Author Topic: DIY reflow oven - suitable UK/EU candidates  (Read 18218 times)

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Offline Lomax

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DIY reflow oven - suitable UK/EU candidates
« on: January 15, 2016, 05:31:29 AM »
So I've come to a point where I need to add a small oven to my workshop - not only to use for soldering my own boards, but also for reflowing laptop motherboards (and graphics cards) which has become a surprisingly common need (I blame lead-free solder & programmed obsolescence!) - and for various other heating related tasks (paint baking, drying silica gel, vacuum forming, melting/heating various materials, etc, etc, etc). I'm not initially planning to replace the controller, but to use an external thermometer with a thermocouple and manually controlling the process, though later on some kind of Arduino based controller will replace the original controls. Having looked at a myriad of "mini" and "toaster" type ovens I've come up with a list of criteria which any candidate oven ideally should meet:
  • High power/volume ratio
  • Non-coated interior (or at least, non-Teflon; ceramic coating is ok)
  • Double glass door (for better heat retention)
  • Quartz heating elements (for lower inertia)
  • Multiple heating elements (at least two above and two below)
  • Fan assist ("convection", for more even heat)
  • Stainless exterior with few plastic parts (to handle higher temperatures)
  • Wide enough interior to handle most laptop motherboards (min 30x25cm)
  • Tall enough interior to handle 3D objects (up to 10-15cm height)
  • Decent insulation (faster/hotter, and lower clearance requirement)
  • Good looks (yes, this is important to me!)
  • Smallest possible external dimensions (my workshop is tiny!)
  • Low cost (ideally no more than £50)
  • Available in a 240V model, and on the European market

And here's my list of candidates:

ModelVolumeExternalInternalPowerTypeU/BFanPriceGlassInsideOutside
Dualit DMO114L45x33x2530x26x181.5kWMetal2/2Yes n/aDoubleCoatedStainless, some plastic
Dualit 8920018L42x36x2530x25x171.3kWMetal2/2Yes£100DoubleAluStainless, some plastic
Abode AMO180118L43x35x2332x28x191.3kWMetal2/2Yes £50DoubleAluPainted, much plastic
Steba KB119L36x29x2225x23x141.0kWQuartz1/1No £60DoubleAluPainted, much plastic
Steba KB1414L40x35x2527x26x191.2kWMetal2/2Yes £70DoubleCoatedPainted, some plastic
Steba KB1919L43x36x2630x28x221.3kWMetal2/2Yes£100DoubleCoatedStainless, some plastic
Brandt FC160MW16L45x37x321.4kWYes £80DoubleCoatedPainted, much plastic
Brandt FC215MW21L46x37x291.4kWYes£100DoubleCoatedPainted, much plastic
Moulinex OX110E30 9L0.5kWQuartzNoCoatedPainted, much plastic
Moulinex UNO OX13023015L43x36x311.3kWNo £70DoubleCoatedPainted, much plastic
Ariete Bon Cuisine 21021L45x33x2332x1.5kWQuartz2/2No
Bon Cuisine 210 Metal21L44x33x26 32x25x201.3kWMetal2/2YesDoubleAluStainless, little plastic
Lakeland Mini Oven18L42x37x26?1.3kW??Yes n/aDoubleAluStainless, some plastic
Efbe-Schott SC MBO100013L46x36x2132x30x111.4kWMetal2/2No £50DoubleSteelPainted, much plastic
Dema 1500W pizzaofen18L46x42x2034x34x61.5kWMetal4/4No £75DoubleSteelStainless, some plastic
Roller Grill FC 26026L47x48x2833x30x231.5kWMetalLoopYes£400DoubleStainlessStainless, little plastic

I've had great difficulty finding any small ovens with quartz type heating elements, though it may be possible to replace the metal bar heaters in some models. The Roller Grill model is only on the list because I liked the way it looks - at £400 it's far outside my budget, and it is also a little bit too large. The Dualit oven is similarly designed, with very little plastic and no painted surfaces, and a much better size, but the current model has been getting terrible reviews and costs too much! The most solid and best looking of the others is the Steba KB14, which has plenty of insulation and few plastic parts, but this is also a bit pricey and maybe not quite large enough on the inside to handle laptop motherboards. It also has some kind of coating on the inside, but I do not know if this is a Teflon or ceramic type. The Abode oven has the best internal dimensions, and also ticks most other boxes, but it has a painted exterior with lots of plastic parts and looks kinda ugly. Comparing internal/external dimensions it is clear that it also has little insulation. The Dema pizza oven is an interesting option, with a stainless catering style exterior and shaped heating elements that cover a large area. The internal height of only 6cm makes it useless for a lot of things though, and I worry that the short distance between elements and PCB will make heating very uneven (despite the larger heating elements).

