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Posted by Dick on January 25, 2008, 5:39 pm
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Hello All. I have one of the 129.99 on sale H/F dual wheel tool grinders
with green wheels for sharpening carbide lathe tooling. I have read on this
forum a number of times that these wheels nor diamond wheels should be used
for sharpening tool steel tooling. I normally use carbide tooling but am
thinking of switching to tool steel as it can be ground so much sharper and
almost all of my cutting is wood or phenolics which needs a sharp edge. Any
way, the question is, what would be the best stones to put onto this grinder
to form and sharpen tool steel?
Dick
--
RHN Custom Billiard Cues
Building fine cues for real pool players at
affordable prices. All work guaranteed.
Dick Neighbors Cincinnati OH
(513) 830-4321
web-site http://dickiecues.com
e-mail dicky@dickiecues.com
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Posted by Ed Huntress on January 25, 2008, 7:55 pm
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> Hello All. I have one of the 129.99 on sale H/F dual wheel tool grinders
> with green wheels for sharpening carbide lathe tooling. I have read on
> this forum a number of times that these wheels nor diamond wheels should
> be used for sharpening tool steel tooling. I normally use carbide tooling
> but am thinking of switching to tool steel as it can be ground so much
> sharper and almost all of my cutting is wood or phenolics which needs a
> sharp edge. Any way, the question is, what would be the best stones to put
> onto this grinder to form and sharpen tool steel?
>
> Dick
The favorite of many people is Norton's white wheels, which are soft-bonded
aluminum oxide. 60 grit is preferred because it cuts much cooler than finer
grits and you're only supposed to use a wheel for shaping, anyway. Most of
us go farther than that, grinding lathe tools almost to completion and only
taking a few finishing passes on a hand stone.
If you do woodwork and you want something that is also semi-safe for
rough-grinding your plane irons and chisels, the white wheel is the way to
go. But high-speed steel -- the real stuff, not the Chinese "M50
equivalent" -- is tempered at 1050 deg. F or higher and actually can be
ground until it glows very dull red. Try that with your plane irons and
they'll be ruined forever, of course. But don't worry if you draw some
color -- straw, peacock or even dark blue -- with real HSS.
For that reason I use finer and harder wheels for grinding my lathe bits:
ordinary blue-gray Norton aluminum oxide. Stay away from Chinese-made Norton
wheels. They have a reputation for glazing badly. There are other good
brands; check around the Web to see what heavy users are using today. And
you really can grind HSS on your green wheels. Some people prefer them but
most stick to aluminum oxide because it leaves a better finish and it cuts
cooler, and it doesn't load or glaze as easily. Just don't use green wheels
on any other type of steel.
--
Ed Huntress
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Posted by Randal O'Brian on January 26, 2008, 1:00 pm
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>
>> Hello All. I have one of the 129.99 on sale H/F dual wheel tool grinders
>> with green wheels for sharpening carbide lathe tooling. I have read on
>> this forum a number of times that these wheels nor diamond wheels should
>> be used for sharpening tool steel tooling. I normally use carbide tooling
>> but am thinking of switching to tool steel as it can be ground so much
>> sharper and almost all of my cutting is wood or phenolics which needs a
>> sharp edge. Any way, the question is, what would be the best stones to
>> put onto this grinder to form and sharpen tool steel?
>>
>> Dick
>
> The favorite of many people is Norton's white wheels, which are
> soft-bonded aluminum oxide. 60 grit is preferred because it cuts much
> cooler than finer grits and you're only supposed to use a wheel for
> shaping, anyway. Most of us go farther than that, grinding lathe tools
> almost to completion and only taking a few finishing passes on a hand
> stone.
>
> If you do woodwork and you want something that is also semi-safe for
> rough-grinding your plane irons and chisels, the white wheel is the way to
> go. But high-speed steel -- the real stuff, not the Chinese "M50
> equivalent" -- is tempered at 1050 deg. F or higher and actually can be
> ground until it glows very dull red. Try that with your plane irons and
> they'll be ruined forever, of course. But don't worry if you draw some
> color -- straw, peacock or even dark blue -- with real HSS.
