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I have no knowledge on this topic but was getting a strong feeling of deja ju, so looked at the archives.

Both this thread Pugmill, Looking To Purchase
and this page
What you need to know about porcelain! https://peterpugger.com/2018/03/28/what-you-need-to-know-about-porcelain/
...discuss the problems of using porcelain (and some stoneware) bodies in aluminium pugmills. Recognising that both inappropriate pH and feldspars can create situations were the protective oxide layer on aluminium can break down.  Offering solutions from changing the pH to operating the pugmill frequently to disrupt spots where the oxide layer is starting to breakdown.

I've no idea if similar suggestions apply to the oxide layer on ersatz stainless steel.
 

Edited by PeterH
typo
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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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9 hours ago, Mark C. said:

I do not see any gum sealant -the two mating surfaces look like they are not tight. The Stainles steel case that looks like it dropped into that . Maybe a repair can fix this with a mig or tig wilder and stainless weilding rod and a grinder.You need a great repair metal shop to do this work.

In terms a of a better machine its a Peter pugger for me as I work in Porcelain . Since you are on the otrher side of pond your options are less.

Thanks Mark. How long have you had your PP? And may I ask which model? Do you have to clean it often? Any issues so far?

 

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10 minutes ago, Ipek Kotan said:

find that it's truly amazing that they expect me to clean a machine like this (2-3 day job) every 2-4 weeks and leave it empty/free of clay between each use. It's ridiculous.

I would agree, replacement seems like the only long term solution and since it’s stainless the assumption would be local failure by corrosion. Not something you could have likely done actually. If I had to live with it I might be inclined to try silver soldering  to repair it using 56% silver solder but would need to get it to 1100 degrees then hand machine and polish the area. SSF-6 is food grade cadmium free and flows to a very bright smooth finish while leaving a very hard repair that’s corrosion resistant. Might be worth a last gasp try followed by sealing it appropriately with a decent gasket material. If you end up trying the repair watch some videos on SSF- 6. Easy to do, great results flows really smooth and shiny but you need to be careful not to overheat. Pretty much like regular solder actually. Once you are done the area might be slightly more magnetic but can be machined by hand and even polished very bright.

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18 hours ago, CactusPots said:

The arrows pointing to 1 and 2 are separate pieces of metal or machined from one piece?  They should be one piece, but if you're questioning the seal across the machined surface of 2, I don't see how you're saying this problem was caused.  A failure of gasket or seal across the machined surface should cause a failure on the machined surface of 2, I would think.  I'm thinking an expert machinist or metallurgist opinion would point to a manufacturing flaw.  That's really a localized corrosion. 

I'm thinking the fix is going to be either a replacement part or grinding out the corrosion and refilling and machine work.  Expensive either way, but Shimpo's "clean every time you use it" is not the industry standard for pugmills.  I don't use porcelain, so maybe someone else has a contrary opinion.    If you can bring expert opinion to Shimpo's attention, they may reconsider their position.  Them replacing the part would be the best case.

resize Shimpo.jpg

If this is like my Peter Pugger, this is a one piece cast part.  The #2 surface is then machined into the casting.  I'm wondering if some type of rustable inclusion would have caused the initial oxidation, kind of like a flux.  Since the corrosion is so localized I don't see how anything inside the machine could have caused it naturally.  I also don't understand the part of our conversation about the seal.  If there was an issue there, the pressure of the clay would cause either a seal or a leak.

Shimpo's advice to clean and empty the machine is a joke.  That would be like telling you to drain the gas from your car if it's going to sit for a month.  5 years, maybe.  

I bet you could get some expert advice by calling Peter Pugger.  They would be what the lawyers call a hostile witness, but expert none the less.

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Curious that the corrosion problem is so localized; not likely to be associated with elevated temperatures - if so, that spot would be steaming! Other likely causes, hrm, concentration of something (e.g. chloride), galvanic action? Perhaps that (otherwise beautiful - no corrosion or discoloration anywhere else?) casting has a bad spot/inclusion ("blob" not the same as the rest).

That unit has a five year warrantee - looks like a valid claim to to me (hey Shimpo, Hulk has spoken!) Perhaps you might find a receptive ear at Shimpo in another department (or "up the chain")?

The casings (no doubt you've seen this Ipek) list for $1139 and $832 (top and bottom, respective, US dollars), wow.

Finding a "used" casing would be plum. A dentist (grind, fill, then machine) solution may serve, good luck!

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The largest model of a peter pugger made from stainless is the VPM 20-SS . That is the the best machine for porcelain for a production potter. Its  not a large machine volume wise as it  only holds 45 pounds of clay. You can leave clay in it forever (no cleaning )

Keep in mind some clay stays in machine at all times. after uses as does your machine. I am production potter  working in Porcelain and after wrist surgery use softer clays. I found a used VPM-30 which is an aluminum cast barrel. It was used in a high school low fire clay program and the inside barrel was pitted. I cleaned it once when I bought it for 1/2 price and have never cleaned it since.I have been around Peter Puggers for about 35 years now and know about thier quality ( I live 3 hours from plant )They where the earliest player to make a great clay mixing machine long ago.I have followed them since the 70s.. They cut the stainless from one solid piece if stainless (mixer body)(this is the reason they have yet to make a larger one )as this CNC machine is limitedcon the size of what it can cut, the barrel is in a few parts that all bolt on.I have visted the factory and know how they are made.

