*Suggestions for improved DIY Kiln Controller*

[oG Glocc Coma]

"Hey Everybody!"(Dr. Nick Voice)

Ok, I am upgrading to a new Kiln(AIM 84BD) from my old clunker that was free! I was in serious need of an upgrade so I'm super excited and can't wait! ANYWAYS... I built my first Kiln Controller for my clunker out of spare parts and whatever I found close to me. This time I want to do it different, I want to over engineer this Controller so I never have to open the box on it again(Dreams, I know).





I'm using the instructable Found Here (http://toblerglasscreations.com/fuji/) as my general guide just like I did with the first. I have a few questions that I'd like to ask about possible upgrades to this design.


1. Merc Relay, I've never installed a Merc Relay.... Are they that much better than a good SSR? Would I wire the same? The Merc relays I found are 1,2,or 3 poles and I know anything about that or what to choose... If someone could point me in the right direction i'd appreciate it ALLLOT!

2.NO/NC Buttons, I left these out on my first design and almost had a failure... not wanting to do that again! Question is... Which one is NC and which one is NO(red/Black)? also is a 1NO1NC Button gonna work like I want it to? I have my eyes on some sweet buttons but not sure if they will work.... Black-16mm-blue-led-circle-1NO1NC-push-button (http://www.ebay.com/itm/Black-16mm-blue-led-circle-1NO1NC-push-button-switch-flat-head-Angel-Eye-/141303490220?hash=item20e65826ac:g:uwYAAOxy3cJTiFW f)

3. Controller, I know Fuji is a good brand but can someone recommend a different brand that may be better or last longer. Please explain why you like the controller better

4. Adding Fan, Adding a PC fan to pull heat away from relay... Good Idea or Bad idea? Not sure if it will let more dirt in or actually help with cooling if needed

5. Project Box, I have been on the search for a really cool project box. Anyone seen a really awesome project box that might work? looking for a minimum of 6x3x4

[istandalone24/7]

about all i can add is that people seem to hate fuji, because programming isn't so easy. i use the sentry express 3 key (orton) and it couldn't be easier to program.

but, everyone who has a fuji says that once you figure out how to program it, it's pretty simple.

cooling fan is a novel idea, but idk about all the dust it might distribute. i think passive cooling holes/fins might be better, but please don't quote me on that :)

[oG Glocc Coma]

I can't find an after market/replacement Sentry Controller on the webs with my quick search. Have you seen them for resale?

[LooseSeal Baller]

Brads is going to have the most detailed answers for you, but i'll give you my 2 cents.

SSR>mercury relay

Cooling fan=yes

use a bigger enclosure if mounting on the kiln.

Pid ramp/soak controllers are fairly common, easy to wire, and use.

Oversize your relay and mount on a heat sink with fan, and do NOT mount the relay to the kiln wall directly, mount it as far from the heat as possible.

[istandalone24/7]

this isn't a standalone unit, but could be made one easily.

http://www.abrimagery.com/store/product_info.php/sentry-xpress-3key-controller-1700f-p-90850

[Icarus]

OGC, have you thought of building one using a Raspberry Pi? I have not, but we have a few members here who've built them with Arduino's and/or Raspberry Pi's, and if I recall right, you work in the tech industry, so this might be right up your alley.

[somewhere]

A mercury relay will out last the ssr many times over.

The thread about SSR and SCR come into play when you are pushing wire to it's upper limits. A kiln running at out temps with a MDR should last until the bricks fall apart. I have a annealing oven that is about 10 cubic feet that has run daily for the past 20 years with little to no maintenance.

I'm a huge Fuji fan and have found them to be extremely reliable.

[somewhere]

No fan or heat sink needed with a MDR but I would not mount it to the side of the kiln.

[oG Glocc Coma]

Thank you for the suggestions all!

Barry, It will be a fully detached separate box. The SSR(if I go that way) will be mounted to metal bottom plate to act as Heat Sink. The Kiln will plug into the switched plug for failover.

ISA, Thanks for the Link bud!

Icarus, the only hesitation I have is that I would want to go touch screen and I don't know how sustainable that is in the dirt filled desert of New Mexico... I might end up replacing things more often. If you have any other info to other people builds I can look at, i'm very interested!

Somewhere, thanks for the Info!