Edit: I've updated the table above with additional models.

To make a long story short: I'm stuck and unable to decide which oven to go for! What to do? The only thing I could think of was to post here and ask for some input, which may tip the balance in favour of one of them :) Here are a few photos (because a picture is worth a thousand words):

« Last Edit: January 19, 2016, 05:03:23 AM by Lomax »
 

Offline Owen

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #1 on: January 15, 2016, 08:12:02 AM »
Steba KB1111L36x29x2225x23x141.0kWQuartz1/1No £60DoubleAluPainted, much plastic

I'm using the Steba KB11 as reflow oven in combination with a reflow controller. It ramps up round about 1°C/sec. The thermal switch is a bit annoying on multiple runs because you have to let it cool down quite a bit or it will stop heating while ramping up. Btw your Volume is wrong it 8 L (so 125 W/L). But i have to admit that i'm only using this oven to reflow my own PCBs and not for repairing motherboards.

hope this helps.
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #2 on: January 15, 2016, 09:13:21 AM »
I'm using the Steba KB11 as reflow oven in combination with a reflow controller. It ramps up round about 1°C/sec. The thermal switch is a bit annoying on multiple runs because you have to let it cool down quite a bit or it will stop heating while ramping up. Btw your Volume is wrong it 8 L (so 125 W/L). But i have to admit that i'm only using this oven to reflow my own PCBs and not for repairing motherboards.
Many thanks Owen, interesting to hear about the KB11 - I included it as I thought it looked really good and I love the small size! It's also the only one on my list that uses quartz heating elements. And thanks for the volume correction - I'll update my table to reflect this. If the only reason for getting an oven was to do my own boards, then it would be my model of choice, but for other uses it's just a little bit too small. I also worry that even if a given laptop MB would fit (and many probably would) the absence of a fan and the single elements might mean that to reach reflow temperature on the problem chip (usually the GPU) other areas of the board might be overheating.

That said, I suppose MB repair could be done with a hot-air-gun instead - but then a quality hot air gun is what I should get, and I couldn't use that for any of the other things that an oven could be used for. I've been over these lines of reasoning many many times and keep coming back to how useful it would be to have an oven with a ~30cm internal width, and tall enough to take a cup or painted object (~10cm). I also already have a Weller hot-air pencil, and a Portasol gas pen, which do most of the things I need hot air for - though neither will reflow a large chip reliably.

P.S. If you're having trouble with the thermal switch, why not just bypass it?
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #3 on: January 15, 2016, 09:24:24 AM »
Can anyone help fill in the missing info on the Lakeland Mini Oven? These are available refurbished for ~£60 and may be a great candidate; I suspect they are made by the same people who make the Breville BOV800XL Smart Oven which has received rave reviews, particularly for providing very even heat (but is only available for the US market and 120V). I think the Breville has quartz heating elements, so maybe the Lakeland does as well? They do look quite similar - see photos.

Edit: I note with envy, and not for the first time, that the options available to US customers far surpass what can be found on the British market...
« Last Edit: January 15, 2016, 09:27:18 AM by Lomax »
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #4 on: January 15, 2016, 03:29:22 PM »
I think I might have found a candidate which uses quartz elements, and four of them (2/2) as well, for a rated total of 1.5kW. It's a little big though, at 20L, and 5cm wider than the Steba KB 14 (my current #1 choice) - and it doesn't have a convection fan. The question is: just how desirable is it to have quartz elements? This oven can supposedly reach 230 degrees in just 3.5 mins (~1 degree/sec), which sounds quite fast for such a large oven.

Is it worth trading off on convection, insulation and size just to get quartz elements? Or is having a fan more important? I really have no idea!
 

