Brandon Phillips on thu 13 jan 11
Vince-
The trick with cups is to keep them flat and moving. When you hold them at
an angle you'll gouge the shelf. I have SiC shelves and they don't gouge
as easy as clay shelves, maybe they're not good for clay shelves at all.
I've been wood/salt firing for years and I constantly forget that not
everyone has to grind every side of their shelf after every firing. Not
using the nylon mesh disks for me is simply an economic choice. I don't
fear using them, I'd just go through too many of them. The diamond cups
just last longer, for my process. You're right, for the occasional drip I
don't see the need to invest in the diamond cup.
I've done a lot of metalwork(was a welder at one point in time) so I feel
my three incidents are fair considering the amount of work I've done. My
accident with the chop saw was because I didn't have the piece clamped in
tight enough and it moved while I was cutting. I've had a couple 4.5"
cutoff disks break on me but it was always when having to cut in an
uncomfortable position(overhead being one, the other was in a crawl space)
so I had a hard time keeping it straight. You're right about positioning,
be steady. You twist the grinder while those little cutoff disks are
going...hope you got your gear on.
Brandon Phillips
supportyourlocalpotter.blogspot.com
> Brandon Phillips wrote:
> "I had one of those disks with the nylon mesh in them explode on me and
> cut
> one of my fingers to the bone. I was using a chop saw, not an angle
> grinder, bigger blade same materials. I've had the small ones for an angl=
e
> grinder break on me too, but never hurt me(thank goodness, knock on wood.=
)
> I'm extrememly cautious when I use them, full protective gear. I was
> wearing all the proper protection but gloves when it happened. I would
> never use these for shelves, even the thicker grinding disks. For grindin=
g
> shelves I would use one of these:
> http://www.amazon.com/DEWALT-DW4770-4-Inch-Grinding-Wheel/dp/B0000VVZZ8."
>
> Brandon -
> The diamond cup wheel you linked to is a good one, and will never come
> apart, but the fiberglass-reinforced grinding disks and silicon carbide
> cup
> wheels I referred to in my post several days ago (and I also referred to
> the
> diamond cup wheels) work great as long as they are used safely. I have
> been
> using all variations of fiberglass-reinforced grinding disks and silicon
> carbide cup wheels since I was in undergrad school in the late 1960s and
> early 70s. I have used hundreds of them for grinding refractories and
> kiln
> shelves and for welding-fabricating projects. The only time I have ever
> had
> a fiberglass-reinforced disk come apart on me was in undergrad school whe=
n
> I
> was using a 9" cutoff disk on a large Milwaukee angle grinder. I was
> cutting a sprue off a cast iron casting, and I slipped and tweaked the
> wheel. It exploded, but I was wearing all the appropriate safety gear,
> and
> no harm was done. My footing was not good, and I learned a very valuable
> lesson - always make sure your footing is sound and you are standing
> comfortable when using a power tool. The fiberglass-reinforced grinding
> disks work great for grinding shelves, and can be used perfectly safely a=
s
> long as one does not bear down forcefully against the side of the disk.
>
> It is certainly true that the diamond impregnated steel cup wheels are th=
e
> safest choice. But as I mentioned in my post several days ago, it takes =
a
> little practice to get used to them, because they are so aggressive.
> Also,
> note that the prices from McGill's warehouse are far lower than the DeWal=
t
> diamond cup wheel on amazon. Here's a short section from my post the
> other
> day:
>
> With any angle grinder from 4" to 9" you can use a diamond cup wheel. Go
> to
> http://www.mcgillswarehouse.com/ProductList.aspx?CategoryID=3D120 or just=
go
> to www.mcgillswarehouse.com and click "Tools and Hardware" and then click
> "Polishing Pads, Adaptors, and Grinder Cups." Scroll down the page past
> all
> the diamond polishing pads and you will come to diamond cup wheels. They
> have 4", 5" and larger ones. The prices are very reasonable.
