Bill Kielb

The bracket on the left looks loose and a bit lower than the bracket on the right. It might be the picture but Neil might have a comment like first level, next set lid flush, then tighten all screws ..... etc....

You know for all its faults it was a decent workhorse simple kiln actually. Lots of them out and about.

I’m not a pi guy - vba, apl, FORTRAN .......... PLC ....... lots of DDC, import error fails on non capitalized file name ? Maybe as simple as that.

No worries, you are aware of switch noise now and issues it can present. As to calibration, you will need to see if it affects it and by how much. If you are asking how would I have done it, probably installed k type connectors but your solution is likely fine.

The lid seems rotated from the body of the kiln. Maybe backup a bit and show the lid and kiln with more context from a few feet away.

Looks pretty perfect to me. To me if your glazes finish how you like, fast is fine. Slow is popular though.

Picture of it and what is it’s measured value. Most pots can be replaced with a little work.

It’s not skookum as they say but it likely will work. In other words you are not supposed to as standard practice for thermocouples. Alpine used to do it, I don’t believe they do anymore and even in the day flipping that switch often cause full scale deflection of the giant (very high quality) analog high limit / operate switch to trip momentarily. If you have two thermocouples and one input and this is not a make before break switch you may need to add a bleed resistor to each to avoid the open circuit spike. In the end for the Alpine gas kilns if it influenced the temp by a degree or even a few degrees it made little difference since these kilns were shut down by observing firing cones. Late in the firing used to be the rule, don’t touch that switch as we would operate as a high limit and if it spiked to set-point the kiln would drop offline. I mention because the spike may or may not affect your high limit or the switching noise may or may not affect your stuff ........ even later on as the switch wears it will generate more or less noise. Hard to know for sure until you try it, but easy to fix should you need to.

Generally works but does often have it’s issues and doubling on an input is a definite not allowed but I have seen many get away with it. You have other issues for sure to work through.

Solder in the screw terminal block, the cable probably won’t solder well anyway. This final junction will be fine.

Any temp difference can be an issue. The thermocouple itself will generate a very specific voltage at a temperature but couples formed by splices are always a concern and less predictable.. K type thermocouples depend on cold junction compensation for their accuracy so any additional couples in the line (even very small voltages) can be an issue. Even when we design with current loop or conditioning transmitters we like to keep the conditioner as thermally isolated as practical for accuracy reasons. The discrepancy is likely due to the wrong cable and the additional couple effect from the wrong cable. As the individual couples by the splice heat up, the ‘splice’ couples are less likely to be equal and opposite. So yes, your theory matches some of the known problems with mixing materials. As an interesting example, for kilns with a top and bottom thermocouple , I will mount both transmitters at the same height and in a cool location to avoid minor differences in the ambient temperature between the two transmitters.

I meant to add since it is still a switch it can only go as fast as a half cycle which you guessed it is .5 seconds. They are zero crossing as well so they always turn on at zero, rather than turn on at peak. Another cool longevity thing.

Looks like you bought all compatible components made to do what they should. 75 meters is a long way for millivolt signal so if your tcouple board is noisy, worst case convert it to current loop.

Fantastic! You should be able to drop the controller relay cycle time to SSR levels which ought to extend the life of the elements a bit more and smooth the control out as well. You may already know but Skutt actually has a design using the old 12v relays upstream of the SSRs instead of the monster contactor. Pretty cool economical idea I think.

Yuck! Send it back it’s for an RTD mine are all k type, never have seen that but maybe never took much notice. I have had some with stripped or seized screws though that were definitely not brass.

Yes, the screws are brass, SS, You name it. The block terminal is the correct metal per the marking in the block. Brass screws seize up less than most especially in chromel and alumel. I didn’t know you got an SSR control. How do you like it?

