Bartlett controller - over firing issue?

[Wayne2]

Hi, I am not new to programming computers, but I am new to programming kilns and have learned a lot from the postings in this group. Thanks to all who have posted.

Kiln-an older three zone Cone Art Kiln BX 2327-1. Elements (6) are relatively new and have been obtained from reputable sources. The controller is a Bartlett Genesis Model LT3140. Its printout:
Software 3.26.0
Serial 799801015
network genesis
Type K max temp 1315C

We tried the C6IRED Firing Schedule from Digital Fire, (top temperature is 1204C or 2200F), but the cone packs (large cones) in all 3 zones were fired to over cone 7, which if I am interpreting the Orton temperature charts correctly is over 1255C. The firing took a bit over 12 hours (Insight suggests it should be around 9:51).

Despite the cone pack evidence, the graph output from the controller suggests that it did what it was programmed to do, going a bit over 1200C.

This kiln is in a group pottery and we fired another load to keep up the output. I assumed a linear thermocouple response and subtracted 50C from the peak, shoulders, and that last segment of the C6IRED numbers, leaving the ramp speeds the same. The kiln just reached Cone 5 and the firing took almost 14 hours (Insight suggests it should have been around 9:36.)

I am not totally sure what really needs fixing but suspect it may be the motherboard.

My first thought it was a thermocouple issue, but the controller hasn’t indicated a failure and they do not look corroded. They are what the local pottery store sells for the kiln, unmarked 8 gauge type K inserts.

The second thought i that it is the motherboard. It was replaced about a year ago, but may be either misconfigured or failing. Aside from the over firing, the WiFi is not working and its acceptance of user input seems a little spotty/irregular.

While it says it is searching for networks and the WiFi light on the front panel flashes regularly, there is no MAC address listed in the controller and it never finds the router. Rebooting re-configuring WiFi as per the Bartlett web page says doesn’t seem to make any difference.

When starting up the last Bartlett automatic Cone firing the controller did not allow the change from a “fast” to “medium” firing.

One other thing; there is apparently confusion on the length of time used for these firings. I have been told a longer firing for a lower temperature is what one should expect when I questioned those firing times. That is counter intuitive to my expectations, as I would expect it should take less time to reach a lower temperature. I also tend to think Insight’s numbers should be closer to the time for firing if the kiln was working properly and the elements in good shape.

[neilestrick]

Hi Wayne, welcome to the forum.

Everyone, here is the C6IRED schedule he's referring to.

Step	°C	°F	Hold	Time
1	138°C/hr to 121C	250°F/hr to 250F	60min	1:42	Evaporate all mechanical water
2	194°C/hr to 1148C	350°F/hr to 2100F	0	6:59
3	60°C/hr to 1204C	108°F/hr to 2200F	10min	8:04	Slow down to even out kiln chamber
4	555°C/hr to 1148C	999°F/hr to 2100F	30min	8:40	Heal blisters, pinholes here
5	555°C/hr to 960C	999°F/hr to 1760F	50min	9:51	Grow iron crystals here

The Genesis controllers have been known to have a problem with the Wi-Fi module. You'll need to send it in to have the module replaced. The new modules appear to work fine. You'll need to contact them to get a repair authorization number.

That module may or may not be the cause of your firing problems, but it's probably not. The only time I've seen the wifi module create problems is when it totally freaks out and gives a 'soft watchdog error' code.

As for not following the schedule exactly, I'm not surprised. Most kilns can't keep up with a 350F/hr rate of climb, especially up to 2100F, and especially when you're running a kiln with zone control. It can't go that fast and keep the sections even. Plus your 9999 cooling times are going to be different depending on the size of the kiln and the amount of mass inside it.

It's possible that you do have a thermocouple problem. Have you checked the logs to make sure they're running evenly? If one is consistently out of whack with the others you should see that. Also check the thermocouple wire connections, especially on the ceramic block where they connect to the thermocouples. The wires can break under the set screws and cause jumpy readings. The second, 14 hour firing leads me to believe you're either getting a jumpy thermocouple reading or you have a relay that's sticking periodically. Again, if you look at the logs you should be able to see if a section is lagging.

[Wayne2]

Hi,

Thanks very much for your response.

I was wondering those climbing rates might be too high for that kiln and you have confirmed that suspicion. The mass in that second load was smaller than the first so I suspect your thought on connections or relays (and/or potentially mother board) may be correct. I am not sure of the warranty status of that controller and will check that with the powers that be. If it is off warranty I suspect a new controller would be the best option.

I am looking forward to getting some better data off the controllers once the WiFi works. The thermocouples all seem to be reading within a few degrees of each other in any of the screens showing temperature. Cone packs from the second firing had only minor difference between the zones. I was thinking a minor thermocouple offset might be in order, but now that I think about it, I did not check the mass in each zone.

