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perkolator

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Everything posted by perkolator

  1. there's a few youtube videos regarding how to replace the bricks, it's not that hard, just time consuming. Nice thing is the Skuutt 818 isn't a very big kiln, so it's easier to manhandle the sections so you can DIY. Basically you unplug, take the control box off then unstack the sections to get to the bottom one. Flip it over onto a flat surface and release the steel jacket. After you replace the bricks, you'll need to sand them down so everything is flat. Replace your element, then reinstall everything back together. Test fire. You may consider getting some backup parts for your kiln if you have the $ - extra thermocouple, relay, element.
  2. In the market for some new blungers/mixers for studio, wondering what your preference is and why? Mainly I've been using the standard paint mixers you get at hardware store, usually the 2.5" diameter for 5-gal buckets, that fits a regular drill's 3/8" chuck. Somehow destroyed 4 of them in the last year and I need to buy some more (I guess they were like 5-6yrs old each). Turns out Home Depot and Lowes stopped carrying the size I prefer and replaced them with a different style with solid fins (they only carry the larger 4" version that fits a 1/2" chuck); I bought one to try out and it seemed to make more of a mess than mix, then last week I saw 1/2 the fins broke off when someone used it. The only place I've seen the old classic blunger is at Harbor Freight, I don't mind picking up a few of them since they're only $4 each, but while I'm in the market I'm wondering if there is something that's "better" and still cost effective so I can let people who don't seem to care about their equipment, abuse it weekly Been using for years and cant' get everywhere anymore: This is what the stores replaced it with: I used one of these in the past with good luck, but it was a little small (like for a 2gal bucket) and then someone decided they wanted to use it to mix plaster and not clean it afterward... Anyways, as you can see below there are many different styles -- so I'm wondering who's tried most of them for mixing slip/glaze/misc?
  3. I agree to buy individual parts and custom fabricate the unit. We have a large 14" hydraulic extruder in our studio that is a one-off piece of equipment. If I recall correct, it was built by someone at Univ. of Minnesota. Ours accepts a 16" square die plate, with an approx 14" extrusion limit. It has a hydraulic cylinder for the main ram, which as control valves for the hydraulic pressure and up/down stroke. I can stop it during mid-stroke, I can also change the speed during mid-stroke...it also tilts into horizontal position AND has a 2nd ram hidden inside the base to make it taller for extruding longer forms in vertical orientation. I can try to take some pics, but in my honest opinion this thing has some major design flaws that I would definitely change if I were to build one myself (the issues mainly are due to the capability of going into horizontal position and being able to change vertical height - it just needs some major improvements for safety). We have the Bailey pneumatic as well, I would likely share some of those design concepts if/when I finally decide to chop into this thing. The original dies we got with our extruder were mainly for extruding slabs/tiles, but we've since made many of our own. The problem with this is that when you have a LOT of hydraulic pressure + a large diameter die plate, you can very easily snap dies in half (depending on the shape, since certain shapes restrict too much clay and create too much pressure behind it). Many of the dies with smaller apertures have to be double thick matieral (3/4" plywood) or made of something else, like steel.
  4. This is true, it depends on what you use your wheel for and what your personal needs or preferences are. Technically a 90hp car can achieve highway speeds just like a 300hp car can, but they'd definitely not be the same getting there. We're not throwing pots, we use the wheel as a tool to make forms used in large scale sculpture...and undergrads destroy everything in their path, so our needs are much different than most other studios...this is why my viewpoint is always skewed toward being overkill with everything
  5. Have you called them yet and talked with Aaron? I've used many of the IMCO pugged clays over the years, I have no complaints. Mainly we make our own clay from dry materials (which I get many from IMCO), but many of our students, local schools, local artists, etc buy their clay and seem to like it. Heck, I was over there one day and saw a pallets of Leslie Ceramics clay bodies, so I guess they're the one who produces some of Toki's pugged clays. I have not used the Starry Night, I think that's a newer clay body of theirs? I have a 50lb bag of that ilmenite they put in it, I got it from IMCO to test out as a potential grog substitute/filler material. My MIL used to teach HS ceramics in Sacramento and she used IMCO clays most of the time vs Laguna or other brand clay from Alpha, since IMCO delivers and Alpha doesn't. They fired to ^6, with commercial glazes and I didn't really see any issues with vitrification. From their IMCO stash I've used over the years: navajo wheel, great white, 50/50 mix, and sculpture 50, IMCO sculpture mix, Elf White, Stoneware #5 and Sculpture 412.
