Ann Brink on thu 22 oct 09
John, would you agree though that MDF is much slower to absorb water than
particle board?
I'm hoping my new bats absorb SOME moisture.
Your bats sound beautiful, tho.
Ann Brink in Lompoc CA
(mostly about pottery)
----- Original Message -----
From: "John Rodgers"
(snip)then - because MDF can soak up water - I
> applied a piece of laminate to one side, then re- drilled the bat pin
> holes through the laminate. Next I applied laminate to the opposite side
> - this time not drilling out the holes. This gave me a 2 foot diameter
> bat with bat pin holes on one side but not the side that would receive
> the clay. I used the router to trim the laminate round, then I sealed
> the edges of the MDF with sealer. and a coat of urethane. Perfect bats
> that have remained flat and true for 10 years. They have been worth
> every bit of the effort in making them.
>
> My $0.02 on bats.
>
> Regards,
>
> John Rodgers
> Chelsea, AL
>
Randall Moody on thu 22 oct 09
I have cut about 8 Hardiboard bats for the Art Center. My recommendations,
if you want to do this, are:
1) do it outside (DUST!!!)
2) wear a good mask (same as above)
3) don't bother with the diamond or expensive blades for the jigsaw. They
cost more and you can get two regular blades for $1.99 at most big box
stores. I got about 2.5 bats per blade. Regular blades seemed to work well.
6 to 8 teeth per inch.
4) I used the scraps for ware boards. (~8"x8")
5) did I mention DUST!
I used my removable wheel head as a template which made things much easier
for marking where the holes were to go. I will let everyone know what the
opinions are on the use. I am hoping that they work much like a plaster bat=
.
--
Randall in Atlanta
Ann Brink on thu 22 oct 09
Hi Randall,
This week I have been making bats of MDF. I've made 8 12" ones, and 6 15"
ones. I made the smaller ones first, and broke about 4 blades. That
material is really dense! I am replacing my particle board bats that have
served me well for over 20 years.
I decided to use MDF because I had a scrap of it here and made one bat of
it, and used it for several months, and liked the fine texture of it. So I
bought a 4x8 sheet. I have enough material left to make 9 more 12 inchers.
There are some things I throw that I just pick up and place on a ware board
and I use canvas squares for mugs and small bowls, but like bats for plates
etc.
Let us know how the Hardiboard works out. I sometimes wedge on it and notic=
e
how it sucks moisture, so it may act about the same as plaster.
Ann Brink in Lompoc Ca
(mostly about pottery)
----- Original Message -----
From: "Randall Moody"
>I have cut about 8 Hardiboard bats for the Art Center. My recommendations,
> if you want to do this, are:
>
> 1) do it outside (DUST!!!)
> 2) wear a good mask (same as above)
> 3) don't bother with the diamond or expensive blades for the jigsaw. They
> cost more and you can get two regular blades for $1.99 at most big box
> stores. I got about 2.5 bats per blade. Regular blades seemed to work
> well.
> 6 to 8 teeth per inch.
> 4) I used the scraps for ware boards. (~8"x8")
> 5) did I mention DUST!
>
> I used my removable wheel head as a template which made things much easie=
r
> for marking where the holes were to go. I will let everyone know what the
> opinions are on the use. I am hoping that they work much like a plaster
> bat.
>
>
> --
> Randall in Atlanta
---------------------------------------------------------------------------=
-----
Taylor Hendrix on thu 22 oct 09
Randall and others,
I have found that blades for metal last quite awhile, but the best for
the job are those blades used for ceramic tile. For some reason the
cheaper store brands last longer than the higher priced ones. Get
medium or rough grit if you have a choice.
And Hardi does for sure tell you to use dusk protection.
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, Oct 22, 2009 at 8:57 AM, Randall Moody wr=
ote:
> I have cut about 8 Hardiboard bats for the Art Center. My recommendations=
,
> if you want to do this, are:
>
> 1) do it outside (DUST!!!)
> 2) wear a good mask (same as above)
> 3) don't bother with the diamond or expensive blades for the jigsaw. They
> cost more and you can get two regular blades for $1.99 at most big box
> stores. I got about 2.5 bats per blade. Regular blades seemed to work wel=
l.
> 6 to 8 teeth per inch.
> 4) I used the scraps for ware boards. (~8"x8")
> 5) did I mention DUST!
>
> I used my removable wheel head as a template which made things much easie=
r
> for marking where the holes were to go. I will let everyone know what the
> opinions are on the use. I am hoping that they work much like a plaster b=
at.
