Monday, April 4, 2011

Cleaned Out Venco Pugmill

I've not cleaned out my Venco Pugmill for several years and it just seemed like the time to do it because I was not getting a good vacuum and there looked to be lots of corrosion. I had decided to install Buna N rubber gaskets all the way around to try to get the vacuum tighter, and to try to have less air seeping through the joints. When I don't use the pugmill for several months there is a noticeable dryness at the horizontal seam that runs the length of the pugmill. Venco recommends electrical tape for the joints, but over time, air gets through and it causes problems with stuff spalling off the sides into the clay, and the hardness I mentioned.

One test that I used was to take a pug and twist it, and in so doing there were air bubbles and delamination. So I decided to tape the screen aggressively so that the total amount of volume that needed to be deaired was less than before, and was nearer the vacuum chamber. As luck would have it, Rick McKinney of MKM Tools stopped by and he noticed that the screens were polished where the most clay went through and suggested that I tape with this in mind and so I did. Not sure how this will work, and for sure the mill will be slower, but I hope it helps. The mill is too fast anyway -- hard to keep up with for one person.


4 comments:

John Bauman said...

Are you milling porcelain with it? I just set up my second venco to work with porcelain. When I did, I noticed the barrel was fairly pitted. I'm assuming that the first 50 lbs sent through will more or less line the barrel as the processed clay is pushed down the middle.

John Tilton said...

Hey John,

I found that the Venco did not work with porcelain, at least mine, which is a Grolleg based one. Over time, the interaction of the barrel with the porcelain clay causes a reaction and you get stones spalling off the sides into the clay, not to be found until you fire the glaze.

I had bought the Venco for porcelain so I was very disappointed. Some clays do not do the spalling thing.

John Bauman said...

wow. That's kinda discouraging. I'll try to put some through mine. I don't relish losing pieces to an experiment, but if I'm going to make 500-1,000 porcelain pieces a year, I could sure use the pug mill's help.

Mine's already capable of shedding chunks from the barrel, so I think I know what you're talking about.

John Tilton said...

Hey John,

I just want you to know about this because I have dealt with it for years and finally bought a Shimpo dual auger all stainless steel and it is not perfect. But it's really good and a once a year cleaning should do it.