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Mark and I both have PP VPM 30.  Although, I wouldn't be surprised if he didn't have another as well.  :)

No one knows why porcelain will degrade aluminum and contaminate the clay?  I guess it's just one of those "conventional wisdom" things that sells the more expensive machine.  My general experience is that aluminum is not all that easily corroded.  

Like I said, Shimpo is feeding a line of BS when they contradict the fact that no one ever regularly cleans a clay pugging machine.  I'd be willing to bet Imerys, Laguna or any other manufacturer of porcelain does not regularly empty and clean their pug mills.  I would be interested to know their commercial large scale pug mills are also stainless for porcelain.  

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Aluminium corrodes because of the ph of the porcelain, it's more alkaline than most stonewares. PeterPugger has an explanation of it here. When I talked with Jim Bailey a few years ago he said th

I would check into the welding thing again a Mig or Tig welder a with stainless welding rod nd then grinding it smooth. It would be like a whole new surface thats as strong as the original metal-it wi

The Peter pugger uised O-rings for sealing between pieces. (mating surfaces ) As do all diving underwater stuff as well. (not sure what gum youi are speaking about?) is the gasket rubber in your machi

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8 hours ago, Ipek Kotan said:

I can imagine. A lot of the people I know said that they never cleaned their pug mill. I think a good pug mill that is made of high quality stainless steel and that is sealed well should not have to be cleaned... I also use a high fire porcelain - PT010B from Imerys - Limoges porcelain. Did you say you have a Peter Pugger? I'm located in the Netherlands.

Yes I have a Peter Pugger

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Aluminium corrodes because of the ph of the porcelain, it's more alkaline than most stonewares. PeterPugger has an explanation of it here.

When I talked with Jim Bailey a few years ago he said they are seeing pitting of aluminum pugger barrels with some white stonewares and low fire high talc bodies also. About 15 years ago before PeterPugger came out with the stainless barrels I had a friend with one of the aluminum ones and using porcelain. It's not just the pitting that was happening but little hard nodules would get pugged into the clay. I'm assuming these were a combination of alumina from the barrel plus whatever it was reacting with in the clay. They could be felt in the clay, and left bumps in the fired pots. Some people tried lining the aluminum barrel with epoxy, didn't work. I seem to remember this is the issue that started the stainless pugger market. Some claybodies are going to produce more of the pitting and nodules than others, plus leaving the clay in the pugger without using it, plus how much clay stays on the walls of the machine without getting churned into the pugged clay. Pitting isn't going to effect the clay, the nodules that can form does.

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Ipek, curious, have you tried dealing with other Shimpo office(s)? You might find a reasonable/sympathetic ear elsewhere, and/or higher in the "hierarchy" of Shimpo. 

From Bailey's website:

Please Note: Aluminum barrels should not be used with porcelain clays as some porcelains contain soda that, over time, will corrode the barrel. (Please note that Laguna B-Mix is a porcelain body.)

My guess would be the mid fire (5/6) porcelains are more aluminally corrosive than high fire material...

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Cactus was curious 'bout the porcelain and aluminum barrel thing; Min nailed that down.

Sorry you're not getting any traction with Shimpo. You might get lucky with finding a used/replacement barrel half? I'll be quiet now...

...and now I want a pugger, lol.

Ooops, one more "thought" - donate the corroded barrel half to local college metallurgy department for section and analysis.

 

Edited by Hulk
maybe I will be quiet now?
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There's clearly a flaw in that spot since it's the only area of the pugger that's corroding. That flaw was there from the beginning, it just took longer than the warranty period for it to show up. If it were my company and I saw that, I would replace it and have the bad one shipped to me for inspection. Unless, of course, they've seen this before...

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On the aluminum pitting note. My barrel is pitted but I have never found any pieces or lumps or bumps in clay.As long as that stays the case it can pit all year long  sit does not interfere with the clay. The reason they (Peter Pugger will not make a larger machine as I stated earlier) is the cot of a huge C&C machine to cut it out of one piece of stainless (the mixer section)

I do recall all of that story Min refers to.I have just not seen any contamination with the type of Porcelain I use. I think the clay body will have a large part to play in this in regards to aluminum pitting

Of course I have two rusty steel extruders and my porcelain never shows rust in clay as well

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37 minutes ago, Mark C. said:

I would check into the welding thing again a Mig or Tig welder a with stainless welding rod nd then grinding it smooth. It would be like a whole new surface thats as strong as the original metal-it will not look as god but who cares inside the chamber

I agree that it's worth investigating having it repaired. It would likely be a lot cheaper than buying a whole new machine. However I think the PP design is better since it's made for mixing as well as pugging.