Brads, Where you at bud?!?!?!

[oG Glocc Coma]

No fan or heat sink needed with a MDR but I would not mount it to the side of the kiln.

Could you point me to a correct MDR?

[LooseSeal Baller]

A mercury relay will out last the ssr many times over

i remember this coming up in previous threads, but i thought the consensus was that while mercury relays will last longer, a properly installed ssr would last and be more affordable.

[dustyg]

i remember this coming up in previous threads, but i thought the consensus was that while mercury relays will last longer, a properly installed ssr would last and be more affordable.

I don't know how much more affordable it could be. My mercury relay was $25.

[LooseSeal Baller]

maybe my understanding of the previous thread was wrong, idk.

hopefully someone can elaborate and clear up some of this confusion.

[istandalone24/7]

it's what position the relay will fail in, when, not if, it fails. ssr will fail open (or kiln on full power) while a merc relay will fail closed (kiln off).

to me, that makes the price difference worth it. that being said, i do not have a replacement relay on hand. i'm going to knock on wood right now :)

[oG Glocc Coma]

So if I go with merc relay would I need the switched electrical plug and/or NO NC push buttons?

[LooseSeal Baller]

I was under the impression that a "properly" installed ssr or scr, would last a very long time.

http://www.talkglass.com/forum/showthread.php?61321-Choosing-and-using-SSRs-and-SCRs-Anyone-interested

I believe in the last post of the linked thread, the graph displays an extended element life of the (zero-cross) ssr, and it is greater than the MDR's.

[istandalone24/7]

it will, or at least should.
but when it fails, it'll fail with the kiln on full power. so if you're not right there, you'll slump all your glass and potentially burn out the elements. i plan on getting a merc relay really soon and putting it in. when i'm done melting for the day, i just skip the garage segment to the anneal cycle and don't even go back in there until the next morning, so i'd be screwed if it happened to me.

[LooseSeal Baller]

it will, or at least should.
but when it fails, it'll fail with the kiln on full power. so if you're not right there, you'll slump all your glass and potentially burn out the elements. i plan on getting a merc relay really soon and putting it in. when i'm done melting for the day, i just skip the garage segment to the anneal cycle and don't even go back in there until the next morning, so i'd be screwed if it happened to me.

If i remember correctly you can use one of the "alarm" functions to kill the power to the elements if the temperature exceeds your desired value.

so in the case of a stuck relay, you could wire in a second relay that would kill the power.

edit; i guess the alarm function would have to trip a breaker, that way the power wouldn't resume once the signal was stopped(if you're following me)

[dustyg]

it's what position the relay will fail in, when, not if, it fails. ssr will fail open (or kiln on full power) while a merc relay will fail closed (kiln off).

to me, that makes the price difference worth it. that being said, i do not have a replacement relay on hand. i'm going to knock on wood right now :)


While it's true that a mercury relay will fail in the off position, my mercury relay is controlled by an electromechanical relay. My understanding is that the electromechanical relay should last much, much longer this way (only running the voltage necessary to throw the mercury relay instead of all the voltage that goes to the elements), but it doesn't seem to me that I've totally eliminated the possibility of the system failing in the on-position.

[istandalone24/7]

great info. thanks guys :)

[oG Glocc Coma]

Thanks all!

[brads]

A mercury relay will out last the ssr many times over.

I'm going to have to disagree completely with that statement. A properly installed SSR will outlast a mercury relay many, MANY times over. A mercury relay will however, outlast an electro-mechanical relay by quite a bit if they are running on the same cycle time. Don't get me wrong on this, I like MDRs and think they work well. But to say they outlast SSRs many times over is just flat wrong. Here is a paper explaining life expectancy of SSRs vs. EMRs (electro-mechanical relays). Although the paper doesn't specifically mention MDRs (mercury displacement relays), they are typically rated for an operational life of about 10 times that of an EMR.


I'm a huge Fuji fan and have found them to be extremely reliable.

I agree with Sky this one though. My personal experience with Fuji controllers indicates that they are pretty much bullet proof. I'm pretty sure i've mentioned it here before, but I carelessly melted half of one quite a while back and it still worked and ran as it did when new.

On the other hand, Fuji manuals absolutely suck, so it may take a little while to figure out the programming. But once you do, they're fairly easy to use. Their main drawback to me is the lack of guaranteed soak capability. But that's not a big problem if you are familiar with your kiln's heating characteristics.

