SG Waterstones for Flat-Bevel Sharpening?

[sweet_strings]

I really enjoy sharpening with the Tormek on the side and producing flat bevels on my chisels and plane blades. Although the diamond wheels work well for this—they're efficient and retain their shape—one does have to use the anti-rust solution (more chemicals and money down the drown) and diamonds are not the best media for sharpening laminated Japanese steel. Also, I miss the "feel" and "feedback" of the SG Waterstones.

Some time ago, Rich Colvin did some experiments in sharpening on the side of the SG Waterstones with the recently introduced MB-100 jig and photographed his results. The flat bevels sharpened on the SG Waterstones, especially the Japanese Waterston (SJ-250), look really good. No chemicals are necessary when sharpening with these stones and there's no need to worry about damaging expensive Japanese steel with Waterstones.

The main problem, of course, is that these stones will wear, hence the million-dollar question: How can one true the sides of the SG Waterstones so that they could be used for regular, flat-bevel sharpening? Could one true (lap) the stone flat on 80-grit wet/dry sandpaper attached to a large granite surface plate or large panel of float glass? Or does the wheel have to be trued on the Tormek? Does the bar of the MB-100 jig have to be parallel to the flat side of the stone when truing the stone? If so, could one attach a small diamond plate to the bar and press it against the stone to true it? Or how about attaching PSA-backed diamond abrasive to one of the flat tool holders, which would be attached to the MB-100, and pressing this against the stone?

I would be grateful for any suggestions on how to accomplish this task so I can enjoy the results that Rich achieved on a regular basis.

Yours on the path to sharpening nirvana,
sweet_strings

[Ken S]

sweet—— strings,

The debate between flat and hollow ground bevels was not new in 1972 when I first encountered it. Back then most home workshops, including mine, had six inch high speed dry grinders with grey wheels and oilstones which were generally not dressed. Hollow grinding and micro bevels were a good labor saving device. The hollow was quite visible.

Today we have eight and ten inch (200 and 250mm) diameter grinding wheels and Tormeks. Overheating tools is no longer a problem. Also, the hollow from a Tormek size wheel is barely detectable. The motorized Tormek does the grinding work. I question how much sharpening really benefits from flat grinding.

I see no reason why some flat grinding cannot be done on the side of an SG or SJ wheel, as long as you are aware that unlike diamond or CBN, these grinding wheels will eventually wear out of true and need to be retrued.

How to maximize the in true time of a grinding wheel?
I would separate tools which really benefit from flat grinding. Those which don't really need it would continue to be ground conventionally.
With damaged or really dull tools which really need flat grinding, I would do most of the grinding on the edge of the wheel, reserving the side for the final touch up.
Although Tormek does not recommend it,I believe the side of the wheel could be flattened to reasonable tolerance using a diamond stone. If you are planning to do this, do it lightly before it gets too worn.

I believe you may be over concerned with the water and solution issue with diamond wheels. I routinely remove the water from my water trough with a turkey baster. If I am using diamond wheels with ACC solution, It can be reused within reason. If it is plain water, I remove most of it with the turkey baster. Unlike water and solution from diamond wheels, water from an SG or SJ contains sludge from the grinding wheel. With the trough almost dry,I remove this sludge with a paper towel and throw it away instead of possibly allowing it to eventually clog my drain pipes.

I have no experience sharpening laminated Japanese steel.
I can't think of any reason why flattening a grinding wheel on a flat granite plate with abrasive would not work. I would lean more toward using a diamond stone on the wheel while running in the Tormek.

Do keep us posted.

Ken

[RichColvin]

Chris,

I was just using the side of both my SB-250 & SJ-250 grindstones.  I used the side to sharpen the flat on a fly cutter for my rose engine lathe.  Worked well, but now I am questioning the value of a flat grind vs a concave one for that.

I'm less concerned about the SB grindstone as I will have to replace it in a reasonable timeframe.  But I was hoping to keep the SJ grindstone for many, many years. 

What you are asking is a good question.  I am interested in what others have to input.

Kind regards,
Rich