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpitelka@dtccom.net; wpitelka@tntech.edu
> http://iweb.tntech.edu/wpitelka
>
>
>
>
Lee on thu 13 jan 11
I've never understood the need for a grinder on a well kiln washed
shelve. I use a brick chisel for any glaze drips. Like this one:
http://www.google.com/products/catalog?q=3D3Dbrick+chisel&hl=3D3Den&safe=3D=
3Doff&=3D
rlz=3D3D1C1_____en&prmd=3D3Divns&resnum=3D3D1&biw=3D3D949&bih=3D3D623&um=3D=
3D1&ie=3D3DUTF=3D
-8&cid=3D3D6830012931012801438&ei=3D3DNZovTYeSEYKglAfyxvX0Cg&sa=3D3DX&oi=3D=
3Dproduc=3D
t_catalog_result&ct=3D3Dresult&resnum=3D3D7&ved=3D3D0CHgQ8wIwBg#
--
=3DA0Lee Love in Minneapolis
http://mingeisota.blogspot.com/
=3DA0"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D9=
7that is, =3D
"The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Maynard Leeman on thu 13 jan 11
Grinder Safety
I have a good friend that lost his eye in a grinder accident a few weeks=3D=
20=3D
ago. I talked with him yesterday. Here is the story. He bought a=3D20
pack of about 4 new grinder disks from a local NAPA auto parts store.=3D20=
=3D20=3D
Took them home. A short time latter he was trying to cut a piece of=3D20
wood stove pipe with some tin snips without much luck. So he got out=3D20
his grinder, but one of the new disks in the air powered grinder. He=3D20=
=3D
carefully marked the stove pipe with a sharpie type marker and got=3D20
ready to make the cut. He put the grinder wheel to the stove pipe.=3D20=
=3D20=3D
The disk immediately came apart leaving only the metal reinforcing=3D20
ring on the grinder itself. Pieces of the grinder wheel hit his eye. T=
=3D
he=3D20
surgeon said that the damage to his eye was so sevier that he=3D20
couldn=3D92t identify all of the eye parts. Sadly my friend lost his eye.=
=3D
He=3D20
is to be fitted with a new glass eye in a few days. He is 38 years old,=3D=
20=3D
=3D20
and has two teen age children and a wife. Luckily all he lost was his=3D2=
0=3D
eye.
The first obvious question was he wearing eye protection? As you=3D20
might guess he was not. The surgeon said that unless he had been=3D20
wearing a welding helmet it would have made no difference.
The second question, is, where were the disks made? No they were=3D20
not made in china. They were made in Indiana, USA.
The grinder was rated at the correct speed for the disks being used.
So what went wrong? The attorney engaged a testing lab to=3D20
determine why this happened. So far it appears that the only problem=3D20=
=3D
was the grinding disk. Nothing else could have prevented this accident.
Hear is the point. These grinder disks are very very dangerous tools.=3D2=
0=3D
=3D20=3D20
People are suggesting that potters use a grinder to remove glaze from=3D20
a kiln shelf. What kinda thinking is that. A grinder disk and glaze on=
=3D
a=3D20
kiln shelf is just an accident waiting to happen.=3D20=3D20
You should never follow the advice to use a grinder to remove glaze=3D20
from a kiln shelf. What is the cost of an eye?
William & Susan Schran User on thu 13 jan 11
On 1/13/11 1:33 PM, "Maynard Leeman" wrote:
> Hear is the point. These grinder disks are very very dangerous tools.
> People are suggesting that potters use a grinder to remove glaze from
> a kiln shelf. What kinda thinking is that. A grinder disk and glaze on=
a
> kiln shelf is just an accident waiting to happen.
>
> You should never follow the advice to use a grinder to remove glaze
> from a kiln shelf. What is the cost of an eye?
The cost of an eye is priceless.
It is a horrible accident, but as you wrote, the individual was not wearing
any eye protection.
I feel for this person's loss, but any piece of power equipment can cause
devastating injury.
One must understand all precautions one must take with machinery that moves
at such a high speed.
I don't know what type of grinder you write about, may be a straight
cutter/grinder, don't know, you didn't write what kind it is.
I do use an angle grinder to remove glaze from shelves and I have
experienced the thin grinding disk coming apart.