Offline DerekG

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #5 on: January 15, 2016, 04:58:13 PM »
and it doesn't have a convection fan

You have to be careful with fans as I have found that they can move the small SMD components around.
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Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #6 on: January 15, 2016, 05:24:57 PM »
You have to be careful with fans as I have found that they can move the small SMD components around.

Thanks Derek, that's a good point! Though I guess that I can disable the fan for all or part of the cycle if this becomes a problem. I've seen it mentioned in several places that having a convection fan is a good way to avoid hot spots, which if you're going to reflow large/expensive/irreplaceable boards (like laptop MBs, or graphics cards) may be a big problem. I would have thought the fan would need to be quite powerful to shift components, but then maybe they are - I've never used one of these little ovens so I don't know. Maybe it's not the airflow that causes problems, but vibrations from the fan motor? If so, I suspect this can be improved by dampening the fan motor mount.

What about the inside coating some of the ovens have? I'm not keen on this and would prefer not having any, but I have no idea if it's likely to cause any problems. I know Teflon can produce toxic gas if heated to too high a temperature, which considering I'll be messing about with the temperature control might well happen...
 

Offline Fred27

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #7 on: January 15, 2016, 11:14:10 PM »
I'll be interested to see what you go for and how well it works. When I was looking I found there was hardly anything available in the UK.

I ended up going for something 9L and very cheap from Robert Dyas. Not great but works well enough for my small boards. Even with some welding blanket insulation it gets too hot to want the controller (and cold junction compensation) inside the oven enclosure.
 

Offline Neganur

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #8 on: January 15, 2016, 11:23:37 PM »
Don't forget the Severin series, e.g. TO 2034: https://www.beta-estore.com/rkuk/order_product_details.html?wg=1&p=16

Fairly affordable.
 

Offline Codemonkey

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #9 on: January 16, 2016, 12:17:23 AM »
I bought one from Currys a while back. At the time it was the cheapest one they did (£24.99) and was branded as LOGIK (their own brand). It looks exactly like the Abode one you listed except the middle knob doesn't have the fan selection as mine doesn't have a fan.

I built my own PID controller which has a 13A socket on it, and just feed the thermocouple in through a small gap in the front door. To use it, I select the stay on option on the bottom knob, turn the top knob to max, and select both top & bottom elements on the middle knob, then plug it into my controller and off I go!

It doesn't seem to have any problems following the profile for lead free solder I programmed into it apart from the cooldown phase where I have to open the door.
 

Offline DerekG

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #10 on: January 16, 2016, 02:09:34 AM »
I guess that I can disable the fan for all or part of the cycle if this becomes a problem.

You can reduce the fan speed to approx half speed by just adding in a 1N4004 diode in series (if it is a 240Vac fan that is).

Small components like 0603 etc are the ones that get pushed around if the fan is too strong.

Quote
I've seen it mentioned in several places that having a convection fan is a good way to avoid hot spots

A lot of this depends on how much heating is actually being done by infrared. The fan helps with convection, but not direct infrared.

You will find by experimentation which way to place your boards in the oven to avoid the larger components "shadowing out the infrared heat" from the smaller components.
I also sat between Elvis & Bigfoot on the UFO.
 

Offline mikeselectricstuff

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #11 on: January 16, 2016, 02:22:51 AM »
You can reduce the fan speed to approx half speed by just adding in a 1N4004 diode in series (if it is a 240Vac fan that is).
Depends on the type of fan. I've not taken apart a convection oven but small fans tend to be shaded-pole motors, which can't be speed-controlled like this. You'd probably be better off controlling  it by blocking part of the airflow.
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Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #12 on: January 16, 2016, 04:47:41 AM »
I'll be interested to see what you go for and how well it works. When I was looking I found there was hardly anything available in the UK. I ended up going for something 9L and very cheap from Robert Dyas.
I was in my local Robert Dyas a few days ago, specifically to look at mini ovens, but they only had two models and one of them had hobs on top (I don't want this). You're right that the options available in the UK are quite limited, but I've looked in France and Germany as well, where you can find many models not available here - often with surprisingly low shipping costs (e.g. I can get the Steba KB 14 from France for £75 including shipping, while it's £90 on Amazon UK)

