Dry kiln for jarred tobacco.

[ShiniKoroshi]

Started a kiln build this weekend. But before I get into that I want to mention something I have yet to see among the kiln discussions concerning runaway kilns.

Every kiln should have this simple and cheap component, a thermal fuse. It is designed as a safety cut-off and is found in just about every household heated device from coffee makers to cloths dryers. You can buy them from specialty stores and Amazon for less than a buck a piece. They do not reset and must be replaced once blown which is totally the point. Also, a current fuse that is slightly above the total draw of the kiln is a good idea but the thermal fuse is a must!

I will likely start with a fuse that will open the circuit between 138°-142°F. Many other temperature ranges are available.


Outside dimensions are 18" x 22" x 30". I didn't use foam because I don't like it and I want to see if its even necessary in a warm climate like Florida. So, the walls are two sheets of 5/8" plywood and the inner box is sealed.

Im building the shelves to hold a total of 24 pint jars which will comfortably hold 8 pounds of lamina, 12 if stuffing the jars full.



More on this later.

 

[ShiniKoroshi]

Shelves are built and temporarily installed to verify measurements and make changes. I could add another shelf if I turned them into drawers but Ill pass on that for now since this build is more or less a prototype to test some ideas.

Next up is ordering the electrical components. Once those are here Ill make the false bottom which will serve as a return duct to the fan. Behind the shelves will be a false wall to direct heated air to the top. Im also planning an access panel in the back to service the fan/heat source without removing everything from the front.

The orientation of the jars serves several purposes, a) maximize space, b) even airflow/heat distribution and c) to allow the unit to be carelessly moved without the jars trading places.

 

[ShiniKoroshi]

Parts came in and Ive finished the wiring on the inside. I put the thermal fuse on the hot lead coming in before it runs to the fan which will be on whenever the kiln is plugged in. Between the power in and the fan I have tapped the line for power to the controller. Then we have a line from the controller to the lights which are wired parallel. If the 60W bulbs burn too hot Ill rewire the lights in series. The bulbs are supposed to be especially "soft"; they were a gift from the American Porphyria Foundation and I got a whole case of them. Didn't help me then but they sure are handy now.

The fan is a typical 120v 30W single-coil shaded-pole motor and should last a lifetime. Its an "upgraded" replacement draft fan for a BBQ smoker for like $18. Supposed to endure more heat than the original though I doubt it will be a concern for this kiln.

The porcelain light sockets are mounted to the multi-function block. Besides a mount for lights, a housing for the thermal fuse (left hole) and a wire loom its also serves to disrupt the airflow for better mixing and distribution. Below that are heat shields where the bulb is close to the wood. Its .002" brass shim stock with the ends rolled over a popsicle stick and stapled in place. This allows for a 1/16" gap between the shield and wood. There will be another pair of these shields on the partition that will be between the fan and the 3/4" vent holes seen below.


The controller is a STC-1000 (120v input/output) knockoff for $7 with NTC sensor. It works for temp only with separate relays for heating and cooling. Rated for 10A which is plenty. Reading is in Celsius only. Ill build a little console and mount this up tomorrow. Then its a matter of routing the sensor, installing the partition and shelves. After that its the seal and latches for the door.

 

[ShiniKoroshi]

This project has been a lot easier than anticipated. Currently the kiln is on its first warm-up. Most everything was in-stock at Shini Studios. Out of pocket for the controller, bulb sockets, latches and thermal fuse was $43. The build is a little crude but this is a test of a lot of ideas.

 

[deluxestogie]

What sort of seal or gasket are you using at the door closure?

Bob

 

[ShiniKoroshi]

What sort of seal or gasket are you using at the door closure?

Bob

EPDM foam rubber with a hollow "D" shape cross section. Its labeled as "marine & auto" and will stay flexible up to 140°F.

 

[deluxestogie]

Added to our Index of Key Forum Threads.

Bob

 

[ShiniKoroshi]

The 60W bulbs were not hot enough, kiln topped out at 43.6°C. All I could find locally were 100W and 150W reptile heat bulbs (incandescent) so I switched them out with the 100W about 30 min ago and we are already at 53°C. Simplified the front and nixed the access panel but it only took a couple minutes to change the bulbs. While I had it apart I added another block to choke the air coming straight up through the center so more air will flow past the bulbs.


Here is the arrangement in the kiln with the floor and back partition installed.


The sensor dangles under the top shelf.

 

[ShiniKoroshi]

Added to our Index of Key Forum Threads.

Bob

Thank you Bob!

Ill do my best to continue adding details and improvements.

 

[deluxestogie]

If it's not too difficult, you might want to briefly place the temp sensor down at the wood closest to the heat bulbs. It may be fine, given the forced air.

Bob

 

[ShiniKoroshi]

If it's not too difficult, you might want to briefly place the temp sensor down at the wood closest to the heat bulbs. It may be fine, given the forced air.

