Improving a T-962A Reflow Oven Part3

[@arjuna207]

who would dislike this? your effort is commendable

[@alexscott4277]

Fantastic stuff. Thanks for the efforts in making this oven more usable. Looking forward to your final recommendations.

[@CoryCharlton]

I just received my T962-A recently and not only did it come with baffles installed but the cooling fan draws the air out of the heating chamber rather than blowing in

[@jontscott]

Very nice, I like the fan. I could see myself adding a fan like that to my unit.

[@chrismr3972]

That's more like it! I had another thought. Suppose you had lots of baffles, all at angles so that the lamp energy never "sees" the board directly, but indirectly the energy is more closely matched. For example, close to the heater the baffles would be narrow and horizontal (like you had), further away wider but at increasingly steeper angles. Then, when when the fan comes on you get a double benefit because the different angles cause different air flow. Just a thought..... keep up the great work. it's really nice to see someone going about it methodically.

[@JerryWalker001]

I did try that but the board never gets to temperature and the maximum ramp up is too slow. Unfortunately the board needs direct heating for the process to work (even then the heaters are running continously). Moving air and masking the hot spots seems to be working best. The actual baffles needed are very small and only cut around 11% of the heating effect. Any more masking prevents the boards reaching temp and also causes the chamber walls and heaters to overheat as they need to work way too hard. You can actually see the discolouration in the top cover which occured during those tests. I think that possibly any one of the three methods (baffle, fan or conveyor) will make the oven much more useable but I would like to find a combination that gives Good results rather than just being acceptable but it may take a while to develop the best balance.

[@chrismr3972]

@@JerryWalker001 I just though of something. Did you try changing the thermocouple probes channels? To cover the possibility that the channels are miss-matched. It's down to a few degrees now so that might make a difference / prevent looking for red herrings!

[@JerryWalker001]

Chris Mr, My company develops specialist instrumentation so I have a number of calibration systems. Before any development I always calibrate all equipment I use. In this case I used a high temp drywell calibrator and a UKAS calibrated TTi-7 (accurate to 0.02C with a resolution of 0.001C). All probes were calibrated in a single drywell as they are small so the degree of uncertainty is currently less than +/- 0.4C which is well within the errors I am seeing. Very good point though so I may make a separate video on this.

[@patrikfloding7985]

15:00 Just the fan in the top middle, and none of the baffles under the lamps? That's a great result, and it would make sense to start by adding the fan before doing anything else!

[@JerryWalker001]

Yes the fan makes the biggest difference. Note that it is not really a fan, more of a 'mixer' to keep the air moving around the chamber but not 'blowing'.

[@GodzillaGoesGaga]

@@JerryWalker001 With the air stirrer what motor did you use and how do you thermally isolate it ? I'd like to do this mod to mine. I have also got the new firmware that allows offset and gain adjustment of the thermocouples. Hopefully this will improve my profile accuracy too.

[@zianzan4536]

@@JerryWalker001 Hi and congrats for your videos ! I have the same question as Godzilla: what little fan motor did you use (is it an AC motor ?) and do you need to thermally isolate it ?

[@zenseidk9011]

Thank you for this, I own this oven too and have made the generally recommended upgraded, fw updates and so on. This could add needed usability to the machine.

[@MrOrangeman18]

on my toaster oven i have been tweaking over the last 6 months, i fitted 3 halogen heater bulbs from those halogen heaters that stand up, these heaters also came with a honeycomb heater spreader in front of the bulbs to stop heat spots as without it you would easily burn your self with 3 400watt halogens, this made the ovens heat extremely uniform, especially with the convection fan built in, looking forward to watching the other follow up vids tonight .

[@JerryWalker001]

I did actually test the honeycomb from one of those heaters but it was so soft and floppy that suspending it accurately across the entire area was too tricky and it also cast IR 'shadows' depending on the angle between the board. The honeycomb was about 3mm thick so it did not cut down the direct heating but cut the angled IT by increasing amounts the further away from the neater centre line and this as the opposite of what I wanted so I gave up on it.

[@MrOrangeman18]

@@JerryWalker001 ahhh ok fair enough. maybe the ir heater and halogen heaters react to this in different ways? mine certainly helped and also stopped the boards getting scorched. is there a part 6 coming anytime soon? thanks

[@MadLabZ]

Thanks for the video Jerry!!! I will be disassembling mine in the next few day so your video is much appreciated, I was refereed over to your channel by YT user (Conservator) =)

[@danarobotmaker3396]

I just received the T962A reflow oven and there are two noticeable differences. One being the fan pulls air from the chamber. The other is a louvered air flow baffle between the inner chamber and the fan. The inner chamber wall near the fan has an opening ~1/3 chamber width and nearly to the top. The louver swings to create ~400 mil opening at most per louver. Three lovers. The behavior of fan off and on for a couple of seconds is pretty much the same as described in the video. This design still has the effect of pulling air straight across the board and down the middle of the board. The built in temperature probes indicate significant differences up to 20 degrees C. The cooling part of the cycle had even greater differences. There was no PCB in the machine during these runs. Adding the angled plate near the fan and in the inner chamber stills seems like the right thing to do.

[@JerryWalker001]

See the video at 5.00 for a view of the baffle I fitted.

[@danarobotmaker3396]

@@JerryWalker001 Yes, I watched all the videos. Should I remove the louvered flaps or just leave them in place.

[@JerryWalker001]

@@danarobotmaker3396 I removed them but it does not make much difference once the baffle is fitted so you may be able to leave them.

[@danarobotmaker3396]

@@JerryWalker001 I have the unit apart, insulation removed, and vacuumed the glass crystal up. While doing this I might as well do the turbulence fan feature. How did you get the thermocouple out? I uncrimped the tube and removed the glob of sealant, yet the wires seem stuck.

[@JerryWalker001]

@@danarobotmaker3396 I just pulled them out. You can easily replace them if they are damaged. It is more consistency you are aiming for in the final machine so absolute accuracy is not important if the calibration is out slightly. You will just modify your profiles based on results so replacing a sensor is not a big problem.

[@symeonkrizias2534]

Jerry,you suggest the centre sensor to be removed ,you mean that we have to make a new hole 15mm from the sidewall and same size as the original? the steel tube will be fastened on the side wall?

[@danarobotmaker3396]

You describe the fan as blowing air into the chamber. My unit sucks air from the chamber. I'm assuming I should turn the fan around while making the air distribution modification?