So getting back to the original question(s)...



I'm using the instructable Found Here (http://toblerglasscreations.com/fuji/) as my general guide just like I did with the first. I have a few questions that I'd like to ask about possible upgrades to this design.

oG, I've seen that instructable before and I'm not all that impressed with it. There are a couple things I would recommend against, including mounting the SSR to the base of the enclosure. If you want to use the box as a heat sink, it makes little sense to use the part of it that is sitting against the table so it can't dissipate heat. Use the side instead, and only if the box is aluminum.




1. Merc Relay, I've never installed a Merc Relay.... Are they that much better than a good SSR? Would I wire the same? The Merc relays I found are 1,2,or 3 poles and I know anything about that or what to choose... If someone could point me in the right direction i'd appreciate it ALLLOT!

A merc is no better - or worse - than an SSR, depending on what things are important to you. Mercs have a shorter lifespan by far (assuming both the merc and SSR are installed correctly). However, a merc has the advantage that it positively cuts the power to the elements when it is turned off, something which an SSR does not do. A mercury relay also has to be oriented correctly - usually vertically - for it to work at all. An SSR can be mounted in any direction with no ill effects. So pick your poison.



2.NO/NC Buttons, I left these out on my first design and almost had a failure... not wanting to do that again! Question is... Which one is NC and which one is NO(red/Black)? also is a 1NO1NC Button gonna work like I want it to? I have my eyes on some sweet buttons but not sure if they will work.... Black-16mm-blue-led-circle-1NO1NC-push-button (http://www.ebay.com/itm/Black-16mm-blue-led-circle-1NO1NC-push-button-switch-flat-head-Angel-Eye-/141303490220?hash=item20e65826ac:g:uwYAAOxy3cJTiFW f)

I'm not entirely sure what you mean by this. Do you mean an on/off switch for the kiln?



3. Controller, I know Fuji is a good brand but can someone recommend a different brand that may be better or last longer. Please explain why you like the controller better

See my reply to Sky's post above.



4. Adding Fan, Adding a PC fan to pull heat away from relay... Good Idea or Bad idea? Not sure if it will let more dirt in or actually help with cooling if needed

Nothing wrong with the idea and it may help with the heat, but an SSR on a small, 15 or 20 amp kiln won't be generating a ton of heat anyway. But the enclosure box should have ventilation holes either way.




5. Project Box, I have been on the search for a really cool project box. Anyone seen a really awesome project box that might work? looking for a minimum of 6x3x4

Check your local Goodwill store for Easy-Bake ovens. That's what I've been doing lately (http://www.talkglass.com/forum/showthread.php?59130-Plug-and-Play-Digital-Kiln-Controller-125&highlight=bake). ;) The first one in that thread is my favorite, but very hard to come by as they were only made for a year due to a product recall. In my second post in the tread that shows three different photos, DON'T use the style in the middle. Those are a raging PITA to take apart. The other two in that post (same style, just different colors) are okay, and pretty easy to find. The drawback to all of them is that they are put together with special tamper resistant security screws and it is VERY hard to find a screwdriver to fit. I wound up making a suitable screwdriver myself with a very long allen screwdriver and a Dremel tool.

[istandalone24/7]

Their main drawback to me is the lack of guaranteed soak capability.

curious what you mean by this? i have a couple friends who's kilns use fuji, they like them once figured out how to speak fuji.

[brads]

it's what position the relay will fail in, when, not if, it fails. ssr will fail open (or kiln on full power) while a merc relay will fail closed (kiln off).

to me, that makes the price difference worth it. that being said, i do not have a replacement relay on hand. i'm going to knock on wood right now :)

That's actually backwards. Failing "closed" keeps the power on. Failing "open", opens the "switch" (relay) and shuts off the power. But it is otherwise correct - when they fail, mercury and electro-mechanical relays ***usually*** (not always) fail open, shutting off the power. SSRs almost always (still, not always) fail closed and keep the power on. If you want to have the longest operational life AND a setup that has the least chance of a meltdown in the event of a failure, a combination of SSR and electro-mechanical (or mercury) relay is best. Use the SSR for the main power control to the kiln, and the EM relay as a failsafe device using a separate overtemp controller or an alarm output on your controller.