Don't forget the Severin series, e.g. TO 2034: https://www.beta-estore.com/rkuk/order_product_details.html?wg=1&p=16
I did look at Severin after seeing the EEVblog videos about the reflow kit from Beta Layout, which is based on the Severin TO 2034. This oven doesn't have a fan though, and it's a little big (20L), and it has a painted exterior with a lot of plastic. In my mind an Arduino controlled oven can be useful for many things - not only reflowing PCBs - some of which may require much higher temperatures than it was designed for. For this reason I'd prefer an oven that has a stainless exterior with few plastic parts, and a plain aluminium or steel interior that isn't coated (or has a ceramic coating). It may be an ambitious goal but it is my plan to buy preciesly one device to serve as "that box I can put stuff into to heat it up real good". For this reason I am now leaning towards the Dualit or Lakeland ovens (see below).

I bought one from Currys a while back. At the time it was the cheapest one they did (£24.99) and was branded as LOGIK (their own brand). It looks exactly like the Abode one you listed except the middle knob doesn't have the fan selection as mine doesn't have a fan.
Yeah, I've seen that one, and it is indeed very similar! As with so many things these days, doing product research is greatly complicated by the fact that no-one makes anything any more; the label on the product bears no relation to where and by whom it was made. There's probably an entire city in China somewhere which only does mini ovens, with whole families spending their entire lives inside in a giant factory/labour camp churning out flimsy junk that is then stamped with Brand X for consumption by gullible westerners. Bosch, Black & Decker, Severin, Steba, Dualit, Breville - they are only brands today and the actual manufacturer is probably the same anonymous state-owned sweatshop.

It doesn't seem to have any problems following the profile for lead free solder I programmed into it apart from the cooldown phase where I have to open the door.
When I get round to replacing the controls on my oven I'll look at including a mechanism that can open the door programatically - I reckon a linear actuator (not a solenoid!) like this one should be able to push open the top of the door wide enough for cool-down without disturbing the soldered board(s).

A lot of this depends on how much heating is actually being done by infrared. The fan helps with convection, but not direct infrared. You will find by experimentation which way to place your boards in the oven to avoid the larger components "shadowing out the infrared heat" from the smaller components.
That makes perfect sense, good point! I guess this explains why it's so hard to find a convection oven with quartz elemets, which (I think) produce more radiated heat than the metal type elements?

Depends on the type of fan. I've not taken apart a convection oven but small fans tend to be shaded-pole motors, which can't be speed-controlled like this. You'd probably be better off controlling  it by blocking part of the airflow.
To be honest I'm not that worried about the fan; I know I would prefer an oven that has one, but should it turn out to cause problems I can probably modify it somehow to fix this - or in worst case not use it at all during the reflow phase. A fan will be useful during the other stages, as well as for many other things (e.g. for drying silica gel pouches, which I have and use tons of!).

Thanks everyone for your interesting and helpful replies - I am now leaning towards the Lakeland Mini Oven, for the following reasons:
  • Stainless steel exterior (well, mostly)
  • Aluminium coated steel interior
  • Fan assisted with two wide fan openings top and bottom (from photos)
  • Large enough for laptop MBs (based on exterior dimensions - I don't know the internal dimensions)
  • Internal light (though this could be retrofitted, having one already is nice)
  • Flat-ish front panel for easy modding
  • Replacing the controller would yield 2x rotary encoders and other nice bits
  • Substantial looking externally removable drip tray (for failed experiments!)
  • At £65 delivered it's close enough to my target price of £50

What do you guys think? Would you choose a different model - and if so, why?
« Last Edit: January 16, 2016, 06:01:02 AM by Lomax »
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #13 on: January 16, 2016, 05:13:21 AM »
Side note: I found some great looking mini ovens from Panasonic, which are only available in Japan and only as 100V models. So while they look pretty nice, they're not on my list, but I wanted to show them anyway :) Putting the control panel below the oven door seems eminently sensible to me, when designing a unit for small footprint/bench-top use. I don't understand why this configuration is so rare? The only ovens I've found on the European market that are laid out like this are from Moulinex (see updated list in first post), and these look quite flimsy.
« Last Edit: January 16, 2016, 05:58:29 AM by Lomax »
 

Offline Owen

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #14 on: January 16, 2016, 06:43:48 AM »
P.S. If you're having trouble with the thermal switch, why not just bypass it?

