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Converting a kiln to digital controller


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#1 jarrett

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Posted 19 May 2010 - 10:18 PM

I am going to convert my kiln to a digital controller. What I have is a Duncan Kiln with a kiln sitter and dial (lo, med, hi) type controller. This works decently for heat treating but I really want more accuracy, predictability.

I have order this: NEW FUJI PXR3 RTD °F TEMPERATURE CONTROLLER PT100Ω from EBAY.

Now, I have zero experience with this and would like guidance. I've read Dee's pinned thread(great by the way). I've also visited the British Blades site.
MOst of what I've seen is associated with new construction though.

I will take any advice I can get on the conversion.

Some of what I've wondered is;
Will I need a SSR?
Will I have to purchase a new thermocouple to make this work? or can I hook up to the sensor in the kiln already.
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#2 richard sexstone

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Posted 20 May 2010 - 04:17 AM

Jarret
I would think yes ,you will need a new themocouple.... wait to till your get your controller and so you can find out what will be compatible... both for the type of plug it has( they can be swapped just like a lamp cord plug) and for the temperature range... the K type usually read the highest temps....
Dick

#3 AlexH

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Posted 20 May 2010 - 10:45 AM

I am going to convert my kiln to a digital controller. What I have is a Duncan Kiln with a kiln sitter and dial (lo, med, hi) type controller. This works decently for heat treating but I really want more accuracy, predictability.

I have order this: NEW FUJI PXR3 RTD °F TEMPERATURE CONTROLLER PT100Ω from EBAY.

Now, I have zero experience with this and would like guidance. I've read Dee's pinned thread(great by the way). I've also visited the British Blades site.
MOst of what I've seen is associated with new construction though.

I will take any advice I can get on the conversion.

Some of what I've wondered is;
Will I need a SSR?
Will I have to purchase a new thermocouple to make this work? or can I hook up to the sensor in the kiln already.


I was considering a Fuji or Auber PID for my gaggia espresso machine. I think that you will need to make sure it has the output to switch an SSR, some are made to give a different output (DC, iirc). I nearly ordered the wrong type because it was a bargain! It looks like maybe you have a problem to me if you have ordered this one http://cgi.ebay.com/...2#ht_865wt_1141

FRONT SIZE: 24 x 48 mm

RTD PT100Ω 3-WIRE TYPE °F

4 TO 20 mA DC OUTPUT

ALARM 1 POINT

ALARM 2 POINT + 8 RAMPS/SOAKS

ENGLISH 100-240VAC

1 TO 5V DC

#4 jarrett

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Posted 20 May 2010 - 10:09 PM

Please look at the attachment below. It is a wiring diagram for the item I ordered.

http://www.instrumar...tall_wiring.pdf

I read up on this a little. What I liked was that it seemed so versatile.

Do you think based on this, I'll be able to use it?
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"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#5 Howard Clark

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Posted 20 May 2010 - 10:37 PM

The device you have listed uses a 100 ohm platimum RTD, NOT a thermocouple. The RTD uses three wires, and is a totally different animal. I do not know if they will withstand the temperatures you seek to measure. I only know about thermocouples, but perhaps someone else can chime n here who does know about RTD devices.

SSR stands for solid state relay, they come in multiple varieties as well, with most using a trigger pulse voltage of 5-20 vdc. If the device has to cycle on and off rapidly, they are truly wonderful things. The life of them is longer than mechanical relays also. However, for most of the types of stuff we use controllers for in the knife shop, mechanical relays are more than adequate.

#6 bronzetools

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Posted 21 May 2010 - 12:30 AM

Please look at the attachment below. It is a wiring diagram for the item I ordered.

http://www.instrumar...tall_wiring.pdf

I read up on this a little. What I liked was that it seemed so versatile.

Do you think based on this, I'll be able to use it?

A lot of these controllers will take different control inputs but they usually are set up to drive certain type of device.(SSR or coil relay or direct 1100 watt output)
I built a ramp and soak kiln controller from Auber instruments from a kit provided by Joppa glassworks.My link
My controller will take RTD and K thermocouple but only drives a SSR . This SSR drives a Mercury relay for safety,Mercury relays are rated for millions of cycles
and more importantly fail in the open state SSR's fail in the shorted state.
RTD's are not as high temp as K type thermocouples.
you can find lots of info. at Aubers siteMy link
and Omega's siteMy link
Good luck
Steve

Edited by bronzetools, 21 May 2010 - 12:34 AM.