>
>
> --
> Randall in Atlanta
>
John Rodgers on thu 22 oct 09
Eleven years ago I bought the Pure and Simple bat system and made a
bunch of plaster bats. They have seen heavy use, and I still have most
of them. At the same time, I bought some MDF and made 24 inch bats for
large platter work. To cut the MDF, I used my router and cut perfect
circles that were 2 feet in diameter. To do this I made a plastic piece
that was an extension to the router and put a hole in the end that would
give as the distance from the center of the whole to the edge of the
router bit - the exact distance for a 12 inc radius cut - thereby giving
me a two foot diameter circle when done. I marked and drilled the bat
pin holes completely through, then - because MDF can soak up water - I
applied a piece of laminate to one side, then re- drilled the bat pin
holes through the laminate. Next I applied laminate to the opposite side
- this time not drilling out the holes. This gave me a 2 foot diameter
bat with bat pin holes on one side but not the side that would receive
the clay. I used the router to trim the laminate round, then I sealed
the edges of the MDF with sealer. and a coat of urethane. Perfect bats
that have remained flat and true for 10 years. They have been worth
every bit of the effort in making them.
My $0.02 on bats.
Regards,
John Rodgers
Chelsea, AL
Randall Moody wrote:
> I have cut about 8 Hardiboard bats for the Art Center. My recommendations=
,
> if you want to do this, are:
>
> 1) do it outside (DUST!!!)
> 2) wear a good mask (same as above)
> 3) don't bother with the diamond or expensive blades for the jigsaw. They
> cost more and you can get two regular blades for $1.99 at most big box
> stores. I got about 2.5 bats per blade. Regular blades seemed to work wel=
l.
> 6 to 8 teeth per inch.
> 4) I used the scraps for ware boards. (~8"x8")
> 5) did I mention DUST!
>
> I used my removable wheel head as a template which made things much easie=
r
> for marking where the holes were to go. I will let everyone know what the
> opinions are on the use. I am hoping that they work much like a plaster b=
at.
>
>
> --
> Randall in Atlanta
>
>
>
John Rodgers on fri 23 oct 09
Ann,
Plaster bats are the only kind that I know of that will absorb water yet
not swell. That is one reason I like plaster bats. You can throw on them
and there is a good bond between the wet clay and the plaster. Then,
after sitting a while, the plaster will absorb enough water from the
clay to the extent that the clay will automatically release from the
bat, leaving a very smooth bottom on the pot. For a person of sufficient
skill, trimming then will be minimal, thus speeding the process of
production.
MDF bats, particle board, chipboard bats or similar, are all subject to
swelling and distortion when they absorb water. They are, after all, a
fiber material simply glued together under pressure. There is nothing
there to prevent the fiber material from entraining water and swelling.
Particle board and the like is more likely to swell than MDF but they
both WILL swell and distort. This is why 1) I chose MDF, and 2) bond a
plastic laminate to both sides of my MDF bats and seal the edges.
There are some fiber type boards that are significantly water impervious
and they are referred to as being "tempered". Sometimes this type is
used in association with components of slab rollers. My small manual
Brent slab roller came with a set of these boards, and they resist water
pretty well.
Finally - by far, most fiber-and-glue type boards from the typical
hardware store or lumber yard will absorb water and swell unless you
treat them in some manner. Cementious boards such as hardiboard will
absorb water without significant - if any - swelling at all.
Lastly - plaster bats are good, hold up well, absorb water well, release
the pots well, and are cheap enough. BUT - they are heavy and take up a
lot of space. So if space is a problem for the potter - they are not a
good choice. But for me - I'll stick witht he plaster bats - except when
I am making my very large 24 in. platters. Then I switch to my laminated
MDF bats.
Hope this helps.
John Rodgers
Chelsea, AL
http://www. moldhaus.com
Ann Brink wrote:
> John, would you agree though that MDF is much slower to absorb water than
> particle board?
> I'm hoping my new bats absorb SOME moisture.
>
> Your bats sound beautiful, tho.
> Ann Brink in Lompoc CA
> (mostly about pottery)
>
> ----- Original Message -----
> From: "John Rodgers"
>
> (snip)then - because MDF can soak up water - I
>> applied a piece of laminate to one side, then re- drilled the bat pin
>> holes through the laminate. Next I applied laminate to the opposite side
>> - this time not drilling out the holes. This gave me a 2 foot diameter
>> bat with bat pin holes on one side but not the side that would receive
>> the clay. I used the router to trim the laminate round, then I sealed
>> the edges of the MDF with sealer. and a coat of urethane. Perfect bats
>> that have remained flat and true for 10 years. They have been worth
>> every bit of the effort in making them.