I wouldn't call it trouble it's just a thing to watch out: I did some measurements and cycled the oven 5 times from 25° up to 230°C, let it cool down to 50°C and so on. While doing this i've noticed that the switch came earlier with after the third cycle and it took longer to reach 230°C. It wasn't a show stopper and after 60 boards or so with this oven i'm not worried about it because every single board went well (up to 4 layer boards with 0201 parts et cetera). So it became my trusty little reflow setup :).
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #15 on: January 17, 2016, 07:31:56 AM »
Ok, since no-one jumped in to stop me, I have now purchased a (refurbished) "Lakeland Electric Compact Mini Oven" for £65 delivered. As tempted as I was by the Steba KB 14, which has many pluses, the non-coated cavity and stainless exterior tipped the balance in favour of the Lakeland oven. It's also much harder to get hold of (it was discontinued some time ago) and the only source I was able to find only had six of them left (now 4) - I figured I'd better take the chance now, before they're all gone. If anyone else is interested, this is the eBay listing.
« Last Edit: January 21, 2016, 08:11:48 AM by Lomax »
 

Offline Neganur

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #16 on: January 17, 2016, 07:54:52 AM »
Don't forget the Severin series, e.g. TO 2034: https://www.beta-estore.com/rkuk/order_product_details.html?wg=1&p=16
I did look at Severin after seeing the EEVblog videos about the reflow kit from Beta Layout, which is based on the Severin TO 2034. This oven doesn't have a fan though, and it's a little big (20L), and it has a painted exterior with a lot of plastic. In my mind an Arduino controlled oven can be useful for many things - not only reflowing PCBs - some of which may require much higher temperatures than it was designed for. For this reason I'd prefer an oven that has a stainless exterior with few plastic parts, and a plain aluminium or steel interior that isn't coated (or has a ceramic coating). It may be an ambitious goal but it is my plan to buy preciesly one device to serve as "that box I can put stuff into to heat it up real good". For this reason I am now leaning towards the Dualit or Lakeland ovens (see below).

I don't think you'll regret your choice, it looks like a nice oven.

Just a heads up on the Severin though: the only plastic it has are the knobs, the handle and the feet. Pretty much like the other ovens you listed.
I don't know what to think regarding convection vs. just heating rods. Maybe it doesn't matter since there is so little volume and I remember some claiming that the heating ramp was not fast enough compared to pure rod ovens. No idea.
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #17 on: January 17, 2016, 09:41:33 AM »
I don't think you'll regret your choice, it looks like a nice oven. Just a heads up on the Severin though: the only plastic it has are the knobs, the handle and the feet. Pretty much like the other ovens you listed. I don't know what to think regarding convection vs. just heating rods. Maybe it doesn't matter since there is so little volume and I remember some claiming that the heating ramp was not fast enough compared to pure rod ovens. No idea.
Thanks Neganur - it's a silly thing to get exited about I guess, but I'm really looking forward to having the ability to "cook" things in the workshop. There have been times when I've had to use my (not very clean) kitchen oven for non-food jobs, and I've been equally worried about the burnt gunk it's covered with contaminating my projects and the possibility that the next pizza I make might kill me :) Not to mention not having the faintest idea what the actual temperature is, or the over-powerful convection fan at the back disrupting things and splattering them with all sorts. I do a lot of spray painting of small parts, and the ability to "bake" what I've painted in a clean environment is very welcome. And I've got a MacBook Air 11" with a glitching GPU that I hope to fix by reflowing the motherboard. And I've got a whole bag of 25g silica gel pouches which have been "used up" and need drying out (living by the coast I'm dependent on these). In short; I'm sure this oven will prove a valuable addition!

