Positive about failing elements.

[Babs]

My elements are failing, oy about half an hour to an hour longer. I have ordered new ones, over $1000 Aus. , an increase of over 60%

My least favourite job is element replacing followed closely by shelf grinding, more confident shelf grinder... Anyway , rising in the night to e there when kiln shuts down, I remembered reading sthing that @Dick White wrote re glazes maturing in a failing element situation. SO, sorry @oldlady, starting with a So, and plus I wanted to return to bed, I switched off about 1180 instead of going through to end.

I already ramp 80°C for final hour but on opening kiln, perfect, glazes loved it and no shelf drips from usual customers!!! Now toying with new elements, less electricity used with the present setting, albeit for just a while.

Edited September 10, 2023 by Babs

[Dick White]

Oh no, Babs, don't fail on us now, we love you and need you. So, what did I ever write about elements and glazes... where do I begin...

A cursory review of the infamous Orton cone tables shows 3 columns of temperatures for each of the basic types of cone. The first column of temperatures is for a slow ramp over the last 2 hours into the final temperature, the middle column is for a medium speed ramp into the final temperature, and the third column is for a fast ramp into the final temperature. A slow ramp will bend the cone at a lower final temperature than a fast ramp, as a fast ramp must continue to a higher kiln temperature before the heatwork has penetrated the ceramic and the cone bends. Elements, as they wear out, produce less and less heat, which means the kiln will heat slower and slower (i.e., take longer and longer), particularly at the higher temperatures of mid-fire and high-fire clay bodies and glazes. A Bartlett or Orton kiln controller (Skutt controllers and the L&L DynaTrol are private label Bartletts, and the Paragon Sentry line is a private label Orton) that is programmed using a custom ramp-hold sequence to finish at a particular ramp rate to a particular temperature will continue to fire to the assigned temperature regardless of the actual ramp rate the elements can achieve in their weakened state (until the elements are so weak they just can't manage any increase in the kiln temperature, and then you get the dreaded E1 failure). Thus, if you are running a program with a set point of 1222℃ at 60℃/hour expecting it to produce a nice cone 6 per the Orton chart - but your elements are so worn that they can only manage 15℃/hour at the end - the kiln still will go to 1222℃ because that is what is programmed, but at the slower rate because that's all the kiln can do. Looking further in the Orton cone table, 1222℃ at 15℃/hour is cone 9, seriously overfired. (I'm just pulling these numbers from the table for the purpose of discussion, your studio practice and kiln condition may be different.)

All that said about custom ramp-hold programs, there is the other side of the Orton and Bartlett controllers - the cone-fire method. You enter a speed and a cone number via the keypad, and the controller knows what to do. The cone-fire method on both these controller types contains some hidden adaptive programming that monitors the actual ramp rate in the final segment in real time. If the kiln is lagging, the controller will adjust the set point down using a proprietary algorithm from Orton so that a proper bend of the cone will occur at an appropriately lower final temperature. Using the above example, if you have set a cone 6 medium speed firing, but the elements are so worn they can only manage 15℃/hour at the end, the controller will stop at 1185℃, 37 degrees early, for a perfectly bent cone 6. Similarly, if you set a fast firing and your elements are still sufficiently robust to accomplish the higher ramp rate, the controller will automatically proceed to a higher temperature.

Note that this adaptive behavior is only available in the cone-fire method. If you are using custom ramp-hold programming, you need to watch your cones and adjust your final set point to match the cone behavior. And when you install new elements that can actually maintain the ramp you set, you need to watch your cones and adjust your final set point to match the cone behavior. But alas, I repeat myself.

Keep calm and carry on. Especially carry on .

[Min]

Just adding one point to Dick’s great post. If you use a custom ramp schedule, with some controllers you can still program in a specific cone within the program. ie X degrees per hour up to  a  specific cone then continue with the custom program.

[neilestrick]

While ailing elements may still do the job, albeit more slowly, keep in mind that those firings are costing you more than with fresh elements. I once ran my e18T-3 until the elements would no longer reach cone 6, and the last firing cost me twice as much as the new elements. Also, elements that are used to the point of failure are generally more difficult to remove because they are deformed, and because they coils tend to expand in diameter as they wear out. In non-L&L kilns that means they'll do more damage to the element grooves during removal, and in L&L kilns it means they tend to break into small pieces as you remove them, therefore taking a lot longer to do the job. Although changing elements may be a miserable job, it's a lot easier to do it before the elements get really bad. Replace them once the resistance is 10% off from new, or the coils start to lay over on each other.

[Babs]

Thanks all, now where is my "Little book of calm"!

My controller, sounds a bit spooky, is a a Brit, Stafford ST316B CE,  and doesnt have some of the magic written about, or I haven't discovered it.

I have had to send pics of wiring etc to the kiln manufacturers as...computer crash, lost all info :-//, hmmm and no longer make the kiln in single phase mode.

I LOVE all of this!!!

Makes throwing pots oh so much more enjoyable 

And I got rid of my gas kiln because of inability to handle the gas cylinders anymore, tears in my morning cuppa, nah

Edited September 11, 2023 by Babs

[PeterH]

8 hours ago, Babs said:

My controller, sounds a bit spooky, is a a Brit, Stafford ST316B CE,  and doesnt have some of the magic written about, or I haven't discovered it.

I expect you are right that it doesn't contain any "smarts" for minimising the effect of failing elements.

PS What information I found (but haven't read in detail)

I think that the CE is just an indication is passes European community standards
CE marking for Electronic equipment - EMC testing
So your controller is probably a Stafford ST316B.



