Author Topic: hollow grinding  (Read 669 times)

Offline Ken S

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hollow grinding
« on: October 03, 2021, 01:59:55 pm »
I think Stumpy Nubs did a particularly good job of explaining the real world effect of the hollow grind when using a Tormek.

https://youtu.be/6oTbMiLn2us

Ken

Offline cbwx34

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Re: hollow grinding
« Reply #1 on: October 03, 2021, 03:55:49 pm »
I think Stumpy Nubs did a particularly good job of explaining the real world effect of the hollow grind when using a Tormek.

https://youtu.be/6oTbMiLn2us

Ken

If you look at other threads on this topic, in particular the posts from Jan...

https://www.tormek.com/forum/index.php?topic=1860.0
https://www.tormek.com/forum/index.php?topic=2413
https://www.tormek.com/forum/index.php?topic=3428

... Stumpy Nubs video doesn't really ring true?   ???
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Offline Ken S

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Re: hollow grinding
« Reply #2 on: October 04, 2021, 03:32:31 am »
CB,

Your point is well made. On a practical level, Tormek users have been successfully sharpening chisels for half a century with their "hollow grind" wheels. That may  not carry much argumentative weight with some of our more technical members; however, it suffices for this Neanderthal.     :)

Ken

Offline RichColvin

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Re: hollow grinding
« Reply #3 on: October 04, 2021, 04:34:40 am »
I’ve not gotten good enough as a woodworker to find the hollow grind as the limiting factor in my production.
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Offline cbwx34

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Re: hollow grinding
« Reply #4 on: October 04, 2021, 05:20:59 am »
CB,

Your point is well made. On a practical level, Tormek users have been successfully sharpening chisels for half a century with their "hollow grind" wheels. That may  not carry much argumentative weight with some of our more technical members; however, it suffices for this Neanderthal.     :)

Ken

The problem isn't the hollow grind though, it's his advice on how to deal with it, by either honing it away, or sharpening at a higher angle?  Both unnecessary IMO, and kinda defeats the advantages of a lower angle?
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Offline Ken S

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Re: hollow grinding
« Reply #5 on: October 04, 2021, 09:03:04 am »
CB,

As much as it pains me, I have to agree with you. Although I believe Stumpy's intentions were good, he has fallen into the very common trap of hollow grinding with a six inch grinder. Six inch grinders were used by almost everyone fifty years ago. (I bought mine in 1973.) I presume almost everyone on this forum uses a Tormek, generally with a 250mm (10”) grinding wheel. Even the CBN dry grinder he shows uses an eight inch wheel, like the T4. Personally, I have never bothered to compesate the bevel angle when using either size Tormek.

Finishing with flat bench stones is another leftover from the high speed dry grinding days. Using a water cooled Tormek, it is easy to forget how often we burned tool edges with a dry grinder. Good practice was to stop short of fully grinding the edge and finish off with bench stones. The hollow from the dry grinder reduced the amount of hand grinding needed. This is not needed with a Tormek. The electric motor provides all the power.

Old habits die hard, especially if we already have several bench stones. We still have devoted followers of bench stones. Like you, CB, I believe using bench stones is unnecessary with a Tormek, especially if light pressure is used with the final passes.

Ken

Offline Herman Trivilino

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Re: hollow grinding
« Reply #6 on: October 04, 2021, 06:55:35 pm »
As the above links to other conversations reveal, when you use the Angle Master to set the angle on a chisel, you are setting the angle at the very tip of the chisel, not the angle described by Stumpy in the video.
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