DrF wrote: 17 Aug 2020 13:40
What about getting one of those controller kits?
They were quite the fashion a few years ago, I suspect they have come down loads now with the masses of cheap micro controllers all over the place.
To control the oven? I'm expecting it to be a lot quicker and cheaper to scratch-build it. Plus, I don't know what kind of display I need to mount on the front yet. It depends on what will fit into the space.
Just a idea, I don't know how tight the tolerance for over temperature or under the parts could take, from when I looked into this before there was ramp up times, time profiles for different stuff/size of boards etc. lots of pretty graphs :lol: so im guessing its a bit more complex than turn the timer on for 10 mins and hope?
There is a fly in the ointment however. After some initial testing it seems that the heat from the heating elements takes about 120 seconds to be fully picked up by the thermocouple. I assume that this is because the large thermal mass of the big metal probe that it's encased in. Probably made for taking temperatures anally or something.
It's a bit useless for negative feedback on the heating element with a delay like that since the entire soldering operation is only supposed to take 240s - I might need to look for a different one that can heat up quicker before I can use this thing without setting all my boards on fire.
OK, I got a "low mass" thermocouple and the response time is very good now. I've put everything together and covered the whole inside with heat-reflecting tape. I did a quick "manual" test with some random blobs of solder on old PCBs and it seems to work pretty well!
Now I just have to make the software a bit more automatic, and, I guess, make up a little bracket for the screen and buttons (low priority).