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Showing results for tags 'heatwork'.
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I have been trying to be scientific about arranging my firing schedule in a small electric kiln with a controller. I understand the concept of heatwork and use cones on all shelves in my kiln to monitor results. I soak at top temperature and fire down so want to compensate for the additional heatwork these procedures involve when I set the top temperature on my controller. I understood that this could be done by looking at the area under a graph of total heatwork, but having compared theoretical models using the Orton cone firing tables, if this is indeed the case, I must be missing something. The following example uses °C, as I am in the UK, and I am referring to the Orton theoretical temperature values. 1. In the Orton table Cone 7 is reached at 1237°C when firing at 60°C /hr, if this is a straight ramp, this would take 20.3hrs, assuming a starting room temp of 17°C ((1237-17)/60). If the x-axis is time and the y-axis temperature, the area under the graph is a triangle and can be calculated as (1237 x 20.3)/2 = 12,555 2. When firing at 150°C/hr cone 7 is reached at 1255°C. As a straight ramp this would take 8.25hrs ((1255-17)/150). Then the area under the graph is also a triangle calculated as (1255x8.25)/2 = 5179 SO, these areas which are supposed to represent total heatwork to achieve cone 7 are not the same. I am clearly missing something here. Can anyone help please. Thank you
Hey all! First time posting here. I'm new to firing, and i've been having some difficulties getting my kiln to fire to cone 6 properly. Here's my problem: When I check the cones at peak temperature (2180 in my case), the cones are not bent properly yet. Last night I just let it cycle down anyway. However, when I opened my kiln at the end of firing, the cones were overfired (at least at the top of my kiln). I've been slow cooling, so is it possible that the heatwork as the kiln fires down is actually causing the cones to bend further even at lower temps? Firing Schedule: 220/60 - 100 degrees/hr 2000/0 - 350 degrees/hr 2180/15 - 108 degrees/hr (still not getting my kiln up to 2192, but that might just be a problem with the PID or thermocouple) 1400/0 - 125 degrees/hr OFF I have no idea how to tell if my pieces are over/underfired because of this. Do I base it on what the cones were doing at peak temp, or what they looked like at the end of firing??