Michael on tue 29 feb 00
I am new to using slab rollers and am seeking advice from the more
experienced. I have used a Bailey 24" that was nice, only one adjustment,
fairly accurate, only one direction. I purchased a Noth Star Super 30" and
it is ok but the thickness gauge is way off and I can't seem to make slabs
less than 1/4" thick - the rollers will not get closer together even at
zero setting. I have a note in to the manufacturer to see if the unit is
defective. The big 4" rolls are good for big wads of stiff clay - making
thick tiles etc. It will pass both directions which seems good to ensure an
even slab - though the Baily seemed more even just once through.
Your suggestions welcomed!
Michael
Don & Isao Morrill on wed 1 mar 00
At 14:19 2/29/00 EST, you wrote:
>----------------------------Original message----------------------------
>I am new to using slab rollers and am seeking advice from the more
>experienced. I have used a Bailey 24" that was nice, only one adjustment,
>fairly accurate, only one direction. I purchased a Noth Star Super 30" and
>it is ok but the thickness gauge is way off and I can't seem to make slabs
>less than 1/4" thick - the rollers will not get closer together even at
>zero setting. I have a note in to the manufacturer to see if the unit is
>defective. The big 4" rolls are good for big wads of stiff clay - making
>thick tiles etc. It will pass both directions which seems good to ensure an
>even slab - though the Baily seemed more even just once through.
>
>Your suggestions welcomed!
>
>Michael
> There coould be several reasons for the lack of close
adjustment. I is possible that you have a slab-rollers which requies a
series of plywood pices of thicknesses less than the 1/4". Beyond that I
would suggst that you do not attempt to roll thick clay in a single pass
but,roll the clay though in stages. I know it appears unlikly but a single
pass of thick clay may be easy for your muscles,however it has been known
to slightly distort even 4"steel rollers. We have a 24" North Star with an
excellent roller surface design of hundreds of 'Delta'-shaped checks which
also assist in releasing strain in the clay and also allow us to roll clay
as thin as 1/8". The new NS at the Rec Centre where we have been
working,has plastic guages at each end of the top roll.While these are
useful,we have found that thin,narrow wood or plastic guages work equally
well.
Don & Isao
Don & Isao Sanami Morrill
e-Mail:
NakedClay@aol.com on wed 1 mar 00
Hi Michael!
There is one aspect of using a Northstar that you may have overlooked: the
thickness of the blanket that covers the clay. This will have an obvious
influence on the thickness of the slab you roll.
The blanket which comes with the slab roller is fairly thin, but I'd measure
it (doubled, as you would use it), and then determine the mechanical problem,
on the thickness adjustment. Both Northstar and Bailey produce excellent slab
rollers, and as far as I know, will answer your questions of their respective
slab rollers.
Milton NakedClay@AOL.COM
Michael on thu 2 mar 00
Thank you all for responding!
I have a call in to Bob at North Star. The plastic gauges mentioned are
there and do function there is just an offset of almost 1/4 inch i.e. at
zero you make a 1/4 slab at 1/2 you make a 3/4 slab using the canvas
provided. Being the engineer type turned farmer now turned potter - I feel
there is an error in the casting (engineer analysis) because the top roller
does not travel to nearly touching the lower roller when bottomed out in
the cast slot. I can see how a simple error in drilling the bearing holes
for the lower roller could cause this offset - since it is brand new I
figure I should hold off on the re drilling until I get a response from
North Star.
The machine does a great job and I think it is a bit more powerful than the
Bailey and the wagon wheel makes a smoother roll force than the 4 way
handle of the Bailey. The double adjustment on the north star can be made
into a single adjustment with the addition of a couple small sprockets and
a chain between the adjusting screw (the engineer redesigning and adding
enhancements!) I might make my own screws with sprockets and a chain if I
decide to keep this one.
Hopefully North Star will replace the roller unit to fix this 1/4" offset
problem - I would like to get to 1/8 without having to add a spacer - I
want the rollers to act on both sides of the clay not just push against a
plywood shim board. There are way around all this but it is new and it
appears that others do not have this offset problem. It is a good machine.
Michael
Michael on thu 2 mar 00
The Solution to the Slab Roller Puzler!
After talking to Bob at North Star and the use of calipers (my engineering
past life is useful again) we determined that the rollers were manufactured
0.10 to 0.15 inch under size in error. Thus the approximately 1/4 in error
(0.25 = 1/4 which is twice the roller error since there are two of them)
A new roller unit is on the way and I am again a happy North Star slab
rolleree.
Thanks for all the suggestions for ways to work around the problem. It
really shows the intelligence and creativity of potters and how working
with so many variable materials and methods breeds such beautiful artist
adaptation to the limitations we face. Sorry if I appeared so anal about
"...but it IS broke and I want to fix it" which is the motto engineers
fling back at the MBA's who say "If it ain't broke don't fix it!"
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