Projects – Hobbybotics Reflow Controller Quad V1.0

Here’s a quick update to the new reflow controller project I introduced earlier.  I have fully populated one of the prototype boards and began to write test sketches to ensure it functions properly.  The project is moving a little slower right now as I am in the process of closing on a new house and that has been taking up a lot of my time.

2013-03-06 02.44.49_1024x768 2013-03-06 02.44.40_1024x768 2013-03-06 02.44.15_1024x768

The last picture shows an early prototype for the LCD/Button interface for the controller.  I am in the process of redesigning the LCD/Button interface to use a 4-way rotary navigation switch with a center select button.  I borrowed this idea from the Viki LCD project over on Kick Starter.  I’ll post more updates in the coming weeks.


45 thoughts on “Projects – Hobbybotics Reflow Controller Quad V1.0

  1. Great looking project! Keep me posted on the progress and availability of a kit.

  2. Curtis… this thing needs an oven. I”ve torn my black & decker (from the 8.03 project) completely down as it has severe limitations when addressing a ROHS profile. The main deal is that it just doesn’t ramp up nearly fast enough so several solutions come to mind. First is the physical cubic inches of the original oven that is being heated. Time is not a large factor when you’re heating a pizza. but its a big deal when you attempt to heat a PCB within a prescribed period of time.

    As you know this oven has 4 coils wired in pairs across the A/C line. What I’m in process of doing is moving the 2 top coils to between the 2 bottom coils. I’m also moving the convection fan to the rear but centered low. Why? because the current central tray position will be the new top (while the lowest tray position now becomes the PCB holder). And my thermostatic cooling fan? I’m moving that to the bottom of the unit and installing an identical fan adjacent to it giving me better distribution of the introduced ambient air. So after reducing the total # of cubic inches to be heated by a considerable amount (probably 40% less than the original oven) and insulating it all the way around with 3.5″ batt insulation I’d be surprised if it still failed to meet ROHS requirement.

    this would be a great kit! but without a decent oven the up-front business goes for naught as everything is moving to ROHS quite rapidly. Your idea of building a “scratch” oven is probably the best way. but one would need to source those coils while still keeping them around 1500 watts total thus staying within the 115VAC envelope. and THAT’S a big issue as none of these manufacturers are selling heat element replacements (as of course they consider the units throwaways). however I did find 1500 watt space heaters (here’s one: that’s very reasonably priced with an obviously small but powerful heating element & footprint. this unit could be used as a basis. the remaining difficult to source part would probably be the front door… but one could use this: Notice that neither of these parts are sized over 12″ which would make for a finished product that is relatively small (as its unlikely that we’d be baking motherboards here).

    finally considering that the cheapest commercially available ovens are over $4K a kit that could probably be procured for a tenth of that sounds like a definite big deal to me. there is also one other element commonly overlooked. the presence of a learning curve. people have little choice but to learn something from a project such as this (as I for one certainly have).


    • Another alternative to using ceramic elements is to get some decent sized power resistors and run them in a series-parallel configuration. They’ll heat up pretty good and can be controlled by PWM. I haven’t tried this on a large scale but, I run a couple of load banks for testing 500+ amp power supplies at work and they heat up pretty quick.

      • never thought of that! years of being away from those things… basically would require 15amps. thus we’d be looking for about 7.5 ohms displacing 1.5kw. those are gonna be big. probably expensive wirewounds. well sourcing is an issue (carrying with it extra $$$) with another requirement being heat sync mounted. well we want ALL that wattage applied to air (not just most of it). ceramic has a big advantage there as of course virtually no thermal is absorbed. easily cannibalised. cheap. so upon further research I wouldn’t go there as nothing beats the price/performance and sizing restraints we’d be looking for compared to ceramic elements.

        Another point I’m looking at regarding this oven. its cavity is huge! but I need its manner of operation regarding the door as I’m using it for thermostatic venting (a disadvantage over PID). the width is dictated by the door and its mounting. then delete the current (and rather fragile as well) “quartz” elements completely as they are just way too long. in their place we’re going with much smaller ceramic elements mounted near (but not “on”) the bottom. the bottom’s breath will actually be determined by the widest width of 2 thermostatic fans lying adjacent.. about 8″ wide. I’d hafta guess that there’s a minimum square inch here as well. thus if I made this around 64 square inches I should be able to handle a PCB sized at half that or smaller. well thats still a huge PCB by SMD standards.

        So with this change the original height of oven portion could be maintained as most of the cubic inch removal will now be coming off the sides. one of the reasons for that is those ceramic elements are gonna require a mount that is not a part of the bottom (as that area is reserved for the vent fans). til next time


    • Daniel, thanks for the interest. I am finishing up a slight revision to the design to add a few suggested features. I need to proof that first before I can set a concrete release date. It’s tentatively going to be ready by mid July.



  3. Curtis,
    I picked up an oven and Harbor freight powder coat system, I am a little disappointed in powder coat system, it did not seem to attract powder very well and oven is a little small for face plates. That was my first try so I will have to try again. Profile is basically heat to 400- 450 for 15 minutes. It wasn’t as smelly as they indicated it would be( or my nose is shot). Looking forward to this project have some SMT projects coming up and my hands are beginning to shake so it is difficult to do by hand.