  6. I've tried that actually, it didn't work as well as I wanted (it's actually what inspired using inflatable pool tubes)....but I want to try it again since I've seen ways to improve the foam cure - like with a spritz of water/humidity. The problem I saw was that we used Great Stuff spray foam in a can, which is a single stage cure - much different than the chemical-cure of 2-part foam used in packaging and modern wall insulation This is why I suggested to faculty to buy one of those machines. Would love to test one out if knew someone who had it. Cost has gone down and the tech seems to have improved - one major hangup was the short shelf life once you open the containers of foam. I think nowadays the containers are smaller and shelf life slightly extended - but still, unless you're using it often it may not be worth it. There's also the question of what to do if it needs return shipping, since the piece was removed from the "foamed in place" packaging. Faculty buy all their own packing materials. The soft sheet foam comes in a roll approx 2ft diameter, the bubble wrap in a 40" diameter roll, she buys from a local shipper but pretty sure you can get it from uLine or similar. The rigid white styrafoam sheeting she usually gets from the guy who builds her crates, but I've gone on emergency to local hardware store to buy foam sheet insulation, which is pretty much the same just more expensive.
  7. We use Brent CXC....they don't get heavily used since we're not potters in our studio, but they've lasted over 20 years of undergraduate abuse. Very simple machines to service if any problems with them, usually it's the foot pedal fork that breaks when someone stomps the pedal or drops pedal. I've thrown on a lot of different wheels in high schools around the area, they always seem to have mixed equipment between schools. I mainly prefer the wheels with a removable splash pan vs the style that's recessed into a molded splash pan. Go for the highest HP rating you can find, I've had small wheels bog down when centering with only 15-20lbs of clay on it. My preference would probably go to the Brent since its what I've thrown on the longest. I was quite fond of my old motorized Lockerbie, but that thing was a beast and took up too much real estate. The ancient Alpine gear driven wheel I replaced it with years ago will torque off your arm if not paying attention Shimpo's are pretty nice too, quiet.
  8. Like said above, clay dust kills motors...so I no longer buy fancy grinders or drills for studio. I have a backup pneumatic grinder, but it's limited to being near air supply (and you have to have a large air compressor to keep up with the CFM requirements) I've had no issues with the Harbor Freight grinder (not the $20 one, the $40 version) for the last 3 years, I'm very surprised with the quality of them, especially since I only expect it to last as long as a brand name Milwaukee/Dewalt/Bosch, etc in a ceramics studio, so why spend more? I LOVE the solid-core diamond grinding wheel I got from Si Products, haven't tried one of those "scalloped" diamond cup wheels yet.
  9. I've had the same issue. Use a large sanding block so you get a more flush surface. I called Skutt and asked their advice - they said to do that and the reason the originals are smaller is because THEY sand down the bricks too after they assemble. They use a giant downdraft sanding table and move the entire kiln ring over it for sanding.
  10. Someone gifted me a NorthStar 30" slab roller - I see exactly your issue with the legs being too flimsy for casters....actually I gave the slab roller away too, I hated that thing and the wonderfully designed plastic gears and roller assembly My solution was to build a platform base, on plate casters, made with 2x3 lumber and a sheet of OSB plywood over the top. To this, I simply lag-bolted down the legs of the slab roller...and I get a storage shelf underneath for misc items. I was ok with the extra 5" of height since I typically don't even bother using a slab roller unless it's larger than 18" square.
  11. I assist with shipping out faculty ceramic sculpture all the time to shows across the US. You can NEVER overpack ceramics, I've seen things I thought were indestructible get damaged by UPS, FedEX, even professional art handling companies have accidents....like when someone accidentally drives forklift fork through your crate, oops! With ceramics you want it packed rigid, so the item cannot shift in the package. If the packing is "soft and squishy" you're asking for breakage. I've learned to ALWAYS insure your fine art when shipping, even if it's only worth $50. Good packing takes time, but for the most part this is what we do: - Everything wrapped tight with soft white packing foam sheeting, filling any voids and wrapping any protrusions if there area any, then a single layer over the top to protect the bubble wrap from popping. If you don't have it, use newsprint paper instead of foam sheet Fasten with masking tape. - 2-3 large diameter bubble wrap layers over the top of the foam sheet. Fasten with masking tape. - 3-5 layers stretch-wrap film tightly wrapped around the bubble - THIS is the material that holds everything together and seems to make it rigid before going into a crate/box. From there, you can double-box or crate your ceramics. For large, heavy ceramics use a wooden crate obviously. Smaller stuff can likely go inside a standard "doubled-cardboard box" packing (Box inside a box, with packing between the two). Since a lot of galleries don't like packing peanuts anymore, we have gone toward using rigid styrofoam sheeting lining the inside of the box (wads/balls of newsprint work well too), you can add more chunks of it to build up voids. If the voids are particularly large, like giant voids of an odd shaped piece inside a rectangular crate - I've successfully used inflatable pool toys to fill the extra space - seemed to hold the air just fine when going from coast to coast over a week's time period and saves a bit of $ since packing materials are expensive. I've jokingly suggested to faculty several times to just invest in one of those expanding foam packing machines - like how kiln parts come foamed into their boxes so it doesn't shift.
