FrogBlog
How to Use a Multimeter to Test Voltage (Digital and Analog)
If you’ve never tested voltage with a multimeter before, you might be staring at all of the different numbers, symbols, and buttons on the device and wondering what exactly you’re supposed to be doing with them.
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Ask Arnold: Arnold's Firebrick Repair Toolkit
Kiln Pointer from Paragon: Arnold's Firebrick Repair Toolbox ------------------------------------------------------------------------------------------------------------- Contents A Firebrick Repair Toolbox Book Recommendation: "Clay: A Studio Handbook" Reader Response Firebrick Repair Toolbox ------------------------------------------------------------------------------------------------------------- A Firebrick Repair Toolbox Ever since I left Paragon and became an independent kiln technician, hunting for tools has been my biggest waste of time. So I have sorted my kiln tools into four tool boxes (along with a vacuum cleaner and air compressor). Recently I put all of my firebrick tools into one box where I can find them instantly. Here they are, going clockwise from left to right in the photo: Plastic or Aluminum Foil Tray: It should be large enough to dip firebrick pieces into kiln cement. This is much faster than applying the cement with a putty knife. You have to work quickly, or the cement will begin to set before the repair parts are pressed together. The faster you work, the better the bond. Kiln Wash: Apply to the firebrick kiln bottom and the Kiln Sitter cone supports. Kiln wash looks like kiln cement. IMPORTANT: Keep these powders separated and clearly marked. Spray Bottle: Spray a little water onto firebrick parts that you are cementing together. This helps the cement to adhere to the firebricks. If you work fast, you won’t need the water at all. Plastic Cups: If you don’t have these, you will constantly hunt for a container to mix the cement in. Clean and reuse indefinitely. 2” Paint Brush: Thin kiln cement to coffee cream consistency. Then brush onto surfaces that you want to harden, such as the top of sidewalls in a top-loading kiln. Immediately wipe off the cement with a rag. Paragon Liquid Kiln Cement: I like the liquid kiln repair cement, because it’s fast and convenient. This is the very same cement used in the Paragon factory. Scrap Firebricks: Cut pieces to replace broken sections in a kiln. Paragon Dry Kiln Cement: This is for when you run out of liquid kiln cement. You can also mix the powder to the exact consistency that you want. Rag: For wiping off kiln coating and for general clean up. Repairing firebricks is messy. Paint Mixing Stick: For mixing kiln cement and kiln wash. Stir kiln wash constantly as you use it. DeWalt DWHT20542 Multi-saw: This comes with a coarse blade and a hacksaw blade. Use it to cut firebricks. I found this at Home Depot. You can find other brands, of course. 3M Sanding Block: Medium grit sandpaper works well in shaping firebricks. 3M Sponge Sanding Block: Sand the edges of firebrick lid grooves to remove loose debris. You can cut the sponge to the size you need. Marinade Injector: I found the “Good Cook Flavor Injector” at Tom Thumb. Use it to inject kiln cement deep into the cracks in firebrick kiln walls and floor. I will cover this in detail another time. HEPA Vacuum Cleaner and HEPA mask (not shown): Wear the mask when working around firebrick powder. Vacuum firebrick parts before cementing. Book Recommendation: "Clay: A Studio Handbook" Vince Pitelka, well-known for his teaching and his contributions to Clay Times, here tells you more than you ever thought you needed to know about pottery. He shares a lifetime of knowledge. Click here to see much more about Vince's book Reader Response Last week I wrote that I left Paragon in August, 2019 to become an independent kiln technician in the Dallas - San Antonio, Texas area. The day after I left Paragon, I was replacing elements at a school in Fort Worth. I also wrote that doing something creative helps one to forget the daily news. A few of the responses from readers-- “Many thanks, Arnold, for your Kiln Pointers and also your paragraph on facing world events,” wrote Ruth Canham of Nahiku Art Glass in Hawaii. “I don’t know how I would have made in through the last couple of weeks without having my kiln to keep me busy. First, I took on the challenge of trying strip construction with reactive glass. After that I went on to making whimsical birds. It’s kind of freeing in a weird way to have the galleries closed. Time to play.” ---------- “Thanks for sharing the electrical knowledge,” wrote Alexander Riedel. “Many are terrified of electricity when it can really be very simple if you know what to look for and how to do it safely. “From my experience working on industrial foundry ovens,” Alexander continued, “it’s always something incredibly simple when it comes to electrical problems. It just takes a while to chase it down: a loose connection, limit switches slipping from loosening, fouled relay contacts, a wire or nut that loosened from expansion/contraction, overheated or broken elements. I also really enjoyed the quote about the studio being a place away from reality.” ---------- “The nose told the story,” wrote Fujie Robesky. “Great detective work. Good to hear you’re still working in what you obviously love.” ---------- “The Kiln Pointer email was a breath of fresh air!” wrote Andy Reeves ---------- “No telling what changes we will see from all this," wrote Pattie Necaise about the virus. “I think there will be good changes. We just might