>
> For that reason I use finer and harder wheels for grinding my lathe bits:
> ordinary blue-gray Norton aluminum oxide. Stay away from Chinese-made
> Norton wheels. They have a reputation for glazing badly. There are other
> good brands; check around the Web to see what heavy users are using today.
> And you really can grind HSS on your green wheels. Some people prefer them
> but most stick to aluminum oxide because it leaves a better finish and it
> cuts cooler, and it doesn't load or glaze as easily. Just don't use green
> wheels on any other type of steel.
>
> --
> Ed Huntress
If you can find one, buy the blue Norton SG (seeded gel)wheels instead of
the normal white ALOX wheels. They cut cooler and don't require dressing
nearly as much as the white ones. They are expensive, but it in IMHO.
Randal
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Posted by Ed Huntress on January 26, 2008, 12:10 am
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<snip>
>> It's call "high-speed steel" because it will take the heat of high-speed
>> cutting -- up to 1050 deg. F or higher -- without losing its temper.
>> That's
>> glowing very dull red; well beyond blue or brown So it will take that
>> heat
>> in grinding, too. What it won't take is thermal shock.
>>
>> Old-time machinists knew this. Somewhere along the way the knowledge was
>> lost.
>>
>> --
>> Ed Huntress- Hide quoted text -
>>
>> - Show quoted text -
> The other thing with grinding HSS is that it grinds pretty slowly with
> light pressure. Grind it with heavier pressure, and it goes much
> faster than the pressure difference might dictate. I'll touch up tool
> bits holding them in my fingers, but for quick shaping you want them
> in a holder so you can bear down.
> John Martin
Yes! When HSS was used for production turning, machinists would grind the
stuff very aggressively. I don't hold HSS in my fingers. I either keep it in
the tool shank or I grab it with Vise Grips. The latter is *not* to be
recommended unless you're wearing full face protection and a bulletproof
vest. But it sure works. d8-)
--
Ed Huntress
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Posted by F. George McDuffee on January 26, 2008, 1:10 am
Please log in for more thread options On Fri, 25 Jan 2008 23:18:09 -0500, "Ed Huntress"
<snip>
>Never dip HSS in water as you're grinding it. The thermal shock will kill
>it; not as quickly as water-dipping will kill carbide, but the risk is
>there. You will certainly create microcracks and they will weaken the tool.
<snip>
==========
I should have been more explicit on this point.
If you have the tool in some sort of holder [so you can hold onto
it] and have ground it until color starts to appear, its too hot
to dip, especially if you use cold tap water.
You don't want to let the tool get hot enough that it "hisses"
when you dip it in the water, and the water should be room temp.
If you have it in a holder of some sort where you can get it to
the point of color change, its too hot to dip. Its very [too]
easy to do this when you have a thin/fine edge for example a high
rake high relief tool. the heat conductivity of HSS is not good
and rapid local heat build-up while grinding is a problem.
One thing you can do in the home shop is to keep a spray bottle
[e.g. used 409 spray bottle] of water handy and mist the wheel
face from time to time. Not so much water that you make a big
mess, but enough to evaporate and keep things cool as you grind.
You can prevent [much of the] rust if you will add a little water
soluble water pump lube to the spray water -- 98 cents at pep
boys or wal mart.
Also if you want to get fancy, you can use fine grit wet-or-dry
finishing paper around a larger tool bit [to keep it flat] as a
lap or hone to put mirror finish on the tool if you would like.
I don't know how much good this does in normal use, but several
model makers I know swear this is the best way to sharpen tools
to machine plastics.
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> with green wheels for sharpening carbide lathe tooling. I have read on
> this forum a number of times that these wheels nor diamond wheels should
> be used for sharpening tool steel tooling. I normally use carbide tooling
> but am thinking of switching to tool steel as it can be ground so much
> sharper and almost all of my cutting is wood or phenolics which needs a
> sharp edge. Any way, the question is, what would be the best stones to put
> onto this grinder to form and sharpen tool steel?
>
> Dick