Bob

I may just try that, thanks for the suggestion. I had noticed that temp would drop by a tenth about two seconds after the lights cycle off. But, the wood temp has stabilized with an external temperature of 92-94°F and the lights cycle on about half the time. Maybe Ill cover the outside with shag carpet like those custom vans of the 70's & 80's. For now though I just loaded the kiln with leaf, blends and cakes and we'll check back in a week.

The fan does move a lot of air. That was another reason I added another block to divert airflow and slow it down a bit.

One nice thing I didn't know until now is that when set properly the controller retains the settings after power loss. Regarding bargain controllers, its worth removing the board and inspecting the components and solder. Spent about an hour cleaning excess flux and resoldring the connections. Its just a matter of poor quality control during this process as the lead-free solder is total garbage. These cold/dirty connections are a point of sure failure in time.

 

[ShiniKoroshi]

Most of the heat loss is around the heat box above the bulbs and the entire top. Put one layer of corrugated cardboard in these spots and now the lights-on time is 30%. When the lights are switched off it will hold 53°C for four seconds. Im wondering if the cardboard would work as well sandwiched between the layers of plywood. Also, can I slip the cardboard in without turning the machine off?

Its going to be a long month.

 

[ShiniKoroshi]

If it's not too difficult, you might want to briefly place the temp sensor down at the wood closest to the heat bulbs. It may be fine, given the forced air.

Bob

I checked temperature in various spots with a IR temperature gun and verified that with a candy thermometer which was verified for accuracy in boiling water. At the partition in the back and on the other side of the bulbs I get 124-126°F (there are heat shields on the partition). Highest temp recorded was in the top shelf near the door at 129°F, the lowest was in the bottom shelf near the partition at 123°F. Temperature was higher in each shelf near the door which leads me to believe airflow is concentrated nearer the door. I suspect that my leaving the front of the false floor open is the cause or at least where I should restrict airflow.

90's vintage technology.

 

[ShiniKoroshi]

Ive made more precise temperature measurements over the past couple days using the candy thermometer (glass type) and letting the kiln temperature stabilize for a couple of hours (with thermometer in place) before taking the next reading. There is more uniformity than previously thought with all measurements falling between 129°-131°F (53.8°-55°C). So I adjusted the controller calibration 3.6°F (2°C) and now we are holding between 127°-129°F (52.7°-53.8°C ). I should let the kiln stabilize over 24 hours and recheck the temperature in a couple places.

I concede to the styrofoam and will reskin this kiln after I have kilned my current stash plus some that Ill order soon. Meanwhile Ive already laid out the design of another kiln, much smaller though it will hold 12 pint jars. Its really a plug-n-play deal with off-the-shelf items that will cost less than $100.

 

[ShiniKoroshi]

Jay found a new warm place to perch (notice the smug face).

 

[ShiniKoroshi]

While this thing does its thing Ill drop some links regarding a much smaller/simpler kiln. We'll call it the "Mini-Cooler Kiln" and make it an open project. Anyone is welcome to make/improve this, even before I do. Because the idea behind this is to propagate the practice of kilning for the RYO consumer making their experience much more enjoyable without waiting years for a tobacco to settle down. Target cost is a $100 Easy-DIY build.

This will be a dry kiln so the usual "Ball" pint jars (wide mouth) will be the center of the kiln. Any jar size can be used, next post explains why.

The pint jars are 3.5in (89mm) in diameter at its widest point and 5.0in (127mm) in height.


The footprint of 9 jars is 11.0in x11.0in (279mm x 279mm), height is unchanged at 5.0in (127mm) unless we double by stacking (18 jars) for a height of 10.0in (254mm).
This gives us the minimum inside dimensions of our cooler.

 

[ShiniKoroshi]

Shipping coolers are available in a wide range of sizes and wall thickness. While there are many companies that manufacture shipping and scientific coolers Ill post the page of one that is easy to look at. Once you select the brand and model of your choice you'll have to find a retailer. Ill share links as I find them.

https://www.polar-tech.com/shop/cat...sulated-containers-and-shippers-food/filter:/


Near the top of this screenshot Ive marked two with the same inside dimensions, which have plenty of room for 18 pint jars, and a wall thickness of 2.0in (51mm). These may be big enough to do the taller quart jars for Cigar leaf. As you can see though there are plenty of combinations possible and even smaller 4 jar kilns. You will understand why I chose 9 in the next post. Prices Ive found so far are between $25-$50.

 

[ShiniKoroshi]

I suppose the proper term is mason jar. Anyhow, I was thinking about the need for a taller jar for dry kilning cigars. Low and behold they do make pint and a half (24oz) jars.

 

[johnny108]

 

[ShiniKoroshi]

This is a mock-up to illustrate the arrangement of the jars and the space we need in the center for our heater/fan.

9 jar square with the center jar removed.


Double stack with center jars removed.


The double stack arrangement in a milk crate. Inside dimensions are 12.0in x 12.0in x 10.5in (305mm x 305mm x 267mm), just an inch shorter than our cooler.


The arrangement using a single stack of quart jars.


In the center there will be a metal canister, likely made from 4 inch dryer duct or stove pipe tube. This tube will connect to a raised floor of perforated or expanded metal sheet. This will allow air to flow under and around the jars.