Lose The Sitter Your Opinion Counts

[ronfire]

I have a Skutt 1027 in good condition with a sitter. I am thinking of upgrading to a Genesis controller an have a few questions. I think I know the route I will go but would like your opinions, you might have better ideas.

 Set it up for Zone control or do the easy route and wall mount a controller? Cost is about $50 difference.

Use the pyrometer protection tubes?

Does the control panel require a power switch from the transformer? Definitely a fuse before the controller but what size?

Should the controller and relays be mounted on a box attached or place it where the sitter was? 

Should I ad some insulation between the controller and the kiln.

I plan to add a port/plug for output 4 and have a relay to run the vent fan. Will build the relay into a small box that can be directly plugged into the wall with an outlet for the vent. This setup will allow the vent to run from its own power source instead of the power from the kiln.

 

 

 

 

 

[Foxden]

There are lots of options. I have a wall mounted controller that the kiln in turn plugs into. It plugs into the 60"amp circuit installed for,my kiln.

 

I only have one zone which has served me fine for my 7 cu ft kiln. I like having the kiln sitter as a back up. I keep a higher number cone (04 for an 06 firing for example) in it to prevent an over fire if the controller relay fails closed.

 

Mounting away from the kiln keeps your controller cooler and likely leads to a longer life of its components. A protection tube for the thermocouple is wise as well.

 

I believe some external controllers can be wired for multi zones, but I have not had experience with those aftermarket devices. A three zone system will have more even firing top to bottom if that is critical for you.

[neilestrick]

Go ahead and do zone control. It's not much more money and very worth it. Don't try to put everything in the sitter box. Use a vented external box so everything stays cool. I think the easiest way to do it would be to put a box on the wall and run jumper cords to the box, like an L&L DaVinci. The cords can be hard wired at each end. For the control box connection put in a terminal strip so it's easy to unhook them when you need to do maintenance.

 

Use SEOOW type cords from McMaster, and put heat resistant sleeving on the wires at the kiln hookup. You can get that at McMaster, too. Get the abrasion resistant stuff or some sort of coated sleeving. All the other stuff frays really badly.

 

Use cable clamps at all penetrations.

 

The thermocouple wires can all be external.

 

Use a 1/2 amp fuse for the control panel.

 

No need to put a switch between the transformer and controller, but it's nice (and cheap).

 

Ground everything!

[Dick White]

Ron, I am in the midst of doing just this with my old L&L J230 manual kiln - ordered the Genesis a week ago but it hasn't arrived yet. I have done a fair amount of basic electrical work (both high voltage and low voltage), some metalworking, and repaired a number of kilns (both manual and with controllers), so the project is not so daunting to me.  Some thoughts, not in any particular order or priority, just what comes out of my head as I type:

 

You can get external hang-on-the-wall controllers, such as Fox mentions above, and as I currently use. These require the addition of a single thermocouple, and the main power plug of the kiln is plugged into it rather than into the wall outlet. You put a cone in the sitter, turn the kiln switches on high, and the controller uses the thermocouple to sense when to turn the whole kiln on and off (essentially unplugging and replugging it electronically) to achieve the programmed heat. If the device has a Bartlett controller (vs. an Orton controller), you could probably order it with the new Genesis board as the physical size, mounting, and wiring is similar to the older Bartlett boards. It is theoretically possible, as Fox suggests, to use one of these in a zone control situation, but unlikely. For zone control, you would need 3 thermocouples, one in each ring, and a means to control power to each ring separately. That would mean 3 25A relays instead of the single 60A relay in the typical external controller, and appropriate power wiring from the controller to each ring. That's a lot to expect from a generalized after-market device.

 

You can get a similar device as a direct plug-through replacement for the kiln sitter. Remove the kiln sitter and tube, reconnect the main power wires to the back of the new controller, and put the attached thermocouple through the hole where the sitter tube was. Some are designed as a box-for-box substitution for a side-mounted sitter originally in its own grey box, while others are set up as a direct replacement for a flush-mounted  sitter. As Chef Tell used to say for each recipe on his cooking show (now I am dating myself) - very simple, very easy, very quick. But you still have a single zone. It is theoretically possible to have zone control as the controller supports it, but that would mean installing additional thermocouples, replacing the single relay with separate relays, and altering the power distribution to the individual rings. Not a deal breaker, but you would have work all that out yourself as it is probably not a factory option. Note that the Skutt standard factory controller is functionally similar to this, except they have worked out all the component mountings inside the red box, and they use separate relays for each section rather than a single relay. But, because it is configured as single zone (only one thermocouple), the controller clicks all three relays simultaneously.

