Wow! This information is great. Tim, the spreadsheet is a great tool. Thank you. There is much information, so I need to sort the key concepts. - First, I have understood that for the isolation, the best material (and cheapest) is rockwool, right?. Does this serve? http://www.leroymerlin.es/fp/16658460/lana-de-roca-cloiselene-15-ud&idCatPadre=244052&pathFamilaFicha=3818 - With regard to the heating source, seems like a good idea to use a hair dryer, an air gun or even a bathroom dryer. With this, we avoid the need for a fan and a heat source separately. - It seems that the most important issue is to control the temperature. As I said at the beginning of the conversation, I have a PID and thermocouple. Can we use it? Lately, the team is not characterized by a time of economic booms, so we must save the maximum, as much as possible. Thoughts? From: tyoung489@xxxxxxxxx Date: Mon, 30 Jun 2014 00:23:55 -0700 Subject: [SS2S-Main] Re: temperature controller with arduino To: sugarshot@xxxxxxxxxxxxx Opps, I noticed that in the SS2S Curing Oven spreadsheet that you need to widen the width of column "J". Currently the value in cells J5 & J6 is 1.5 but because the column is too narrow so it is displaying the number 2. It shouldn't affect the calculations but it is confusing. On Mon, Jun 30, 2014 at 12:00 AM, Tim young <tyoung489@xxxxxxxxx> wrote: Hello all, First off have you looked into the possibility of using an industrial oven at a local University or a local Business? They may be receptive to helping out a grass roots project like this. I did some poking around & put together a little interactive spreadsheet of Basic Oven Parameters. This will help you evaluate more than just this one heating project. (sorry all dimensions are USA, I put in some conversion info) You can vary the: Interior Oven Dimensions Values for insulation (R Value & Thickness) Starting Temperature Maximum Temperature Weight of product Specific Heat of product Time to reach Max Temperature and it will tell you: Watts to heat product Heat loss in watts Total Watts Interior surface area in Square Feet NOTE: Total Watts = (Watts to Heat Product + Heat Loss Watts) x 1.6 This should account for Door heat loss, Probe heat loss, etc. If you are only going to build the oven for this project, with the conditions you gave (80-C) you should be OK using polyurethane or polyisocyanurate rigid board for insulation. If you need to go to 200-C you should use Mineral / Rock Wool Batts (Not loose wool). You may find that the mineral wool is less expensive than the foam insulation anyway. Vicente, with the example you gave, there is very little wattage required for this project. If you want to keep the cost at a minimum you should use the PID (REX-C700) you already have. With the PID you set the target temp & the controller automatically adjusts the heater output so you don’t radically overshoot the set point temp. With the amount of curing you have to do I would get a timer & a six-pack of beer or a bottle of wine. If you need to go from 25-C to 80-C at 10-C / Hr, then break the job in to 20-min increments. 1st 20-min 29-C, 2nd 20-min 33-C, etc till you get to 80-C. If you then set the timer for the soak time required for the Composite System you’re using and the PID controller will maintain the temperature.. The least expensive way to obtain your original stated desire of having a system that has a programmable controller with an interactive graphical interface would be to go with the BCS-460. I understand your budget doesn’t allow you to purchase this. Perhaps you could hold a fundraiser to purchase one. Or perhaps there is a Home Brewer of Beer in your area that already owns one that you could borrow. Here's a link to a simple Curing Oven Airframe Composite Curing and Post Curing Ovenhttp://www.privatedata.com/byb/rocketry/composites/ovens/Airframe%20Composite%20Curing%20and%20Post%20Curing%20Oven.html On Sun, Jun 29, 2014 at 9:52 PM, Peter Johansson <rockets4kids@xxxxxxxxx> wrote: On Sun, Jun 29, 2014 at 8:40 PM, Nathan Asdourian <rawliquid@xxxxxxxxx> wrote: [ ... arduino ... ] The Arduino is an incredibly awesome tool for its intended purpose: Enabling artists to produce interactive art. Beyond that my opinions of Arduino drop off dramatically. (I'll reserve the remainder of my rant until asked.) > That said, it should be taken into consideration that you could get an > actual pid controller for around the same price as an arduino uno r3. I too would agree that a COTS PID controller is the preferred way to go *IF* it includes the capabilities to do the temperature profile out of the box. If you need to add a microcontroller to the PID box to adjust the temperature, you are doing things completely wrong. [ ... description of software functionality ... ] I think we should let the person who volunteered to write the code make a proposal as to what features he is willing to provide. -p.