Robert Edney on tue 10 oct 06
Geez, I can believe I remember and wrote all this, but if you're into slab
rollers read on: By far the easiest (and cheapest) sort of real slab roller
to build is one that uses a basic frame and two rollers, one under the frame
and one on top -- the top roller is the one doing the work, while the lower
one (under the bed) follows it along and holds it down. In other words, the
entire bed is sandwiched between the two rollers, and the clay - being on
top of the bed - is compressed by the top roller. The rollers are connected
(and synchronized) by a clever arrangement of cable (aircraft cable is best,
flexible and strong) tensioned by a couple of turnbuckles. The thickness is
determined by varying the number of shims in the table frame (masonite in
1/8" increments works well). Something like this is made commercially
(Google Brent Model SRC) and there's some guy on EBay peddling them - search
EBay with slab roller and you'll see a picture. The only tricky part of the
design is the path of the cable as it wraps the upper and lower roller, but
a close examination of a catalog photo will give up the secret. This is
actually quick and fairly easy to build from hardware store parts and
doesn't require much skill. If anyone really, really cares I might be
enticed to draw up some basic plans. I built something like this with a
wooden frame years ago and it worked very well. However, the slab is
compressed and rolled from one side only, and the contraption takes up a
fair amount of room. It is possible, however, to roll the slab to double
the final thickness, flip it over (it's nicely laid out on the masonite
shim) and do a final roll to finished thickness. In theory this will even
out the stresses and make for a slab that will dry as flat as anything else
will.
The real dual roller machines use a clever arrangement of gears - there's a
gear on both ends of the top and bottom rollers and they are synchronized by
an idler gear under spring tension to the side. As the rollers are opened
up the idler gear moves in, staying in contact with both of the roller gears
(same arrangement on both sides). This provides for compressing the clay
evenly from both sides and seems to be the preference of most slab folks.
The throat opening is controlled by a couple of worm gears on both sides
with sprockets and a chain linking the two. Crank one side up or down and
the other side follows. This design also has the advantage of being able to
roll a theoretically limitless length, whereas the first example is confined
to the size of the bed (although you could make the bed as long as you
like). The parts to make such a thing are readily available, but now we're
talking about some fairly precision metal working to hold them all together.
Used slab rollers pop up frequently on EBay and Craig's List and could
probably be had for the cost of building something like this more
complicated variety.
Lastly, there seems to be an absence of plans on the web for slab rollers
that really work (and belong in a classroom).
Good luck!
_____
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Melissa Michael
Sent: Tuesday, October 10, 2006 12:57 PM
To: CLAYART@LSV.CERAMICS.ORG
Subject: Slab roller - make your own?
I have a zealous student in my Ceramics IV class who is also interested in
engineering. He'd like to build me a slab roller as a school project. Does
anyone have a good set of plans on how one can be made from scratch? He has
come up with a lot of great ideas on his own, but still struggles with how
to "adjust the width" of the clay.
Melissa Michael
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