Reflow Oven Controller

Projects General Guidance
21

I got the one sparkfun carries, couldn't seem to locate a much better price anyplace else.
Is just the wire with the shield material (fiber glass? asbestos? whatever it is) over the outside.

My Extech 330

came with a thermocouple probe, the outer cover material turned pretty dark after being heated to 250C a couple times but still seems to be working fine.

Can you send me the updated code? Will file it away until I get chance to build up a board. I have some simple LCD displays, bought 1 (or 2), forgot I had them, bought a couple more...
Got 1 active design gig going, 1 waiting on payment and then I'll send files, started design discussions on another last night - still working my taxes too, have everything entered that I have on hand, companies are late sending out docs this year so I can't finish up.

22

I bought this one
1st run the black plastic boot just melted away
second run the yellow cable that was in the oven turned black and gave off noxious vapours before shorting out completely!

have now ordered one of these
here's my code
features:

  • range check thermostat on startup
  • hold button 1 at boot to go into button test mode
  • hold button 2 at boot to go into thermostat test mode
  • button 1 = start
  • button 2 = panic stop! (when running - see button 1)
  • button 2 = next setting (when not running) loops through settings then back to ready
  • button 3 = increment setting
  • button 4 = decrement setting
  • door button detects door open (not actually connected yet!)
  • all settings saved to EEPROM with checksum
  • invalid checksum sets deafults and drops to settings mode
  • preheat shows actual and target temp, counts timer up until temp reached
  • flux increases more slowly, shows actual and target temp, counts down
  • ramp increases to reflow temp, actual and target temp, time taken
  • cooldown shows actual and target temp and time taken
  • door open waits for the door to open

if you find anything missing or make changes do let me know

cheers
Mike

ReflowOven.zip (8.99 KB)

23

and here's the current design

OvenBrd.jpg|x
OvenBrd.jpg|x836×475 1.14 MB

OvenSch.jpg|x
OvenSch.jpg|x713×503 1.03 MB

ReflowOven.zip (50.9 KB)

24

mmcp42:
1st run the black plastic boot just melted away
second run the yellow cable that was in the oven turned black and gave off noxious vapours before shorting out completely!

I don't think you are supposed to have anything more than the metal part of the thermocouple in the high temperature area. IIRC the thermocouple itself is fairly small and is in the tip of the metal part.

25

dannable:

mmcp42:
1st run the black plastic boot just melted away
second run the yellow cable that was in the oven turned black and gave off noxious vapours before shorting out completely!

I don't think you are supposed to have anything more than the metal part of the thermocouple in the high temperature area. IIRC the thermocouple itself is fairly small and is in the tip of the metal part.

fair cop, but the insulation round the inner core melted as well
then it all shorted out on the probe body

what do you expect for 6d eh!

26

They do offer a 30 day warranty so if it's within that period you could return the charred remains? :slight_smile:

27

hee hee
by the time I paid the postage - hardly worth the effort
I cut the corpse up and now have three baby probes
nooooooooooo - I mean small probes!

thanks for the thought though!

28

I used the k-type that adafruit carries. The insulation survived to 275C. (The hottest my oven ever got.)

29

That e-bay probe looks like a nice one. Drill a small home in your oven and secure it in place.

30

I just ordered one too.
http://www.ebay.com/itm/K-Type-5cm-Probe-Thermocouple-Temperature-Measurement-Sensor-0-8M-/230914145011?pt=LH_DefaultDomain_0&hash=item35c38e3af3