Cress kiln failing/failed relay?

[Lara-Poppyseed]

Hello!

I have been having issues with my kiln not reaching Cone 6 recently and have assumed my elements were getting old. It had been reaching Cone 4 and 5 okay so far. I just started a new firing today and noticed there is an occasional buzzing sound between some of the clicks. I tried to search online and it looks like this could be a sign of a failing/failed relay or infinite power switch? Does anyone have any advice for me on this? I have had the kiln for about 1.5 yrs and haven't had to replace the elements as they were new when I got it and don't fire it super often. I emailed Cress today and the email I got back was "It sounds normal." Literally that is all the message said so I'm a little annoyed. I swear I haven't heard this noise before. Unfortunately it doesn't look like I can post videos here of the sound I am referring to but did post one on the r/ceramics subreddit here: 

 

Thank you for your help!

Lara

[Hulk]

Hi Lara!

Looks like that kiln is fitted with a kiln sitter + timer mechanism, hence, my guess is no relays involved.
...however, I'm not sure how that thumbwheel works.
Any road, is there a thermocouple there anywhere? If not, almost certainly no relays.

If it had been taking longer and longer to reach target cone with about the same load (weight of ware, shelves, and posts), then struggle to reach target, then eventually not reach target, that sounds like wearing elements. If you can find resistance spec on your elements, that's another test, however, nice to compare against the resistance when they were brand new... The suggestion to check that all elements are glowing the same, that's easy.

The sound*, hrrmm, try turning off the kiln vent for a short while.
For one, would make the sound easier to hear, and two, to me sounds like somewhat bouncing about in the fan cage.

*looks like this is the post; there is audio: Failing Cress kiln relay? I have been having issues with my kiln not reaching cone 5 or 6 recently and assumed that my elements are getting old. (Contd in comments) : Ceramics (reddit.com)

 

[PeterH]

Suggest you post a picture of the label with kiln model number etc for the experts.

PS If you haven't found it already this may be helpful  https://www.cressmfg.com/resources/  especially
Kilns - Instructions Manuals (and parts replacement guides)
Kilns Diagrams
Kiln Price Lists (both kilns & kiln parts)

Looks like a Firemate controller, which does have relays (and infinite controllers switches, it's an ingenious design).

PPS Can you guesstimate how many firings you've had? Do you regularly fire to near your kilns maximum temperature?

 

Edited May 17, 2022 by PeterH

[neilestrick]

Are you talking about that little static noise near the end of the video as it switches? To me that sounds like an infinite switch that's not switching very smoothly, or it could just be the relay and switch going slightly out of sync. You should check the resistance of your elements, because if it's getting to cone 4/5 but not 6 then it's most likely due to them being worn. It could also be because of the switch not cycling properly or  a relay sticking,  but I'd start with the elements.

[STONEWARECAFE]

hi,am having trouble with a used Cress kiln and received a great diagram of the thumbwheel drive from PeterH.you can find it under the  ques "Trouble shooting Cress kilns" ... it turns out there is an infinite  switch connected to  the bottom of the drive and like neilstrick just said that could be acting funny. I am trying to trace down the problem in my Cress but am dealing with 2 infinite switches and 2 relays plus the thumbwheel  so there could be a relay in there being controlled by the thumbwheel drive. It is very easy to remove the controller box from the kiln and take a picture of whats going on inside your box to get a better idea of whats going on.Just unplug it before doing anything else.

[PeterH]

@STONEWARECAFE I haven't sat down with the diagram for your FTX28 UP with coloured pens to clarify the connections, but my initial impression is that:

1) The shaft of the lower infinite switch is shared by the thumbwheel and the motor.

2) The lower infinite switch directly controls both relays (one for the top element, the other for the rest).

3) The top infinite switch is used to control the speed of the motor, so it steadily ramps up the temperature by turning the  shaft of the lower infinite switch.

PS Kiln diagram for your FX28UP  FTX28
OP still hasn't given their kiln number (or pix of label), but the details will be in the Kiln Diagrams section of https://www.cressmfg.com/resources/

[neilestrick]

These kilns are the most complicated systems ever put on a pottery kiln. It's a smart design in that it automates the firing without a digital controller, but diagnosis can be very difficult, especially if you are not handy with a meter.