Anytime I use this machine, I examine the grinding disk to look for signs o=
f
cracks. I ALWAYS wear a full face shield and the grinder is positioned so
that if the disk comes apart, it will be away from me.
I understand your concern and I'm sorry for your friend's loss, but to make
a blanket statement that a grinder should not be used to remove glaze from =
a
kiln shelf would probably be better received as individuals should take
great care in using power equipment and wear appropriate protections and
select the proper equipment for the task.
Bill
--
William "Bill" Schran
wschran@cox.net
wschran@nvcc.edu
http://www.creativecreekartisans.com
Taylor Hendrix on thu 13 jan 11
I am sorry to hear of your friend's accident. I wish him a speedy recovery.
I would not advise folks to us any type of cut off disk for removing glaze
from kiln shelves. The auto parts disks sound like they were cut off disks,
and they are just not the disk to use for grinding-shelves work. If one
is going to try and use a grinder to remove glaze drips, he or she should
use a wheel designed for grinding and be very careful how one orients the
grinder to the work and to the body.
Find someone who knows how to use that tool and have them show you.
Grinding is what grinders were made for and they do a great job of it.
Taylor, in Rockport TX
wirerabbit1 on Skype (-0600 UTC)
http://wirerabbit.blogspot.com
http://wirerabbitpots.blogspot.com
http://www.flickr.com/photos/wirerabbit/
On Thu, Jan 13, 2011 at 12:33 PM, Maynard Leeman wr=
=3D
ote:
> Grinder Safety
>
> I have a good friend that lost his eye in a grinder accident a few weeks
> ago. =3DC2=3DA0I talked with him yesterday. =3DC2=3DA0Here is the story. =
=3DC2=3DA0 H=3D
e bought a
> pack of about 4 new grinder disks from a local ...
jonathan byler on thu 13 jan 11
depending on how you engage the grinding wheel into a piece of metal, =3D20=
=3D
especially thin sheet metal, it can come apart quickly. The wheel can =3D2=
0=3D
bind very easily, and from what I can tell, if the metal is a certain =3D20=
=3D
thickness it flexes and moves and makes it even easier for the wheel =3D20
to bind and possibly break.
that is why they make guards for grinders that are going to be used =3D20
with the cut-off wheels. and that is why you don't put your face in =3D20
line with the periphery of the wheel. and wear your safety glasses. =3D20=
=3D
and a face shield if you have one.
sorry to hear about your friend, hope he recovers quickly.
On Jan 13, 2011, at 12:33 PM, Maynard Leeman wrote:
> Grinder Safety
>
> I have a good friend that lost his eye in a grinder accident a few =3D20
> weeks
> ago. I talked with him yesterday. Here is the story. He bought a
> pack of about 4 new grinder disks from a local NAPA auto parts store.
> Took them home. A short time latter he was trying to cut a piece of
> wood stove pipe with some tin snips without much luck. So he got out
> his grinder, but one of the new disks in the air powered grinder. He
> carefully marked the stove pipe with a sharpie type marker and got
> ready to make the cut. He put the grinder wheel to the stove pipe.
> The disk immediately came apart leaving only the metal reinforcing
> ring on the grinder itself. Pieces of the grinder wheel hit his =3D20
> eye. The
> surgeon said that the damage to his eye was so sevier that he
> couldn=3D92t identify all of the eye parts. Sadly my friend lost his =
=3D20=3D
> eye. He
> is to be fitted with a new glass eye in a few days. He is 38 years =3D20=
=3D
> old,
> and has two teen age children and a wife. Luckily all he lost was =3D20=
=3D
> his
> eye.
>
> The first obvious question was he wearing eye protection? As you
> might guess he was not. The surgeon said that unless he had been
> wearing a welding helmet it would have made no difference.
>
> The second question, is, where were the disks made? No they were
> not made in china. They were made in Indiana, USA.
>
> The grinder was rated at the correct speed for the disks being used.
>
> So what went wrong? The attorney engaged a testing lab to
> determine why this happened. So far it appears that the only problem
> was the grinding disk. Nothing else could have prevented this =3D20
> accident.
