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Slump bowls

Flipping heavy slump mold

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I think I would work out some sort of jig to fit the slump mold in so you can pivot it upside down. Closest I could find of this type idea is this Rotating Slip Casting Table. I'ld make it with a few alterations, forget all the slip casting stuff in the video for starters. Make it so the cradle is just a bit taller than your slump mold. Have the slump mold on a piece of plywood with some holes drilled around the edge then have another piece of ply (same size) across the top of the mold. Put the mold onto the rotating table sandwiched between the two pieces of ply and then secure them together with some webbing (or rope) then rotate the table upside down. Undo the webbing/rope and remove the top piece of ply and the slump mold, leaving the slumped clay bowl upside down on the bottom piece of ply. It could then be flipped right ways up again. 

Other option would be to get another pair of hands to help flip it over onto a board.

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I was thinking about something like this, but could not nail down specifics.  I did not want to make a dozen prototypes.

Yeah, another pair of hands would be ideal.  But, where I live does not make this very doable.

Thanks, the video gave some possibilities on how to approach the issue.

B.

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I seen a video one time of a man who makes big giant three part vessels, like hundreds of pounds, and he made a contraption to flip them over so he could join pieces.  It functioned like a teeter inversion table, you sandwiched the part, removed a pin from the table and flipped it over and then put the pin back in place before removing the piece.  Was real impressive, but didn't look expensive, just well engineered.  Good luck to ya!

 

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And fill the cavity with something, sponges, crumpled towels, anything to help support the clay, so it doesn't try to collapse.  Unless it is very dry, of course.

Edited by Chilly

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11 hours ago, liambesaw said:

I seen a video one time of a man who makes big giant three part vessels, like hundreds of pounds, and he made a contraption to flip them over so he could join pieces.  It functioned like a teeter inversion table, you sandwiched the part, removed a pin from the table and flipped it over and then put the pin back in place before removing the piece.  Was real impressive, but didn't look expensive, just well engineered.  Good luck to ya!

 

A flip top table with an accessible opening underneath should work. If you used something like a pneumatic stool underneath so when the mold was flipped over you could push the stool underneath it and raise it up to support the piece then undo the strapping and roll it out. 

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How about this: lay a piece of plastic in the bowl. Get a couple of cans of spray foam from home depot, lowes, walmart...  fill the inside of the bowl and let it harden (might take overnight). Trim the excess foam flat with a bread knife. You now have a reverse slump mould.  should be much easier to flip the bowl with the inside support... or outside? Whichever it is.

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On 9/5/2019 at 11:59 PM, Russ said:

How about this: lay a piece of plastic in the bowl. Get a couple of cans of spray foam from home depot, lowes, walmart...  fill the inside of the bowl and let it harden (might take overnight). Trim the excess foam flat with a bread knife. You now have a reverse slump mould.  should be much easier to flip the bowl with the inside support... or outside? Whichever it is.

Hi,

It is a surprising idea.

Would this foam mould need to be isolated? Foam looks a bit rough, will the mould be sleek, or does the spray leave some lines ?  I have seen that foam spray forms cavities.

What would you recommend as a release agent?  

I am right into the "big heavy mould" problem, for bowls with diameters like 46 cm.

Cannot wait give it a try with a smaller bowl tomorrow!

 

 

 

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You might try the thin  plastic sheeting to line the inside of the bowl  ........or if its greenware and youre finished with it and ready for bisque  firing you could try a non stick food spray that would burn off quite quick.  there are also several types of spray foam. Some that expand alot... some for windows that expand a lot less and some that cure very dense.  Experiment for us to see what works the best.

Ive used spray foam to build LARGE slump moulds three feet or approx 1 meter across. They work very well.

Edited by Russ
add thoughts

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I fellow potter I know who does large stuff has an engine stand modified as a pot flipper.  From my experiments, the issue is supporting the clay and having enough tension on it so it doesn't slide when it's in the half way position.  If it's leather hard or better, it's easier.  I need to flip it while it's still as soft as possible, so I can work out joints on the inside.  Much harder.  Big pots are fun to do, but lots of extra trouble.  50 lbs would definitely require some advance logistics.

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On 11/30/2019 at 10:47 PM, Russ said:

You might try the thin  plastic sheeting to line the inside of the bowl  ........or if its greenware and youre finished with it and ready for bisque  firing you could try a non stick food spray that would bu

Hi,

Unfortunately  I didn't  stick to your manual..

 I sprayed backing spray  on the glazed ceramic prototype, and it got stuck... Can the foam residues be somehow cleaned ?

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If you need to dissolve residue, you need some acetone. It’s in nail polish remover in smaller quantities, but you can get it uncut from places that sell auto body supplies. Canadian Tire has it for sure, and I think you can also get it at Home Depot in the paint section. 

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On 12/3/2019 at 9:39 PM, liambesaw said:

Or fire! Fire works

Hi liambesaw,

Fire ? That is how - with a gas burner ?

Yes, the platter is glazed.

I will try acetone first and, well, report..:

Edited by Leila

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On 11/30/2019 at 10:47 PM, Russ said:

Ive used spray foam to build LARGE slump moulds three feet or approx 1 meter across

Hi Russ,

The foam forms cavities,  how do you avoid this?  Do you compress the foam  somehow ? 

Because if I do not manage to clean the foam from inside the glazed plate, I will try  to make a hump mould.

 

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53 minutes ago, Leila said:

Hi liambesaw,

Fire ? That is how - with a gas burner ?

Yes, the platter is glazed.

I will try acetone first and, well, report..:

I was thinking you could scrape as much as possible off and then put it in a bisque firing

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There is a high density foam that only forms small bubbles. Dont go for the "big gap" filler foam.  The bowl you want to use for the mould should be lined with a thin plastic and then pealed off the hump mould after its set. Where it contacts the plastic it should be bubble free UNLESS you sand or rasp the surface.  Once the inside is complete  cover the hump mould again with plastic and make the negative mould.  using the set of moulds you can easily flip the bowl either way to work on the inside or outside.

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Russ-

Don’ t forget about the thickness of the clay used. The way you are suggesting doesn’t allow for it and, if made that way, won’t allow the form to be flipped without marking or distorting the clay form.

Regards,

Fred

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If i remember correctly the inside is made first. Clay at the correct thickness is  slumped over the mould. Then the outside mould is made. Its been about 20yrs since ive done this...

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