I know over time my porcealin will distroy the cast aluminum  barrel parts but I do not care. If it ever makes a hole all the way thru I will buy a new barrel. The barrel is in pieces and one can buy whatever section is needed. I need about 5-10 years from it before I'm done with the machine as I'm in my later 60s.

The VMP holds 85#s of clay which is about right for my needs. If I was buying new I would go with the all stainless model. that VPM 20-SS .My aluminum model leaves no metal ever in clay. There is no steel at all in the design so no rust ever.The stainless model is beautiful and will give your long life of service .I feel they are the best in pugging and mixing (same machine does both)No air in clay with the vacuum system -no screens as well ever to clean as well.They are costly machines but for a production potter worth it. 

I think i have had mine for about 6 years now at least and it was used hard in a school setting for about 5-8 years first.

Edited by Mark C.
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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 machine ?

 

I would do whatever you can with shimpo to make this right as its a manufacturing flaw in that particular machine. Tell them that is the story -not the limited warranty  time. Tell them its posted on a International  ceramic info board and they need to do the right thing and fix it.Reputation is everything.

I still think a good metal shop can fix this with mig or tig welder.

Edited by Mark C.
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We bought a Peter Pugger before they started making stainless steel ones to handle porcelain (at least for the model we had, VM9) and I have left it full of porcelain for over a dozen years now and while the inside does have some pitting there is not any rust at all. I think I have cleaned it once since we got it and that was such a pain that I just decided if the pitting caused the thing to not de-air properly I would just send it back and have it fitted with the stainless steel. Never even thought about rust. Because of my experience I am not even sure that the rust has anything to do with porcelain at all.  Cleaning mine is only a few hour job but I still wouldn't want to do every month. Hope the repair works for you.

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Is there any corrosion on the matching part of the barrel?  The picture basically shows half of the barrel, I believe.  The other half should mate with the machined surface in the picture.  If there's nothing more than discoloration on the matching surface, it would point even more strongly to an inclusion in the casting, I would say.

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Maybe we should just all email Shimpo this picture asking them if this could be anything other than a manufacturing defect.  I'd really like to see Ipek recover his investment, partly because I'd like Shimpo to be a valid choice for future purchases.  Sometimes you just have to hold their feet to the fire.

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8 hours ago, CactusPots said:

Maybe we should just all email Shimpo this picture asking them if this could be anything other than a manufacturing defect.  I'd really like to see Ipek recover his investment, partly because I'd like Shimpo to be a valid choice for future purchases.  Sometimes you just have to hold their feet to the fire.

I would love to recover my investment and thank you for the offer to email Shimpo. I've talked to two people there and they both tell me to empty the machine and clean it often. As if I don't have enough on my plate, now I have to clean a pugmill every 2-4 weeks. I am truly disappointed in Shimpo and already in touch with Peter Pugger. They told me I will never have to clean a stainless steel PP because it's made to last 20-25 years, even without emptying. That's the kind of guarantee, service and reliability I'm looking for. 

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2 hours ago, Hulk said:

Shimpo's webpages list several business units http://www.nidec-shimpo.com/locations/ (if you haven't tried corporate headquarters yet, mebbe give that a try) and two contacts for ceramics (Kyoto, Japan and Glendale Heights, IL USA).

Glendale Heights, IL is where you should call.

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16 minutes ago, Ipek Kotan said:

Thanks, I did. They told me it's out of warranty (7 years old) so that I should just buy a new upper barrel... They also told me that I should not have left porcelain in the machine, that I should have opened and cleaned it between uses, ideally every 2-4 weeks. 

That is absolutely ridiculous. A pugmill should only need to be opened up and cleaned out when switching clay bodies or making repairs/cleaning screens, etc. I worked for A.R.T. Clay for a while. and we ran 15,000 pounds of clay through our machines every day. In the 3 years I was there we never once opened up the barrels except when one started leaking and needed to be re-sealed. That's the whole point of having a stainless steel barrel.

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Have a look at Bailey puggers too, I've been very happy with my stainless mixer/pugger from there. Their customer service is top notch, have a chat with Jim Bailey if you can before you make a decision on a new one, even if you don't go with a Bailey they might have something to say that is helpful in making a choice. I'm pretty sure he would be interested in what happened to your Shimpo.

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3 hours ago, Ipek Kotan said:

Thanks, I did. They told me it's out of warranty (7 years old) so that I should just buy a new upper barrel... They also told me that I should not have left porcelain in the machine, that I should have opened and cleaned it between uses, ideally every 2-4 weeks. 

What exactly (theoretically) would cause porcelain to be corrosive to stainless steel?  I understand there are varying qualities of stainless and that it is only stainLESS,  but really, is there a PH cause or something else?  Why doesn't stoneware (or earthenware) have this quality?

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I have only cleaned my pug mill once and that is when It was trcked in and had some low fire clay in it from the schoool that sold it. As a high fire porcelain user I had to get all that clay out of it-all of it. Took the whole machine apart. Never plan on that again. Its been full of clay for all these years now.

Where are you located?

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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.

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