Thanks also for the additional info about the Severin ovens - I thought much of the front was plastic on these, happy to hear that's not the case(!), though I think I'd still go for the one I picked; while the convection fan might not be that useful for reflowing PCBs, it is essential for many other jobs, and I do like the stainless steel housing. One way to improve the thermal responsiveness would be to add additional heating elements, I've seen this done for DIY reflow ovens, and even some where the metal elements have been replaced by quartz ones. Just having the enclosure opens a lot of possibilities I think!
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #18 on: January 23, 2016, 07:38:06 AM »
Ok, so my Lakeland oven arrived a couple of days ago, but it turned out to be DoA; only the hum of a transformer could be heard when plugging it in. After some discussion with Lakeland customer services - who were very friendly and helpful - it was agreed that I would keep the oven but with a substantial discount. All the remaining units had been sold, so a replacement was not an option, and the money I saved would allow me to pay for a reflow controller to replace the faulty built-in one. Unless it turned out to be fixable of course! As soon as the deal was made I busied myself with opening up the oven, which turned out to be surprisingly fiddly for two reasons: first, the feet, which have to be removed, are attached with triangular "TA" type screws, which I didn't have any drivers for, so I had to make one by grinding down a small Robertson bit. Secondly, in order to remove the cover you have to remove four screws on the rear of the front panel (ringed in red in photo below), needing a driver with a 30cm+ long blade to reach. Luckily I have a ridiculously long home-made 1/4" hex extender which saved the day. Once the cover was removed, it immediately became apparent what the likely problem was: the controller is shielded with a thin sheet of metal, which also acts as a duct for a small cooling fan at the bottom of the cabinet, and this had been forcefully bent into the controller PCB. I bent it back into shape and noted that no damage had been done to the PCB - however the pin header connector at the top had been partly dislodged; pushing this connector back in brought the oven back to life! Some photos:
 

Offline Fred27

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #19 on: January 23, 2016, 09:22:12 PM »
Sounds perfect. I hope it works out well. It'll be a bonus if the electronics area stays cool enough to put a reflow controller in there.
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #20 on: January 24, 2016, 04:34:02 AM »
Some further observations after re-assembly:

Set to 230° (the highest setting), and with the convection fan switched on, it takes 3m45s before the controller switches off the heating elements. I'm still waiting for the digital thermometer that I've ordered to arrive, so I have no way to verify if indeed it reaches 230° - or even overshoots it - but based on this simple test it does look a little sluggish. I will be adding ceramic fibre insulation mats to the sides and bottom, which currently have no insulation, and I need to see what the back looks like as well (I forgot to check this when I had it open!). If I'm still unable to get a ~2°/s ramp-up I might look at adding an extra element at the bottom, and maybe one at the top as well.

The overall build quality is as one might expect from a cheap Chinese oven; all sheet metal is of the thinnest and softest type, and one has to take care when dismantling so as not to cut oneself. It is also very easy to bend and dent things, and care must be taken not to overtighten any screws. The exterior shell is not "proper" stainless steel, but some cheaper ferritic alloy (400 type), which became clear when I was trying to navigate my magnetic bit-holder with screw deep inside during reassembly; the bit-holder (and screws!) would happily stick to the shell, making reassembly a rather frustrating exercise.

That said, there are some better bits: the convection fan motor looks quite nice, and so does the ceramic light bulb holder. The PCBs for the controller are of the "FR-4" type and look to be well made. Unsurprisingly, it doesn't use SSRs to control the heating elements, but mechanical relays, though they are a hefty 10A 250V type. Since it has a digital controller it is also equipped with a (probably K-type) thermocouple (this can be seen to the left of the lamp socket), and all most of the wiring is a fiberglass insulated type. Interestingly, there are two tiny SCRs mounted on the power PCB - I expect these are used to control the light and convection fan, though I don't understand why an SCR would be chosen for this? Maybe the PCB labelling is misleading. In any case, once I get around to replacing the controller, there will be plenty of interesting and useful left-overs; one thermocouple, two relays, one high-temperature lamp holder, one 50x50mm 12V cooling fan, a piezo-electric buzzer, two rotary encoders, one small 10V transformer, a bright blue LED backlight plate, and a few PCB mounted push-buttons. More photos:
« Last Edit: January 24, 2016, 05:23:01 AM by Lomax »
 

Offline engineertype

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #21 on: February 21, 2016, 09:09:32 AM »
Nice looking oven, but not surprising that it under-performs.  This is a very large oven (lots of thermal mass) and at 1.3kW it is under-powered.  This can be remedied though:
1. Add a lot of insulation, both inside and outside the oven chamber.  Don't skimp here - you'll regret it later
2. Add a thin aluminium (or copper) sheet to rest your PCB's on.  Aluminium and copper (used by heat sinks) conduct heat far better than steel.  Also, a solid sheet is better than the steel grate that comes with the oven - unless you like tan lines on your PCB's  :)
You might want to rest the aluminium sheet on top of the steel grate, which is fine.  Just remember to remove as many of the grate bars as possible to reduce thermal mass.
3. You should consider adding an additional heating element, especially if you plan to use lead-free solder paste.  The rate of rise of temperature in the reflow phase is pretty steep.