 

Or you could go the route I am going. I am sourcing all the separate parts and fabricating my own metal box for it all. You might be able to avoid the sheet metal fabrication by altering the power box on your Skutt. The Bartlett board requires a larger rectangular opening than the Dawson sitter, so you will need to do some cutting. You will also need to figure out appropriate mountings (and buy the parts) for the other requirements - a 24V center tapped transformer, the 3 relays, the thermocouples and associated wiring, various power distribution terminals, and other miscellaneous switches, fuses, and wiring components (not all of which are available at your local LowesDespot).

 

The other consideration in using the existing red control box on your Skutt is ventilation. The kiln sitter is not heat sensitive like the controller board. The factory installed controllers have some insulation between it and the kiln, and usually more/bigger vent slots than in an older panel originally designed for a Dawson. You have covered that scenario with your output 4 fan control.

As for the thermocouple tubes, they provide some protection from the harsh corrosive atmosphere in the kiln so the thermocouples will last longer, but not forever. The thermocouples will still deteriorate just from the heat. The real advantage of a tube is that it will prevent all the spalled rusty  crap that comes off the thermocouple from sprinkling all over your beautiful glazed ware on the shelf below it. The downside is that it will introduce some lag in registering the temperature (i.e., it will be slightly hotter in the kiln than inside the protection tube where the thermocouple is), so you have to allow for that in programming your ramps.

 

Hope this helps, and ask if you have any more questions.

[Bob Coyle]

Leave the sitter. Digital controllers can fail, but gravity does not. Put a cone higher than you will reach in the sitter. It's there already, so why not have one more layer of fail safe.

[ronfire]

My biggest drawback for leaving in the sitter is then not having zone control. But at this point with a sitter there is no zone control and I do ok with the firing being maybe ½ to ¾ cone difference between the sections with the bottom being the coldest. The nice thing with zone control is you can pack all levels as tight as you want.

[Foxden]

Not necessarily. If you or someone knows what they are doing with regard to rewiring the kiln, the sitter can still be used cutting the one leg of the 240 shared between all three elements or zones. This would essentially shut the system down when the sitter trips. The controller will continue trying to heat if it's upper limit has not been reached, but with no power going to kiln any longer, the firing will register as a "fail to heat" or some similar error. In reality, however you will have reached cone temp according to the sitter. I use a 04 for cone 06 firings and it is more of a safety, shutting off if something goes wrong in programming or with a failed relay.

 

Also, if your sitter has a timer, that will serve as an additional backup. The timer, however, will only run when power is delivered to the elements so you must take that into account. Setting it at 6 hours will probably fire for maybe 10 or more until it shuts off. A few firings will give you an idea of where to set it.

[neilestrick]

Leave the sitter. Digital controllers can fail, but gravity does not. Put a cone higher than you will reach in the sitter. It's there already, so why not have one more layer of fail safe.

 

Sitters cause over-firing events far more than digital systems. I've seen it dozens of times. It's nice to have it as a backup, but not necessary.

[Foxden]

Neil is correct, kiln sitters can fail, too. Definitely kiln firings should be monitored. Luckily I have never experienced a failure with my kiln sitter, but know it can easily happen. Wrong cone, wear blocking the tripper, or some other freak accident. I have had relays fail in a closed position that the tripper shut off for me though. I will opt for a backup safety anytime.

[ronfire]

Might just have to look at that option as a backup and still use zone control. Should not be hard to wire it that way.

or could just use the timer portion of the sitter and remove the cone portion .

[Foxden]

Keep the cone, it is better and more accurate. The timer only will run during the moments the controller is actually on, not continuously as it did pre controller. That means setting your timer for 5 hours,for example, might actually fire for 10 hours or more.

[Dick White]

Ummm... well... not really... In my experience running a wall-mount controller on a manual kiln, I typically lost only about 20% time difference between the controller and the sitter timer. A 9-hour glaze firing per the controller would run down about 7 hours on the sitter clock. 

 

As for the accuracy of the cone sitter, that's largely a myth based on near-universal user ignorance perpetuated by supposedly knowledgeable experts who don't know what they are talking about. First, the sitter has to calibrated to spec (with the factory calibration disk in place, exactly 1/16" gap between the claw, no more no less, and the drop plate and exactly clearing the claw as it swings, no more no less) or it will drop too soon or late (i.e., underfire or overfire), and not many people even know what the calibration process is, much less actually calibrate their sitter. Second, the usual cone type used in a sitter is a triangular junior cone. These are notoriously inaccurate in a sitter. If using a properly calibrated sitter to achieve a specific outcome, the proper choice of cone type is a pyrometric bar, not a junior cone. Not only does the bar not require precise positioning on the cone supports, it is designed to correct for the slightly different heatwork flowing up and down the kiln sides around the shelf edges vs. the center of the shelf. However, most ceramic suppliers don't even carry the bars. "Everybody" uses the junior cones.

 

The only truly accurate cone is one in a cone pack (self-supporting or standard poked into wadding at the correct angle) on the shelf with the ware. The design intent of the kiln sitter is a safety shutoff with a cone one higher than the desired target; thus if it fires faster than expected or you are not able to constantly monitor the cones through the peep at the end and manually turn it off at exactly the right cone bend, it will nonetheless turn itself off before too much damage has been done.

