Rock hard felt vs SJ-250

[khun]

are the rock hard felt and SJ-250 wheels intended for the same purpose, presumably final polishing, and does one wheel have an advantage over the other?
I debate purchasing a felt wheel that requires diamond spray and low humidity storage, especially if the SJ-250 will accomplish the same end.

[cbwx34]

are the rock hard felt and SJ-250 wheels intended for the same purpose, presumably final polishing, and does one wheel have an advantage over the other?
I debate purchasing a felt wheel that requires diamond spray and low humidity storage, especially if the SJ-250 will accomplish the same end.

Not really... a felt wheel removes the burr and cleans up the edge (and can polish), while an SJ wheel will refine the edge and polish the bevel, but still leaves a burr that needs to be removed.

[RickKrung]

Not really... a felt wheel removes the burr and cleans up the edge (and can polish), while an SJ wheel will refine the edge and polish the bevel, but still leaves a burr that needs to be removed.

I'm going to be a bit more emphatic.  Definitely not, for the reasons cbwx34 says.  Following Knife Grinders deburring principles, whether I use the SJ wheel or not, I always finish using a rock hard felt wheel with 1µ diamonds (I use paste rather than spray) at some "degree" of higher angle, usually 1°-2°. 

But, now that I mention the higher angle for deburring, I'm not recalling at the moment if anyone has tried to deburr using only the SJ at one of those "higher" angles (someone must have).  I suspect it would not work to the same degree due the significant difference in abrasiveness, SJ ~ 4,000-5,000 grit, 1µ ~ 14,000 grit. 

[3D Anvil]

I think the hardness of the stropping substrate is at least as important as the grit.  If your "strop" has absolutely no give, it will create a microscopic burr, no matter how fine the grit rating may be.

[John_B]

When I want to go for a sharper edge I have been successfully using a dedicated leather wheel with 1µ diamond spray.

[Sir Amwell]

Not really... a felt wheel removes the burr and cleans up the edge (and can polish), while an SJ wheel will refine the edge and polish the bevel, but still leaves a burr that needs to be removed.

I'm going to be a bit more emphatic.  Definitely not, for the reasons cbwx34 says.  Following Knife Grinders deburring principles, whether I use the SJ wheel or not, I always finish using a rock hard felt wheel with 1µ diamonds (I use paste rather than spray) at some "degree" of higher angle, usually 1°-2°. 

But, now that I mention the higher angle for deburring, I'm not recalling at the moment if anyone has tried to deburr using only the SJ at one of those "higher" angles (someone must have).  I suspect it would not work to the same degree due the significant difference in abrasiveness, SJ ~ 4,000-5,000 grit, 1µ ~ 14,000 grit. 

For some reason I've hardly ever got the rock hard felt wheel to work for me. The sharpness invariably goes down and not retrievable with subsequent honing. So I'd given up on it really. I tried again using the new angle setter to see if accuracy would improve it. Same results, regardless of varying the angle.
Maybe it's my bad technique. I've posted about this in the past with mixed answers.
So I wonder if you could give a detailed overview of your technique Rick, when using the felt wheel with 1 micron diamonds?

[RickKrung]

...snip...
So I wonder if you could give a detailed overview of your technique Rick, when using the felt wheel with 1 micron diamonds?

Happy to try.  Pretty simple and I've posted on it a few times before, peripherally to other discussions. 

Nominally, whatever grinding wheels, SG, SB or CBN/Diamonds, both followed by the SJ at the same grinding angle.  There have been times when I did not follow with the SJ, but not often  Then setting the angle 1°-2° higher for deburring on the rock hard felt. I apply fresh past before starting a sharpening session, but keep is sparse and spread out as much as possible.  Sharpening sessions for me usually amount to 4-5, up to a dozen knives. 

I use the SVM jigs with two milled down, 0.5mm and 1mm, as Vadim did, with shims for centering.  Most of my SVM are not milled but I use the shims to improve centering for the knives thin enough for it to work.  I have a KJ jig but truly hate the loss of adjustable projection, so I just don't use it. 

As mentioned, I use diamond paste rather than spray, simply because this was worked out with Vadim about the time he first came out with the deburring book and before he went from pastes to spays.  I bought a full range of pastes at that time, but setttled very quickly on just using the 1µ, probably in large part because I have only one felt wheel and the SJ is functionally the same as using 5µ diamonds.  I do not have a set routine of working only one side and then the other or number of passes per side, more by intuition perhaps. 

Final treatment is stropping on dry, hanging leather (the kangaroo tail Vadim sold).

Back at that time, I bought several paper wheels and was going to try going the multiple-grits/paper wheels like Vadim used, but found the above routine worked to my satisfaction.  I have been able to achieve sub-100 BESS readings, but never gotten that close to the 50 range.

I still use a phone app for determining USB setting and always use an FVB or MB-102 for deburring.  I use the distance from the USB to the grinding wheel approach (rather than USB distance to the machine case) - much faster, easier and in my opinion more accurate.  I DO grind on the SJ edge-leading and have never had a problem with catching or grabbing. 

Rick