Newbie questions about the Stone Grader SP-650

[Hatchcanyon]

I'm relatively new with the Tormek T-7. My wife started turning some month ago, asked me after some time for help sharpening the tools. There was a set of Japanese water stones from grid 120 to 8000 but these are in my opinion not very effective with turning tools. The simple bench grinder did more harm than good.

Then wo got a T-7 with the standard grindstone. Learning that this might not be the best stone for HSS steel we bought an additional SB-250. Works very well.

But it seems to influence the Stone Grader. After some uses - 5 to 8 times maybe - on the SB the Grader becomes quite slick, doesn't do a good job on reactivating the stone. A closer look showed a modification of the Graders surface. In the middle the grains are flattened reflecting light while the grain more to the end are still coarse.


The middle of the stone shows flattened grains


Magnified

What is going wrong and how can I get the SB stone back to a fresh fast cutting surface without truing?

Thanks for any help and advice.
Rolf

[Ken S]

Excellent question!

Welcome to the forum, Rolf. You are not alone. I am dealing with the same problem.I ordered a replacement stone grader. That cures the symptom, however, it doesn't really solve the problem. I think we need some high powered help from Sweden.

I used to think that I just wore out my old stone grader. Now I think the situation is not that simple. Now I am wondering if my touch might be part of the problem. I have learned that because of the hardness of the grit particles, the SB-250 cuts more effectively with a lighter touch. This is the opposite of the SG-250, which responds better to a heavy touch.

Another factor may be frequent sharpening or turning gouges. A knife, chisel, or plane blade presents a flat or nearly flat surface to the grindstone. A gouge presents a more concentrated surface.

I am curious to read other posts on this topic.

Ken

[Herman Trivilino]

My stone grader looks like that, too, and has since shortly after it was new, which was about 14 years ago.

Apply the corner (line where two surfaces meet) to the grindstone. That should refresh it. If not, the truing tool is the only other solution I know of, but that is a drastic measure that shouldn't be needed.

[Ken S]

I would like to interject my (minority) thought on truing the grinding wheel. I am a proponent of more frequent light truing. On several occasions I have found my grinding wheels have stealthfully become untrue. While heavy truing can be drastic, truing with a light touch before the wheel gets really out of true removes very little from the wheel. I usually make cutting depth less than one number on the microadjust, making several passes if necessary. Stop when a light cut is made on the entire grinding wheel. I must state that not everyone on the forum agrees with this point of view. One t hing I like about this forum is polite disagreement among friends.

Ken

[Dakotapix]

I agree with Ken on frequent but light truing of the Tormek wheel. My main problem is that I don't use my Tormek every day (or week) and I forget how to set up the truing tool and must refer to the instructions. However, I keep a small machinist square handy and frequently check the wheel for squareness. Stealthiness is a pretty good term to describe how the unsquareness of the wheel can occur.

[Hatchcanyon]

Thanks for the answers!

My feeling is, that a stone shouldn't need truing after that little amount of use - 7 irons - especially if it has not got grooves. Our stone is simply glazed and the grader unable to reactivate it quickly.

Do I expect too much?

Another finding from the last 24 hours:
A dirty SJ stone ca be cleaned without the grader using simply a kitchen paper towel to wipe away the dirt. Its better to do that on a still standing stone to get not too much water on the towel.

Rolf

[jeffs55]

There is a difference between cleaning and truing, I am guessing you misspoke. Your stone will never be "clean" again unless you true it. It will always have metal residue from use embedded in it. I agree that unless your stone is grooved or out of round it is too early to have to true it after only seven uses. On the other hand, I do not have that stone and do not know if it is able to have the grit value changed. Your grader does not true the stone, it only changes the grit substrate to another texture. Use the corner of the grader and bear down to the point of stalling the machine in an attempt to freshen the surface. When/if it refreshes then grind the grader and see if that roughens it up. But, the grader will always wear down unless it is made of diamond and even then, diamond wears out. In a nutshell, you cannot refresh the grader, you cannot resharpen the grains in the grader as you cannot access the grains individually and if you could it would take forever. Even if you used a diamond plate to flatten the grader because they wear, the grains would still be polished flat. Even if you true the stone, your grader will still be polished flat as it is now.  Just my 2¢ worth which is on sale today only for 1¢. Good luck

[Ken S]

Dakotapix,

A good Tormeker is never far from his machinist square! I have the same memory difficulty with the DBS-22 drill bit jig. It's a great jig, even more so if one remembers how to use it. A quick watch of the short video of the TT-50 at the accessories tab of tormek.com will temporarily restore your expert status.

Rolf,

The glazing issue with the SB-250 has arisen from time to time. In my opinion, it has never been fully resolved. I hope we can bring the issue to completion. People I respect have opposite opinions on the SB-250. The SB-250 has been in production for six years. I can't imagine Tormek adding a problem product to the line up and keeping it, which makes me think we might have a usage issue. Hopefully Sweden will ring in on this.

