Rework oven option?... - Page 1
Forum section: electronics / projects

author: 0xFFFF
author_rank: Contributor
timestamp: January 27, 2015, 01:01:16 am
content: Hi everyone,I noticed that ALDI are selling a Lumina 12L toaster oven and I was wondering if it might be suitable for reworking (with mods)?...https://www.aldi.com.au/en/special-buys/wednesday-28-january-2015/wednesday-detail-wk-5/ps/p/12l-toaster-oven-1/1200WSuitable for 4 slices of toast or a 9 inch pizza65-240 degree temperature controlNon stick coatingTempered glass door$29.99Lead free would likely be an issue given that the maximum temp is 240C. Has anyone had experience with this sort of thing before?Could the toaster be hacked to get a little more than the rated 240C?Most of the work I do is leaded but I would prefer to get a unit capable of lead-free.TIA,0xFFFF

author: MacAttak
author_rank: Unknown
timestamp: January 27, 2015, 03:35:07 am
content: Yes, you can bump up the power easily.http://www.ebay.com/itm/9-5mm-x-180mm-Red-Wire-Lead-Cartridge-Heater-Heating-Element-AC-110V-500W-/321057317287I have one of those in my reflow toaster (in addition to the two it had already) to give it just enough extra juice.You can also make the oven a good bit more efficient by lining the interior (and inside of the door) with Reflect-A-Gold. That stuff isn't cheap but it works well.

author: 0xFFFF
author_rank: Contributor
timestamp: January 27, 2015, 04:11:28 am
content: Thanks for the Cartridge Heater Heating Element idea MacAttak. I'm looking at getting a suitably rated 220V unit.How did you mount the element in your oven? The sellers do not appear to have any mounting hardware for sale.NVM found 'EPDM Rubber Lined P Clip 10mm Clamps Cable Wire Fuel Hose Petrol Pipe 10 Sizes'. I'll just remove the rubber before installing.

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: January 27, 2015, 07:47:53 am
content: I purchased a $30 from KMART just a few weeks and had good success re-flowing a new board. Although I was using Lead paste.. shhh don't tell any one. I even did double sided reflow with it.. just risking turning the board over and protecting the underside with tin foil and ramping directly to the spike temp nothing on the bottom fell offThe problem you will have is getting to the temps you want within the desired time I found a small increase in thermal mass had a large impact on the times and I had to go over time on a few runs.Also I'm not sure I can hit 250 as advertised hence the use of lead solder paste.

author: David Chamberlain
author_rank: Frequent Contributor
timestamp: January 27, 2015, 07:53:51 am
content: Also a comment on all these fancy pants toaster oven controller circuits. Don't bother with them!Just stick a probe in a do a few dry runs with a bit of trial and error you will come up with easy to follow instructions like mine1. Preheat to 40. Place board in oven.2. Turn Oven to full (RAMP) @ 130 turn oven off. Temp will coast to 147. RAMP = 90 seconds.3. Turn Oven to BOTTOM Mode (SOAK) and hold for 60 seconds. Temp will go from 150 - 1754. Turn Oven to FULL Mode (SPIKE) Temp goes to 220 in 60 seconds.5. Open door and turn oven off.Do not follow these instructions you will need to experiment with your own oven and solder paste profile but you get the idea.

author: aargee
author_rank: Frequent Contributor
timestamp: January 28, 2015, 02:18:41 am
content: Is that the KMart Homemaker 14 litre toaster oven?

author: mrpackethead
author_rank: Super Contributor
timestamp: January 28, 2015, 04:09:48 am
content: Quote from: pixulator on January 27, 2015, 07:53:51 amIf you don't value your time, i guess. But for a few dollars its worth it to me.

author: wraper
author_rank: Unknown
timestamp: January 28, 2015, 04:19:41 am
content: Strange choice for rework, I understand for reflowing the new boards but for such use... That means melting all the solder / stressing all parts on the board at least two times per every rework. Don't you worry that connectors will fall of the board and heavy parts on the bottom side of PCB as well. As well not suitable if there are electrolytic capacitors on the board.

author: mjkuwp
author_rank: Unknown
timestamp: January 28, 2015, 11:47:20 am
content: Quote from: pixulator on January 27, 2015, 07:53:51 amyes, this will likely work. I do have my home-made PI controlled oven and like it but I have noticed that the resulting commands match these instructions from pixulator.I don't think you can or should walk away from even a controlled oven so either way your time is pretty much totally occupied for this short time.by far, I have found the biggest challenge to be finding a good and efficient way to get temperature feedback. After all - the temperature of the oven is not the same as the board. In my latest I have the board rest directly on a blackened copper sheet and the thermocouple is stuck to the copper sheet. I can only do parts on one side and I would add any required thru-hole parts after the oven cycle.During the cycle I watch for the displayed temperature at the moment most of the solder melts and note this difference in my head (perhaps 5C to 10C) and make the adjustment of when to open the door and aim the fan in/take the board out. I usually take the board out when the copper sheet temperature reads 215C to 220Cto the OP - I suggest looking for a convection toaster oven but only if it is still a pretty small one like what you have found.