Possible to repair SJ-250 Japanese Waterstone ?

[Ken S]

Very good post, Nico! I like your controlled experimental method.

My cautious attitude with the truing tool came from personal experience. When I first started using my Tormek, I had what I call "My Precious Tormek Grinding Wheel Syndrome". I did not want to wear out my grinding wheel by using the truing tool. I believe this foolish attitude is common among new users. I compare it to not wanting to wear out the expensive brakes on your car by using them to stop. I did not use my truing tool for a long time. Then disaster hit......

I forgot to lock down my truing tool. The loose truing tool became misaligned and dug into my grinding wheel hard enough to stall my motor. I was certain that I had ruined my diamond truing tool, and maybe my grinding wheel. I even purchased a replacement TT-50. When I eventually calmed down, I decided to assess the damage by very carefully approaching truing. I lowered the microadjust by just a fraction of a number. My "dead" truing tool was coming back to life. The initial pass touched only the highest spots on my grinding wheel. Subsequent passes eventually covered the entire wheel and made it like new.

Some will say this caution is unnecessary. I agree. However, the caution was as much to prepare me as to prepare the grinding wheel. The gradual truing of my grinding wheel reminds me of the joy I knew watching images gradually emerge with fiber paper in my photographic darkroom. My prints would remain in the developer tray for at least two minutes. I never felt this control with the newer resin coated, quick developing "paper" (or with digital printing).

I enjoy sharpening, which includes enjoying the truing process. Over the years, I have experienced several occasions where my sharpening was not going well. One very light pass with my truing tool revealed the problem. An out of true grinding wheel can be a very sneaky gremlin. Frequent, light truing can prevent a lot of problems.

I would offer an alternative to lifting the support bar before exiting the grinding wheel. Years ago, Jeff Farris, the founder of this forum, once commented that he gradually ground a small radius on the inside corner of his grinding wheel with his stone grader.  Following Jeff's lead, I did the same, although I did not understand his reasoning at the time.
In recent online classes, Wolfgang Hess has wisely suggested grinding a slight radius into both corners of the grinding wheel to safely eliminate the risk of finger cuts with the sharp corners. I would carry this one step further and suggest that by grinding the radius before truing, we may reduce the risk of chipping the grinding wheel. This may have been at least part of Jeff's thinking in grinding an inside radius years ago.

Keep up the good work, Nico, and keep us posted.

Ken

[RickKrung]

...snip...
This is interesting. So I followed the recommendation in the Tormek TT-50 tutorial video and lowered the USB height by exactly 1 numeral on the adjustment ring each time. Being the curious type, I did want to see what would happen if you run the diamond tip off the edge of the stone (instead of lifting and repositioning). With the cut being set to 1 numeral, I experienced quite noticeable chipping of the stone's edge as the tip ran off it, even though I was going extremely slowly. To your comment, Ken, I guess that means the cut wasn't shallow enough so next time I will move the adjustment ring by maybe half a numeral and see if this eliminates the edge chipping.

Many of us radius the corners of the SJ to reduce the chipping.  I was putting modest radiuses initially, but in 2018 my SJ suffered significant damage as a result of falling off of my bench.  It had huge chunks taken out of the corners in a spot or two.  I put in what seemed like a huge radius, but I like it.  Definitely avoids chipping and I do not interrupt truing passes to only move onto the corners. 

...snip...
Rick Kruger made some upgrades to his TT-50, making it automated.  He was able to set the speed very slow.  I seem to remember that he would complete a pass in 10 minutes or so.  And that the resulting surface was quite smooth.

Not sure where the 10 minutes came from.  Longest I recall using is about 4 minutes. Still seems like an eternity, but it works nicely. 

[RickKrung]

...snip...
I like the idea of automating the feed screw of the TT-50! I had exactly the same idea as I was doing it manually. I have a few spare stepper motors... perfect application for one!

Here is the thread where I posted many of the steps involved with motorizing the TT-50.  I did not use a stepper motor, just a small geared DC motor, for low speed and reversibility.  I made significant improvements in the drive train, mostly to tighten it up to reduce vibration, which are not necessary to simply motorize.  My TT-50 is the older version.  I believe the new version was designed, at least in part, to reduce vibration that resulted in striation marks on the wheels, so the tightening mods I did might not be needed if using the new model. 

One important feature is the slip joint between the motor and TT-50 shaft.  Avoids the need for ultra-precision alignment. 

This is the type I used. 


I like the looks of some of these, especially the spring one. 

Rick

[sharpening_weasel]

Somewhere on this site there's a picture of the truing tool with a zip tie wrapped around the parts- I did that to mine and it was an absolute gamechanger. No more harmonic ridges, exponentially less chipping of the edges, and the truing tool doesn't bounce around as much. My advice for truing the SJ- whatever the depth of cut you're setting, halve it. Whatever the speed you're thinking of going at- quarter that. I'm no expert here but when truing mine that's what I've found to work. Could somebody more experienced help me track down that zip tie photo?

[RickKrung]

?

[sharpening_weasel]

Yes! Spot on. Thank you Rick!

[Ken S]

Somewhere on this site there's a picture of the truing tool with a zip tie wrapped around the parts- I did that to mine and it was an absolute gamechanger. No more harmonic ridges, exponentially less chipping of the edges, and the truing tool doesn't bounce around as much. My advice for truing the SJ- whatever the depth of cut you're setting, halve it. Whatever the speed you're thinking of going at- quarter that. I'm no expert here but when truing mine that's what I've found to work. Could somebody more experienced help me track down that zip tie photo?

The first posting of using the electrical ties with the TT-50 truing tool was from Ionut. Ionut was one of our most innovative members. Among other things, he was also the Tormek demonstrator for Big Bear Tools, the Canadian Tormek agent. I don't know if the photos he posted are still there, however, doing a member search for Ionut will bring up his 209 posts. (Consider yourself fortunate that the post was his with only 209 posts and not mine.).

Ken