>
> Hear is the point. These grinder disks are very very dangerous =3D20
> tools.
> People are suggesting that potters use a grinder to remove glaze from
> a kiln shelf. What kinda thinking is that. A grinder disk and =3D20
> glaze on a
> kiln shelf is just an accident waiting to happen.
>
> You should never follow the advice to use a grinder to remove glaze
> from a kiln shelf. What is the cost of an eye?
James Freeman on thu 13 jan 11
Maynard...
Sorry to hear about your friend's mishap. Was he really misusing a grindin=
g
wheel as a cutoff disc? They are very different things. A cutoff disc
should never be used for grinding, and a grinding disc should never be used
for cutting. Cutting discs are often mildly flexible, and usually contain
fiberglass or other mesh to add stability. Grinding discs are usually
rigid, and are quite brittle. If a grinding disc is misused for cutting an=
d
happens to bind in the cut, it can easily break apart.
Also, and with all due respect and sympathy for your unfortunate friend,
using an angle grinder without eye protection is sheer insanity. I never
operate any of my angle grinders without both hearing and eye protection,
and with all guards in place. I am not sure where you were headed with
reference to a welding helmet, but a welding helmet would not be the right
tool for the job. Welding helmets are designed to protect the face and eye=
s
from sparks and infrared radiation only, and any impact protection would be
strictly secondary and coincidental. Angle grinders are potentially
dangerous tools, especially if misused. Polycarbonate safety goggles are a
must. Some jobsites require both goggles and a face shield; good advice,
though I don't personally go that far.
Also, all abrasive wheels have maximum RPM ratings. Using any wheel at
speeds higher than that for which it is rated can lead to catastrophic
failure. Electric grinders typically spin at relatively slow speeds of 800=
0
to 10,000 RPM. Air grinders often spin at 20,000 to 25,000 RPM. It is
quite possible that your friend's air tool greatly exceeded the safe
operating range of the grinding wheels he purchased at the auto supply
store.
I wish your friend a speedy recovery.
...James
James Freeman
"...outsider artists, caught in the bog of their own consciousness, too
preciously idiosyncratic to be taken seriously."
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Thu, Jan 13, 2011 at 1:33 PM, Maynard Leeman wrot=
e:
> Grinder Safety
>
> I have a good friend that lost his eye in a grinder accident a few weeks
> ago. I talked with him yesterday. Here is the story. He bought a
> pack of about 4 new grinder disks from a local NAPA auto parts store.
> Took them home. A short time latter he was trying to cut a piece of
> wood stove pipe with some tin snips without much luck. So he got out
> his grinder, but one of the new disks in the air powered grinder. He
> carefully marked the stove pipe with a sharpie type marker and got
> ready to make the cut. He put the grinder wheel to the stove pipe.
> The disk immediately came apart leaving only the metal reinforcing
> ring on the grinder itself.
>
<#>
<#>
<#> <#>
Brandon Phillips on thu 13 jan 11
I had one of those disks with the nylon mesh in them explode on me and cut
one of my fingers to the bone. I was using a chop saw, not an angle
grinder, bigger blade same materials. I've had the small ones for an angle
grinder break on me too, but never hurt me(thank goodness, knock on wood.)
I'm extrememly cautious when I use them, full protective gear. I was
wearing all the proper protection but gloves when it happened. I would
never use these for shelves, even the thicker grinding disks.
For grinding shelves I would use one of these:
http://www.amazon.com/DEWALT-DW4770-4-Inch-Grinding-Wheel/dp/B0000VVZZ8
or your brand of choice. I'm pretty sure one of these will never come apar=
t.
Brandon Phillips
supportyourlocalpotter.blogspot.com
>> Hear is the point. These grinder disks are very very dangerous tools.
>> People are suggesting that potters use a grinder to remove glaze from
>> a kiln shelf. What kinda thinking is that. A grinder disk and glaze
>> on a
>> kiln shelf is just an accident waiting to happen.
>>
>> You should never follow the advice to use a grinder to remove glaze
>> from a kiln shelf. What is the cost of an eye?
