastic handles are now mandatory in all commercial food processing. As goes industry, so goes consumer goods.

[Ken S]

Good point.  I hadn't thought of that.

Ken

[Herman Trivilino]

I wish Jeff would chime in here.  Is the SG-250 just a more expensive and better alternative to the SG-200?

Is the lower cost the only advantage to the SG-200?

[Jeff Farris]

Herman,

Don't know if you're getting your part numbers mixed up, but an SG-200 is exactly the same material as an SG-250. The SG-200 is 8" diameter and about an inch and a half wide. It's the replacement stone for the T-3.

Now as for the SG-250 original stone compared to the SB-250, in theory, the SG-250 should handle carbon steel tools like chisels and plane irons better than the SB-250, which is formulated for HSS. That theory stated, Rob is not the first person whom I've heard from who felt the SB-250 performed well on carbon steel. Grading is not as effective or as quick on the SB-250, that I can vouch for.

[Rob]

That's interesting input Jeff, re the grading. 

Because I'm so early into my experience with the SB-250 I've only trued it once and graded to 1000 grit once.  I must say I found the grading to 1000 grit a doddle. I couldn't discern any difference between that and the old stone?  It must be going to 220 that's harder I guess. That would make sense, reactivating a harder stone has to require greater effort.

I also don't quite get the logic behind it not performing as well as a softer stone in a softer material (carbon steel). Wouldn't the fact it's formulated for HSS mean it cuts softer materials more aggressively?

[Herman Trivilino]

Rob, if the SB can't be graded as effectively it seems to me that it wouldn't perform as well in areas where that's a factor.  For example if you're sharpening a thin (carbon steel) kitchen knife you want the stone graded to as fine a grit as you can get.  As Jeff is fond of saying, smooth as glass.

Then, if you want to sharpen your (carbon steel) lawnmower blade you're going to want to switch back to the course grit.

Of course, if you have both stones you could use the SB on your lawn mower blade quite effectively.  But having both stones is not the comparison we're making here.  But since you now do have both stones you can easily switch between them.  Use the SB when you want to take off a lot of steel, use the SG for touch ups when aren't removing a lot of steel and you want to get that smooth mirror finish.

[Herman Trivilino]

Jeff, yes I had my part numbers mixed up.  I was comparing the SB-250 to the SG-250. Thanks, maybe I'll buy the SB-250 the next time I need a present for myself!

[Rob]

When Jeff said it can't be graded as effectively I assumed he meant its more difficult (effort) and time consuming to switch between 220 & 1000. I didn't think he meant it would be less effective at cutting once it had arrived at either of those grits?  But perhaps you've hit the nail on the head Herman

What I still don't really understand is why.......why wouldn't a stone formulated to cut a hard material (HSS) not cut a softer material (carbon steel) as well?  Surely it would cut faster?

[Jeff Farris]

Rob, you're spot on. What I meant was that it is harder to change, but you're right, it is just as effective once graded.

I'm not an abrasive engineer, nor a metallurgist, so I can only pass on what those who are have told me. It has to do with the softer steel gumming up the silicon carbide surface more than the aluminum oxide surface.

Herman, just to clear something up in your post, SB=Blackstone=HSS  SG=Original=Carbon Steel.

[Rob]

Ok thanks fir that Jeff. Maybe the carbide surface has harder and finer particles, so it has the "valleys" fill up with swarf faster?  Like you I don't know. It sure did well on the carbon steel plane iron though so for practical purposes I guess it doesn't matter.

Ill still report on the planar blades when I do them but for right now I'm impressed with the blackstone

[Herman Trivilino]

Herman, just to clear something up in your post, SB=Blackstone=HSS  SG=Original=Carbon Steel.

Dang, that's two in a row.  Ok, I went back and fixed it.

Just out of curiosity, would it be possible to purchase the T7 equipped only with the SB-250 HSS grindstone?

[grepper]

Unlike most here, I've never experienced the joy of woodworking.  So, when I purchased my T-7 I asked if I could get an alternative assortment of jigs.  The answer was no.  It comes prepackage from the factory. 

As I remember, I had to purchase the scissors jig separately.

It would be interesting if Jeff would chime in here, as to if there is any benefit at all with the SG over the SB.

From this thread, I have yet to see any benefits of SG over SB other than grading may take longer with the SB.

[Rob]

Why not try a small project Mark. You might just love it. :-). Nothing like the smell of freshly planed pine or having your entire torso covered in foot long green oak shavings as you hollow out a bowl.....ah....marvellous :-)

[Jeff Farris]

As I mentioned in an earlier post, the SG is considered to have a wider application than the SB. It handles normal carbon tool steel better than the SB and still will cut HSS. It is a better choice as the foundation of the system.

[grepper]

Jeff, got it.  That makes sense.  Thanks.  Sorry to have missed the earlier post.

From what Rob said, the SB did a gobsmackingly good job on normal carbon steel, but that is just a one person, one tool experience review.  Maybe the SB loads up with a lot of normal carbon steel use? 

But I'll willingly take your word for it!  So maybe it's "Bob's your uncle" on the SB/SG debate.

Rob, thanks for the new expressions "gobsmacked" and "Bob's your uncle".  Being from the US I had to Google both.