Building and Maintaining My First Flow Through Bin

[Ben]

I'd posted this on another forum in November when I began this journey, but for the sake of documenting my worm bin experience, I'm going to post it here and add updates now and then. For myself, the more I was able to read about other people's experiences with bin construction, worms and general maintenance, the better I got at building and assessing my own bins. Hopefully this will help others as well.

A little background first: I live in Portland, Oregon, and I've had a worm bin on and off for about 2 years. I started with a 14 gallon nested rubbermaid, moved to two when it couldn't keep up with our food scraps, and then added a Wormbin 360 a friend had stopped using. After two rather unsuccessful attempts at maintaining bins past the 4 month mark, I gave up for a short period of time. Most of my initial problems revolved around overfeeding, over-watering, temperature variations, and/or not leaving the poor critters alone. 

A little background on the location, which is important because after one horrible infestation of fruit flies, the worms have been exiled to the great outdoors. My wife is very understanding, even supportive, of my worm habit. But having to vacuum fruit flies from the living room on a daily basis, despite the fact that the worms were in the basement, isn't something either of us wants to deal with again. Yes you can maintain a bin so it doesn't have fruit flies, but it's easier if you can just keep it outside where flies don't really matter in the first place. After all, the flies aren't harmful to the bin, they just tend to be a nuisance. 

Temperatures in Portland run from 20-30 in the winter up to 95-100 in the summer. About 95% of the time in winter, it's 30-40° and rainy. About 95% of the summer, it's 50-65° during the night and 70-85 during the day. We have nice stable temperatures, but it's still too cold outside to have an un-insulated worm bin all the time. In light of that, I decided to go with Bentley's design for a VB24 and included foam insulation and a heating cable.

This is the story of my construction, and maintenance of the bin. I'll break it up into multiple posts as I rewrite it for this forum.

Just so you have a visual in your head as you read, this is what the completed bin looks like:

That's Bentley's pic by the way, I did not take it. Credit him appropriately if you use it I suppose! :)

The Build:

For the frame, I used some old Douglas Fir 2x4's I had left over from assembling sawhorses. It's a slightly heavier variant, but it's good wood and it holds up well. Seeing as I'm in the pacific northwest, I opted for a western red cedar outer shell since cedar is fairly prolific in this region and it has excellent anti-rot and anti-fungal properties. Additionally, it doesn't generally succumb to insects. (For a better idea of why I made this choice, check out this page. The other sustainable option that was open to me was juniper, but you shouldn't buy juniper boards in 1" thickness because they tend to splinter/break apart. Usually they're only sold in 2" thickness.

My goals for this bin were as follows, and the choice of cedar reflects some of them.
1: Outdoor Usage (Cedar is a good heat insulator, resists rot… and Portland gets 8+ months of rain most years.)
2: Usable down to to 20° (Insulated enough that a warming cable or other low energy heating element should keep it heated through winter.)
3: Low maintenance, high yield (Precisely what a flow through system should be.)
4: Low cost – as much as possible use old scrap wood and extra lumber I already have, no new tools, minimal investment.
5: Longevity – at least 5-8 year lifespan. (Treated cedar and doug fir with internal wood stabilizer from TimberPro, and stain it for UV protection and water shedding. Both of these are left over from previous projects. Painted the internal frame with low VOC latex outdoor paint left over from fixing up the house trim.)
6: Happy Worms! (I got tired of my wife referring to me as the worm killer, worm annihilator, and wormicidal maniac.)
7: Castings, of course!

The only "tools" I ended up using were a drill, hacksaw, carpenter's square, yardstick, pencil, safety glasses, ear plugs, a few wood clamps, and my trusty beat up, abused-but-still-kicking craigslisted miter saw.

If you have any questions, feel free to ask in the comments. Woodworking is a BRAND NEW hobby, so feel free to offer advice and criticism! I'm always looking to learn! Never had a family member who was very handy, so I'm picking everything up as I go.

The frame itself is fairly standard, and it produces roughly a 45 gallon enclosure, plus space for catchment/harvest trays and wheels. The bin could be modified in any variety of ways to make it more space efficient depending on your needs, but for me space wasn't a huge consideration since it's an outdoor bin and I was attempting to make it, if not aesthetically pleasing, at least unlikely to become an eyesore. This is what it looked like mid-construction, once the internal frame was painted and the outside had part of the shell attached. 

Making the top was an exercise in scrounging old bits of wood and putting them together. I had some extra cedar 2x2's that I made a nested frame out of: 

And then I used left over pieces of 6 foot 1"x4" and 1"x6" fence. At this point I was running out of fasteners, so I had a haphazard array of screws and nails.

I'd run out of longer pieces of 1"x6" cedar at this point, so the mitered frame ended up being made from 1/2 length pieces. I assembled it so that the back edge (Top edge in this pic) would fit flush against the back of the bin, in case I wanted to add hinges at a later date. A $2 grill was all that was needed to supply airflow, and I attached it with some tacks so I could remove it easily later if I wanted to put a bug-proof screen in there.