[High Bridge Pottery]

I can hear a rattle in between the clicks but hard to tell what it is. I have certainly had kiln elements hum and rattle until they warm up a bit then the rattle goes.

The second click sound a bit like it's either not connecting/unconnecting properly and the contact is bouncing but it could just be two different clicks. Don't see why any of that would change the top temperature you could hit.

[PeterH]

22 hours ago, neilestrick said:

These kilns are the most complicated systems ever put on a pottery kiln. It's a smart design in that it automates the firing without a digital controller, but diagnosis can be very difficult, especially if you are not handy with a meter.

Assuming that the OP has already checked that all the elements get hot (glow, burned test papers, etc) ...

Most of the smarts seem to be in the automatically controlled ramp-up, would a manual firing of the empty kiln with the thumbwheel full-on provide any useful information?

PS A  full-on infinite switch may well be on all the time so perhaps there wouldn't even be any relay switching.

[Callie Beller Diesel]

I have a larger Cress model with the same thumbwheel/rheostat setup, and I had to go through mine with a fine tooth comb last year because I did something dumb and melted down a kiln load of work. 

I know it wasn’t a satisfactory answer you got from Arturo, but I don’t think it was wrong, just very incomplete. The recording you made sounds pretty healthy to me too. I’ll tell you what I hear. 

Even with headphones on and the volume cranked, I mostly* only hear your kiln vent fan/background air movement between the 2 loud relay snaps in that video. Those snaps both sound pretty normal to me. There are 2 relays in that setup, and like has already been mentioned, the second snap sounds like the two are a hair off sync, but I don’t think that’s a concern. 

*I did say mostly.  There’s a very faint, almost crickety sound that I can only pick up on headphones, and it’s otherwise covered by fan noise. I had to go outside and turn on my kiln and listen to it for a bit to confirm it, but that’s the servo motor/gear box that turns your kiln up. Yours is a hair louder than mine (I’d need a more sensitive mic than I own to make a recording), but they’re running at the same frequency and yours doesn’t seem irregular in any way. It doesn’t sound unhealthy to me. Mine is about a year old now, so I’m confident it’s in good shape. I suspect yours is more audible because it’s more worn in. I was told last year that I probably didn’t need to replace mine at all, and I suspect that was correct, but I did it out of an abundance of caution anyways, as I was ordering parts from the US and only wanted to pay shipping once. It’s apparently  the part of the assembly least likely to fail. It’s a sealed unit, so unless it cracks somehow and gets dust in it, they’re pretty ironclad.

If the servo motor was going, it would affect how fast the % output of your elements got turned up. Even though the motor is mounted on the thumbwheel, it’s powered by the infinite switch. I did manage to trace the Gordian knot they call a  wiring diagram that far.

When you say your kiln didn’t reach temperature, what exactly happened? Did the kiln stall for several hours without the cone dropping in the sitter,  or did the timer run out? Was the thumbwheel not progressing past a certain point, or did it top out at ten and the kiln still wasn’t hot enough?

 

[STONEWARECAFE]

Thank you PeterH I did not know that the fire mate switch controlled the speed of the thumb wheel drive which in turn controls the two relays that I have at the bottom of the panel, incidentally I did get to diagrams from Arturo at Cress but these diagrams for an ftx28 show a relay at the top and a relay at the bottom, unfortunately my ftx28 kiln has two relays at the very bottom. I will be going through their schematics to see if I can find mine. Thanks again for the info it really helps

On 5/20/2022 at 2:56 AM, PeterH said:

@STONEWARECAFE I haven't sat down with the diagram for your FTX28 UP with coloured pens to clarify the connections, but my initial impression is that:

1) The shaft of the lower infinite switch is shared by the thumbwheel and the motor.

2) The lower infinite switch directly controls both relays (one for the top element, the other for the rest).

3) The top infinite switch is used to control the speed of the motor, so it steadily ramps up the temperature by turning the  shaft of the lower infinite switch.

PS Kiln diagram for your FX28UP  FTX28
OP still hasn't given their kiln number (or pix of label), but the details will be in the Kiln Diagrams section of https://www.cressmfg.com/resources/

 

[PeterH]

11 hours ago, STONEWARECAFE said:

I did get to diagrams from Arturo at Cress but these diagrams for an ftx28 show a relay at the top and a relay at the bottom, unfortunately my ftx28 kiln has two relays at the very bottom. I will be going through their schematics to see if I can find mine.