>>
>> My $0.02 on bats.
>>
>> Regards,
>>
>> John Rodgers
>> Chelsea, AL
>>
>
>
Richard White on fri 23 oct 09
I made some hardiboard (lower case usage of the brand name intentional -
some were from Hardiboard brand sheets, others were whatever Home Despot =
=3D
was
selling that day...) bats several years ago. They have served me well. Th=
=3D
ey
do absorb some water without swelling the way MDF and other fiber board
does, and the ware pops off in due course just as with plaster bats. Some=
=3D
thoughts about the way I made them:
I used an 8" abrasive masonry circular saw blade on a radial arm saw. You=
=3D
probably could achieve the same result with a table saw. First, I cut the=
=3D
hardiboard sheet into square blanks slightly larger than desired bat, usi=
=3D
ng
the usual score and bend on the line method for gypsum drywall. The mater=
=3D
ial
is manufactured with a sheet of fiberglass mesh just below the surface on=
=3D
each side, so you only need to cut deep enough to get through the mesh. O=
=3D
f
course, your utility knife blade will be useless forever after, but
replacement blades are cheap and plentiful.=3D20
Then I made a plywood sled with a nail sticking up through the middle tha=
=3D
t I
clamped to the saw worktable, positioned so that the nail was on a line
perpendicular to the the blade center of rotation (i.e., parallel to and
aligned with the arbor shaft) and exactly the desired radius distance awa=
=3D
y
from the blade. On the radial arm saw, I had to pull the saw out and rota=
=3D
te
it as as if I were ripping; on the table saw, just work in the area to th=
=3D
e
right of the blade.
Draw an "X" from corner to corner on each hardiboard square to locate the=
=3D
center of the blank, and drill a small hole that is very slightly larger
than the nail. With the radial arm saw blade raised well above the work
area, or with the table saw blade fully lowered, set a blank on the nail
through the hole so that it rotates beneath/above the blade.=3D20
Turn the saw on and lower/raise the blade until it just barely cuts the
surface of the hardiboard blank. Slowly rotate the blank about the nail s=
=3D
o
that the abrasive blade scribes a circle. Lower/raise the blade slightly,=
=3D
and rotate the blank around again, cutting the circle a bit deeper. Repea=
=3D
t,
cutting slightly deeper each time, until you have cut all the way through=
=3D
.
You might even cut half way through and then raise/lower the blade, flip =
=3D
the
blank on the nail, and finish the cut from the other side. This might giv=
=3D
e
you a cleaner edge.
As noted by others, the dust production will be HUGE! Most stationary saw=
=3D
systems have a dust collection port. Even if you don't have a full-scale
dust collection system on your home saw, you should put your shop-vac on =
=3D
the
dust collection port to draw off the dust and chips. If your saw is a
smaller contractor type, take it outside for this operation. It's gonna m=
=3D
ake
a mess! The other usual safety precautions of eye, ear, and breathing
protection are implicit!
After cutting the blanks into rounds, I drilled them for bat pins with a
3/8" carbide-tipped masonry bit. For this, I carefully made a jig out of =
=3D
a
15" piece of 1/8"x1" strap steel. I drilled a hole at the exact center th=
=3D
e
same size as another nail like the one in the plywood sled on the saw, an=
=3D
d
then carefully drilled a pair of 3/8" holes exactly 5" toward each end of=
=3D
the strap. These holes must exactly match the bat pin holes on your
wheelhead. Push a nail through the center hole of the jig, set the nail
through the hole in the center of the round bat, and clamp the strap to t=
=3D
he
bat securely at both ends. Now you can use the holes in the jig to align =
=3D
the
masonry drill bit in the proper place for bat pin holes.
Finally, I noted that the cut edges of the hardiboard - both around the
circumference and the bat pin holes - tends to crumble when exposed. I go=
=3D
t
some two-part epoxy and mixed a small batch, which I then smeared all the=
=3D
way around the outside edge and in the bat pin holes. After the epoxy cur=
=3D
ed,
I sanded the edges smooth and used the pin drilling jig again, this time
with a standard steel twist bit, to redo the edges of the holes.
This all may sound like a bit of a production, which it admittedly is, bu=
=3D
t
you are better off to approach it this way if you are going to make more
than one or two bats with the scraps leftover from a bathroom tile
remodeling job.
dw
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