Reducing hot and cold spots is very important.  A well insulated, powerful oven means the heating elements don't have to be on 100% of the time.  As you might imagine, a brightly glowing element can easily create a hot spot.  Another thing to consider is the direction of the heat; ideally the top heating elements are not used much to minimize the exposure of the components to heat.  This is especially true if the oven's elements are infrared, which is better absorbed by dark components (like microcontrollers) and reflected by lighter ones.  It is good to see your oven uses resistive elements - this is a plus.

Your list of ovens is very useful.  I make and sell ControLeo2 reflow controller and often have customers in Europe asking me to recommend ovens.

<shameless plug>
ControLeo2 is the only reflow oven controller offering multi-relay support so you can control the direction of the heat (top Vs. bottom).  http://whizoo.com
</shameless plug>
 

Offline IconicPCB

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #22 on: February 21, 2016, 11:54:39 AM »
If your oven uses calrods ( 6 to 8 mm diameter heater rods ) consider adding cooling fins onto the rods to improve effectiveness of the fan.

These cooling fins often come as a sheet metal spiral to enhance the heat transfer from rod to air. If unavailable attach aluminium strip to the rod to improve heating effectiveness.
Do not be worried by increased thermal mass of the heater. IT IS ALL GOOD. You need an oven with decent thermal mass to ensure proper process window. You achieve good effective thermal mass by controlling temperature which is further enhanced by the action of convection fan.

At 1.3Kw the oven will not be able to handle a multilayer board. You will be lucky to process a double euro format double sided board in the oven.

Seriously double and triple installed power or at least increase installed power to reach the limit of the householed power socket ( may be 2.5Kw).
 

Offline Lomax

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #23 on: March 08, 2016, 11:47:23 AM »
If your oven uses calrods ( 6 to 8 mm diameter heater rods ) consider adding cooling fins onto the rods to improve effectiveness of the fan.

These cooling fins often come as a sheet metal spiral to enhance the heat transfer from rod to air. If unavailable attach aluminium strip to the rod to improve heating effectiveness.
Do not be worried by increased thermal mass of the heater. IT IS ALL GOOD. You need an oven with decent thermal mass to ensure proper process window. You achieve good effective thermal mass by controlling temperature which is further enhanced by the action of convection fan.

At 1.3Kw the oven will not be able to handle a multilayer board. You will be lucky to process a double euro format double sided board in the oven.

Seriously double and triple installed power or at least increase installed power to reach the limit of the householed power socket ( may be 2.5Kw).

Thank you, some great tips there! I'll definitely keep an eye out for those spiral heat-sinks, sounds like a simple way to improve the performance a little bit. TBH, I haven't really used the oven to do any reflows, apart from a simple test on a piece of veroboard, which came out brilliant. I have used it to dry two lots of silica gel pouches, heat up a piece of acrylic i needed to bend to a shape. and to harden the paint-job on a tripod mount for a vintage camera I've been restoring (pictured). It works very well, and I'm happy with my purchase!
 

Offline EPLan

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Re: DIY reflow oven - suitable UK/EU candidates
« Reply #24 on: April 20, 2016, 12:08:02 PM »
Is it worth adding this oven to the thread?

Quote
Gourmetmaxx Infrarot-Ofen, 9 L




1000 watt, 9 litre, two quartz elements - delivered to the UK from Amazon Germany for £32.85

Link



Reflow conversion guide here (you may need Chrome's auto-translate feature) -

http://wiki.ccc-ffm.de/projekte:reflowofen:start






« Last Edit: April 21, 2016, 03:48:07 AM by EPLan »
 


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