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single pass vs multiple pass slab roller


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I'm shopping for a slab roller for my daughter and I'm wondering if I should get her a Bailey that can flatten a lot of clay in a single pass or a Shimpo that requires multiple passes. Do those multiple passes compromise the clay? Or is the single pass just a matter of convenience? 

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I have access to both Bailey and other rollers. Based on what I know about the properties of clay, I believe the single pass capability of the big Bailey rollers is inappropriate advertising. Clay, when rolled into slabs tends to shrink more in the direction that it had been rolled. A slab rolled in a single direction, whether in a single massive crunch through a Bailey big boy or multiple rolls by hand with a kitchen rolling pin (all in the same direction, contrary to conventional practice of rolling in different directions) will shrink back more in that dimension. Thus, a perfect circle cut from a unidirectional slab will dry to an oval. Perfectly fitted pieces will dry together uniformly only if assembled when the direction of the roll is maintained across all the pieces. All that said, I love and prefer the Bailey big boys, but I never roll in a single pass. Set the roller for a thick slab, flip it and rotate it for a second pass with the roller set thinner, and maybe a third time to the final thickness.

Edited by Dick White
typo/word
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Wow. Thanks for the detail. Very generous of you. Sounds like multiple passes are actually a good thing, resulting in a more reliable shape in the end. Maybe there's a lower end Bailey I should get her? She's only making a piece here and there, so she doesn't need speed, but she does need good quality.

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I started out with  a pastry chefs rolling pin,   I didn't buy my Baily slab roller until I started  making tiles.   I still get out my rolling pin  on smaller projects.   I bought the Baily without the table and my husband built me one from the instructions that came with it.   I have had it for twenty five years,  still works like its new.   Just make sure this is what she really needs and has the room for it.    Denice

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Dick is spot on with the two directional rolling -that said I still think Bailey is the better roller

also that said I never roll my clay thru more than once -but I use a special clay body that can take the slab to baking dish forms without monkeying around to much.

The double  power rollers do a good job-I also make wall fish and never pass them thru more than once.

Edited by Mark C.
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Amen to the multiple passes. 

NSEW flip NSEW flip NSEW flip NSEW flip.

Do you know what she intends to build?

I only ask because if it doesn't require super long and wide slabs, maybe a pugmill would be a better gift?

I don't mean to fully change gears on you, but gaining insight to give the perfect gift is something I'm into.

Sorce

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2 hours ago, Mia Dad said:

I see that the tables sold have a short side for where the clay goes in. Would it make it easier to feed the clay through the second time if the two sides were equal?

 

That would seem to be so just looking at the pictures (and there are some who actually do that, perhaps because they don't know better). When the slab is passed through the rollers, it will be thicker before it enters the roller and thinner when it exits. That's obvious. What is not obvious is that the table on the outfeed side of the roller is exactly level with the top of the lower roller, so that the slab slides evenly onto it as it exits. The table on the infeed side of the roller is slightly lower than the top of the bottom roller, so that both rollers are able to grab onto the leading edge of the incoming slab and pull it through.

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9 hours ago, Dick White said:

I have access to both Bailey and other rollers. Based on what I know about the properties of clay, I believe the single pass capability of the big Bailey rollers is inappropriate advertising. Clay, when rolled into slabs tends to shrink more in the direction that it had been rolled. A slab rolled in a single direction, whether in a single massive crunch through a Bailey big boy or multiple rolls by hand with a kitchen rolling pin (all in the same direction, contrary to conventional practice of rolling in different directions) will shrink back more in that dimension. Thus, a perfect circle cut from a unidirectional slab will dry to an oval. Perfectly fitted pieces will dry together uniformly only if assembled when the direction of the roll is maintained across all the pieces. All that said, I love and prefer the Bailey big boys, but I never roll in a single pass. Set the roller for a thick slab, flip it and rotate it for a second pass with the roller set thinner, and maybe a third time to the final thickness.

Have you ever actually tried this as an experiment in practice or are you only talking theory?  I'm not disputing what you are saying, just asking if you've ever set up a trial and measured results.

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20 hours ago, Dick White said:

That would seem to be so just looking at the pictures (and there are some who actually do that, perhaps because they don't know better). When the slab is passed through the rollers, it will be thicker before it enters the roller and thinner when it exits. That's obvious. What is not obvious is that the table on the outfeed side of the roller is exactly level with the top of the lower roller, so that the slab slides evenly onto it as it exits. The table on the infeed side of the roller is slightly lower than the top of the bottom roller, so that both rollers are able to grab onto the leading edge of the incoming slab and pull it through.

I have the Nidec/Shimpo SR-3050 slab roller, and both tables are at the same level, slightly below the top of the lower roller, so you can indeed roll in either direction.  Rolling through in one direction, rotating the slab 90 degrees, slightly decreasing the thickness setting, and rolling back through in the other direction works just fine.

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I actually did an experiment in slab rolling clay,  I was making tiles and wanted them to fire as square as possible.   Rolling it thick and rotating it and rerolling  made a huge difference,  the third time through made very little difference in the shrinkage in my square test.   I only run it through twice saving time and my energy.     Denice

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22 hours ago, CactusPots said:

Have you ever actually tried this as an experiment in practice or are you only talking theory?  I'm not disputing what you are saying, just asking if you've ever set up a trial and measured results.

I’ll give you one nerdy worse .... actually made a penetrometer once to see if there is a best way to compress the bottom of my clay while throwing. Same concept, if I push down harder to compress more at some point the plasticity of the material turns my downward force into force that makes the clay grow axially and become less evenly compressed along the bottom. Pretty funny trying to test that actually but the conclusion was compress from out to in on the last few strokes appeared to consistently allow for maximum compression without a whole bunch of thought.

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For those who doubt the learned folk, try it yourselves because as always it depends....and logic is for those with ope eyes and ears.

Re compression of bottoms, making bowls using length of pipe to flatten clay, didn't do the out to in on a couple, but lots of compression  overall, S cracks on the ones without the out to in action...could have neen Murphy though

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46 minutes ago, Babs said:

For those who doubt the learned folk, try it yourselves because as always it depends....and logic is for those with ope eyes and ears.

Re compression of bottoms, making bowls using length of pipe to flatten clay, didn't do the out to in on a couple, but lots of compression  overall, S cracks on the ones without the out to in action...could have neen Murphy though

I've learned a lot from the posts on this forum.  I do think though,  that never more than today, "how do you know this?" is always an appropriate question.

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  • 2 weeks later...
On 2/11/2021 at 11:34 AM, Mia Dad said:

<snip> She's only making a piece here and there, so she doesn't need speed, but she does need good quality.

A slab roller sounds like overkill at this point.  A rolling pin with slab sticks  should do the trick.  Get a couple of  different thicknesses of the sticks so she can make thinner or thicker slabs depending on need.

 

Edited by S. Dean
Clean up grammar
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This is how I did it until I started making large amounts of tile.   I will use a roller still for a small slab.   A larger roller helps,  rolling slabs helps build up your muscles that you need for working with clay.     Denice

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