Did something boneheaded the other day and accidentally damaged my Japanese Waterstone.
It'd been a while, and I'd forgotten that you're supposed to use this stone edge-trailing. I was polishing the blade into the wheel and the inevitable happened: as I lifted the blade off the stone, the edge caught the wheel and dug into it, creating a small gouge.
I am hoping (praying) that this can be repaired somehow, maybe with something like the TT-50 Truing Tool?
Any advice greatly appreciated.
First of all this can - and will - be fixed with the truing tool.
I'd suggest you use diamond plates or the Tormek stone grading tool on the fine side to smooth the edges of the broken area.
Also, I think the conventional wisdom for using the TT-50 with the japanese stone is to always contact the edge of the stone with the diamond tip going inward, and not outward. In other words you true from the outside to a bit past halfway, then lift the truing tool by rotating it slightly around the USB axis, then proceed from the other side. That avoids small chips along the edges.
Back to the source of your woes, sharpeing edge trailing sure avoids that kind of issues. Still, I only use the SJ stone edge-leading (as I find it makes honing much faster) : you just have to make sure you apply constant pressure with your hand on the jig toward the USB, even when lifting the blade. This is true whatever the stone used, and it gets more important when the sharpening angle increases.
Cheers,
Nick.
Thanks a ton for that advice.
I will give it a go... and let you know how it went.
Nico
To the community: Pontus from Tormek support has also responded to my request for help and offered this instructional video:
https://youtu.be/_9izVW7g6uo?t=591 (https://youtu.be/_9izVW7g6uo?t=591)
The video confirms tgbto's comment about always truing from the edges to the center of the stone with the TT-50.
Thanks to all,
Nico
Oh yes, I've seen way worse (saying for a friend). Truing tool is your friend.
There is an old saying that what something does to you, it can also do for you. Superabrasive wheels (diamond and CBN) are promoted because they do not wear down in diameter. While this is convenient for consistent setup, it also means that any damage to the single layer of abrasive can ruin the wheel. The "old reliable" SG (and SB and SJ) wheels can still function after a lot of surface damage.
Ken
Thanks guys for all the feedback. Haven't repaired the wheel yet, but will get to it in the next few days.
I had assumed that from now on I'd have to be measuring the diameter of that wheel each time I grind (polish) a new angle.
As we say in Japan, "shoga nai".
Nico
Nico, when I true my SJ grindstone using the TT-50, I have learned to advance it VERY SLOWLY across the surface. The slower you move the TT-50's head across the SJ grindstone, the smoother the remaining surface will be. That makes the next step easier.
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.
Hi everyone.
I did the deed this evening and got the stone surface back to almost new. Albeit with new dimensions: Ø248.2mm. I guess I am going to need to use calculators in the future to get accurate angles...
I did go very slowly back and forth so got a very smooth and even result.
However! That TT-50 does have a learning curve! In particular, I noticed something unusual happening each time I approached the edge of the stone and had to stop to move the TT-50 tip to the outside of the stone to complete the pass coming inwards again. What I found was, even though I took extreme care not to move the USB adjustment nut as I loosened the clamp screws to raise and lower it, when it came down again it was not at the same height as it was before. Most times it was a bit lower which meant when I started my finishing pass (from the opposed side of the stone inwards), the amount of material removed was greater.
However, by doing several passes at the same height, I ended up getting a smooth and level result.
When I investigated this phenomenon in more detail I found the cause was due to the fact there is only 1 adjustment ring nut on the USB. And even if it does not change position, when you loosen the 2 clamping screws, there is a tiny amount of play in the USB (between the USB leg that has the lock ring vs. the leg that is free). This results in the TT-50 cutting bit ending up in a slightly higher or lower position when you re-clamp. Because you are coming in again from the outside of the wheel, it's hard to get this exactly right with the pass you made from the opposite side to get a perfectly even result. I tried to re-clamp as consistently as possible but was surprised how hard it was to get it perfect.
Anyway, you can overcome this by doing several passes with the USB ring nut at the same setting until you hear no more material is being removed any more from either direction. Then you can adjust down a tiny bit for the next level.
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!
Hey,
Glad it worked for you. The japanese stone has a tendency to wear down quite quickly anyway, be it by truing, heavy cleaning or sheer use.