#7 AlexH

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Posted 21 May 2010 - 07:12 AM

I think that is a 'global' connection diagram for all pxr3 subtypes and yours will have 4 and 5 output 4-20ma DC. I do recall that I decided not to order one of those from that seller for my espresso pid project (shelved) based on my research into it.

I hope you are able to work something out with it. I'm not sure what that output will drive, if it will drive a mechanical relay then maybe you are good, given what is posted above about mechanical relays being adequate.

Edited by AlexH, 21 May 2010 - 09:51 AM.


#8 jarrett

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Posted 22 May 2010 - 09:57 PM

Thank you all for the information. I've committed to buy so we'll see when it gets here. Lesson learned, I should have asked here before I bought it. Maybe this one will work out. If not, any one looking for a Fuki controller; cheap.
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#9 jarrett

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Posted 23 May 2010 - 08:32 AM

So, last night I almost ordered again but decided to ask before I did. (I learn; slowly, but I do)
Below are my cart contents from Auber Instruments (thanks for the link) I included a link to the pages for the SSR and for the controller.

I think this will all work. What do ya'll think?

As a side note, I have decided to not retrofit my kiln but build another. I have two duncan kilns. ONe in working condition(an ebay deal), the other (a junk yard find) I have disassembled and have all the components out of; controlls, shell, elements, bricks. I'm going to use these parts to build a kiln. The large one I have works great but takes ages to heat up.


Here is the parts list. I think with this, and some minor compnonents I can get locally I'll be in good shape.

25A SSR $15.00
http://www.auberins....o&products_id=9


PID Temperature Controller w/ Ramp/soak, Kiln (SSR Output) $77.95
http://www.auberins....o&products_id=4

High Temperature Thermocouple for Kiln $23.50
•Probe wire diameter - Gauge 11
•Cable length - 3 ft cable


Heat Sink for 25 A SSR $9.65
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#10 AlexH

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Posted 24 May 2010 - 03:36 PM

Jarrett, I think that is what you need, but have never built one myself. I shelved my espresso PID project to concentrate on grinding some knives.

#11 jarrett

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Posted 24 May 2010 - 08:10 PM

Thanks
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#12 Brian Shafer

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Posted 02 June 2010 - 08:06 AM

Here is a small tutorial I made when I converted my manual kiln to digital.
http://forums.dfoggk...showtopic=14254

Edited by Brian Shafer, 02 June 2010 - 08:11 AM.

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#13 jarrett

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Posted 03 June 2010 - 10:23 PM

Here is a small tutorial I made when I converted my manual kiln to digital.
http://forums.dfoggk...showtopic=14254


Thanks for the info. I recieved my components a day or so ago and will begin work on it in a few weeks following my AT. Your tutorial was informative and gave me a much better "visual" for what I've been reading in the directions with my gear.
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#14 bronzetools

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Posted 03 June 2010 - 10:34 PM

You will probably want to make a trip to radio shack to get some switches , fuses and a small fan to cool the SSR.
SSR's like too have a fan to be happy at full current loads. Even with a heat sink the fan is a good idea.
I will try to find the info I used to build my controller . I'll scan it and PM it to you in the next few days,if time allows
I have the same setup and controller with a SSR driving a mechanical mercury relay.
Good luck
Steve

#15 jarrett

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Posted 04 June 2010 - 10:25 PM

Thank you. Any assistance or guidance is appreciated. I will pay a visit to Radio Shack.
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#16 jarrett

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Posted 05 July 2010 - 11:19 PM

So I'm bringing this one back to life. I've built the control module, and the oven itself. Tested all circuts and outputs as I went and it seems to be working fine. My wiring setup is as follows. The controller operates an SSR which is actuating a relay. The relay is double pole feeding 240v (120 per leg) into the heater element. I wired the heater element up as follows; the two "hot" wires are connected one to each end and the "ground" is connected to the metal shell of the oven.

I believe this is the correct set up for a 240 element. Someone please correct me if I'm mistaken.

