I have spent some time shaping and sharpening chisels and hand planer blades with ok results. I used the supplied stone to refresh and alter the grit of the wheel. I am surprised to find that I seriously altered the shape of the angle of the surface of the stone by my actions. I concluded that the grinding stone is quite soft and I needed to be very careful to apply even pressures to the surface or it quickly wore unevenly. This was identified by putting a set square across the surface of the wheel. I used the truing tool to good effect. A little more shaping and sharpening and the wheel needed re-truing! I estimated that I removed about 3 mm with the truing tool, and the water bath was carrying a lot of suspended grey sediment. At this rate I'll need a new wheel sooner than I expected!
My questions:
Could it be that the the pressure I applied across the surfaces being sharpened was too heavy and uneven?
Can the surfacing stone grind the surface out of square if pressure is applied unevenly?
I was using the square edge jig and it was not good enough to place the right hand side of the blade against the jig and tighten the knobs. I needed to measure with a set square and tighten carefully. Then I needed to ensure that the finger pressure was even across the blade. If not, the the sharpened edge was soon out of square. Is this a correct conclusion?
I assumed that if I was using a jig and a rigid support system then I could set and forget and go at the shaping and sharpening. Is this an unreasonable assumption for any of the Tormek jigs?
PS. I like working with the water cooled system. It may be that when I have my tools in good order and settle down to resharpening then I will have less of the problems I have described.
When you say chisels and plane blades, are you moving them across the stone while your sharpening? Using one spot, or too much pressure on the grading stone could cause more wear on the stone. When I flattened my stone, I left one groove in the stone from leaving the diamond tip in one place too long. (dropped something and left the Tormek in that position when I went to pick it up).
I know at the garage I worked at, the stone was always beveled towards one side, that received the most use.
Quote from: CleanCut on November 12, 2013, 07:12:18 AM
Could it be that the the pressure I applied across the surfaces being sharpened was too heavy and uneven?
Uneven, yes. When the stone wears quickly it's usually because you're grinding something like machine planar blades. In those cases the SG stone might give better results.
QuoteCan the surfacing stone grind the surface out of square if pressure is applied unevenly?
Yes, although you seem to be convinced it's due to the stone grader being applied unevenly or with too much force, I'd be more inclined to think it's due to uneven grinding on tools.
QuoteI was using the square edge jig and it was not good enough to place the right hand side of the blade against the jig and tighten the knobs. I needed to measure with a set square and tighten carefully. Then I needed to ensure that the finger pressure was even across the blade. If not, the the sharpened edge was soon out of square. Is this a correct conclusion?
I assumed that if I was using a jig and a rigid support system then I could set and forget and go at the shaping and sharpening. Is this an unreasonable assumption for any of the Tormek jigs?
Your experience with the square edge jig is common. It takes some fuss and muss to get square ends on chisels and plane irons. For the other jigs, I'd say that for most things it pretty much is a set and go shaping and sharpening process. It does take some practice and requires the same set of skills required of craftsmen.
QuotePS. I like working with the water cooled system. It may be that when I have my tools in good order and settle down to resharpening then I will have less of the problems I have described.
I agree. That was my experience and many others have reported here on this forum a similar learning curve.
Thanks for the help. I can confirm that I move the blades across the stone as I sharpen.
I looked at the surface of the truing tool with a 10X lens. It looks odd to me. I expected an even surface with diamonds (?) embedded like sultanas in a pudding. What I see is the embedding surface (copper coloured) in three ridges that run in the direction of travel of the grinding stone. The centre ridge is much higher than the others. The centre ridge has a prominent crystal (is it really a diamond?) that does all the cutting. Consequently the finished surface of the grinding stone has oblique ridges across it that are obvious to my naked eye when the water drains from the surface! Have I got a dud truing surface? The mechanism works well and I have used various speeds of travel.
Some ridges from the truing tool are unavoidable. They'll disappear soon after you start using the grindstone. They actually improve the cutting action...if you want it to cut fast. On the other hand, if you want a finer cutting surface, the stone grader will smooth the ridges quickly.
It's good to true the grindstone before a rough grind. Makes it go faster.
On the other hand, it's not a good idea to wait until you have a fine grinding to do. I used to hold off on using the truing tool because it wears away my precious grindstone. But then I realized that the grindstone is made to wear away, and you're supposed to keep it true. Doing so will make it last longer and work better.
Quote from: CleanCut on November 14, 2013, 01:46:36 PM
I looked at the surface of the truing tool with a 10X lens. It looks odd to me. I expected an even surface with diamonds (?) embedded like sultanas in a pudding. What I see is the embedding surface (copper coloured) in three ridges that run in the direction of travel of the grinding stone. The centre ridge is much higher than the others. The centre ridge has a prominent crystal (is it really a diamond?) that does all the cutting.
At 40X I see fourteen protrusions, presumably small clusters of diamond crystals. The largest ones are three or four times wider than the smallest ones. There are seven much shallower ridges in the substrate. It looks like a moonscape.
Thanks for the helpful replies. I remain surprised with the "moonscape" of the truing tool. If there is a diamond sitting up above all others then the truing is done by this point source. Practically, I will end up with a ridged surface of the grinding stone. Should I routinely follow truing with the smoothing stone?
I always apply the coarse side of the stone grader to the grindstone after truing. The only exception might be if I'm working on a beat up mower blade or something like that.
When I'm taking a new flat-ground blade - even my best blades - and establishing the initial hollow, I do it straight off the truing tool. Those grooves and ridges are your friend when re-forming the harder tool steels.