[istandalone24/7]

You know what I mean. They fail, the kiln is off.


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[istandalone24/7]

Instead of stuck on full power.


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[brads]

curious what you mean by this? i have a couple friends who's kilns use fuji, they like them once figured out how to speak fuji.

LOL, I can relate to "speaking Fuji". Their manuals seem to have a language all their own that is somewhere between Japanese and English.

Guaranteed soak - also called "assured soak" or "holdback" by different manufacturers (and probably some other things too) - means that a segment setpoint MUST be reached before the next program will segment start, or that a ramp rate MUST be within the user defined limits before the controller will continue the program. It stops the segment timer/program and goes into a "holding” state if the temperature goes out of a user programmed temperature differential tied to the segment setpoint or ramp rate, and only continues the timer/program if if the temperature enters the range again.

This allows you to program shorter segment times without worrying that setpoint temperatures won’t be reached. Here’s an example of a program using guaranteed soak that goes to 1100F as fast as the kiln is capable of, soaks there for 1 hour, drops to 1000F as fast as it can, soaks for another hour and then shuts off.


segment 1 ramp time (in hours) = 0.01
setpoint = 1100F
segment 2 = soak 1 hour
segment 3 ramp time = 0.01
setpoint = 1000F
segment 4 = soak 1 hour
off

With guaranteed soak this program will run as it is supposed to. The temperature will go to 1100F and soak there for 1 hour, drop to 1000F and soak there for 1 hour, and then turn off.

But WITHOUT guaranteed soak, the controller will start counting off the first 1 hour soak as soon as 36 seconds has elapsed (0.01 hours), no matter what the actual temperature is. Then, after that hour plus another 36 seconds has elapsed - once again regardless of the actual temperature - the second one hour soak will start counting down. At the end of that hour the kiln will shut off, even if it never reached the original setpoint.

As long as the segment times are long enough that the kiln can reach the programmed temperatures in the time allotted, it will still work okay without guaranteed soak. But you need to be more careful with your programmed times and temps.

[istandalone24/7]

Cool! I'm a sentry xpress guy so Fuji is all new to me.
Thanks for the explanation :)


Sent from my iPhone using Tapatalk

[oG Glocc Coma]

I'm not entirely sure what you mean by this. Do you mean an on/off switch for the kiln?


Yes in their design they show an On Button(NO Push) and an Off Button(NC Push)... Do I not Need Both of these? I'm not an electrician but it seems to me that if I Depress the On Button after use it would open the circuit and cut off the power... do I need the extra NC Button for "Off" capability? Does a Ramp/Soak controller automatically power off after running its segments?

I was under the impression that these NO/NC buttons were part of the Fail safe on the switched Port I will be pluggin into... above that I dont know what they do, I've seen other design with just a flip on off switch so not sure I need the whole two button setup.

[shawnette]

Here are a couple more DIY controller tutorials:

http://www.bladesmithsforum.com/index.php?showtopic=14254
http://www.steveghilliard.com/my-first-diy-kiln-controller/

[brads]

1. Merc Relay, I've never installed a Merc Relay.... Are they that much better than a good SSR? Would I wire the same? The Merc relays I found are 1,2,or 3 poles and I know anything about that or what to choose... If someone could point me in the right direction i'd appreciate it ALLLOT!



I'm back at the computer just long enough to answer this. If your kiln runs on 120Vac all you need is a single pole MDR. Run the hot wire - NOT the neutral - through it. This also assumes that your house, garage, shop, or wherever your power is being drawn from is wired correctly (not everywhere is) with the power coming out of the correct side of the electrical outlet. If it's wired backwards, then a single pole relay will shut off the kiln, but the elements will still be electrically live if you touch them. You can buy a cheap outlet tester at any hardware store, or probably even Wally World.

Two and three pole relays will work fine for 120Vac too. Just run both the power and neutral lines through the terminals. NEVER run the ground wire through a relay. You don't want the ground broken, EVER.

You'll want at least a two pole relay for 240Vac, although a three pole relay will work too by using just two of the three poles.

I'll be back later... Gotta run again.

