Sasha Hill Posted January 15 Report Share Posted January 15 Hello! I am having a persistent problem with the Peter Pugger VPM-20 power wedger at a studio where I work. The process I use is stuffing the chamber completely full while mixing, then letting it mix for 6 minutes, turning the vacuum on and then pugging. The problem is, the first half of the batch comes out with twists and air bubbles in the clay. When bending the log, it is very short and breaks. By the time several logs have plugged out, the second half of the clay is properly de-aired and plastic. But I'm wasting a lot of time and effort having to put a full half of the batch back through each time I pug. I have called and spoken to the company several times and they've recommended several tests of the vacuum seal, but that doesn't seem to be the problem. The vacuum gauge goes up all the way to between 28 and 30 when I turn the vacuum on (although it does dip a bit when the pug first starts coming out and then restabilizes), and there was no effect on this problem when I lined the rim of the latch door with clay to test the vacuum seal as the company recommended. Has anyone had this problem? I'm kind of at a loss for what to do about it! Thank you! Quote Link to comment Share on other sites More sharing options...
fergusonjeff Posted January 16 Report Share Posted January 16 The dip in pressure you are getting is the vacuum finally getting to the mixing chamber. When the mixing chamber is full and you are mixing mode, there is a seal of clay that forms between the back chamber (where the vacuum port is) and the mixing chamber. When you start pugging it allows a small gap to form along the mixing shaft that then removes the air from the mixing chamber. This is more pronounced if the mixing chamber is overstuffed. After getting the vacuum established in the rear chamber using mixing mode, I switch to pugging mode and slow speed. Usually where there is about 4-8 inches of clay out of the nozzle the seal will break that releases the vacuum into the mixing chamber. Keep slowly pugging until the gauge shows the vacuum back up. then reverse direction to mixing and allow the extruded clay to be sucked back into the chamber (be sure to replace the cap). After a few second of mixing, then return to pugging and extrude the full batch. Usually, the first 6-8" has some minor bubbles so that just goes back in the next batch (or I keep that aside for handles and other attachments). Piedmont Pottery and Hulk 2 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 16 Report Share Posted January 16 I use my VPM 20 and VMP30 like Jeff describes. I also put the first log back in for next time about 1/2 the time if it funky .You can get the machine to such clay back into mixing chamber easy(put the cap back on when the clay goes past nozzel end into chamber. On a more curous note what are the vacuum tests that they mentioned ? Hulk 1 Quote Link to comment Share on other sites More sharing options...
Sasha Hill Posted January 19 Author Report Share Posted January 19 Thanks for the responses! I tried it and was still getting 12-14 of twisty airy clay at the beginning. The vacuum also 'popped' and the gauge jumped even the second time I started pugging after sucking the clay back in. Only some went back in when I switched it to mix, I had to cut some of it off. I'm attaching a picture of the twisty clay so you can see what I mean! As for the vacuum tests I guess the main thing was the one I mentioned: lining the outside latch door of the mixing chamber with a coil of clay to see if that improved the vacuum. That might indicate a problem with the seal on the rubber ring but, but lining with the clay didn't make a difference. I also cleaned the rubber ring and the opening of the latch door and checked the ring for scratches or indents. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 20 Report Share Posted January 20 So as far as a new Oring as thats what the door is sealed with. Look for a nick.A nick in the ring can ruin the seal. I suggest taking out the ring and cleaning the grove and ring and putting some silicone grease (only a little bit) on the oring and reinstalling and try that as youi can inspect teh ring well at that time its out. Do not use any sharp object on it. Only use plastic tools on it to claen scrap clay away. I run a rubber rib around my Orings and try to keep clay away from the seal. Especially dry clay. This is true with the overflow door as well. That door also will leack if not kept claen. Sometime I have to push on my overfloow door while vacuum is on to get a seal. Have you tried that???? Hulk 1 Quote Link to comment Share on other sites More sharing options...
Sasha Hill Posted January 22 Author Report Share Posted January 22 The thing is, on a visual inspection without taking the o-ring out, it looks fine. Also, the vacuum gets up to full pressure without leaking before the pugging starts. And the same problem happened when I lined the door with clay which should mean that it isn't a problem with the o-ring. Quote Link to comment Share on other sites More sharing options...
Sasha Hill Posted January 22 Author Report Share Posted January 22 Continuing to experiment with the first technique of sucking the clay back in and it seems to be helping, thanks! Hulk and Mark C. 2 Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 22 Report Share Posted January 22 No need to ever stuff clay on door seal (line door with clay) . Is this the side door or the main top feed chamber you are talking about?-both should be clay free on the oring seal. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 22 Report Share Posted January 22 My other suggestion is to mix the clay under vacuum not just at the end cycle. Quote Link to comment Share on other sites More sharing options...
Kelly in AK Posted January 24 Report Share Posted January 24 I appreciate this conversation, I had similar issues since getting a Peter Pugger (VPM20) a couple years ago. After using it I learned how it’s different than every other pug mill I’ve used. Had trouble maintaining a vacuum at first, tried all sorts of gyrations including sealing with clay. That all went away, it works without thinking about it now…magically. I’m still trying to get every ounce of perfectly mixed de-aired clay with the least amount of effort though. This thread helps. Quote Link to comment Share on other sites More sharing options...
Mark C. Posted January 25 Report Share Posted January 25 For some reason may new users seem to stuggle with these units when they first use them This is one in many other with same issue that does go away after some use-I think they figure out how to use tham over some time Kelly in AK 1 Quote Link to comment Share on other sites More sharing options...
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