Based on the suggestion of a fellow potter who commented on one of my previous blogs, I approached a plastics company to see if they could form a sleeve to fit inside the barrel of my pugmill. Unfortunately, this particular company was unable to help us, mostly because of the curve of the barrel at the extrusion end. But the fellow suggested we try an epoxy coating like ones used in elbows of pipes that carry grains and salt, and was even kind enough to give us a batch of the epoxy to use.
I was hopeful...
The first week went well. The epoxy seemed to be staying put. There weren't any more pesky chunkies buggering up my thrown work. And then, slowly but surely, I started finding the hints of chunkies. Small ones. But definitely chunkies. I brushed it off as dried bits of clay? maybe? hopefully?...
In the mean time my show in Ottawa came and went (thanks everyone, for a great show!) and when I got back, I had about 2 weeks to finish all the work I needed to get done for the remainder of my Christmas shows. So the first day back to work... pug some clay... start throwing...
CHUNKIES!
HUGE freaking chunkies. The size of m&m's.
And then...
EPOXY!
Yup. Slices of epoxy, coming off in the clay.
Shit.
So we took apart the pug mill, cleaned it out, and here's what we found:
In some spots, the epoxy had peeled right off and was mixed into the clay. In other spots, it had let go of the aluminum and was acting like an envelope. From what we can figure, the pressure from the vacuum pulled the epoxy away from the aluminum and clay got stuffed between the epoxy coating and the pugmill barrel.
We still can't really figure out where the chunkies were coming from. They did not appear to be stuck to the epoxy. And the clay that had slipped between the epoxy and the barrel couldn't get into the mixing clay because the epoxy holding it against the metal was still in tact. And the small chunk of epoxy that DID break off, was fresh and the clay didn't have time to react yet.
Soooooo.....
Luckily, the rest of the epoxy peeled off like cheap nail polish but we're back to square one again.
So, either I give Peter Pugger a call (I'm sure they'll be ecstatic to hear from me!) and find out if they are willing to get the sleeve made, or I get my incredibly talented husband to machine me a new barrel out of stainless steel and be done with the whole problem. The materials for this would cost us about $1000.00, and my hubby has access to the equipment to get the job done. All we would need is the time...
i have been following your pug saga on clayart and am so sorry that this is such a lingering issue...what a gigantic pain in the ass.
ReplyDeletei wish i knew some solution but you've had the best minds at work on this. just know that you are not alone in the drama that being a potter involves. best of luck, i will be interested to know what the final outcome of this might be.
well, i don't know what peter pugger is doing as a fix, but you might try nickle plate or chrome plating the interior of your part. or even black anodizing the part.
ReplyDeletefor a test, your husband might make three aluminum extruder dies and you could run them with each plating for a while and see if there's any reaction to the dies that you have in the pugger?
My freind had the same problem with her peter pugger and it took months of complaining.But in the end they sent her new parts lined with a special epoxy coating (blue in color).The chunks you are getting are small bits of alum. flaking off the inside of the barrel. It was easy to change the back plate and barrel about an 1/2 hour repair
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