[brads]

Yes in their design they show an On Button(NO Push) and an Off Button(NC Push)... Do I not Need Both of these? I'm not an electrician but it seems to me that if I Depress the On Button after use it would open the circuit and cut off the power... do I need the extra NC Button for "Off" capability? Does a Ramp/Soak controller automatically power off after running its segments?

I was under the impression that these NO/NC buttons were part of the Fail safe on the switched Port I will be pluggin into... above that I dont know what they do, I've seen other design with just a flip on off switch so not sure I need the whole two button setup.

I'll freely admit that I'm having a little trouble deciphering his wiring diagram. But my take on it is that you don't need the two on/off buttons. It makes more sense to me to simple use a rocker switch for turning power to the elements on/off. I would (and do) personally leave my controller powered up as long as the power cord is plugged in. Not that it has a lot to do with this, but one disadvantage of a plug and play control system is that it makes it difficult to power the controller from an uninterruptible power supply/surge protector.

As far as a ramp/soak controller automatically powering off after the program has run, it depends on the particular controller. Virtually all of the ones I know about give you at least 3 programmable choices of what happens at the end of the program.
1) The controller shuts off power to the kiln.
2) The controller holds the last setpoint temperature.
3) The controller reverts to a previously programmed setpoint.
There are other possibilities as well, but I think those three are probably the most common.

[brads]

oG, I was looking at the the page you linked to again and followed the link to the 220Vac wiring diagram (http://toblerglasscreations.com/fuji/220v.htm). WARNING - Do NOT use that diagram and expect it to be safe because it uses two SSRs for power control (which is a stupid way to do it). Even on a 220/240 system you only need one SSR. A second SSR will do nothing but give a false sense of security. To be safe you need a way to mechanically disconnect both incoming power lines. A solid state "disconnect" doesn't cut it.

[oG Glocc Coma]

Kiln: AIM 84 BD - 110v
Control: Fuji Electric PXR-4 PXR4-REY1-5V-D1

Sorry I didn't get this info sooner.

[brads]

Kiln: AIM 84 BD - 110v
Control: Fuji Electric PXR-4 PXR4-REY1-5V-D1

Sorry I didn't get this info sooner.

Well you can forget about an MDR. It won't work with that controller. Neither will a standard SSR, unless you have one with an analog input board or phase control module like the ones shown near the bottom of the page in this thread (http://www.talkglass.com/forum/showthread.php?61321-Choosing-and-using-SSRs-and-SCRs-Anyone-interested). The PXR4 model you bought outputs a 4-20mA signal, rather than the pulsed dc that is used to drive a standard SSR, or the type of signal to drive a merc relay or EMR. You still got a killer deal on it. The only problem is that you can't use it exactly the way you hoped. If you want to use it you'll either need an SCR for power control, or one of the aforementioned phase control modules or analog input boards for an SSR. Whatever you choose will likely add some extra expense. Not an insurmountable issue, but probably one you didn't expect.

[oG Glocc Coma]

That's what I get for bargain hunting! :(

[kq9ak]

One thing I have found and not noted anywhere. I had a ssr catch fire on me, never seen it happen from other types. My cooling fan burnt out, next thing I know nasty black smoke everywhere. Still run an ssr though

[brads]

Ouch, I guess I can see that happening if you lose the cooling for a high powered one, although the worst I've seen was one that melted because it was not only undersized for the job but also not mounted on a heat sink.

I remember many, many years ago when I lived in Massachusetts there was a hazmat situation at Faneuil Hall in Boston. One of the food places there had a mercury displacement relay on a stove blow up and scatter mercury around. The fire department got called in and shut everything down for several days, if I remember right. I also seem to recall that the place that had the mishap - and possible a few others nearby - was forced to trash all the food they had in stock due to possible contamination. That had to REALLY suck for them.

Thankfully, situations like these aren't at all common, but they are still a possibility when things go badly wrong.

[shawnette]

Well you can forget about an MDR. It won't work with that controller. Neither will a standard SSR, unless you have one with an analog input board or phase control module like the ones shown near the bottom of the page in this thread (http://www.talkglass.com/forum/showthread.php?61321-Choosing-and-using-SSRs-and-SCRs-Anyone-interested). The PXR4 model you bought outputs a 4-20mA signal, rather than the pulsed dc that is used to drive a standard SSR, or the type of signal to drive a merc relay or EMR. You still got a killer deal on it. The only problem is that you can't use it exactly the way you hoped. If you want to use it you'll either need an SCR for power control, or one of the aforementioned phase control modules or analog input boards for an SSR. Whatever you choose will likely add some extra expense. Not an insurmountable issue, but probably one you didn't expect.
Hey Brad, I snagged a PXR4--RAY-5V for $40. Am I going to need additional parts, as well? It came with an SSR & thermocoupler.

