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Brad, what did you mean by "play"? Place?

Also, why two PID controllers?

Thanks,
Scott

Oppps....play should have been "place". The termocouple needs to wedge between the blanket and slat or wood. For my bender I found this to cause problems with getting a good reading. I eventually went to a infrared non contact thermocouple which worked great.

As for two controls. I have one for the main blanket and one for the cutaway/waist blanket. My bender is a different type of setup but basically I have blankets on both sides of the wood.

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Brad
Avon, OH

Ahhhh, got it. Thanks.

Is the infared doable from the fellow who sells the PID that fred sent us a link from e bay??.Am more confused than ever.But whatever thats my usual state anyhow.

I don't think so. They are fairly expensive new so you need to keep your eyes open on Ebay. I would recommend just getting a standard thermocouple and if you have problems then you can always upgrade. `1`

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Brad
Avon, OH

thanks brad, ernie

Hi All
I bought the PID that Fred Tellier found on ebay. I also bought a few other parts: Thermocouple, plastic box (Radio Shack), a timer and some electrical wire. I tested it today and IT WORKS! So wanted to thank Fred for all his help. Thanks Fred - Mike

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guitarsbygiltzow.com

Fred and glitz I decided to forego the PID and opted instead to buy an Omega 4by 30in blanket.It doesn./t need a heat control ,the blanket takes almost 15minutes to get to 350 deg F By that time I/ve got my wood bent. But the watlow 6 by 36 heats to 350 in 3 minutes and needs to be regulated so that PID equipment will be on the back burner, and I will give you a rain check Fred .Thank you for all your helpful info , ernie

Great to hear it went well Mike, did you mount it all in the box yet. I have a modification I need to make on mine as I now also use it to control my Little dipper hide glue pot and need to do a bypass switch for the timer.

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

Got it all mounted in the box. I got one of those K thermocouples you gave us a link to on ebay and am waiting for a thermocouple receptacle I ordered from Graingers. Thought it would be nice to be able to plug it in and then remove it for storage. Should bend a set of sides next week. I'll let you know how it works. BTW the PID I used is only centigrade, which I don't see as a problem but if anyone is looking for F, they might want to check other units on ebay. Thanks again Fred - Mike

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guitarsbygiltzow.com

The one I have can be programmed to either but when in F the displayed setpoint is wrong by 32 deg, the conversion formula they used must have forgot about the 32 deg F freezing point.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

I'm also in the camp of, "I don't know anything about this stuff," but I was just searching around the Sears website and saw this:

http://www.sears.com/brainydeal-digital-pid-temperature-controller-25a-solid/p-SPM7422838202?prdNo=8&blockNo=58&blockType=G58&PDP_REDIRECT=false&s_tnt=39869:4:0

What else, if anything, is needed in order to make this work as a temperature control for bending?

I already have this temperature probe:

http://www.sears.com/shc/s/p_10153_12605_03482377000P?PDP_REDIRECT=false&s_tnt=39869:4:0

It has everything you need except a box, a timer and a receptacle to plug the blanket into. I made my box from scrap wood, the timer came from Home Depot and I had receptacle in my junk box. The timer is optional but can prevent burning down the shop if you get careless.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

Would the probe James has linked to above be used by cutting the wires and wiring into the PID?

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Thank You and Best To All

I have bought a couple PID's from Auber. Good people to deal with

HI - any chance you have a picture or few pictures for how you have it wired up ? I am considering the same kit from ebay - or making my own to read Fahrenheit
Here is the ebay link - very similar to the Sears link with the dual C/F display - http://www.ebay.com/itm/Digital-PID-Temperature-Controller-25A-Solid-State-Relay-w-6FT-Sensor-20-420-/180927493397

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It's this new idea from recent decades that everyone gets a participation award. - MUX

That ebay one will work fine, all that is needed extra is a bathroom timer and a receptacle to plug the blanket into. It does not have on/off control that I prefer to use but the default PID values will work well enough for our needs.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

Hi John
I'm attaching a picture of the finished box. I had pictures of the wiring, that I sent Fred so he could tell me if I was doing it correctly, but I didn't save any of those. I'm going to PM you with the basics for wiring and then you can confirm yours with Fred. I'm sure Fred will help you - he's a nice person. thanks again Fred - Mike
download/file.php?mode=view&id=39262

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guitarsbygiltzow.com

Mike I just checked if your pictures were on my computer but I erased the email when you declared your unit was functional. I am always glad to help with any ones controller.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

Fred, you're too kind. Thank you.