  12. I just went through this with our 714 -- it takes a 20A dedicated circuit. Was having issues with out smaller 609 (turned out to be a bad receptacle) and had an electrician in studio to inspect power on both our 120v test kilns. I was questioning the 20A circuit for the 709 since its amperage rating is too close and if we managed to fry a less amp kiln's wiring, what about the one drawing more juice. Both Skutt and the electrician confirmed 20A was the common setup on both models since a 25A circuit is only possible at the breaker side, there are no 25A receptacles and the kiln would have to be hard-wired to a shutoff for this to work. I need to be able to unplug the kiln for stuff like element and brick repairs after someone blows up their test tiles in these powerful little kilns - so I chose to just switch to dedicated 20A twist-loc receptacles and plugs for ease of service. The other way suggested by the electrician was to possibly setup the kiln with 30A and install a lower amperage inline fuse on the control box.
  13. Silicone generally takes around 24hrs to cure. It cures with humidity in the air, so I suppose if it's in a humid environment, possibly with heat and airflow it will cure faster. I like E-6000, it generally takes 24hrs, but sometimes takes longer. These I'd go 72hrs if you had the time available. I usually prefer a 2-part epoxy though. Not too much a fan of the quicker 5min stuff, the longer the cure and the more opaque, the stronger it is. If it doesn't have to be a clear, PC-11 (white) and PC-7 (charcoal) are my preferred "strong" paste epoxy. I believe the PC epoxy is stronger than JB weld, but JB beats it in thermal resistance. I can only find it on the shelf of Ace Hardware; or online. Don't really have a preferred clear 2-part epoxy yet, but I'd go 30-min cure.
  14. Late to the party and I didn't read everything in the entirety but it sounds like in order to satisfy some concerns from higher up, you need better shutoffs in case of emergency. In a setting with multiple users, the kiln should be wired to a shutoff/disconnect box like pictured above, from there it gets power from the main panel. This way the technician/staff can lock out the electrical panel for whatever reason and everything will be completely dead. When they want to give access, they tun on the breaker and leave the shutoff/disconnect box to kill power in case of emergency, the user will notify the staff of emergency shutoff so they can lock/tag out the equipment. I've had relays fail in both directions, but I never really saw any bad problems from a relay getting stuck closed (powered on). In those instances (WAY fewer than relay stuck open/off) the kiln just held temp longer as it tried to cool down. You kinda notice when your control box says complete, yet you still hear power going through the box. My kilns are plug-in, so I just pull the plug or flip the breaker. On the gas kiln, you can get a large main gas solenoid or manual lockout valve that can be used to lockout the gas supply upstream. Since kiln most likely has electronic components, you can also simply have an electrical shutout to keep non-authorized users from tinkering - can't really start up the kiln without power. I never rely on the gas solenoids when shutting down my kilns, I ALWAYS close the burner and pilot valves manually afterward. I like the idea of an external timer on the gas solenoid - but in this setting being at a school they may want an actual lockout device.
  15. 12"x12" isn't that big of a slab. dunno what firing schedule you're using but likely it's too fast. slabs and similar work with large flat surface areas against a shelf (like slabs, and big platters/pots without a foot trimmed into it) tend to have two main issues with firing. -One is that they are a big surface area, sitting flat against a shelf, thus the heat cannot easily penetrate to the bottom, center, of the clay. Because it was cooler than everywhere else during the time you were candling your kiln, by the time you go to your next stage of firing, this cool section kinda rapidly heats up and thus you get blow-outs. Raising/elevating the piece will help tremendously. Also slow down your firing to compensate for lack of heat penetration. Kinda the same concept if you were to stack a really tight, low height shelf in the bottom of your kiln - the heat can't penetrate very well. -Second issue is more likely with larger work than the scale we're talking about, and the problem is usually cracking due to the friction and drag caused by the physical weight of the mass as it's trying to expand/contract in the kiln. Something under the piece Yes, silica sand can work if you need to sit it flat. Grog will also do the same thing. Putting a layer under your piece will act as ball bearings and facilitate the movement as the clay expands/contracts. Since it's not a solid, it will also allow moisture and heat to pass through the interstices and make its way to/from the bottom. Another alternative is raising the piece on pieces of broken kiln shelf or clay pucks. Most of the time with big work, I use either the broken shelf bits or balls of kiln wadding (1/3 each: grog, silica, clay) - they do the same thing, but they have one main factor that makes me go toward them before loose sand/grog......Grog/sand can fall through the shelf crack/joint to the work below, the wadding stays put. Another benefit to the wadding and sand is that they will self-level out which is great if your kiln shelves aren't perfectly flat, but your piece was built on a flat surface. Yes, slabs fired at an angle on their side can definitely warp. Depends on how thick/thin, how heavy, how big, the temp you're firing to, etc etc. I lean stuff on soft brick all the time as long as there's no glaze.
