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PID Temperature Controller
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Author:  Shane Neifer [ Mon Jan 12, 2015 11:47 am ]
Post subject:  PID Temperature Controller

I have been planning and collecting parts to make one of these for a few years. Last summer I bought more parts from the OLF classified (thanks Scott!) and just recently picked up the last few things I needed. I have looked through the posts and couldn't find what I was looking for so decided that as I struggle through this I would post on my successes and failures and hopefully at the end have a system that works. First off a couple of things:

1) I AM NOT AN ELECTRICIAN!!! I am documenting how I build this unit but you need to be comfortable in your process or seek advice. Electricity can be dangerous and can cause fires!

2) I am using two blankets so this unit may be more than most people want/need

3) Fred Tellier deserves consulting credit on the advice on some parts and wiring

I have a couple of goals in my design. They are:

1) I want to know the temperature as the sides start to cool, that means when the relay to heat is shut off I still want a temperature reading

2) I may want to use other blankets or a different configuration so I am making this controller a stand alone unit with the blankets being able to be plugged in and out so I can change them.

So, I started last evening when Rod True indicated that he was thinking about the same thing. We have recently moved and we are still unpacking so I don't access to my table saw, CNC machine, jointer, etc. Small hand tools will be all that I have. So, here goes!

This is the bender I use, I may build a new one once I get the heating blankets all figured out.


To get started you need to collect your parts


Then you need to get something to place them into, for me it is 1/4" plexi glass because it was closest at hand. (for these parts and their mounting system I suggest going with 1/8" material as I had to make some modifications to get them installed into 1/4")


Next, layout where you want the parts mounted


Then cut out for the components (this took a couple of hours or more with drill press, coping saw and files)


And then install the components into the faceplate


When I bought a but of the pieces as a lot it came with switches that light up and require a separate power 12V supply, so again this may be more than is required but "non-powered" switches are readily available and would simplify the project. Anyway, I will start wiring today and will explain what is going on as that progresses.


Author:  James Orr [ Mon Jan 12, 2015 12:50 pm ]
Post subject:  Re: PID Temperature Controller

Shane, thanks for the thread and taking the time. Do you mind detailing what the parts are?

Author:  Fred Tellier [ Mon Jan 12, 2015 1:34 pm ]
Post subject:  Re: PID Temperature Controller

Looks good Shane a bit more than I use but will be a very functional unit with expansion capabilities.
As Shane said, make the blanket plug in and the timer should only turn off the power to the blanket leaving the controller powered up. Another suggestion is run the controller in on/off mode as full PID mode is way more than we need as far as control. My box is a work of ugliness but protects the components, I often thing of improving the enclosure but guitar building gets in the way.

The nice thing about a programmable controller with a timers is once the bend is completed you can work on other things while the side is cooking without any risk for a fire. I never leave the shop while the timer is running but can ignore the bender and get on with other things.

Another thing get the 1/8" diameter long ( usually 6") Thermocouples or if it is a J or K couple you can cut off the large metal end and twist the two wires together which becomes a thermocouple where they are touching. See 1st photo below. We created radiant zone thermocouples by twisting the wire and crimping it into ring eyelet connectors that were screwed to the metal walls in the paint ovens at Chrysler.




Author:  Ed Haney [ Mon Jan 12, 2015 9:17 pm ]
Post subject:  Re: PID Temperature Controller

As an alternate I put my controls all in a line. I almost did the two controller option for two blankets and that amount of equipment would fit. (use of same basic components as Shane) Removal of 2 screws allows the control front panel (lower half of box front) to come out to access all components and wiring. Above the controls box is a storage area in the box for clamps or whatever (see pic). Above that is the bending mold. The power chord for blanket is inside the box out of the way of everything and never needs to be touched. One power chord coming out of the box powers all components.

The master switch (right most) shuts down everything and is "on"/green in the picture. The blanket switch is next to it and "red"/off in the picture. Note that the controller still shows the thermocouple temperature with the blanket off (thermocouple plugs in on left (white cable) so that an second thermocouple can be plugged in its place easily for a second temp view and/or control - e.g. temp of wood Vs temp of blanket). The timer automatically comes on when the main power is turned on and times down to shut off the blanket so that it does not have to be touched to start or stop.



Author:  Rod True [ Tue Jan 13, 2015 10:23 am ]
Post subject:  Re: PID Temperature Controller

Looking good Shane.

Nice set up there Fred and Ed.

I'll post pictures of mine when I've got it done. Just waiting on components.

Author:  Allen Ughoc [ Sat Feb 21, 2015 4:14 am ]
Post subject:  Re: PID Temperature Controller

Good stuff gentlemen. I'd like to upgrade my old LMI controller, electricity is not my strongpoint...

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