| Electronics > Beginners |
| Best Re-flow Oven for Hobby electronics |
| << < (4/8) > >> |
| jmelson:
--- Quote from: wilfred on April 04, 2019, 09:43:58 am ---I found this toaster oven for A$20 at Officeworks. I like it because it is small with the elements closer to the tray than is possible in larger ovens. It is 650Watts. Does anyone have experience with it for reflow? I'll take opinions too. It is super cheap but doesn't hurt to ask first. Thanks https://www.officeworks.com.au/shop/officeworks/p/heller-professional-stainless-steel-6l-toaster-oven-hpovt6#reviews BTW I saw this one at Kew East store. --- End quote --- Well, this looks similar to one I have used for over ten years. Mine has two heating elements that run left-right above the tray, and two below. I spliced in a thermocouple ramp-and-soak controller in series with the thermostat. I poke the thermocouple into a plated through hole in the board, so the control loop is actually controlling temperature on at least one spot of the board. It has worked very well, and I've done close to 2000 boards with it, I think. Mine has a convection fan in it, but it doesn't really move much air at all, so I don't think it actually accomplishes anything. Jon |
| Simon:
Air is a poor conductor of heat so moving the heated air to the board makes a lot of difference. |
| wilfred:
I went and bought one. But I certainly don't recommend it for food. When starting from cold it goes to 295 Celcius and switches off after 4min22sec. Then it cools to 136 Celcius and switches on. It takes a minute and a half to get back to 295 Celcius. And the cycle repeats. I set up a DMM to measure the temperature and a video camera to watch it. The temp probe (EEVBlog 235 DMM) was in free air just above the wire rack. I'd take it back if I wanted it for food. There is another review on the Officeworks website which said something similar so I don't think my unit is particularly defective. It's still only two samples of course so it is hard to read too much into that. But you'd think it would stay on for the entire 15minute timer cycle and vary the temp by a lot less than 160C. But since I don't want it for food and intend to put a PID temperature controller to drive it I thought I'd seek further opinions. I'll see if I have time to plot a graph of the time/temp tomorrow. BUt for now I can say at full power it will heat from 136C to 295C in 94 seconds. I'll try manually holding it from 250-270C and see if that doesn't trip the thermal cuttoff. Do you think that is satisfactory for solder reflow? I think it might be OK but I've never built a PID controller or a reflow oven. If it is OK I can say that since it is about the size of a loaf of sliced bread it would be good for a space constrained lab that does only one or two boards at a time. It seems pretty well built. It just doesn't work for its intended purpose. Edit: Here is a plot of time/temp. |
| Simon:
I have a little fan oven that i use for food, i have noted that it is very "loose" on the temperature control as turning it up after it has cut power to the element on the current setting does not turn the element back on so it must be greatly overshooting the set temperature and have a big hysterysis. Works fine for food though. |
| Doctorandus_P:
For me I would not consider a pre-built oven like the T962. I've heard some bad reveviews about un-even heating, but those reviews are 10+ year old and with a new version those reviews are unreliable. The main reason I would not buy such an oven is that you can not see what is happening with your solder job. And if you can not see what is happening, you can not adjust to improve it and you can only see the end result. For me I can see a few options. I would consider a hot plate, which heats the PCB from the underside. The cheapest version of this would be a simle frying pan on a kitchen stove. I would not reccomend this for long term use, but I've heard success stories about it and it seems like a good idea to try it to get some experience on how it works. There are some relatively cheap hot plates directly from Ali / Ebay / China, and there are also some on Tindie, or started with a kickstarter. Another option that looks good is to use a (kitchen) oven with a glass window. These need a fan for heat distribution, and you have to upgrade the temperature control with a thermocouple and a temperature controller, but there are lots of opern source projects of these (check github) and also kits and pre-build controllers. |
| Navigation |
| Message Index |
| Next page |
| Previous page |