SG-250 clogging / cleaning

[MerryMadMick]

Hello,

I've started resetting the primary bevels on my plane irons and chisels, mainly due to creeping skew from years of hand sharpening.  I picked up a Tormek bench grinder adapter + wolverine plate so I can use my 8" low speed with a 180 CBN for quick material removal, then I move over to the Tormek for final sharpening and honing.

I've noticed that the SG-250 clogs/looses it's cutting speed pretty quick when sharpening PM-V11 and A2 steels.  After about a minute or so the wheel looses its bite and I redress with the coarse side of the grading stone.
 There is, of course, a slight difference in the radius of the hollow grind between the 8" CBN and 10" SG-250 which means I'll be using the SG-250 to remove a bit more material to match radii.

I realize that after I'm done, I won't be resetting any primary bevels for a long time and, in theory, I'll only need to touch up the edge on the strop wheel on sharpening day.  That being said, for these harder steels, would I be better served with a different wheel?

Thank you.

[RichColvin]

The SB-250 was designed for harder steels.  You might want to get one of those if you're going to be sharpening such metals often. 

[MerryMadMick]

Thanks Rich.

Would it make more sense to invest in a few of the diamond wheels?  Since I use an 180 CBN for shaping, I was thinking the 600 + 1200 diamond wheels to round out the grits.

Thank you.

[John Hancock Sr]

To sharpen you need to use a harder material than that which is being sharpened. The SG wheel is aluminium oxide which is perfect for carbon steels but is not so good on harder tool steels since they are harder that aluminium oxide. The SB is silicon carbide which was the wheel of choice for high speed steels back in the day but this has been supplanted by diamond, and latterly CBN, cubic boron nitride, which is not quite as hard as diamond and better when high speed grinding.

Your issue with the SG is common and is due to glazing of the stone surface due to the hardness of what you are sharpening.

I went out and bought the DC, DF and DE wheels since I sharpen a lot of harder steels. The SB is perfectly fine and cheaper than buying the three diamond wheels but I prefer the diamond wheels since they are consistent grit and do not change size.

[Ken S]

My chisels and plane irons are all high carbon steel. Most are oder than I am (74).
With no disrespect toward modern tools, my venerable tools have always served me well.

Whenever I read posts like this, I am curious (not critical) about how many tools are invoved and in need of major sharpening. Ideally, much work can be done with three or four planes and about the same number of bench chisels. In the online classes, the Tormek instructors freqently refresh the SG frequently (around once per minute) with the stone grader. From the standpoint of cost effectiveness, in my opinion, the clear winner is a well maintained SG. Admittedly, the initial reshaping/sharpening will take longer than with harder grinding wheels.

If cost is no object, by all means go for the harder, more expensive wheels. I realize sharpening is somewhat of an enjoyable luxury for any of us, myself included. I am merely presenting the option of proceeding a little slower at lower cost.

Ken

[MerryMadMick]

Point taken Ken.  All my addictions have to be non-chemical these days, so tools and the accoutrements are filling that particular void.

I'll continue with the SG and if I can convince myself that the SB is the direction to take, then I'm sure I'll post questions about it. 

Actually, I do have a question about the SB.  I've read that the SB tends to glaze the grading stone making it less effective with the SG.  Is this true?

All the best.