    • Bill, almost there. I have the new boards in and all of the components. I just need some time away from daytime job so I can get them together. I have a sample of the case in hand also and need to get some pics up on the site. I’ve been fine-tuning the firmware for a couple different interface options…text LCD/buttons and a touchscreen interface. I really like the touchscreen interface but, they are a little pricey unless I purchase in bulk.


    • Yep, got new boards in. In process of putting one together for testing. I changed some components out to decrease board costs. I also finished all of the libraries for the boards.



  4. Cool was just checking myself, did you get the interface board updated with the new selector ?


    • Yep, got it working like a champ. I had to create a component by hand and that was pretty tedious. More updates on the site soon.


      On Wed, Jul 31, 2013 at 10:12 AM, Hobbybotics

  5. Curtis… well regardless of what front end we’re using to drive these ovens the real issue is with an elegant oven. one that is relatively economical (under $500 or so) but also actually works for an ROHS profile. now my ugly thing works but you’ve seen the pics. nobody wants something this ugly sitting in even a very messy garage burning up 3KW! but… is the chinese $250 unit gonna actually work? because I have my doubts to be quite honest about it (they’re using long thermal latency ceramics… and I’m not spending $250 to find out). hell for another $200 or so I can build my own which I KNOW will work.

    this would be out of stainless, double-walled, insulated between same, with a really big convection fan assembly sporting 2 fans on a common axis (one to cool the electronics, and the biggie to convect the inner box). I’d stay with a fan for a more rapid cooldown. and I’d stay with the basic 8.03 design. oh. and using three Osram (59822) 500T3Q/IR/7 quartz infrared 500w lamps. Look that up and you’ll find that these are the types of bulbs used in expensive reflow ovens. these would be well suited for ROHS under PID control due to their fast latency… not as fast as nichrome wire though! but a lot more elegant as these lamps can easily be changed individually when/if they burn out (they sport a 5000 hour give-it-up time).

    Next year though I’m gonna build that “pretty” oven. lift out stainless tray (no slides just one more thing to go amiss). hopefully I can get the size down on the inner compartment enough to use the aforementioned lamps. anyhow next project!


    • Things have been moving a little slowly lately as I’m testing Seeedstudio’s manufacturing service so I can produce the boards quicker than I could in house. Unfortunately, that takes about 3 weeks turn around.

      To answer your question, still not ready to release yet and still not fully set on a price. I do appreciate the interest and definitely will be publishing the design and boards.


  6. Curtis, will be possible to control two sources of heat ( one upper IR heater, 4 parallel bottom heaters ) ? How with software? Will be updated fot this?
    Need your controller for my custom IR rework station.
    Thx for info.
    Hope its all OK.


    • Yep. However, the controller has the capability for 4 sensors. The design will have the capability for expansion in order to add other sensors. The control scheme is adjusted in the firmware and can either be set through software control or on-board control through the LCD/button interface. I am making a subtle change to the design so that the boards can be stacked/expanded through a common connector scheme. This will allow easier breakout of the SPI and I2C pins.


      On Thu, Sep 19, 2013 at 12:28 PM, Hobbybotics

      • Thx for info, for me only 2 sensors will be used for independent controling, one for bottom SSR relay – 4 IR heaters in parallel and second SSR relay for top IR heater … 3rd and 4th sensor maybe only for temperature check …
        Will be selled with LCD/button interface?
        And if its nor secret thing, how about price? Only approximately …
        Thx for info and have a nice day.


    • Daniel, sorry for the late response. Some how I managed to not see your post. I’m almost there. I finished an I2C dual 7-segment PID display add-on for the project (I’ll post about that soon). this new board will supplement the LCD display. I’m also finishing a couple of other expansion boards with one containing SSR’s. The SSR board will be an option for those that don’t want to use external SSR’s.



    • That’s the plan. I’ve been working this slowly and testing each phase. I haven’t been watching the blog as much since I’ve been pretty busy trying to source parts and make changes.

  7. also interested in using it for a rework station…. Is this still moving forward?

    “Curtis, will be possible to control two sources of heat ( one upper IR heater, 4 parallel bottom heaters ) ? How with software? Will be updated fot this?
    Need your controller for my custom IR rework station.”

    • Yep, that is the reason for 4 separate probes. I assume you are referring to the windows application so, I’ll have to develop a protocol that allows different options depending on the number of probes connected. Same thing with configuration for the firmware.

  8. Are you ready to release this to the eagerly awaiting public? I really like your design but need to get my reflow oven done. Thanks for all the hard work

    • Not yet but, I just jumped back into the design after getting more free time from my day job. I know this reply is a year late but, I’m still on board with the project.

  9. Hi, I’m really interested on this new controller. I’have been looking around for a decent reflow controller that meets my requirements, a sure this is the best I’have seen so far. How is the project coming along? can I buy one?

    • I’m still hacking on it off and on. I kind of put the project on pause while I worked on a couple of CNC designs to make it easier to produce prototypes. This project is not dead and lives on. I have switched to a different AVR chip for more options/availability.

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