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1 hour ago, Mark C. said:

I would check into the welding thing again a Mig or Tig welder a with stainless welding rod nd then grinding it smooth. It would be like a whole new surface thats as strong as the original metal-it will not look as god but who cares inside the chamber

I am thinking of this too. Next week I'll go to a butcher nearby, they make their own sausage there and I'm sure they need to get their stainless steel equipment coated/repaired from time to time. :) I'm never buying another Shimpo pugmill again but I do agree that it will be worth it to get this fixed rather than buy a replacement upper barrel. Mark, have you ever heard of anyone complaining of air bubbles in their porcelain when using a PP pugmill or their porcelain becoming short after running it through a PP? I've heard of this and am wondering if it's a model specific problem or not.

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1 hour ago, neilestrick said:
1 hour ago, Mark C. said:

I would check into the welding thing again a Mig or Tig welder a with stainless welding rod nd then grinding it smooth. It would be like a whole new surface thats as strong as the original metal-it will not look as god but who cares inside the chamber

I agree that it's worth investigating having it repaired. It would likely be a lot cheaper than buying a whole new machine


Since different stainless steel grades have different compositions, a good welder will need to know what grade welding rod(s) to use to make a reliable repair.  I have seen repair welds in piping and pressure vessels fail due to the wrong welding rods (some quickly, others not so quick). 

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8 minutes ago, Magnolia Mud Research said:


Since different stainless steel grades have different compositions, a good welder will need to know what grade welding rod(s) to use to make a reliable repair.  I have seen repair welds in piping and pressure vessels fail due to the wrong welding rods (some quickly, others not so quick). 

Shimpo might be able to provide that information. I just think it's worth checking.

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2 hours ago, Min said:

Aluminium corrodes because of the ph of the porcelain, it's more alkaline than most stonewares. PeterPugger has an explanation of it here.

When I talked with Jim Bailey a few years ago he said they are seeing pitting of aluminum pugger barrels with some white stonewares and low fire high talc bodies also. About 15 years ago before PeterPugger came out with the stainless barrels I had a friend with one of the aluminum ones and using porcelain. It's not just the pitting that was happening but little hard nodules would get pugged into the clay. I'm assuming these were a combination of alumina from the barrel plus whatever it was reacting with in the clay. They could be felt in the clay, and left bumps in the fired pots. Some people tried lining the aluminum barrel with epoxy, didn't work. I seem to remember this is the issue that started the stainless pugger market. Some claybodies are going to produce more of the pitting and nodules than others, plus leaving the clay in the pugger without using it, plus how much clay stays on the walls of the machine without getting churned into the pugged clay. Pitting isn't going to effect the clay, the nodules that can form does.

I have heard somewhere that some porcelains have an organic component that aids plasticity.  Do you have any knowledge of this?

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1 hour ago, neilestrick said:

I agree that it's worth investigating having it repaired. It would likely be a lot cheaper than buying a whole new machine. However I think the PP design is better since it's made for mixing as well as pugging.

Make it salable at least if you do decide to go to another make.

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2 hours ago, Ipek Kotan said:

I am thinking of this too. Next week I'll go to a butcher nearby, they make their own sausage there and I'm sure they need to get their stainless steel equipment coated/repaired from time to time. :) I'm never buying another Shimpo pugmill again but I do agree that it will be worth it to get this fixed rather than buy a replacement upper barrel. Mark, have you ever heard of anyone complaining of air bubbles in their porcelain when using a PP pugmill or their porcelain becoming short after running it through a PP? I've heard of this and am wondering if it's a model specific problem or not.

If the pugmill has agood vacuum system then air bubbles should not be an issue. In terms of short clay yes that is more an issue of not have the fines in the mix-Fines are the throwing slap in your splash pan. I add this to my pug/mixer every time I mix recycled clay . The fines add  much to the aging process and if they are not in the mix the clay will be short.these fines can also be found in the bottom of your throwing bucket of water.Save them for the clay mixing. This slop has much value in helping prevent short clay. There has been much written on this issue here, use the search function  on main page to find this info .

Shimp will know what type of stainless they make the machines out of-it looks like there may be two types in your photo of that area.Find out what they are so the welder knows as mentioned above .welding rod must be the correct kind to make this work

Edited by Mark C.
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5 hours ago, CactusPots said:

I have heard somewhere that some porcelains have an organic component that aids plasticity.  Do you have any knowledge of this?

Everything from Additive A to Tom Colemans secret food additive to old school stuff like pee, milk, beer, vinegar etc. I think the theory is the truly organic stuff, not products like Additive A, break down and the bacteria feeding on the organics alters the ph of the water in clay and is supposed to make it more plastic, albeit pretty smelly too.

 

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On 8/28/2020 at 10:53 AM, Min said:

Pitting isn't going to effect the clay, the nodules that can form does.

I get the the OPs is stainless but just want to add to Mark C, our PP is a dozen years old now, is pitted, not stainless, we use porcelain, never clean it out but use it almost daily these days and have never found anything coming off in the clay while throwing or slabbing. I would guess that maybe something else was in the clay and being attributed to it possibly? I've always wondered if it might pit in a way that is keeps from getting a good vacuum seal but so far never had any issues with it.

I was pissed about it at first but now we have gotten enough use out of it that I really can't complain if it bits the dust. 

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