  16. I would also replace the rod tube assembly as a whole unit vs just the rod, I want to say they run around $50 or less. Then re-adjust your plunger latch settings with the tool and test fire the kiln. Also, are you consistent with bar placement in the sitter every firing? If it's consistently doing this, you may need to set your plunger catch tab so it gets where you need it.
  17. For stuff like this, we simply use broken pieces of old kiln shelf. I break or sometimes cut them into little pieces around 1" square. Place them under the perimeter of your work and they'll help facilitate the sliding. For flat work, I don't use the rigid kiln shelf, I use balls of kiln wadding/putty instead, approx 1" diameter, sometimes larger. Kiln wadding is equal parts: silica, kaolin, and grog or sand.
  18. If your block walls are hollow, you can use toggle bolts or similar anchors made for grabbing the back-side of the block - use this method to mount a piece of 2x6 or 2x8, which you'll then lag bolt your extruder to. If the wall is concrete-filled block, you'll need to drill and use anchors made for wedging in solid block. you may want to go further and epoxy them in for extra insurance. The metal-stud wall shouldn't be a problem - use a piece of plywood or 2x material anchored to at least 2 studs to spread the load, then anchor the extruder to the wood addition. hope this helps. BTW just to throw it out there - I've seen extruders mounted in places other than on walls -- like on the side of a big, heavy work table with either an extension or even on the table leg itself (it was a tall table with 4x4 legs). Bailey makes a free-standing extruder base for his systems, not sure if it'll work with a manual extruder but for our pneumatic one it's very convenient. It's a simple design and I don't see why someone couldn't make a version for a manual extruder themselves with some steel.
  19. It's done by building up the surface with texture and a fluid transparent glaze that slightly breaks. In this case the texture seems to be done with a slip trailer, baby snot bulb syringe, or a syringe of some sort. heck, you could do it with dipping a brush in slip if you wanted to. Anyways, slip is liquid clay - so if you're putting clay on clay, it needs to be similar wetness in order to achieve the best bond as they'll dry and shrink together. If it's not, they'll dry and shrink apart, making the dots fall off. This is pretty much the same concept if you wanted to add say a handle to a cup. So in other words, do it when it's wet clay, before leather hard. The thicker the slip, the wetter the clay has to be. You CAN apply slip to bone-dry ceramics, it just needs to be watered down...but then you have the issue of more water being introduced to a bone-dry piece...which has its own set of awesome problems
  20. OP: You mentioned "single firing to ^6" in your post. Is this a piece of glazed ceramics or just raw paper clay? Yes you can once-fire, but not all clay bodies and glazes will allow you to do this. I would think that paper clay, having a higher organic content, would have some slight interference as those materials need to burn out through a membrane of glaze. Kiln firing itself is an art form and many people fire differently, so I wouldn't be surprised to find tons of variations of schedules to fire your work. You can try them all and see what works. Personally I recommend blowing up a few firings to force yourself to learn. There's only one way to find the limit of how fast you can fire a certain mass of clay, lol. I've blown up plenty of work I fire fairly slow and take a conservative approach to most work nowadays, but really I change the schedule depending on WHAT it is, how it's made and how the kiln is loaded. In general, I like 5 ramps. I learned to use 3 ramps that go progressively SLOWER on each ramp as the kiln gets closer to ~212*F/100*C where water turns to steam, this adds more time in the water purge/preheat in order to safely fire thicker, wetter ceramics that are being once-fired. From there I go medium speed up to around 500* and then fire it off faster rate to whatever cone and give it a hold at the end. Thicker work needs to be down-fired sometimes. An example of this might be: 50/hr to 185* for 1hr 40/hr to 195* for 2hr 30/hr to 205* for 3hr 100/hr to 500* no hold 200*/hr to cone temp, 10 min hold I keep the first 3 ramp rates the same every firing and change up the hold times at each stage depending on the needs of the work - sometimes this is 8hrs, 9hrs, 10hrs for questionably wet and thick ceramics. i also change the rate for the last two ramps depending on the work. The 100 and 200 are acceptable for most work, but thicker work needs to be slowed way down, more like 65*/hr to 500*, then 125-150/hr to temp. Try out lots of different firing schedules and learn from each one. Blow up your work and get disappointed, with mistakes you'll learn faster as you try to do it over and over again trying to get the results you want. If you fire perfect every time you're not really learning from mistakes because there's no "need" to change and learn. I know, I'm pretty brutal with my approach. Hope this helps some. Good luck.
