Author Topic: What Does It Matter If The Stone Is Out-Of-Round A Little?  (Read 3828 times)

Offline Wyo6050

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #30 on: July 09, 2018, 03:21:38 pm »
Rick & cbwx34,

Thank you for the reply and tips for setting the USB.  Light is showing on the left/inside.

The first time it got out of round was when it was under 2 hours of use.  I've been sharpening hand plane blades, bench chisels and turning tools to include skews, gouges, and scrapers.  Nothing too serious. If I had to remove a lot fo metal I ran it trough the slow speed grinder first and then touched it up on the T4.  I could feel the high point in the wheel while applying pressure on the item being sharpened and see it as it made its rotation.  Since then I have paid more attention to it after I trued it out.  The wheel started to do it again, I could hear it and feel it while grinding.  I do grade between the coarses and noticed that sometimes the wheel 'grabs' the stone grader, makes a rotation and grabs it again.  I believe the spot(?) that is grabbing is a flat spot created either by the stone grader or a flaw in the stone as the metal trail in the stone after sharpening doesn't show any gaps or problems where the wheel isnt against the tool. That's another thread though. I don't think I was pressing too hard.  Then just recently while doing a hand plane blade it started getting out of round again.

I think that play in the vertical position is what caused the slant in the wheel.  My horizontal holes seem to be solid.




Offline jeffs55

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #31 on: July 10, 2018, 08:39:14 am »
I am starting to wonderif I havemisinterpreted "egg shaped". I would interpret egg shaped to mean not having a consistent radius if a compass was laid flat on the grinding wheel. I would interpret crowned to be if the grinding wheel had a high spot in the middle and tapered if one side was lower than the other.

I think it is good practice to regularly eliminate any of these problems.

Ken
You are correct, that is what has happened to my stone. I have not mucked with it yet but would say that a bent shaft would not cause my problem. A bent shaft would change the left to right motion of the wheel. In order for it to affect up and down, well you simply cannot bend the shaft like that. It would have to be bent like a crankshaft with the wheel being in another plane. I have yet to remove the stone in order to check. I am in GA and it is so hot here that I just burst out into a big sweat by opening the doors to the house!
You can use less of more but you cannot make more of less.

Offline Ken S

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #32 on: July 10, 2018, 02:48:56 pm »
Jeff,

I think many (most) Tormek users are afflicted with what I call the "precious grindstone syndrome". I am old enough to have ancient memories of the cost of a replacement six inch grinding wheel from my local store several decades ago. Compared to that, the cost of an SG-250 seems astronomical. However, looking a little deeper, The SG has a diameter of 250mm and a thickness of 50mm. It is physically much more grindstone. It is produced in much smaller numbers and is probably specially formulated. If we compared its cost with the same size grindstone from Norton purchased today, the cost would not seem so excessive.

We all suffer from a deep seated belief that grading the stone will shorten its life, and even worse, truing it will lessen its useful life even more. If we carry that logic even further, even sharpening with it shortens its life. This causes us to try to avoid grading and truing.

I have been criticized for suggesting frequent and light truing. I want my grindstone cutting at near 100% efficiency. With frequent and light truing, it will remain close to full efficiency. With practice, the truing operation becomes very efficient. I don't think most of us true often enough to ever develop that fluency and confidence. We do not wait until our knives will not cut butter to sharpen them; why do we procrastinate in maintaining our grindstones?

Ken

Offline cbwx34

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #33 on: July 10, 2018, 03:00:23 pm »
... I could feel the high point in the wheel while applying pressure on the item being sharpened and see it as it made its rotation.  Since then I have paid more attention to it after I trued it out.  The wheel started to do it again, I could hear it and feel it while grinding.  I do grade between the coarses and noticed that sometimes the wheel 'grabs' the stone grader, makes a rotation and grabs it again.  I believe the spot(?) that is grabbing is a flat spot created either by the stone grader or a flaw in the stone as the metal trail in the stone after sharpening doesn't show any gaps or problems where the wheel isnt against the tool. That's another thread though. I don't think I was pressing too hard.  Then just recently while doing a hand plane blade it started getting out of round again.
...

My only thought is what I mentioned somewhere else... perhaps mark the location of the flat spot on the side of the wheel... and see if it reappears at the same location?  Whether or not Tormek sees this as a flaw that they would replace... you would probably have to email Tormek support and ask them.

Offline jeffs55

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #34 on: July 10, 2018, 03:43:22 pm »
[

My only thought is what I mentioned somewhere else... perhaps mark the location of the flat spot on the side of the wheel... and see if it reappears at the same location?  Whether or not Tormek sees this as a flaw that they would replace... you would probably have to email Tormek support and ask them.
I will do that, if I can determine the location of the "flat spot". It would be interesting to know if it always appears in the same place. It could well be a problem with the mixing of the slurry that composes these stones. Having used mine for many years, I am not going to pursue a replacement. As for Ken, you are right about me and so many others. I can't get past the purposeful degradation of the stone. I mean, you do not turn your brake rotors when it is not needed in an effort to make them last longer. On the other hand, I can see where increased performance as in less time grinding would make the stone last longer. Then it goes back to taking that away by grinding off the surface. I will true mine as it annoys me to see the rise and fall of the wheel and just knowing that it is not right. Gotta let it cool off some or bring the Tormek indoors. With the little grinding that I do, it can wait.
You can use less of more but you cannot make more of less.

Offline Ken S

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #35 on: July 10, 2018, 04:22:02 pm »
Jeff,

I worked out a procedure for maintaining a constant rotational of the grinding wheel. I start at the dry end, marking an up arrow on the side of the drive wheel and leather honing wheel. This fixes the position of the shaft. With that fixed, an up arrow drawn on the grinding wheel at the optimal position fixes everything. When the grinding wheel is switched, make sure the arrow continues to point up.

A refinement of this would be to also mark an up arrow on the dry end of the shaft to make sure the tested rotation point was preserved during bushing regreasing. In the mechanic/machinist world, these arrows would be called "witness marks". Whether we like it or not, the deeper we venture into the precision sharpening capabilities of the Tormek, the more we must understand of the mechanic/machinist world.

I understand your brake rotor analogy. I think the brake pads would fit better. Every time we use our brakes instead of just removing our foot from the accelerator, we degrade (cause wear) on our brake pads. Every time we sharpen a knife, we remove metal, thus degrading it. Am I suggesting we stop using the brakes on our car or not sharpen our knives? Of course not. Sadly, our Tormek grinding wheels, like operators, are not immortal.

On a practical level, many light truings will have minimal effect of the wheel size. I start with a very light cut which barely touches the high spot. I continue with very light cuts (half a micro adjust number) until such a light cut become continuous. At that point the wheel is true. No more "one pass more for good measureā€.

Ken

Offline Grizz

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Re: What Does It Matter If The Stone Is Out-Of-Round A Little?
« Reply #36 on: July 12, 2018, 02:16:33 am »
same here Ken. ! :)