value people more than things.” ---------- “It was good to hear from you, like hearing from an old friend, although we’ve never met. Thanks so much for the many pointers through the years,” wrote Colleen Gilligan Gilbert of Cypress, Texas. “I work at a non-profit that serves adults with intellectual disabilities, and I help them earn a paycheck by making and selling fused glass,” she explained. “We have three big Paragon kilns--two Ovations and a Pearl-44. We got the first Ovation on my first day here over 10 years ago. We have used the heck out of these kilns, firing them every afternoon. “Right now it’s very quiet here, as all our folks are staying away from our Learning Activity Center for their own health and safety. I continue to do paperwork, and look forward to the hustle and bustle of their return.” The Rain in Mesquite This morning before dawn, I sat in my sunroom listening to the rain. It drummed softly on the steel roof and splashed into a puddle outside. I felt like I was in the steel-roofed A-frame that I built in Leilani Estates near Pahoa, Hawaii. The rain fell in sheets there. The rain cleanses the world and sounds comforting. Thank you, Arnold Howard Mobile 972-333-1437 www.instagram.com/arnoldhowardkilns www.facebook.com/arnoldhoward
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Hunting for a Dead Short in a Kiln
This post was written by Arnold Howard, a former employee at Paragon Industries who is now an independent kiln technician at Howard Kiln Services. The owner of a Paragon A-24B called to tell me he saw sparks flash inside the switch box on his kiln, and the circuit breaker tripped. He could see the flash through the ventilation louvers on the side of the box. “It made a loud noise that scared the hell out of me,” he said. “It happened when I turned the bottom switch to high.” “Your kiln has a dead short,” I told him. A dead short causes a large amount of electricity to flow suddenly through the wires. This shuts off the circuit breaker for your kiln because the surge of electricity is much greater than the amperage rating of the circuit breaker. A dead short usually happens when the protective insulation on a wire has been damaged, and the bare wire touches either another wire, an element connector, or the steel case of the kiln. After arriving at the customer's home, the first thing I did was open the switch box by removing hex-head screws with a 1/4” nut driver. The screws are on the sides of the switch box of most kilns. You can buy the 1/4” nut driver from a hardware store. Some brands of kilns require a different size nut driver. If the size you need is not available locally, you can order one online. This may be the case overseas as the 1/4” size is uncommon there. Remember, always BE SAFE! If you ever remove the switch box on your kiln, first unplug the kiln. This is essential because otherwise you will be exposed to live wires inside the opened box. In the first photo, you can see the element connectors, which are small brass barrels with a screw-on each end. Notice that a wire is attached to each connector. In the A-24B, those wires go to switches. In digital kilns, the wires go to relays, which turn the elements on and off. Lying on the garage floor, under the shadow of my lamplight, I hunted for the dead short. Since the sparks flashed when the bottom switch was turned to high, I started my search at the bottom of the switch box. In the second photo, you can see where the short occurred. Look at the element connector in the bottom center half of the photo. It is the blackened brass barrel that is against a white porcelain insulator. The element connectors are the hottest items in the switch box. If a wire touches an element connector, the insulation on the wire can eventually burn off and cause a dead short. In the bottom right corner of the photo is a red wire with a burned spot. That burned spot is where the wire touched the element connector. The spark blackened the connector. With any routine kiln maintenance, you or your kiln technician will need to open the switch box or protective cover panel on your kiln if you ever change a thermocouple, relay, switch, or repair a damaged wire. As you can see from the photos, it is important that as you reinstall the switch box or panel onto the kiln, check that the wires will not touch an element connector. To be sure that the wires would not touch element connectors or the kiln case, I looked at the wires from the side while closing the switch box, tucking some of the wires out of the way inside the box. Then I carefully positioned the switch box on the kiln and installed the screws. You might want to shine a flashlight into ventilation slots or louvers to check the position of the wires one last time after you have reinstalled the switch box. As you can see from this story, major kiln problems can be avoided by taking just a moment to check the small details whenever anyone works on your kiln. Thanks, Arnold!
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Troubleshooting Your Controller
From electrical power issues to temperature, display, and keypad problems, Paragon Kilns has designed a Troubleshooting Guide for the Sentry Controller. Even though it was created by Paragon for the Sentry 2.0, this guide can help with almost any digital controller as the basic principles are the same. With of all the great insight included in the guide, my favorite part is how it describes the six basic parts a digital kiln uses to control heat. And, understanding how your kiln works will simplify all of your troubleshooting efforts!