(This this thing is wayyy smaller than I was expecting!)

http://images.tapatalk-cdn.com/15/10/22/b843f9b2caf348375dc24ec5f85a3681.jpg

Sent from my D5503 using Tapatalk

[shawnette]

The label underneath says it's a PXR4RAY1-GV0A1

[brads]

Hey Brad, I snagged a PXR4--RAY-5V for $40. Am I going to need additional parts, as well? It came with an SSR & thermocoupler.

(This this thing is wayyy smaller than I was expecting!)

http://images.tapatalk-cdn.com/15/10/22/b843f9b2caf348375dc24ec5f85a3681.jpg

Sent from my D5503 using Tapatalk

Yeah, they're pretty small.

That's a damned good deal if it works. (And I've got no reason to think it doesn't.) What type of SSR came with it? That particular model number of PXR has a relay output, so if your SSR isn't one with AC input you'll need something different.

[shawnette]

It came with a FOTEK.

http://images.tapatalk-cdn.com/15/10/22/37e6e9f59fa3d54388b871db2941a7b7.jpg

Sent from my D5503 using Tapatalk

[brads]

The label underneath says it's a PXR4RAY1-GV0A1

The model number on the label should be the correct one Shawnette, unless it's been reconfigured. But either way, I don't think the SSR will be of much help. Both of those model numbers denote a PXR controller with a relay output, which won't work with a dc input SSR. If it was a model that will drive a standard SSR, the first "A" in the model number would be a "C" instead. So you'll probably need either an electro-mechanical or mercury relay to use with it.

[shawnette]

Hmm. I also have a Chilipepper. I've had to replace the relay a couple of times, so I ordered extras the last time. Could I use one of those? It's a Potter& Brumfield T9AP1D52-12. http://www.newark.com/te-connectivity-potter-brumfield/t9ap1d52-12/power-relay-spst-no-12vdc-30a/dp/17M3058

If not, is there on that you suggest? And can OG use the one that I have with the controller he's getting from you? If so, I'll just toss it in with the kiln.

[brads]

I'm not surprised your Chilipepper eats relays if you use it a lot. I was in a studio a couple of moths ago that had several of them, and judging by the relay clicking on/off they seemed to have a cycle time of about 10 seconds, which is a sure way to kill EM relays pretty quickly. I've looked at the literature for the 3 key controller they use and can't see any indication that there's a way to adjust the cycle time to get better relay life. So keeping spares in stock is a very good idea. The programming on that controller really seems to be set up for running a mercury relay instead of an EM relay.

Getting back to your Fuji, unfortunately, even though you were wise to buy extra relays for the Chilipepper, you seem to be more or less SOL as far as using them with the PXR4 because they are dc input relays. There is a way you could use one - or even your SSR - but it may be more trouble than it's worth because it would require a small dc transformer and some extra wiring. (It would probably also take me more explaining than I have time for.)

So unless the guts of your Fuji controller have been changed so it outputs a dc pulse for your SSR (which is possible because you can never really be sure what you're getting when you buy something on eBay), I think you're going to need to buy a 120Vac input relay to connect to it.

[brads]

One thing I have found and not noted anywhere. I had a ssr catch fire on me, never seen it happen from other types. My cooling fan burnt out, next thing I know nasty black smoke everywhere. Still run an ssr though

I didn't mention it in my other post due to lack of time, but this is a situation where a high end SCR power controller does have an advantage over a lower budget SCR or SSR setup. The high end SCR power controllers made by companies like Spang, Control Concepts, etc. very often include a thermal shut-off that will disconnect the power if the SCR gets hot enough that it might self-destruct, especially the ones that use a cooling fan. The thermal overload relay goes a long way towards preventing these kinds of meltdowns. Essentially the same thing can be done with an SSR, by installing an additional thermocouple that measures the heatsink temperature, an alarm output and a relay, but very few people using SSRs go to those lengths.