First, excuse me if I'm trying teaching you how to suck eggs.

The positions of things on the schematics is essentially arbitrary, all it guarantees to do is get the connections between the components right. Components can be, and are, shuffled around the schematic to hightlights connections, minimise white-space and fit the page. As a lesser priority components are sometimes labelled  or positioned on the schematic to reflect their interconnectivity or geometric relationships. 

When I talked about the "top" and "lower" infinite switched it was based on my limited knowledge of the physical layout of the control panel, not their positions on the schematic. (Although they happen to be in those positions on the schematic.)

On the other hand when I said  "top element" I assumed that the label "top element" on the schematic related to its geometric position on the kiln.

Looking at the schematic the labelling of the top/upper-middle/lower-middle/bottom elements reflects their geometric position in the kiln. Their positioning from to to bottom  of the schematic is presumably aimed to make the schematic more intelligible.

IMHO the positioning of the relay feeding the "top element" on the the schematic is to clarify the connections on the schematic, not to define the geometric position of that relay.

Which is a long-winded way of saying I think you have already got the right schematic. (Just confirm that the connectivity of the  relay feeding the top element conforms to that shown by the schematic.)

[STONEWARECAFE]

Sorry grew up under an electromechanical engineer who specialized in cooling systems, anyone who ever sent a schematic like this to the production floor would be in a lot of trouble. An engineer who has drawn parts incorrectly so you are unable to actually put the pin and the connector together on a production floor for example. You send down an accurate schematic and or blueprint in order to ensure people are assembling something in the right space. I've read plenty of these schematics and they usually pretty accurately reflect what you have in front of you when you're working on a kiln. In regards to White space being wasted what's really being wasted is someone's time having to redraw the plans, in addition and most especially if you would look at the numbers on the relays you would have seen two different relays. Now that is why I said I need to look for other schematics because my kiln has two p&b t92 p11 relays and this schematic clearly shows two different relays. So when I look at a schematic like this and then I look at the reality of my kiln and how it is actually built what I see is somebody cutting costs because they got a good deal on one relay and they can interchange it in addition they're also cutting extra costs by reducing the run of the wiring. These things are always redrawn for a final schematic and the extra white space is usually left there so they can annotate additional information in the schematic so they don't have to redraw it. An engineer has to account for heat exchange between components, resistance values in the wiring since they go with the lightest and therefore least expensive wiring for the job, there are a number of factors that require an accurate reflection of what's going into a control box or building any mechanism. Most of the time these things are found on the production floor, they're sent back up for reevaluation and a new schematic is drawn. Later on a component's purchaser gets a good deal on a component that can be interchanged with something else and the schematic is yet again adjusted for it. But there will always be a final schematic. This isn't a final  even though it may provide the essential information necessary. What really bothered me was finding two different relays now I had to go and look up both relays to find out why they're interchangeable Because when I go into the cress parts replacement catalog they're only offering one relay for this model. So when I start with a schematic that shows me something completely different it sure is adding to my workload and it has not been my experience in any production system that's schematics handed down do not reflect information that isn't expected to be followed. People treat schematics like blueprints all the time because they're not paid to figure out the finer details of why something goes where when they're only required to build the mechanism.

 

[STONEWARECAFE]

Oh and also I do agree with you this is the drawing of my kiln.

[Hulk]

The kiln in question had never been worked on - is in original condition?

[PeterH]

1 hour ago, STONEWARECAFE said:

Oh and also I do agree with you this is the drawing of my kiln.

Different cultures, different practices. It can be very confusing at times.

[STONEWARECAFE]

1 hour ago, Hulk said:

The kiln in question had never been worked on - is in original condition?