Other than that data from the WiFi/downloaded logs, I am not really sure what log/data item that would tell me that a section was lagging?

I am not at the studio now and will check the data menu log for the relay cycling later this week once the weather clears here.

I did not notice there was a last error code on that screen and will recheck that (and also that error codes have not been turned off by someone.)

Thanks again

Wayne

[neilestrick]

4 minutes ago, Wayne2 said:

Other than that data from the WiFi/downloaded logs, I am not really sure what log/data item that would tell me that a section was lagging?

Yes, it would have to be connected to the wifi to get the firing logs. Sorry about that, I didn't think that through.

When controllers have problems it doesn't typically manifest as a firing problem like this. It's always something a lot more obvious like buttons stop working, or one section of the programming won't respond to inputs (cone fire mode won't work, for example), or you get some random error code that's specific to a mother board problem. Slow firings and such are almost always caused by the stuff connected to the controller (thermocouples system or relays), or even some sort of electrical interference. Since your controller was working fine before this, I expect it's not a controller issue. That said, I would definitely get the wifi module repaired and update to the most recent software just to be safe.

 

[PeterH]

18 hours ago, Wayne2 said:

One other thing; there is apparently confusion on the length of time used for these firings. I have been told a longer firing for a lower temperature is what one should expect when I questioned those firing times. That is counter intuitive to my expectations, as I would expect it should take less time to reach a lower temperature. I also tend to think Insight’s numbers should be closer to the time for firing if the kiln was working properly and the elements in good shape.

Are you sure that this isn't an indirect  reference to heat-work? Perhaps in the context of unachievable ramp speeds.

[Wayne2]

It might be.  Its hard to think in color rather than controller temperature. 

While a change in the mass in the kiln changes the heat-work required, my expectation is that it would change the achievable ramp speed in a 'challenged' kiln in an inverse manner (higher mass=lower speed).  That lower ramp speed would also lower what the controller sees as the temperature for a Cone firing perhaps requiring changes to that firing schedule (and one reason why I want to get that WiFi data to find out the real ramp speed).

The second firing (50 degrees C lower temperature according to the controller) had lower mass and took two hours longer.  Given the kiln and shelves have a relatively constant mass, shouldn't a smaller load need less heat-work and take less time to heat up and less time to cool too?

My guess is that a problem in connection resistance or arcing would probably have a similar affect (perhaps increasing resistance and decreasing heating rates with time until something fails) during each firing.

Does relay sticking vary in effect this much between 2 firings?

[Bill Kielb]

35 minutes ago, Wayne2 said:

My guess is that a problem in connection resistance or arcing would probably have a similar affect (perhaps increasing resistance and decreasing heating rates with time until something fails) during each firing.

Does relay sticking vary in effect this much between 2 firings?

This might help
It’s important to go the correct speed in the last 100c of the firing to achieve the expected heatwork, so whether worn elements, not enough power, stuck relay,, anything that extends the last 100c will have a dramatic effect. Prior speed, not so much. 

[Wayne2]

3 hours ago, Bill Kielb said:

This might help
It’s important to go the correct speed in the last 100c of the firing to achieve the expected heatwork, so whether worn elements, not enough power, stuck relay,, anything that extends the last 100c will have a dramatic effect. Prior speed, not so much. 

Thanks.  On a longer term I am wondering if changes are needed for a firing schedule to accomodate any kiln's recent performance.

So at a lower ramp speed in the top segment, when the programmed temperature is reached the load could be overfired? 

Here is a picture of the graph from the controller of the second firing.  Assuming that the controller/thermocouples are getting the right temperature, the graph suggests the kiln rose from 121C to 1098C in ~8-9 hours--if it was 9 hours very roughly a ramp speed of ~110C/hour. 

Any idea of if and how much that final segment's actual ramp would be lower than the initial ramp at higher temperature?  Would it be different than the program's called for speed of 60C/hr or would it be totally random depending on the relays being stuck open or closed?

 

 

 

Edited January 26, 2023 by Wayne2
Picture is not right? But I apparently can't fix it

[Dick White]

I'm going to pop in here for 2 things, one old, the other new.

First, back to the wifi issue. It may be that Neil is right (is he ever wrong?) about a defective board, but in some of my work with the Genesis controller, it may just be a weak wifi signal from the access point router being too far away. When I first installed them on my kilns in the garage, I got almost no signal out there because of 2 brick walls and 3 floors and interior walls in the way. An old saw in wifi-land is "3 walls and you are out" and a diagonal signal path through a wall or floor counts as 2. My solution, and one I have recommended to others, is put an inexpensive wifi extender/repeater somewhere in between to boost the signal through the last wall or farther distance to the kiln. Maybe that will help your kiln connect and then you can download the log files.

