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At this point i'm not yet convinced that this aluminium scrap material is the right choice for the knife rest, as it seems to exhibit some flex in the hollow part.
I think the surface needs some more rigidity, but i intend to find out with practicing.

I do indeed use my slower speed bench grinder with various Wheels quite a lot, but my trusted T7 fitted with an SB-250 stone is my choice for repairing broken points, hollowed out edges, bent bevels as well as establishing initial edge grinds on heavily used knives.
For intermediate work i use 2 Rubber Wheels coated with diamond powders, and for finer work as well as deburring i use various Paper Wheels coated with fine diamond compounds.

I have been using MDF benchstrops (as well as leather and hard cardboard) for quite some time now, and i also give them to certain customers sometimes.
They work more aggressively than either leather or cardboard using the same compound, and function well for both deburring and touching-up of various high carbide volume steel types, based on my own use as well as customer feedback.

On the Tormek leather wheel i've experimented with both the original Tormek paste (friable mix of 3.0 to 1.0 micron aluminium oxide in oil) as well as 1.0 micron diamond compound (non-friable mono-diamond in a mixture of oil and clay) made by 3M
On the MDF wheel so far i have only experimented with the same 1.0 micron mono-diamond compound, while on various handstrops (MDF, cardboard, and leather i've experimented with 0.25 micron, 1.0 micron, 3.0 micron, 6.0 micron, and 15 micron mono diamond compounds.

Currently doing a bit of tinkering, as in making my own version of Herman Trivilino's knife rest (using a cut-off piece of Torlock and 2 scrap pieces of aluminium), plus testing an MDF wheel with 1.0 micron diamond paste.
I'm already a bit further with the knife rest (ground in the hollow part on the SB-250 stone and put plastic tape on top to avoid scratching knife blades), and the first cheap knives i did came out quite well.
Probably going to replace the aluminium pieces with one piece of more rigid steel, but for now it seems to do the job.



The MDF Wheel is a testbed to find out what it can do exactly and how well.
I have been using MDF benchstrops with diamond compounds succesfully for quite some time now, and it was time to see if a motorized version would also work.
So far i found that it indeed works very well for removing burrs on harder & more wear resistant steel types (think S30V, ZDP-189, etc), as well as touching up existing edges on the same steels.
On softer steel types the leather wheel works noticeably better.
Also experimenting with various slots in the surface, both to trap steel debris as well as to find out if the direction of the slots has any influence in burr removal.
Will make a few more of these wheels in the future.

With Blue Wonder i think i use about a tablespoon on a full water basin.
You'll know when you've used too much when foam starts to build and "climb" the stone during operation, up to a point where it obscures your view on the knife's edge by making the otherwise clear water all bubbly.

If you're in the US you could also try Windex.
A few knife sharpeners on Bladeforums.com use this product on silicon carbide bench stones with good results, so maybe it would also work on the SB-250 Blackstone.
I must say that i have no personal experience with this product, as it isn't for sale where i live.

Roll the blade tightly in a few layers of cardboard just a bit longer than the blade itself & tape it shut with packing tape.
Using more than just one layer of cardboard makes these knife protectors thicker as well as stiffer, which will prevent both the edge as well as the point from slicing or sticking through when handling.
You can also make thicker rolls that can hold multiple knives at the same time.
I make both for kitchen knives i've just sharpened, and many Chefs like them so much they keep using them for extended periods.

To truly polish S110V steel you will need fine CBN or diamond, as no other abrasive is able to cut & shape the relatively large amount of vanadium carbides in the steel.

I use various diamond compounds on dedicated Paper Wheels for polishing work, and a while ago i did this Spyderco PM2 in S110V steel, freehand on Paper Wheels with successively 15, 6, 3, and 1 micron diamond compounds.
You can click 2 x on the pics for a bit more detail.









Close-ups using a USB microscope:

My idea would be to combine a KME self centering clamp with these:

A swivel bar mount:


and

A linear ball bearing:

Personally i don't do that, i always set the edge angle that works best for a specific knife (and it's user)
Now that edge will last longer on a good end grain wooden cutting board, as plastic in general tends to be more abrasive on knife edges.
Especially those thick plastic boards used in commercial kitchens here in Europe are real edge killers.

Now there seem to exist high quality plastic cutting boards that are gentle on knife edges, and those are made from a material called polyvinyl acetate.
These boards are mostly only used in Japanese commercial kitchens, and so far i've never seen them where i live.

I can't specify a range of pressure, but that company always provides me with several pieces of their most finicky fabrics for test cutting, and that is what i use for the adjusting of the scissors after sharpening.

One of my customers for scissor sharpening is a small company that specializes in making custom made ballroom dancing clothing as well as custom made swimwear, and they use quite a few different fabrics (many of which can be very finicky to cut well with scissors, a.o. Lycra-based fabrics)
The female owner knows exactly how she wants her scissors to cut, and she tests each pair herself on a few different fabrics every time after i sharpened them (and i've been sharpening their scissors for over 10 years now)

I sharpen all their scissors on the SB-250 stone at it's natural coarseness (no extra grading beforehand), both edges the same, and remove the tiny burr by laying each blade flat on a clean Spyderco fine white stone and doing a few light edge leading passes.
The resulting edge lasts them about a year (give or take, also dependent on steel quality) before they return it for a new sharpening, unless they manage to cut a needle with it (which happens sometimes)
What is extremely important to the edge life is the adjusting of the scissors, and the range i aim for is when the scissors open & close effortlessly while at the same time the fabric won't fold or slide.
Too tight and you will lessen the edge life, while too loose will make the fabric fold and/or slide.

The edge angles on most of their larger scissors (they have many different sizes) i keep in the 60-65 inclusive range, and so far i have found that for artificial fibers a toothy edge works better & longer (especially on harder to cut fibers like kevlar & dyneema), while for human hair a (much) more polished edge works better & easier for the user.
These i do freehand on Paper Wheels with diamond compounds.

[self centering clamp.]

Thanks for all the work and update.

But this thread really shows the need for a self centering clamp. 

Hopefully Tormek is paying attention... and will come out with one, like many of the other clamped sharpening system have.... 

(... and fix that crazy wide jig stop too). 

Exactly what i've been thinking for years now.
Sometimes i think i have to buy a KME knife clamp and modify that for use on the Tormek.

Maybe Blue Wonder is only for sale here in Europe, i don't know.
But there must be some equivalent in US shops i'm sure.
What you want is an already watery thin substance (not a syrupy thick liquid) that has comparable properties.

What i wanted for this specific purpose was a detergent with a strong degreasing & cleaning effect but with as little foam build-up as possible.
So far Blue Wonder has proven to work well for me, as long as i don't put too much of it into the water basin.
But i'm definitely not stuck on this specific product, and from time to time i will try something new.

I had the same problem with the leather wheel when I bought my used T-2000 except that it was in much worse condition.  I started by softening the leather with oil and let it set for several days.  Then I turned the machine on and used a carbide paint scraper to scrape away the crust.  I can't say that I got great results because the inside of the leather is pretty well dished out.  But before I replace it, I'm going to turn an MDF disk on my lathe and see how that works with some green stropping compound on my chisels and plane irons.

Great minds seem to think alike, as i'm currently experimenting with an MDF ring over the leather honing wheel & 1.0 micron diamond compound.

Try using your SB-250 stone with some Blue Wonder detergent in the water basin (but don't use too much of it as then foam will start to build up)
From what i have found it will prevent the stone from clogging/glazing much better & longer than using only water.