Because of the internal wood stabilizer, I wasn't able to stain it for 3 weeks, but the completed bin is about 4 feet tall, and for the time being I used plant flats as catchment trays. I may replace them with a wooden catchment tray later, but they seem to be work well enough for now. The false bottom (double wall corrugated cardboard) I installed when I put the bedding in didn't leave much room for anything to escape anyway, except the occasional drip of water. 

And here's another view, with the top taken off. I never have added those hinges... they just didn't end up being necessary. My wife now jokingly refers to this as the "Backwoods Worm Lodge," because of it's rugged good looks. (Or at least I like to think that's the reason she refers to it that way.) For all the jokes she makes about using the worms as kindling for our wood stove, she's quite grateful they now reside outdoors!

Over the course of the first couple weeks of use, I discovered that even with the internal wood stabilizer, the lid would get soaking wet from the condensate. Particularly when I was using the heating cable to keep temperatures stable in the 70s! (This was in November, after all. And Internal Wood Stabilizer is designed to work over time to keep the internal wood from breaking down under prolonged exposure to water, so it's not really supposed to shed water like a stain.)

Even a couple solid sheets of cardboard over the top of the bedding didn't reduce the evaporation much. Once it had a couple coats of stain though, it shed water like a champ. It's been going for 2 months and the bottom of the lid still looks like it was assembled yesterday. 

Oddly, the use of egg cartons I picked up from a bakery's recycling pile one week seems to do a much better job of containing evaporation. I think perhaps it does a better job soaking up the condensate, whereas the corrugated cardboard didn't have the same absorbency. Perhaps the shape also helps condensation drip back down rather than continue upwards. I couldn't tell you honestly. But it did lead to this practical realization: if you leave egg cartons in place on top of a flow through bin for 5 or 6 days, they will double as your next bedding addition! They come apart as you pick them up with little to no effort, and then you just add new ones to cover the top again. Beats the hell out of shredding cardboard.  

For what it's worth, my brother tells me his catering business goes through a stack of 100 of these a week. Bakeries go through more than that usually, and many restaurants have a huge stack as well. Since most towns now have recycling, it's often just a matter of asking for them at a restaurant.

Or, like most worm composters, you tend to find yourself walking by piles of what other people consider trash and discovering new and interesting additions to your worm bedding/food mix! 

I've posted all of the pics of the construction process, as well as the initial bedding mix and worms here. I'll continue adding photos as things progress, but the most interesting photos are always seem to be during the start up and harvesting process! And sadly, I'll be getting rid of my dSLR soon, so I may not have many decent photos for quite some time. As it is, most of these were from my camera phone. It's just easier to use that when you have a hammer in one hand and nails held between your teeth. ;)

[Harry Lightball]

Well executed plan and nicely crafted.

Should serve you well for a good long time.

[Nomar Cuaresma]

Wow! I like the look of the bin. Seems manly, besides the purple in the inside haha.

How many worms do you have in this bin?

Is this bin located in an open shed (probably cause you have to keep your wood dry somehow :) ) ?

What do you plan using the VC for?

[Ben]

Thanks guys. I added about 3 to 3.5 lbs of worms to the bin to begin with. In the last two months, they seem to have expanded somewhat, and I'd estimate the weight at 4 to 4.5 lbs at this point. It's hard to say without harvesting, obviously.

The bin itself was located underneath an overhang on the porch when I took these pics. I hadn't stained it yet and wanted to keep drain off it so I could do so without waiting for it to dry out. Cedar doesn't dry out very quickly in the 30-45° weather that we've had the last couple months, so I just kept it dry til it was stainable. There's a 3 week lag time on the wood stabilizer where you need to leave it unstained to allow the stabilizer to alter the wood. 

It has since moved to the other side of the wood pile, out from underneath the overhang and it's been firmly planted in the rain, wind and sleet and snow for the last month. It routinely has some drops of water on the top since it's not slanted, but it seems pretty weather proof so far. I'm sure I'll need to re-stain it every couple years. 

Oh, and the VC will be for the veggie garden and/or flowers. Probably a bit for the houseplants too. Never a shortage of things to put it on!

[Andrew from California]

"...if you leave egg cartons in place on top of a flow through bin for 5 or 6 days, they will double as your next bedding addition! They come apart as you pick them up with little to no effort, and then you just add new ones to cover the top again. Beats the hell out of shredding cardboard."

Actually works the same way with cardboard, but egg cartons always seemed a safer choice to me. They have minimal/no printing and are meant to carry a food product.

Great job on the FT, Ben! Makes me blush to think of my very rough FT 2.0...still incomplete. LOL.

[Ben]

I did try cardboard on top when I was trying to solve my drying out problem. It was taking a really long time to break down on top of my bin, unless I tore it up first. At least 3-4 times as long as the egg cartons.

FT systems don't have to be pretty. I just did that in deference to my own perfectionism, and my desire to get better at woodworking.