Vince Pitelka on thu 13 jan 11
Brandon Phillips wrote:
"I had one of those disks with the nylon mesh in them explode on me and cut
one of my fingers to the bone. I was using a chop saw, not an angle
grinder, bigger blade same materials. I've had the small ones for an angle
grinder break on me too, but never hurt me(thank goodness, knock on wood.)
I'm extrememly cautious when I use them, full protective gear. I was
wearing all the proper protection but gloves when it happened. I would
never use these for shelves, even the thicker grinding disks. For grinding
shelves I would use one of these:
http://www.amazon.com/DEWALT-DW4770-4-Inch-Grinding-Wheel/dp/B0000VVZZ8."
Brandon -
The diamond cup wheel you linked to is a good one, and will never come
apart, but the fiberglass-reinforced grinding disks and silicon carbide cup
wheels I referred to in my post several days ago (and I also referred to th=
e
diamond cup wheels) work great as long as they are used safely. I have bee=
n
using all variations of fiberglass-reinforced grinding disks and silicon
carbide cup wheels since I was in undergrad school in the late 1960s and
early 70s. I have used hundreds of them for grinding refractories and kiln
shelves and for welding-fabricating projects. The only time I have ever ha=
d
a fiberglass-reinforced disk come apart on me was in undergrad school when =
I
was using a 9" cutoff disk on a large Milwaukee angle grinder. I was
cutting a sprue off a cast iron casting, and I slipped and tweaked the
wheel. It exploded, but I was wearing all the appropriate safety gear, and
no harm was done. My footing was not good, and I learned a very valuable
lesson - always make sure your footing is sound and you are standing
comfortable when using a power tool. The fiberglass-reinforced grinding
disks work great for grinding shelves, and can be used perfectly safely as
long as one does not bear down forcefully against the side of the disk.
It is certainly true that the diamond impregnated steel cup wheels are the
safest choice. But as I mentioned in my post several days ago, it takes a
little practice to get used to them, because they are so aggressive. Also,
note that the prices from McGill's warehouse are far lower than the DeWalt
diamond cup wheel on amazon. Here's a short section from my post the other
day:
With any angle grinder from 4" to 9" you can use a diamond cup wheel. Go t=
o
http://www.mcgillswarehouse.com/ProductList.aspx?CategoryID=3D120 or just g=
o
to www.mcgillswarehouse.com and click "Tools and Hardware" and then click
"Polishing Pads, Adaptors, and Grinder Cups." Scroll down the page past all
the diamond polishing pads and you will come to diamond cup wheels. They
have 4", 5" and larger ones. The prices are very reasonable.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
Vince Pitelka on thu 13 jan 11
Maynard Leehman wrote:
"Here is the point. These grinder disks are very very dangerous tools.
People are suggesting that potters use a grinder to remove glaze from a kil=
n
shelf. What kinda thinking is that. A grinder disk and glaze on a
kiln shelf is just an accident waiting to happen. You should never follow
the advice to use a grinder to remove glaze from a kiln shelf. What is the
cost of an eye?"
I am sorry about what happened to your friend, although it is hard to
imagine what he could have been thinking, using such a tool without eye
protection. Your information above is completely inaccurate and misleading=
.
Grinders are commonly used for cleaning kiln shelves and for grinding other
kiln furniture, and can be used very safely, ALWAYS WITH EYE PROTECTION.
Standard fiberglass-reinforced grinding disks (not cutoff wheels!), heavier
silicon carbide cup wheels, and diamond-impregnated cup wheels all work
great for grinding glaze deposits off of kiln shelves, and they are the
standard, acceptable method for removing heavy glaze deposits and for
restoring damaged kiln shelves and other refractory pieces.
Again, I am sorry about what happened to your friend, but that is no reason
to overreact and post such an inaccurate and misleading warning.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
jonathan byler on fri 14 jan 11
you obviously don't deal with some of the students we (and I'm sure =3D20
others) occasionally have. Despite the best training, they still find =3D2=
0=3D
ways to cause "accidents" and some of them are rather messy. like =3D20
someone slipping a raku piece onto the shelf with the ^10 ware...
life is easy when you work on your own, for the rest of us, thank god =3D20=
=3D
there are angle grinders.
