Great tip - why re-invent the wheel each time you need a gear. Plus if you're using standard sized parts in your model, you can either use 3D printed or off the shelf components depending on your requirements.
Thank you for your concern. This is not intended to be used unattended in an industrial environment, but in a workshop where you can keep an eye on it. If the thermocouple (which I've now replaced with a PT100 sensor) reads room temperature while it's in operation, then this is a pretty good indication that something is wrong.
I've recently needed to remove a bolt that had sheared off inside a recessed area - I tried the bolt extractors that you have pictured (which I've successfully used in the past) but they couldn't get enough grip to back it out (thanks to whoever thought some locktite would be the solution last time they put it back together). A mechanic mate saw the strife we were in and had a different set of extractors that worked amazingly well. They looked more like torx driver bits (and made from super hardened tool steel). The idea is you drill a hole that's a bit too small for them to fit and then hammer them in. This gives you plenty of purchase to then back out the broken bolt.
I'm don't think that there's a 12V output on the PID.It takes in 110-240V to power itself, and it must convert that down to 12V or 5V internally, but I can't see any outputs on it that supply 12V to an external device.You'll need to get a mains to 12V power adapter and wire it in parallel with the power input lines to the PID.
The PID and SSR completely replaced the original thermostat. There were two wires going into the thermostat, and the thermostat clicked to turn them on or off (join them or separate them).These two wires from the thermostat went instead into the SSR. In the photo I had, the OUTPUT from the PID went to the INPUT lines on the SSR.The wires that previously went through the old thermostat instead connected to 1 and 2 on the SSR.If you connected both wires from the thermostat to a single terminal on the SSR, this effectively joins them together, so takes the SSR out of the equation and the oven would be permanently switched on.
I ran the output from the PID to the input on the SSR.The SSR was then put in-line with the power to the heating element.The PID and SSR completely replaced the original thermostat. There were two wires going into the thermostat, and the thermostat clicked to turn them on or off (join them or separate them).These two wires from the thermostat went instead into the SSR. In the photo I had, the OUTPUT from the PID went to the INPUT lines on the SSR. The wires that previously went through the old thermostat instead connected to 1 and 2 on the SSR.
The PID I used doesn't have a timer. This modification retains the original timer for the oven, however it only goes up to 90 minutes or something like that.There are many digital timers that could replace the timer dial quite easily. Inkbird have a timer module that's on Amazon (but strangely not on their website)https://www.amazon.com/Inkbird-Digital-Switch-110-220V-IDT-E2RH/dp/B008KV65MSIf you were to cut out the dial for the timer and install this module below the PID, you could then route the 110 or 240V mains through the timer module and have greater control over the timing of the unit.
These look delicious - they're very similar to a traditional Australian bread called Damper. Damper is generally made from a flour and water dough, and you can use baking powder (or SR flour) if you want it to rise.You can make a big damper by forming the dough into a cob and bake it directly in the hot coals of a campfire (breaking off the charred outside crust to eat the soft interior) or wrap the dough around the end of a stick and cook it in a fire like this.We used to make damper over the campfire on the ends of sticks whenever we went camping - the dough is very easy to make and when it's cooked, you can put all sorts of things down the middle (butter and golden syrup or honey was a favourite!)https://en.wikipedia.org/wiki/Damper_(food)
Thanks for the update. I've got a PT100 sensor on order, I figure that if it's made to spec so it is 100Ω at 0°C then it should be much more of a known quantity than the thermocouple I have. I'm concerned that with the thermocouple I have that something isn't right having to put in such a huge offset (more than -70°C)
Awesome work! That looks mint. Good to see that the temperature is spot on according to three different sources too.What temperature probe are you using with the PID? The Type K? What temperature offset did you need to program in for it?Glad my instructions helped in getting the PID set up correctly - the instructions are pretty confusing.
Yes, but where's the fun in that? ^_^
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Pretty much this. Insulation has to resist heat and trap a large amount of air within it's mass. Most, if not all, materials that have these properties are not good to breathe as they're fine mineral fibres - Asbestos is a naturally occurring insulation fibre. Synthetic insulation is not as bad for you as asbestos, but you still don't want to get it into your lungs as the fibres can become lodged in there, build up over time and cause health issues much later down the track.
If you want to make a super-deluxe reflow oven, you'll want a slightly more advanced PID controller - one that adds timing to it.It's my understanding that for reflow, you need to heat up at a certain rate, hold it at a particular temperature and then let it cool at a certain rate as well. A more advanced PID will allow you to program in all these ramps automatically, whereas with my version you'd need to monitor it yourself.
I got over to the workshop today and installed the insulation. It was pretty fiddly, but on the right side, you can see how I cut some slots for the heating elements to fit into and it all holds in place very well.https://www.instructables.com/id/PID-Temperature-Controlled-Oven/step12/Add-Insulation/
Yeah, there are probably a few other alternatives, but I had some of this stuff on hand, it's totally non-flammable and is rated at temperatures up to at least 1000°C, so it doesn't matter that it's directly in contact with the ends of the heating elements. If I was buying some materials directly to do this project, I probably would have got some rockwool or something similar to that. Isowool is easer to work with for this application as it's in thinner sheets (~20mm thick or so) whereas rockwool is designed for home insulation so comes in much thicker batts.
I wasn't sure about that - whether or not a large initial error away from 0°C was an issue or not.Despite this large offset, it does seem to be pretty much spot-on for 0°C and 100°C.The eBay listing definitely said it was a Type K thermocouple. According to Wikipedia, red and blue are sometimes used for Type K, whereas it's red and purple for Type T.This is the first (and so far only) thermocouple I've had to calibrate an offset for, I have no prior experience with these devices.I've ordered a PT100 sensor and am waiting for it to come in from overseas, the only thing is that taking the oven apart and putting it back together again is a right royal PITA. What I now plan to do now is run a few spot checks at different temperatures and check with an IR thermometer or something...
I wasn't sure about that - whether or not a large initial error away from 0°C was an issue or not.Despite this large offset, it does seem to be pretty much spot-on for 0°C and 100°C.The eBay listing definitely said it was a Type K thermocouple. According to Wikipedia, red and blue are sometimes used for Type K, whereas it's red and purple for Type T.This is the first (and so far only) thermocouple I've had to calibrate an offset for, I have no prior experience with these devices.I've ordered a PT100 sensor and am waiting for it to come in from overseas, the only thing is that taking the oven apart and putting it back together again is a right royal PITA. What I now plan to do now is run a few spot checks at different temperatures and check with an IR thermometer or something else to make sure that I'm getting a relatively accurate reading.
The oven had a thermostat that went up to 240°C.For tempering metals, this is about perfect. 230°C is ≈ 450°F. If you're tempering any higher than this, you're losing a lot of hardness.I've got a piezo buzzer on the way that I'll wire up to the alarm outputs of the controller and set the high temperature alarm at something like 250°C
I will be installing the insulation on the weekend and will take more photos to update this instructable.
Yes, you're right (according to Wikipedia) - SSRs tend to fail closed whereas mechanical relays tend to fail open.The Inkbird PID does have a high temp alarm (and a low temp alarm too) - I might have to look into hooking it up to a buzzer to the alarm outputs.Temperature regulation with a failed SSR will be more critical when the oven is insulated as the temperature will be retained more than with the factory configuration of just an air gap for insulation.
PID Temperature Controlled ...View Instructable »
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I think I got there in the end - although my mesh seems to extend over the edges of the block on two sides...
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