Maybe using a counter-nut (is that even the right word) against the first you can avoid the issue you mentioned with the height changing ever so slightly each time ?
I must be missing something. I true my SG, SB, and SJ wheels with straight, side to side traversing passes. I take very small bites, usually no more than half a microadjust number, and very slowly, usually around two minutes across.
I have occasionally used deeper cuts and faster passes. I confess that I enjoy the slower pace of seeing the wheel gradually become more true with each pass. I have become a believer in the value of frequent, light truing. It helps clear my mind knowing that my wheel is true; it lessens the number of unknown sharpening gremlins.
As for a wheel with 248.2 mm diameter, I am not worried. I recall a forum discussion with our late member Jan. Jan was an engineering professor. He was one of the shining stars of our forum. He was very intelligent, highly educated, and still retained his practical passion for sharpening. I have always used Dutchman's (Ton Nillesen) grinding tables which use 10mm changes in wheel diameter. They are precise enough for my needs.
Jan favored using changes for every five mm changes in diameter. Jan was practical as well as highly technical. In my opinion, if five mm changes provided adequate precision for Jan, that was more that sufficiently precise for me. We are not mating knives. If two knives are both very sharp, in my opinion, minute differences in bevel angles are insignificant.
Please let me be clear. I am not disputing the value of our various computer programs. They all have their uses. However, computers are capable of far more precision than is usually required. No carpenter uses a micrometer to frame a house. Machinists regular work to standards of tolerance. Machining parts beyond normal specified tolerances adds cost and no practical value. I would suggest the same applies to knife sharpening.
Ken
The suggestion for a lock nut on the USB adjusting ring is good to stop you accidentally moving it, but it won't completely remove the slight amount of play when the USB is un-clamped. It's because the other leg is free to travel minutely. If the other leg also had an adjusting ring, then I think the play would be eliminated. Anyway, we are only talking about a slight amount of play, the only reason I noticed it is that when coming in from the opposite side of the wheel back to the center, the 2 cuts don't match up. If, when you lifted the USB to reposition the TT-50, it came back down at exactly the same height, this phenomenon wouldn't happen. Anyway, not a big issue, just something to be aware of.
Thanks Ken for your input. It's good to know that for most sharpening applications rounding the wheel diameter to the nearest 10mm will give an acceptable result!
Tormek's suggestion of lifting the support bar and moving the TT-50 diamond to be able to travel inward is fairly new. The SJ was introduced around 2009, several years before the lifting suggestion.
I suspect the lift was started because of chipping complaints from users who set the TT-50 to cut too deeply. (Who wants to take "forever" to true a grinding wheel?) By making very shallow cuts and not needing to lift the support bar, there is no problem with misalignment. True your grinding wheels frequently and lightly. A light pass or two does not take forever.
Ken
I did a similar repair not so long ago. Additionally, ran a diamond plate in the SE-77 over the stone surface. I didn't go slow with TT-50, so it was bit rough.
I did Grit 80, followed by 400, 1000 and 2000. The result was pretty much the same as I remember it was out of the box.
Quote from: Ken S on October 29, 2022, 02:02:39 AM
Tormek's suggestion of lifting the support bar and moving the TT-50 diamond to be able to travel inward is fairly new. [...] I suspect the lift was started because of chipping complaints from users who set the TT-50 to cut too deeply. [...] By making very shallow cuts and not needing to lift the support bar, there is no problem with misalignment. [...]
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.
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
Quote from: Nico on November 01, 2022, 09:00:36 AM
...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.
Quote from: RichColvin on October 27, 2022, 10:25:54 PM
...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.
Quote from: Nico on October 27, 2022, 10:56:20 PM
...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 (https://forum.tormek.com/index.php/topic,3339.0.html) 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 (https://www.mcmaster.com/shaft-couplers/set-screw-high-parallel-misalignment-flexible-shaft-couplings/) is the type I used.
(https://forum.tormek.com/index.php?action=dlattach;topic=5123.0;attach=6858)
I like the looks of some of these (https://www.mcmaster.com//for-shaft-misalignment-type~parallel/), especially the spring one.
Rick
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?
???? (https://forum.tormek.com/index.php/topic,3053.msg16372.html#msg16372)
Yes! Spot on. Thank you Rick!
Quote from: sharpening_weasel on November 14, 2022, 08:02:48 PM
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