I would respectively disagree with this statement. Extension wire, holders and connectors are made of dissimilar metals side for side to minimize the unwanted couple issue. It does seem to be a common sentiment by many folks though but everyone also seems good with using the extension wire religiously, go figure. Anyway Proper holders are made the same way, one side one metal, the other side different. All these items are polarized for a reason to minimize adding new couples along the way. Anyway in practice, it likely will work; however Rasberry Pi’s have had noise issues with different tcouple boards, and pid controllers generally favor conversion to current loop for noise and transmission reasons. So I definitely would not suggest it. Actually shielded tcouple wire is a thing now since more electronic controllers are in use. In industry is this allowed, (the toggle switch, dissimilar metals) the simple answer is no, absolutely not. Can it work -yes it might. As far as accuracy, K type thermocouples although economical are impressive at .75% from 0 to a max of 1372 C - 2.2 degrees in over 1300C. Quite impressive actually in my view, not sure where they ever got a bad reputation.

This usually works but in thermocouple world is strictly not allowed as each connection becomes a couple because of the dissimilar metals. It all depends on the sensitivity of the equipment and of course the condition of the couples that form inside and outside the switch. In theory since at the same temperature they will be equal and offset. If your controller is sensitive, this might not work. A standard I type plug in might be just as easy and it is made for swapping. Just put male ends on the kiln tcouple and a female in your device that way everything is designed with tcouple matching metals. The manufacture will provide graphs and design criteria and you pick a heatsink size with that or greater capacity. A 50 amp SSR’s performance or effective limit decreases rapidly with temperature so designers like to oversize and keep as cool as practical and Max the load at maybe 30 amps. Convection is free and deependable. Not hard to do for yourself just follow the graphs and use realistic ambient temps. 80c Max can derate your SSR by 50% or more. Your prox. Cfm fan required can be approximated by sensible heat formula and Max makeup air temp. Your variable speed setup is a great start and should reveal very quickly if you do a continuous run for a reasonable time. I would set it at 35 - 40c though to start.

These both look well thought out. Some potential ideas for you Protecting SSRs Protection for SSRs (If you are interested in protecting) generally requires fast fuses which the manufacture will list the requirements for based on their design components. Cooling: When we design with SSRs we try and use passive cooling rather than a fan. To That end in the states I have always been able to fulfill the need economically and in a custom fashion at https://www.heatsinkusa.com/ I am sure there are plenty of other extruded aluminum sites around though. An interesting thing to watch on mating surfaces and thermal transfer is here: https://youtu.be/8MOTMq9g8Nk Interesting in that thermal paste is not all that good in reality and good surfaces are truly the best. Economical safety or Dp relay. Take a look at a skutt SSR schematic where they have integrated a simple 12v relay for safety / lid switch. It’s pretty economical approved idea.

We have had similar mystery things happen especially after red heat. Folks often don’t realize that infrared radiation is a thing. Had a sectional L&L as I recall but could have been any. A kiln that did not have continuous sheet steel wrapping each section, it left a brick on brick interface between the sections. I remember seeing a red glow between the sections to which I really didn’t give it a bunch of thought at the time, pretty small light leak. Until the molded plug for the kiln began burning up. Turns out that neat red infrared stripe went right across the back of that plug and over time the plug overheated and began failing. Ordered a new cord end and in the meanwhile stuck some foil tape on the plug to reduce its temp by 30 -50 degrees or more until the new one arrived days later. Just a small innocent red stripe!

Full or two half shelf’s protecting the bottom, always at least half inch off the floor, more like 1”. Staggered stacking as practical as after red heat there is really not much convection happening and even if there was the air is so thin it does not hold any real heat and to prove it to yourself pull a peep and feel the blast of hot air leaving. Oh, you won’t actually because the atmosphere is so thin. So the staggered stacking is created with an eye to make the wares able to “see” as many elements as practical for even heating. Sort of like standing in the sun or under a shade tree. And to add, the first layer is rarely staggered unless I have something very tall and I really have never experienced difficulties. Congratulations on the new kiln, you have done this for so long my guess is you will figure cool ideas to try.

Cute! Battery or corded?

Looks to be in great shape actually. Since you are resigned to elements and a controller And are ok with the size I think it’s worth the drive.

In a pinch a solo cup works fine, just punch a hole in the bottom of the solo cup first.

I love the idea of a tapered tool but Bill Van Gilder's is sold out. Can you give me some examples of plastic containers you use? Any tapered cup. A previous bisqued cup or bowl or vase. A word of caution if you use a smooth round object it can get trapped by suction so careful how hard you push on this and make sure you can release it.