I just wanted to share my experience building a 5-gallon TLUD charcoal cooker. I have gotten most of my info from this site, but I did not see a dedicated build thread anywhere, so I decided to start one of my own and share my experience with all of you.
1 or 2 - 5 gallon steel buckets (I use one for the cooker and one to hold the finished charcoal while it cools) -- free from scrap yard
2 Steel lids for buckets (remove the rubber seal before use!) -- Also free from scrap yard
1 8 steel ducting starter -- about $3.50
1 8 to 6 steel ducting reducer -- about $7.25
1 6 by 24 steel ducting pipe -- about $3.50
6 - #6 x 3/8 hex head sheet metal screws -- about $0.89 for 15
1 Big bag of cedar bedding chips -- about $7.50
3/8" and 1/8" drill bits
The first thing I needed to figure out was how many holes, and of what size to drill in the bottom of the bucket, and in the angled portion of the reducer. I would like to thank Dagabu for that info. He suggested 5% of the buckets area for primary air holes (bottom of bucket) and 5% for secondary air holes (in the reducer). The bucket has a diameter of 11" so using (pi*r2)*.05 I came up with 4.75 square inches. A 3/8" diameter circle has an area of .110 square inches. 4.75/.110 = 43.18 3/8" holes, so I decided to start with 40 3/8" holes more or less evenly spaced for the primary intake (much easier adding holes then removing them) and 42 for the secondary intake (just kind of worked out easier that way).
Once I had all the holes drilled, I took the starter ring and centered it on the lid. I traced the outline with a sharpie, dilled a hole just inside the line, and finished cutting out the circle with a pair of tin snips. The starter ring slid inside the hole, making sure to hold it tight to the lid, I folded over the tabs thereby securing it in place. I then fit the reducer over the starter ring, drilled three evenly spaced 1/8" holes through the reducer and the starter ring, and screwed it together using the sheet metal screws. Next, I inserted the pipe into the reducer and secured it with screws the same way as I secured the reducer to the starter ring. That is about it for the construction. It was a fairly easy build, taking about an hour (and a couple beers).
Now comes the fun part (Playing with fire!):
Once again using the advice of the more experienced members on here regarding wood selection, I decided to try using red cedar bedding chips. I found a big bag (expands to 5 cubic feet when uncompressed) at a local farm supply store, I heard good things about the charcoal from red cedar so I grabbed a bag to see how it worked. For the first run, I just dumped in the chips, leveled them out, put the lid/chimney on, and lit it up. Ignition using these chips could not be easier (a good size chip lit and dropped down the chimney) and it was roaring away in seconds. About 30 seconds into the burn it started making a howling sound (pretty cool actually) and was shooting flames about three feet out of the top of the chimney pipe. After about 5 minutes, the sound and flames died down, and I could tell the burn was coming to an end (the masking tape down the side of the bucket works great for this as well). I popped the lid/chimney off and quickly dumped all the hot coals into the other bucket, and secured the lid tightly. You can also use the same bucket you burned in, replacing the lid/chimney with a solid lid and placing the bucket in some loose dirt or sand to seal up the bottom holes. Basically, you just need to seal the coals off any oxygen otherwise; they will quickly burn to ash. After cooling for about an hour (probably longer then needed) I opened the bucket and had about 25% by volume of nice black charcoal chips that crushed to dust in my hand. For the next burn I wanted to see what would change if I packed the chips down tighter before burning them. I filled the bucket about half way with chips, then using my hands I very firmly compacted the chips into the bucket ( decreasing volume by almost half) I continued in this manner until the bucket was full to about 1 from the top. Ignition was just as easy this time, but I could tell right away that the burn was much less energetic. I had no howling sound and no flames coming out of the chimney, it also took much longer to burn down this time (maybe 30 minutes). After the burn was done and the chips had cooled, I was left with almost ¾ of a bucket of charcoal chips. Some of the chips from the bottom corners were not fully burned (I could have let the burn continue for another minute or two before sealing) but they should be easy enough to screen out later. I am still playing with the ideal compaction for good yield, but so far, it has been working far better than I expected for a first try.
I am very happy with this method of making charcoal so far. I have to admit I've never made charcoal before by any method so I cant say if this is better then other methods or not. I was planning on making a retort, until I saw some info on TLUD's. I really like not needing extra wood for the process, and the almost complete lack of smoke during the burn (I am sure my neighbors do as well). The parts were cheap, the wood chips are cheap, and the build was easy. It is also a lot of fun seeing it burn and working so well.
If anyone has questions or comments about my build please feel free to respond. I am glad I got a chance to share something of mine on here, after getting so much knowledge on here from all you folks I hope that this might help someone else wanting to get started making charcoal.
Edited by chuckufarley, 10 April 2016 - 09:03 PM.