Ken

[Jan]

As I have already mentioned in another topic for me the whole grading/dressing procedure remains somewhat mysterious.

In my understanding the most important for successful grading is reaching the necessary depth of dressing cut. The only way how to do this is often the use of brute force. 

I have searched www for recommendations concerning the depth of dressing cut but unfortunately I have got only a few and even more ambiguous results. 

The best reasoned guidance was to make the depth of dressing cut equal to 10 to 30% of the average grain diameter. For 220 grit stone the average grain diameter is some 0.07 mm and so the recommended depth of dressing cut would be 0.007 to 0.02 mm. To measure such a small diameter changes is beyond our possibilities. To give you an idea it is less than one tenth of light truing cutting depth's mentioned by Ken.

Jan

[Hatchcanyon]

Hope to understand the difference beetween cleaning and truing.

The SB stone is still true but somewhat glazed. Trying to remove dirt with the grader from the stone did not work very well and I feel that using the truing tool for such a job is inappropiate. By the way, with the SB the grit value may be changed exactly the same way as with the SG stone.

In the afternoon I tried something different. Shaping a plane iron with 49 mm width. After a while the stone again worked more aggresively more or less the same way as in the beginning.

That reminds me of an experience I had years ago with a japanese King Waterstone grid 300. After a while this stone stopped removing metal as espected. Later I was told that this stone does not work well with alloy steel, is usable with CS steel only. Maybe it is something similar with the SB stone. I worked different makes of iron (Steiner, Kirschen, Crown) on it and maybe one alloy might be a problem.  Especially the Steiner iron is an old one from the 1960ies or early 1970ies.

Rolf

[Herman Trivilino]

My feeling is, that a stone shouldn't need truing after that little amount of use - 7 irons - especially if it has not got grooves. Our stone is simply glazed and the grader unable to reactivate it quickly.

Do I expect too much?

As I said, truing shouldn't be necessary to resolve this problem.

Did you apply the corner of the stone grader with lots of force? If you do, the corners will start to round over. This is what you want as it's the fastest way to get to fresh grains in the stone grader.

Do not worry about wearing out the stone grader. Such a worry is likened to a reluctance to apply the automobile brakes for fear it will wear them out. The brakes are made to wear, as are the stone grader and the grindstone.

[Dakotapix]

Good tip on watching the video, Ken. I just did that and I believe I can set up the TT-50 without a crib sheet. That was better than the written instructions.

Dakotapix,

A good Tormeker is never far from his machinist square! I have the same memory difficulty with the DBS-22 drill bit jig. It's a great jig, even more so if one remembers how to use it. A quick watch of the short video of the TT-50 at the accessories tab of tormek.com will temporarily restore your expert stat
Ken

[Ken S]

Dakotapix,

The older I get, the more frequently my memory needs to be refreshed!

I do not want to leave the impression that I believe the glazing issue can be resolved with the truing tool. The truing tool is an essential component of grinding, wet or dry. It should be included with the T4 and the price realistically adjusted to include it. The marketing department may have a point that not all sharpeners need a square edge jig, however, every Tormek user requires a truing tool. In fact, the wheel should be trued before it is used to sharpen the first tool. However, we should not include truing with deglazing.

There is a real problem with the SB-250 glazing. Sharpening seven plane blades or chisels should not necessitate truing the wheel. Chip carver Wayne Barton uses the expression "refreshing" his tool's edge. I think that would apply in this case. I don't know if the deglazing, cleaning or refreshing problem is a product problem or a problem caused by incorrect technique. I suspect it may be more related to incorrect technique, however, if that is the case, Tormek needs to address the issue more fully. Based on the number of blackstones probably sold, the number of complaints is low. The number of glowing reviews is considerably lower. I suspect many owners have poor results and just leave the blackstone on the shelf. I did that for a long time. Only after hearing of Steve's success with it did my blackstone reemerge.

Tormek has successfully resolved the problems of rusty shafts, out of square chisel grinds and diffuculties with the gouge jig. Let's finally resolve the problem of the blackstone!

Ken

[Hatchcanyon]

Some news about the glazing of the SB stone:

After dismounting it an letting it dry for a night - this was not a controlled test setup - the glazing problem was solvable with the grader.  Why? I don't know exactly.

Rolf

[Ken S]

Interesting observation, However, it does not solve the problem for the sharpener part way through sharpening his planer blade. There is more involved than we are presently seeing. The black srone seems to cut better with a light touch. Maybe the stone grader might work better with it by using a lighter touch. Too heavy a touch with the stone grader on the black stone might be the source of the premature wear on the stone grader.

I think we really need some help from Sweden on this.

Ken