I have an external SSR in the middle of a short extension cord that the oven is plugged into. The SSR, and my controller are all powered via the USB interface to the controller.
Just for fun, I've been trying to model the thermal behavior of the oven, and I've come pretty close with an electrical equivalent in LTSpice. I ran some tests with the heater at 10% and 30% duty-cycle to see what the steady-state chamber temperature was for a given heater power, and logged the door-closed cool-down cycle to find the chamber thermal mass (capacitance) and the chamber-to-ambient thermal leakage (resistance). I also empirically added a second R-C delay to the circuit to model the heating/cooling lag in the heater element. This gives me my overshoot. The component values look strange because I've been playing with time-scaling and other normalizations. Now the scale is 1 second = 1 second, and a heater voltage of 10,000V = 100% duty-cycle. It comes pretty close to matching my oven, but if I ever want to use the model for anything practical I will need to dial it in a bit more.
I am actually using an SSR wired into an extension cord as well, but I consider that to be "just for the prototyping phase."
[...]
It would never have occurred to me to model thermal mass as capacitance, and so on. Very clever. I wonder if that's been done before?
did you measure temperature with the housing on to see what temperature that stuff in there will operate at?
Before you do more work, I suggest putting the lid on and measuring the temperature in that cavity.
You might be really disappointed by the temperature you will get in that cavity now that you put work into it.
if you add an exhaust fan without insulation its going to cool the oven and make a thermal gradient because its like putting a big flat heat exchanger on the side of the oven wall, minor, but the wider the PCB the more an effect it will have
also for deburring the vent, there is NO better tool then a abrasive rubber point for a dremel, they wear quick but your vents will be like, ultra smooth
https://www.amazon.com/Dremel-463-Rubber-Polishing-Point/dp/B00004UDHR
also, this is the video where dave jones has problems with his reflow oven overheating the controller
For my oven I used a $50 panasonic SSR, you want to treat the cheap ones real well, and downrate to ~50% of their real rating, some people going down to 25% on the forum
I think I read one mod where the control electronics had the wrong temp because of the heat, did dave jones not have this problem when he left his controller on top of the oven also?
oh yeah, beware, the ebay one needs a smaller collet, so only do it if you got the dremel collets that are smaller size.
a worthy investment because that is a stupid thing that can really hurt you, a wire shorting to a chassis
0,32.07 # Turning OVEN on
2,32.02
4,32.00
6,32.14
8,32.19
10,32.27
12,32.58
14,32.73
16,33.04
18,33.50
20,34.02
22,34.76
24,35.52
26,36.57
28,37.66
30,38.92
32,40.30
34,41.87
36,43.73
38,45.73
40,47.59
42,49.76
44,52.20
46,54.50
48,57.03
50,59.53
52,62.30
54,65.22
56,68.00
58,70.88
60,73.99
62,77.14
64,80.24
66,83.70
68,86.94
70,90.18
72,93.50
74,96.86
76,100.28
78,103.61
80,107.03
82,110.55
84,113.97
86,117.37
88,120.83
90,124.18
92,127.52
94,130.96
96,134.51
98,137.98
100,141.34
102,144.68
104,147.96
106,151.04
108,154.31
110,157.45
112,160.57
114,163.62
116,166.90
118,170.00
120,173.01
122,175.91
124,178.99
126,181.87
128,184.95
130,187.66
132,190.41
134,193.12
136,195.82
138,198.71
140,201.43
142,203.96
144,206.62
146,209.16
148,211.86
150,214.37
152,216.88
154,219.20
156,221.53
158,224.07
160,226.59
162,229.07
164,231.50
166,233.75
168,236.12
170,238.33
172,240.43
174,242.69
176,244.88
178,246.95
180,249.17 # Turning OVEN off
182,251.67
184,253.84
186,255.20
188,256.70
190,257.71
192,258.92
194,260.00
196,260.85
198,261.16
200,261.45
202,261.39
204,260.24
206,257.87
208,255.59
210,252.52
213,249.80
215,247.70
217,245.39
219,243.34
221,241.15
223,239.01
225,237.31
227,235.59
229,234.06
231,232.01
233,230.41
235,228.35
237,226.08
239,224.27
[snip]
823,39.70
825,39.62
827,39.50
829,39.41