 

Data sheet, installation guide and user guide at https://staffordinstruments.co.uk/st316b-controller/
Site https://staffordinstruments.co.uk/
Contact https://staffordinstruments.co.uk/contact-us/

Edited September 12, 2023 by PeterH

[Babs]

3 hours ago, PeterH said:

I expect you are right that it doesn't contain any "smarts" for minimising the effect of failing elements.

PS What information I found (but haven't read in detail)

I think that the CE is just an indication is passes European community standards
CE marking for Electronic equipment - EMC testing
So your controller is probably a Stafford ST316B.



 

Data sheet, installation guide and user guide at https://staffordinstruments.co.uk/st316b-controller/
Site https://staffordinstruments.co.uk/
Contact https://staffordinstruments.co.uk/contact-us/

@PeterH Yes that is the model I have, thanks Peter, for the links and explanation.

[Hyn Patty]

I feel you.  My now 20 year old Skutt failed to reach temp on a firing for the first time recently and gave me an error code that suggests either the elements or the thermocouple are failing.  Ugh.  With the price of rhodium gone through the roof, that could be costly.  Tbh I haven't replaced ANYTHING on this kiln, or my Olympic, since I got them new 20 years ago with the exception of the relays - and I have used them a lot.   The relays went out on both kilns in the past year so they are brand new.  As much as I have used the heck out of my Olympic Doll E, I have no clue how on earth I haven't had to replace anything else in all these years.  I've just been amazingly lucky, I suppose.  My SKutt however was in storage for about a decade and has been used a great deal less than my little Olympic.

Good news is I found a platinum rhodium replacement thermocouple S out of China that only cost $15 shipped (instead of $400) but I haven't tested it yet.  It is supposed to be good to fire up to cone 16 and since both of my kilns only fire up to cone 10, that would do very well if it works.  I'll be swapping it to test shortly but hadn't gotten around to trying it yet. 

Alas, testing my elements on my big Skutt showed a lot of resistance and one bad element.   No wonder my electric bill has been going higher and higher when using the Skutt.  Thankfully a full set of 4 new elements for my KM1018 have come down in price.  During COVID I had already priced them and they were about $400 USD with shipping.  OUCH.  But now I got them for $253 postage paid.  Whew!  That is a nice surprise.

 

Edited November 1, 2023 by Hyn Patty
Oops, typo!

[neilestrick]

3 hours ago, Hyn Patty said:

During COVID I had already priced them and they were about $400 USD with shipping.  OUCH.  But now I got them for $253 postage paid.  Whew!  That is a nice surprise.

 

If someone quoted you $400 for 4 elements then they were overcharging, probably due to the element shortage. But the list price has never been higher than they are now.

The difference in the cheap type S thermocouple is probably the thickness of the metal. A lot of the cheap type K thermocouples from China are very thin compared to what we usually use, and won't last nearly as long. Your may fry out a lot faster than a more expensive version, but keep us posted.

[Hyn Patty]

12 minutes ago, neilestrick said:

If someone quoted you $400 for 4 elements then they were overcharging, probably due to the element shortage. But the list price has never been higher than they are now.

The difference in the cheap type S thermocouple is probably the thickness of the metal. A lot of the cheap type K thermocouples from China are very thin compared to what we usually use, and won't last nearly as long. Your may fry out a lot faster than a more expensive version, but keep us posted.

Yes, that was the going rate at that time from ANYWHERE (for my kiln) so yeah, I decided to wait.  I always price shop around and look at a lot of different places and at that time everyone's prices were stupid crazy.  Some had them cheaper like $350 but then the shipping was insane so I'm glad I waited.    I was able to get backup relays at that time for regular price thankfully.

As for S thermocouple that may well be true and that is my concern also.   Which is why I want to test it but hadn't yet.  I may put it into my little Olympic kiln and try it rather than in my larger Skutt.  I really detest K thermocouples and how they flake off bits of metal.  I am always having to steel brush whatever part of them that isn't fully sheathed and vacuum out my Olympic before any glaze firing - else risk little bits of black flakes in my finished pieces.  As I typically get several thousand dollars per piece I just can't  have flaws like that in my scupture.

[neilestrick]

2 minutes ago, Hyn Patty said:

I am always having to steel brush whatever part of them that isn't fully sheathed and vacuum out my Olympic before any glaze firing - else risk little bits of black flakes in my finished pieces.

A thermocouple protection tube will stop that from happening, but it sounds like the type S is a worthwhile investment even at the higher price.

[Babs]

Oh you guys, my new elements were$1500 AU plus postage!!!! 

My kiln has gained 1hr in firing time to get to C6, I am putting off replacing them, got the new ones in the cupboard. Need to feel very strong before ripping out what " works" out here. 

Go for the expensive thermocouple, you'll get your money's worth, less error codes and pos flawed firings.

[Hyn Patty]

Problem with my K thermocouple is that not ALL of the wire is sheathed.  Just the tip where the two are joined it has no covering - so it still drops flakes off of the tip.  So yes, I am a huge fan of a good S thermocouple instead so not to risk ruining my work.  For whatever reason those are fully sheathed and last so much longer too.

So sorry you had to pay SO MUCH for your elements, Babs.  I assume a lot of that is freight cost but likely your kiln is much larger than my Skutt which is about medium sized for a kiln.  Large compared to my little Olympic but fairly small compared to my Mother-In-Law's huge Skutt that's easily twice the size of mine.  Hers probably does utilize twice as much element wire so that would make sense if the cost were at least doubled.

[Babs]

No, freight not included in that amount! Just how it is here. Sheath for a long gas kiln s thermocouple, $70 many years ago...middle factor making the $