Hi, it is in original condition, I inspected the Dawson kiln center tube and found considerable erosion on the cone rod that drops. But when I inspected the coils I could see that somebody had installed brand new coils. Also when I bought it the control panel had been removed and nobody had ever screwed it back on it was taped with duct tape haha. When I untaped it to inspect the wiring I found one loose wire I also found where it needed to go back onto the relay but at that point I suspected that I needed to go through all the circuitry to make certain somebody hadn't screwed around with it. What I think happened was their kiln stopped working then they went out and bought new elements, then when it didn't work they realized that there was something in the control panel that was wrong. So they pulled it off and probably became overwhelmed at what they were dealing with, taped it up until they could get a better understanding and then just gave up on the kiln. I just want to go through the circuitry to make certain they didn't mess up the wiring and what I suspect is that the primary relay failed but they didn't know how to test it, or simply replace both relays. Now that may not be the problem, but seeing how much use the kiln got I'm going to go with the relays.

[STONEWARECAFE]

Anyway, I'm willing to go through it for the $200 that I paid for it. I've been waiting on replacement coils for my Skutt 1027 and I can't really afford to wait much longer. I hadn't realized there was still a supply delay and getting coils so this was worth it. Besides I got a $5,000 kiln for 200 bucks not bad. Just a little work

[neilestrick]

I wouldn't be at all surprised if someone changed out the relays at some point and used different but equivalent models. I do that every time I work on a kiln. I'm not about to stock 8 different brands/models of relays when I can stock 1 that is equivalent to all the others. Plus, part numbers change over time, and the relay or switch that was originally put on a kiln 30 years ago probably doesn't exist under the same part number today. And with the internet it's easy to find replacement parts that are less expensive than the originals or than getting them from the kiln manufacturer. And some kiln companies use their own part numbers on the wiring diagram, not the manufacturer's model number. So I generally just look for the same specs and ignore the part number.

[Bill Kielb]

6 hours ago, STONEWARECAFE said:

Sorry grew up under an electromechanical engineer who specialized in cooling systems, anyone who ever sent a schematic like this to the production floor would be in a lot of trouble.

Don’t ever troubleshoot a Trane rooftop unit from the 80’s! All white wire, no color coding. LOL Your schematic is a bit ugly but with some colored highlight markers and diligence you will figure it out. Neil is spot on for generic items like relays: voltage, load and form are important. Many of the original part numbers have changed or been changed to a different manufacture. While you are going through It though I would suggest measuring the element resistance, recording and comparing to new. When they have risen by about 10% in value it’s time for replacement. Just a suggestion while you have it all apart, often it’s really hard to tell visually just how much they are worn.

[STONEWARECAFE]

15 hours ago, Bill Kielb said:

Don’t ever troubleshoot a Trane rooftop unit from the 80’s! All white wire, no color coding. LOL Your schematic is a bit ugly but with some colored highlight markers and diligence you will figure it out. Neil is spot on for generic items like relays: voltage, load and form are important. Many of the original part numbers have changed or been changed to a different manufacture. While you are going through It though I would suggest measuring the element resistance, recording and comparing to new. When they have risen by about 10% in value it’s time for replacement. Just a suggestion while you have it all apart, often it’s really hard to tell visually just how much they are worn.

Yeah I've run into those systems too, so I've already begun the color coding on the wiring and about the elements, somebody replaced those a long time ago. Long enough for the coils to have become discolored over time but they are still smooth. I think they replaced them and when that didn't work they got overwhelmed. But yes I will be checking the the coils just to see what the resistance is. Thanks for reminding me I had gotten involved with all the other stuff.

[STONEWARECAFE]

17 hours ago, neilestrick said:

I wouldn't be at all surprised if someone changed out the relays at some point and used different but equivalent models. I do that every time I work on a kiln. I'm not about to stock 8 different brands/models of relays when I can stock 1 that is equivalent to all the others. Plus, part numbers change over time, and the relay or switch that was originally put on a kiln 30 years ago probably doesn't exist under the same part number today. And with the internet it's easy to find replacement parts that are less expensive than the originals or than getting them from the kiln manufacturer. And some kiln companies use their own part numbers on the wiring diagram, not the manufacturer's model number. So I generally just look for the same specs and ignore the part number.

Luckily I don't believe anyone changed out anything I don't think they had any idea what to do. But I am having to relearn all this because I usually just change elements, I don't have to do anything else. And I do change the relays out as well they don't cost very much compared to elements. And yeah you're right manufacturers often use their own part numbers, that always makes me laugh because when I get the part I now know what it is. Luckily I was able to find those parts on the internet and like you said a much more reasonable price than the manufacturer.