[neilestrick]

Ditch the cones. Why go to all the trouble of putting in a zone control digital system if you still have to mess with cones? I've fired almost 2,000 times over the last 8 years without cones, and my work has not suffered. If the kiln doesn't get to temperature, having a cone in their ins't going to tell you anything. The controller will tell you how hot it actually got. Neither is going to prevent the problem. If it over-fires, the cone doesn't tell you anything, but will melt all over your sitter or your shelf, and won't prevent the problem. If you know your glazes, you'll know if the firing was a little cool or a little hot, and having the cone in there won't prevent the problem.

[Johnmicheal]

I see that an electro sitter with the right control board has a provision for multiple zones, but if I'm understanding your forum correctly, it's designed to only support one zone, and if you want multiple zone control you have to cobble together the relays, ect to run it in a multiple zone mode

[ronfire]

Instead of trying to modify an existing wall controller or sitter replacement it would be best to just build a whole system.

I have not started the project yet, hoping the CDN$ will get better, the exchange right now is a killer at more than a $ 1.30 .

Have not yet decided on a wall mount or add on box where the sitter was, am tending toward an add on box like the one below and add vents.

 

 

https://www.digikey.ca/product-detail/en/lmb-heeger-inc/MDC973-PLAIN/L127-ND/1725

[Dick White]

Johnmichael, you are on the right path in your understanding of the Olympic ElectroSitter and zone control. Let me try to clarify it for you. The ElectroSitter uses the same Bartlett control board as in numerous other kilns. The control board can be configured as either single zone or multizone. The number of zones is a function of the number of thermocouples together with an equal number of relays that can turn the elements on and off. In the ElectroSitter, there is only one thermcouple that pokes through the hole in the kiln where the old Dawson Kiln Sitter tube was removed. It has a single 60A relay that turns the whole kiln on and off as directed by the single thermocouple input. It accomplishes this almost as if repeatedly unplugging and plugging it. A more technically correct analogy would be as if you were standing there with the old kiln sitter constantly pushing in the white button when the thermocouple called for heat and then flipped the weight down to click off when the thermocouple says hot enough for now and then push the white button again for more heat. The original switches for the kiln sections remain in use, but are simply permanently left on High.

 

Moving forward to, e.g., a Skutt with the same controller and single zone (i.e., the whole kiln), there still is only one thermocouple, but since the control panel is integrated with the wiring box, there are now two or three 25A relays, one for each section and the controller turns them all on or off simultaneously. The only functional difference between this and the above ElectroSitter is that here each section has its own relay and associated wiring, so the power requirement of each relay is smaller than for the whole kiln.

 

Moving forward one more step to, e.g., an L&L with multiple zones, each section has its own thermocouple and relay, so the controller now can turn the sections on or off independently. But it is the same controller, you just change the settings in the configuration menu.

 

Going back to your question of adapting the ElectroSitter to multizone, I don't think that would be easy. First, depending on which model you are working with there might not be enough space in the box for the additional relays, and you would have to rework the whole wiring harness for the power distribution to the separate sections, plus install the additional thermocouples. I think if you are going to do all that, you should just go straight for the raw controller from Bartlett and build it from there. If you want to go whole hog, get the new Genesis touchscreen controller - it is really sweet, I love mine.

[Bob Coyle]

One thing I found out the hard way.... solid state relays ability to supply current ( amps) to the kiln drops off sharply after they get to about 50-60 F. Where ever you put them, make sure they are on good heat sinks and isolated from the radiant heat of the kiln...

[neilestrick]

One thing I found out the hard way.... solid state relays ability to supply current ( amps) to the kiln drops off sharply after they get to about 50-60 F. Where ever you put them, make sure they are on good heat sinks and isolated from the radiant heat of the kiln...

 

Another reason to use a wall mounted controller. But still use good heat sinks.

[ronfire]

Are the solid state relay much better or last longer given that they are kept cool.

[neilestrick]

Solid state relays will last longer, and can improve element life.

[Bob Coyle]

Addendum... I meant to say they drop off after they reach 50-60 C  I think that is about 120- 150 F and as Neil said, they have no moving parts or mechanical contacts, so they last a lot longer than the old bi metal duty cycle contacts.

[Johnmicheal]

Soooo, looking at solid state relays, do you have preference

[Bob Coyle]

I just buy them on Ebay. They are cheap enough that I over spec the relay by at least 50% or more.  For a 17 amp kiln I get a 45 amp relay. My bigger kiln at 38 amps  is running a 50 amp SSR with a heat sink and cooling fan, located remote from the kiln. Even then, you can feel pretty warm air blowing out of the enclosure.

 

Never paid much attention to the brand.