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How Low Voltage Affects Firing Time
Knowledge is POWER! Making sure you have the correct voltage is one of the most important factors of kiln efficiency! Plug the kiln into the correct circuit. Low voltage can double the firing time. If your kiln is firing too slowly, make sure the voltage listed on the kiln’s electrical data plate matches the voltage of the electric circuit. The electrical data plate is usually located on the side of the kiln or the switch box. Firing a 240-volt kiln on 208 volts reduces the kiln’s power by 25%. Even a small drop in voltage can affect the firing speed. Low voltage has the same effect as firing with worn out elements. Even a small drop in voltage can slow down your kiln. For example, we test-fired a 120-volt kiln that took 5 hours and 3 minutes to reach 2331°F (1277°C). On a separate electric circuit, the same test kiln took only 2 hours and 30 minutes to reach 2350°F (1287°C). The difference in voltage between the two circuits? Only 7 volts. Fire the kiln when the voltage is highest. Turn off other large appliances. If your kiln ever slows down temporarily, do not assume that it is due to worn elements. The voltage to your building may have dropped due to peak demand. Have an electrician check the voltage under load while the kiln is firing. Until you know the voltage, an amp reading of the kiln won’t tell you much, because low voltage also causes low amperage. If the voltage is low during a period of peak demand, fire your kiln when the electrical demand is lower and the voltage is higher. Fire at night or early morning. Also, turn off other large electrical appliances such as a clothes dryer while the kiln is firing. Program at a slower rate. A digital controller will show error messages when it has been programmed at a faster rate than the kiln is capable of firing. This can happen even when the voltage is normal and the kiln is new. You may be using a firing schedule that is designed for a faster kiln. In this case, program at a slower rate. Moist clay can slow down the kiln. Another reason your kiln may be firing slowly is that the firing chamber has too much moisture. Firing moist ceramic greenware or moist glass molds can slow down the kiln. Dry these materials before firing them. Reduce the load density. Overloading a kiln with a dense load of ceramics and kiln furniture can also slow down the firing. Have the power company check the transformer. If the kiln still fires too slowly after following the suggestions above, have the power company check your voltage and readjust the transformer for your area if necessary. You can also request that your power company put a voltage recording unit at your location to check the voltage over an extended period.
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Is it time to change your mechanical relays?
It seems like every November we get the same phone calls and the same e-mails... "My kiln has stopped working and I have a show this weekend. Please HELP!" With that in mind, it's important to remember... owning a kiln is like being a Boy Scout, it's important to always BE PREPARED! Murphy's law says that whenever you need your kiln most and are firing the most, that's just when it's going to have a problem. So.... we all know that an ounce of prevention is worth a pound of I told you so. This is not directed to any one of our clients who've contacted us this month with an OMG moment! This is for all of us, who are just very busy and forget to take care of the basics. And yes... this has happened to me so, you're not alone. If you don’t already know, a relay is the part of the kiln that controls the power or current to the element, allowing the element to either receive current and get hot, or to interrupt the circuit thus not allowing the element to receive current and cool down. The mechanical relays, which come standard on most kilns, are what is responsible for the ubiquitous opening and closing clicking we hear while our kilns run. ALL MECHANICAL RELAYS in U.S. kilns are virtually the same... no matter the manufacturer. Mechanical kiln relays have a life of up to “X” amount of clicks and then they fail. This failure can either be in the closed position (Yikes, my kiln temperature keeps rising and it won’t turn off… everything is ruined!”) or they can fail in the open position. (Yikes, my kiln won’t heat up at all!) If they fail, it is not the manufacturer's fault, since they do not make the relays. They test them to make sure they work at the factory, but after that... it is your responsibility. We know that all failures stink and that is why we recommend changing your relays every 12-24 months. If you are a heavy kiln user, you should be smart and change your relays once a year. Think about it like an oil change or new tires... you wouldn't let your car drive on bald tires or your engine run on old oil. Pick a month and make it kiln maintenance month. Install new relays, paint the bottom with kiln wash, etc. and give your kiln a thorough inspection. Don't be the cautionary tale!! Finally, if this is something you don't want to hassle with... you can eliminate the problem by upgrading to mercury or solid state relays and almost never have to change a relay again. In our opinion, it's the best upgrade money can buy. With mercury relays it is important to make sure that regulations in your area don't prohibit them. The following states have prohibited the import of Mercury Displacement Relays within their jurisdictions: CA, CT, RI, IL, NH, MA, MN, ME, VT, NY, LA, MD, WI. If mercury relays are not for you, many kilns come with the option to add solid state relays for an additional charge. Hot Shot takes it one step further and makes all kilns with solid state relays by default.
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Why is my Kiln or Oven Not Heating Properly?
Let's be honest... using a kiln comes with its share of emotional ups and downs.
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