Mike, it looks great. I like the compactness of your design.

i built mine for about $40. Parts purchased on ebay. I had the wood, aluminum and electrical outlet.

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Michael F Smith
Goat Rock Ukulele
http://goatrockukulele.com

Looks really good Mike. Where did you get those rocker switches? Ebay?

I just got the linked PID from Ebay and am not that thrilled with the Centigrade readout. I've contacted the seller to see if I can exchange it even though the conversion is really easy I'd rather not bother. Oh did I mention I have absolutely no clue how to wire this thing up? I'll start building a box and see where that leads me. Who gets the first PM?

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Thank You and Best To All

Hi All

I did some side bending today and encountered some irregularities in the way the PID works. Maybe not irregularities, maybe just quirks and maybe just with the unit I have. So here's what happened: I have been using a meat thermometer and a router speed controller for the past 8 years. The router speed control is a PITA, it never works on the same setting and I am continually readjusting it as I'm bending sides. I thought the PID would be a big step up from that. The unit I got is Centigrade only which I don't see as a problem - just do some conversions so I know when to start bending and what to set the high temperature at. I wanted to get to about 305 F so that converts to 152 C. I set the PID at 152 C and started bending. I used my meat thermometer and the K thermocouple because I wanted to see how close the readings would be. It turns out that the PID went to 152 C and stayed there with-in 1 or 2 degrees C. That's good but the meat thermometer was only registering about 279 F. Not good. I increased the setting on the PID to 156 and the meat thermometer went to 305 F. While the PID told me that the temperature was staying between 155 C & 157 C the meat thermometer was showing a 10 degree swing from 296 F to 305.7 F.

So do I have a bad meat thermometer that I have been using for 8 years or is the PID registering higher than actual temperatures. I tested the units at room temperature. The thermometer in my shop registered 73 F. The meat thermometer read 72.8 F and the PID read 27 C (80.6 F). So I'm thinking the PID is showing a higher than actual temperature. One more test - boiling water. Should be around 100 C but here in Boise at 2600' altitude should read a little less. The meat thermometer read 96.8 C and the PID read 113 C.

The PID seems to be telling me that I have a higher temperature than actual. Maybe there is a way to recalibrate that - Fred? - but if not I think I'll just set the PID value higher and use both the meat thermometer and thermocouple to check the temperature. I don't see this as a big problem but I did want to let others know that you might not be able to just set the PID and assume that it will get you the temperatures you are looking for.

Again I don't see a problem if you check the reading but it does make you wonder - and I hate to say this without waving a flag , maybe, just maybe some of the electronic stuff coming out of China might be a tad inferior. Perhaps spending a little more money on an American made PID might be a good idea - Mike

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guitarsbygiltzow.com

It would be interesting to see how the thermometer and thermocouple read in a more controlled environment. Stick them in a cup of ice water, holding each so they don't touch the glass. See how they read after a minute. This way you can see which is showing better accuracy, which should be between 30-34F.

I started with my PID controller and was checking with a thermometer also and finally decided that it was a waste of time worrying about the different readings. If the sides are bending well at the settings you use just bend sides. The PID temperature will have a range of values around the set point as there is always a lag in the response as the temperature will always overshoot a bit the drop below before the blanket temperature can respond. The whole idea of the PID control settings is to tune the response to the load, if you use the auto tune function the PID will learn the settings it needs but we do not run enough cycles to make this really happen. That is why I just use the ON/OFF mode on my unit as iot is plenty good enough for our needs, using the default values will give a response that should be fine. On some units you can select proportional P only mode and that will make the response faster but more overshoot will be seen.

Here is a link to some theory on what the controller is meant to do http://www.ni.com/white-paper/3782/en read the part about tuning the loop, id describes in simple terms what we need to do to improve the response time.

For the more interested this is a little heavier in detail http://www.pcbheaven.com/wikipages/PID_Theory/

The biggest benefit of the controllers is a level of repeatability and safety that the manual control can not give.

Fred

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Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866