Here is my dilema. The heater element I'm using is out of a scrapped paragon kiln model B99B. The data plate indicates this is a 240v kiln system. I've used up two elements. Both ran for a minute or two, then melted down and were severed. The first I thought "old element to bad". When the second went I'm thinking now something else is wrong.

I figure there are two options.
a. These are not 240 volt elements.

b. I've got them wired incorrectly even though I think I've got them done correctly.

Any help is appreciated.
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#17 AlexH

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Posted 13 July 2010 - 03:37 PM

So I'm bringing this one back to life. I've built the control module, and the oven itself. Tested all circuts and outputs as I went and it seems to be working fine. My wiring setup is as follows. The controller operates an SSR which is actuating a relay. The relay is double pole feeding 240v (120 per leg) into the heater element. I wired the heater element up as follows; the two "hot" wires are connected one to each end and the "ground" is connected to the metal shell of the oven.

I believe this is the correct set up for a 240 element. Someone please correct me if I'm mistaken.

Here is my dilema. The heater element I'm using is out of a scrapped paragon kiln model B99B. The data plate indicates this is a 240v kiln system. I've used up two elements. Both ran for a minute or two, then melted down and were severed. The first I thought "old element to bad". When the second went I'm thinking now something else is wrong.

I figure there are two options.
a. These are not 240 volt elements.

b. I've got them wired incorrectly even though I think I've got them done correctly.

Any help is appreciated.


Have you tried an unfired element yet? How does it fail? Can you see it short to the body or does the wire just melt? If you had to manipulate the old element to fit it into your oven I think that this my cause failure as once it has been heated it loses flexibility. Maybe try buying new kanthal wire and making elements?

I do not know about how your split 240v-120V electrickery works being a UK expatriate. The british tutorial shows the elements insulated from the body. http://www.freewebs....NACEbackup2.pdf

#18 jarrett

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Posted 16 July 2010 - 10:52 PM

electrickery aptly describes what i do with it.
Thanks for the input. The tutorial was fantastic by the way.

I have now used a new element and so far so good. I've not yet ran it up to HT temp but will tommorrow. I believe the used elements I was trying were 120 ac. The kiln I salvaged indicated it operated off of 240 volt, but that could have just been the power supply required; the elements may have been 120(obviously they were). When 240 was put to them, they glowed intenselely more and more and then just melted into with a small amount of fireworks. I was of course observing from a distance for safety sake.

I've learned more about our 240-120 system through this. Our (U.S.) main coming into the house is 240 however, each alternating pole in a breaker box is in opposite phase to the ones next to it. So, when a device requires 240 v power, both "hot" legs supply 120 each at a different phase. The

Thanks,


I do not know about how your split 240v-120V electrickery works being a UK expatriate. The british tutorial shows the elements insulated from the body. http://www.freewebs....NACEbackup2.pdf
[/quote]
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."

#19 Howard Clark

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Posted 17 July 2010 - 06:00 AM

I had one old heat treat oven which had a 240 VAC input, but then had a huge transformer, with multiple taps and a multi-pole switch, with the max. voltage out being 32VAC, and the low end was only 6, if I remember right. Strange elements as well. I do not remember the brand name.

I think it is likely your conclusion is correct, and the old elements were 120V. Your understanding of the electricity coming into your service is also spot-on, with 120 each leg, and the earth ground to the case.

It gets even weirder when you start dealing with industrial sites in the US with both single phase and three phase and multiple voltages. Domestic service for most of us is pretty simple once you understand the basics, which now you do. :)

#20 jarrett

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Posted 18 July 2010 - 11:25 PM

This craft has caused me to dable in many areas; and learn to advance. Learning is good though, keeps us fresh. Sort of like the highschool geometry I thought I wouldnt use in life. Years later as a metal mechanic and pipe fitter, it all came flooding back.

As for the oven, it is working great now. I've fired it up twice to 1750 slowly and then cooled it slowly as well, to break everything in. Seems to work great. I used the thermocouple with the controller and another independent one to double check the temps. I am going to relocate the thermocouple but when that is done, I think I'll be cooking.

Thanks, again for all the input and guidance from everyone.
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God bless you. I thank God every day for the freedom to spend time with those I love, and time to pursue this craft.

"Adversity is a test for strong men."
"What one man can do, so can another."
"NO excuses, just do better next time."




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