Second, yes, as we all know (or as some don't fully understand) a slower ramp rate in the last 100C yields the cone bend at a lower temperature. Whether that lower temperature is achieved sooner on the clock or not, you'll have to do the math. Intuitively, I suspect that because it is running slower, it will take longer even though it doesn't have as far to go.  And if the slowdown is being caused by challenged elements, the runup to that last 100C is probably going to be a lot slower too, so the whole firing will take a lot longer, not shorter. Anyway, it is also important to note that in the cone-fire mode, the controller is tracking the actual achieved ramp (vs. expected ramp) and adjusting the final cone temperature to account for a faster (to a higher temperature) or slower (to a lower temperature) ramp.  That is not going to affect this discussion because Wayne is running a custom ramp-hold sequence to prescribed temperatures in each segment. For those, if the kiln cannot maintain the requested ramp rate for whatever reasons, the controller will keep chugging at the slower rate until it finally gets to the setpoint. That will mean, for an expected cone bend, it will be overfired.

[Bill Kielb]

50 minutes ago, Wayne2 said:

Any idea of if and how much that final segment's actual ramp would be lower than the initial ramp at higher temperature?  Would it be different than the program's called for speed of 60C/hr or would it be totally random depending on the relays being stuck open or closed?

The graph did not post, but the controller I believe will allow you to look at the firing on a more granular level to determine what it was. Kilns have the greatest losses at the top end of their firing. Most kilns with new elements fail to achieve a reasonable final rate0 once the elements wear by about ten percent. For a cone 10 kiln firing to cone six this is often in the neighborhood of 150 firings, glaze and bisque. Not saying that is your issue but anything that causes the firing to lose power or slow down in the last 100c of the firing will begin to over fire because time and temperature are what make up heat work. 

So stuck relay, bad thermocouples, poor connections and of course worn elements can all cause the over firing.8-9 hours would be correct, My understanding is it took 14 hours, hence the answer to your question if going too slow could make it over fire.

[Wayne2]

2 hours ago, Dick White said:

I'm going to pop in here for 2 things, one old, the other new.

First, back to the wifi issue. It may be that Neil is right (is he ever wrong?) about a defective board, but in some of my work with the Genesis controller, it may just be a weak wifi signal from the access point router being too far away. When I first installed them on my kilns in the garage, I got almost no signal out there because of 2 brick walls and 3 floors and interior walls in the way. An old saw in wifi-land is "3 walls and you are out" and a diagonal signal path through a wall or floor counts as 2. My solution, and one I have recommended to others, is put an inexpensive wifi extender/repeater somewhere in between to boost the signal through the last wall or farther distance to the kiln. Maybe that will help your kiln connect and then you can download the log files.

Thanks that is a good thing to check and a good fix.  I will check the signal strength.

2 hours ago, Bill Kielb said:

My understanding is it took 14 hours, hence the answer to your question if going too slow could make it over fire.

Actually that second run was underfired (didn't reach a good cone 5 when the first firing overfired to Cone 7+) which makes this so perplexing.

[neilestrick]

18 minutes ago, Wayne2 said:

Thanks that is a good thing to check and a good fix.  I will check the signal strength.

Yes, the wifi on the controllers is pretty weak, so you need a good signal. Just because your phone is finding it doesn't mean the kiln will. I have a very strong signal on my phone by my kilns, but a very weak signal on the controllers. One way to check if the controller's wifi module is working is to set up your phone as a hotspot and see if the controller can find it. You could also do a firmware update, and download the firing logs by hooking up your laptop to the same hotspot. I realized mine wasn't working when it wouldn't find any of my neighbor's signals either, when it usually find 3 or 4.

 

18 minutes ago, Wayne2 said:

Actually that second run was underfired (didn't reach a good cone 5 when the first firing overfired to Cone 7+) which makes this so perplexing.

This is why I think you have a thermocouple or relay issue.

[Wayne2]

Thanks Neil,  I agree with your comments and expect all the relays need replacing and the thermocouple connections need to be checked/cleaned.

The hotspot is a great idea to try before working on a more permanent solution and using a laptop to connect to that hotspot rather than the router (which it normally does) is something I wouldn't have tried.

As the controller is not reporting a MAC address I have assumed this is a hardware issue.  Your earilier comment on the WiFi module supports that assumption.  Next time I am in the studio, I will also check if the controller is actually broadcasting a signal and the strength of the router's signal in the kiln room.

 

[neilestrick]

3 hours ago, Wayne2 said:

Thanks Neil,  I agree with your comments and expect all the relays need replacing and the thermocouple connections need to be checked/cleaned.

The hotspot is a great idea to try before working on a more permanent solution and using a laptop to connect to that hotspot rather than the router (which it normally does) is something I wouldn't have tried.

As the controller is not reporting a MAC address I have assumed this is a hardware issue.  Your earilier comment on the WiFi module supports that assumption.  Next time I am in the studio, I will also check if the controller is actually broadcasting a signal and the strength of the router's signal in the kiln room.

 

If you can get it to do a firmware update that would be a good start.