  21. Have you tried firing it even hotter than ^6? Like up to ^7 even though it's a ^6 clay? IMO it's worth a test (use a waste tray/shelf underneath just in case) You mention you "can't see any crazing"....to a molecule of water or a tiny bacteria, a teeny tiny fissure in the glaze is like the grand canyon, of course it will make it's way through! If your glaze is crazed, the glaze and clay body do not fit one another, their coefficient of expansion is too dissimilar. This is only part of your problem, the other seems to be lack of vitrification in the clay itself. For those experiencing seeping on thicker forms - this is because the thicker it is, the more heat work it requires to penetrate the core of that clay mass and bring it to full maturity - which is why reducing thickness via trimming the foot resolved the problem. To test if your clay is vitrified: fire object and then weigh it. soak in water for 24hrs, dry it off as best you can and then weigh it again. calculate % of absorption from the difference.
  22. I've personally never seen a glaze drip go all the way through a soft brick, even though it's possible. Usually you would catch it and give it attention, or kiln wash over it and neutralize the fluxing materials. I HAVE, however, seen unchecked glaze spots eat all the way through kiln shelves. Top of the shelf just kept getting washed over, but the glaze was still in the core and progressively made its way all the way through and formed a drip. I think I saved it in my pile of treasures somewhere...
  23. ^yes, but then you have the dust hazard when grinding dry powders.... I recall the ball mill posted in the youtube link -- looks like a great DIY solution! Another cheap alternative might be a Harbor Freight rock tumbler.
  24. Any CA glue should work (cyanoacrylate aka super glue, krazy glue, etc) but a 2-part epoxy is technically stronger, but harder to control/wield/apply. I'd just use the CA glue in this instance. You can mix all sorts of materials in with adhesives. Whether it actually improves the surface afterward is highly subjective.
  25. Well yes, the more mass in the form, the more they are susceptible to the forces of nature/physics/kiln firing/etc. Hard to give specifics since it varies so much depending on what it is, how it was made, etc etc. As for quartz inversion - 2% expansion doesn't seem like much to a little cup or plate, but to a 6ft tall sculpture with a 1" thick wall will definitely have some concern and you may have to make some big changes to accommodate making that item. With bigger work it's inevitably going to be "moving more" as things shrink especially. You actually have to engineer your sculpture to accommodate certain shapes, kiln firings, etc etc. For example, everything made from clay will shrink to some degree and obviously clay can be heavy. You may not be able to perceive the shrinkage from your average cup/mug, but if you scaled it up to a 24-36" diameter vessel you're definitely going to be able to see the shrinkage as it will be obvious at this scale. Big heavy sculpture often gets vertical cracks originating from the foot, likely due to the heavy weight of the form and the friction on the work-surface as the piece dries, this continues as it fires and shrinks again. Big work makes "walls" in the kiln that make heating uneven sometimes, so how you stack your kiln will likely effect the work too. Example of that might be firing several long-necked forms - if you cannot place these centered in relation to the heat source, it's likely the uneven heating will warp the piece and it will lean toward the heat source since that side shrinks more. If you fire very conservatively your chances of surviving these forces are much much higher. Obviously you won't be able to fire big stuff on a fast kiln firing schedule, sometimes you even have to down-fire your work so it doesn't get dunting cracks. Keep in mind that my studio operates outside the box of your typical ceramics studio. Most of our work is fired earthenware temp, with a forgiving stoneware clay body...oh yeah and did I mention most of our stuff is once-fired?! Most of my gas kiln firings with big stuff takes about 1 week turnaround for firing - 1-3 day drying/pre-heat, up to 24hrs to fire, 2-3 days to cool. Go slow from pre-heat to quart inversion. Remember, it's not only quartz inversion to be concerned with...all ceramics still have chemical water that needs to come out too...so if you go too fast with a 1" thick piece of clay...boom....
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