Hi guys i want to buld a curing oven and i need a contoller to contol the temp, any idea where i can get a contoller @ reasonable price :). please share pictures of your oven and controller.
Thanks.
I think Susho already has done a lot of work on oven controller design. Perhaps he can share his ideas.
A while back I was thinking of building an oven as well ( Still am but waiting for funds so any info on oven building would be greatly appreciated:D)
For temp controllers I searched ebay and found a lot of digital controllers at reasonable price. Try searching for “PID digital temperature controller”
Cheers
I suppose you need a bunch of temperature controller in a large oven to control that the heated air warms uniformly. maybe placing feelers in the corners where no continuing airstream flows.
I still havent found cheap air fans/ oven fans that resist slighlt over 120ºc.
Havent decided on the insulating box building material. maybe homebuilding plaster walls but very heavy dusty and heavy and they break easily when disasembelded.
Use these sandwich panels:
good idea, thanks
I’ve just put my oven into service. Basically I took an over-sized kitchen oven and extended the oven cavity. It already had a convection fan built in. I added a PID controller from ebay, which works great. It keeps the temp within 1°C - verified with a temp-logger. The only down side to these is that you have very little control over ramp-up and none for cool-down rate.
To extend the cavity I used sheet metal (because I had it laying around) and Rockwool. I have the original door but I still need to make hinges for it. For now I just close the front with rockwool.
The good thing about this set-up is that I have a double failsafe to prevent overcooking the part. The original thermostat is still in service and is set just above the desired temp so if the PID should short I won’t burn the part. The oven has a time so I can preset dwell time.
I would really love to see a decent ramp up and down computer on it.
PID controller with ramp/soak functions. But you would have match the heating unit to your oven, so it can keep up with the controller, and not overshoot too much. Airflow inside the oven off-course is important, not crating heat and cold pockets. Temperature sensors on your mould surface/part provide better information than air temperature.
The cool down part is a lot harder in air heated ovens. I did work with one which had openings at the top opened by the controller. Mostly just fully opened, hardly cooling hard enough. I suspect it to be much more usable with directly heated moulds with liquids.
I would love to be able to find one that doesn’t cost more than the entire oven.
I found some days ago a link where there is for sale a heather controller for beer. He sell the thermoregolator, probe and pc interface (200€). It’s near my home, so next weeks I go to met this people. If can interest I can post it (for take ideas)
Maybe one like this?
One of these would be OK to get you going…
http://www.ebay.co.uk/itm/PID-Digital-Temperature-Control-40A-SSR-K-Thermocouple-Biodiesel-UK-FAST-POST-/121085046547?pt=UK_BOI_Industrial_Automation_Control_ET&hash=item1c313b2f13#ht_3384wt_904
I have been using one of these for 10 years on two ovens.
http://www.instrumentwarehouse.com.au/product_info.php?products_id=844
Can programme ramp and dwell but the ramp really depends on your heating capacity. My oven is flat out at 2 deg per min with light moulds/mass in oven.
The one Morepower posted above is good value though??
Those three are all the same and exactly what I’m using. There might be slight differences in programming. Mine will let me adjust the ramp time by adjusting the cycling time of the heating element, which isn’t the same as saying 2°C/minute. Really would like that function.
I am converting a large toaster oven to a composite oven and have picked up this controller to use, only $78. It is programable for ramp up and down rate as well as soak time. The resin I am using needs 3 hours at 150, 200, 275, and 325 with no more than a 2 to 5 degree change in temperature per minute both up and down. This controller will do it.
http://www.auberins.com/index.php?main_page=product_info&products_id=264
The toaster oven was $100 and has a convection fan built in. I am in the process of insulating it now and then I will move to the controls.
could you post a play-by-play of your build. The electronics/regulation of the elements is beyond my understanding. I too would look for an oven that I could modify but I can’t even begin to comprehend how to gut/rewire everything so that it can be managed with ramp rates and max/hold etc.
Thanks.