On Jan 13, 2011, at 10:06 PM, Lee wrote:
> I've never understood the need for a grinder on a well kiln washed
> shelve. I use a brick chisel for any glaze drips. Like this one:
>
> =3D
http://www.google.com/products/catalog?q=3D3Dbrick+chisel&hl=3D3Den&safe=3D=
3Doff=3D
&rlz=3D3D1C1_____en&prmd=3D3Divns&resnum=3D3D1&biw=3D3D949&bih=3D3D623&um=
=3D3D1&ie=3D3DU=3D
TF-8&cid=3D3D6830012931012801438&ei=3D3DNZovTYeSEYKglAfyxvX0Cg&sa=3D3DX&oi=
=3D3Dpro=3D
duct_catalog_result&ct=3D3Dresult&resnum=3D3D7&ved=3D3D0CHgQ8wIwBg#
> --
> Lee Love in Minneapolis
> http://mingeisota.blogspot.com/
>
> "Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97t=
hat =3D
is, "The
> land of eternal youth is behind the house, a beautiful land fluent
> within itself." -- John O'Donohue
Steve Slatin on fri 14 jan 11
Yes, Vince, but we live in a world where --
right here, in our cozy little clayart-world
-- people will recommend doing things that
have a very significant risk of a small degree
of harm (like exposure to dust, note that none
of the cautions about grinding shelves have
recommended use of a respirator, which I
personally would consider as necessary as
eye protection), or a very slight degree of
risk (if you don't know what you are doing)
of a great deal of harm (like using a flame
source on a freezing gas tank, for which no
single person recommending CHECKING TO SEE
THAT YOUR HOSES AREN'T LEAKING GAS FIRST.
(Again, I would consider that an essential
precaution.)
Now I know that various folks here will say
that I'm just overcautious -- fair enough,
perhaps I am -- but I'm here and healthier
now than I was 10 years ago. (Liver enzymes
down to normal range, HgA1C almost at normal,
pulmonary capacity up about 6 percent, weight
down about 16 percent, vision as good in left
eye and only slightly worse in right.)
Cruel people dismiss others, and say that
it's OK for them to use lead glazes in=3D20
shared kilns because it's the other person's
responsibility to make sure their glaze doesn't
pick up the lead. Or they say that they can
recommend whatever they want, and if someone
who doesn't know safety procedure follows
their advice and blows themselves up, that's
OK because only a stupid person would follow
their advice without knowing everything that
they know. Or that you don't need to know
anything about electricity to work on a kiln,
you just need to be trained by the right person.
I say, differently, that human stupidity is
rare (put differently, in the movie Ruthless
People, "Complete morons are rare") but human
ignorance is quite the normal state of affairs.
I'm totally unsurprised that someone ground a
shelf without eye protection; I was only sad
that it wasn't mentioned earlier as a risk.
We all know that, for ourselves, safety comes
first. We should likewise remember that in a
world awash with ignorance, safety reminders
should be encouraged, and not dismissed out of
hand.
Steve Slatin --=3D20
--- On Thu, 1/13/11, Vince Pitelka wrote:
>=3D20
> I am sorry about what happened to your friend, although it
> is hard to
> imagine what he could have been thinking, using such a tool
> without eye
> protection.=3DA0 Your information above is completely
> inaccurate and misleading.
> Grinders are commonly used for cleaning kiln shelves and
> for grinding other
> kiln furniture, and can be used very safely, ALWAYS WITH
> EYE PROTECTION.=3D0A=3D0A=3D0A
Vince Pitelka on fri 14 jan 11
Lee Love wrote:
"I've never understood the need for a grinder on a well kiln washed shelve.
I use a brick chisel for any glaze drips."
Hi Lee -
Based on your comment above, I assume that you have never taught in an
academic setting, and have never adventurously experimented with glazes.
- Vince
Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpitelka@dtccom.net; wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka
| |
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