Burn Test - Episode 2

     No pictures with this one, just a brief update on the rocket stove burn tests.

     It was fairly warm here this afternoon so I took the rocket stove out for another test drive while I shoveled the sidewalk. No real success to report, but I did learn a few things from the failures.

     1) Do not overfill the fire chamber.
     2) The rocket stove does really sound like a rocket engine once you finally overcome the overfilling of the fire box.
     3) The top of the chimney needs to be more than 1/8" away from the bottom of any pan you place on the stove to heat. There is not enough space to provide adequate draw to keep the fire going.
     4) The bio-fuel briquettes are too large to restart the stove from hot ashes. You really need a good fire going with thinner material before adding these.
     5) The liner stores a lot of heat. The ten minutes of burning stored enough heat to radiate for about an hour even after I packed the stove with snow to snuff it.

     So... tomorrow I'll probably try it out again with a screen pan support I made. Pictures and test results after the next testing.

Time Travelling Zombie Hunters

     Sculpting is moving along. Another week or so and things for myself and a couple of clients go into a master mold. Not much blather for this post just images of a few more 15mm pieces for Rebel Minis.

     Enjoy.

Burn Test

     I cheated. There, I said it. I got impatient waiting for the bio-fuel to dry so I put a batch in the oven to dry for several hours. I did two burn tests this evening.

     I broke off two approximately 1" lengths of a briquette. I put one in a tin can and tried to ignite it. The first thing I learned is that these compressed paper pellets are really hard to ignite on their own. I couldn't get it ti do more than smolder and singe the edges.

     The next test was with the same bit of fuel except this time I used a cotton ball soaked in vaseline as a fire starter. The cotton ball burned long enough that the paper caught and burned quite well.

 

     About 20 minutes later the flames were pretty much done.

     At 30 minutes there was still a solid coal left burning. I decided to put it out at that point. Not too bad for 1" of compressed paper fuel.

     The second test was in the rocket stove.

     One cotton ball and one 1" piece of briquette.

Side view

 

     I placed a pan with 2 cups of water in it on top. Ten minutes later we still had some good flames going. The chimney does seem to speed up the burn, but not enough for a single pellet of fuel to boil the water.

10 minutes in

     After 20 minutes I still had a small flame going, but there simply isn't enough energy in 1" of fuel to bring water to a boil.

     Later this weekend I'll try a water test with more fuel. I'm satisfied for now that the paper briquettes do burn at a consistent rate without any quick flare ups. On a side note I put the fire out half an hour ago and the stove with it's refractory is still radiating a gentle heat.

Long Time Gone

     I'm still fighting the cold weather and sinus/ respiratory issues here, so I've been lax about posting. There are several sculpting and painting projects on the table to be wrapped up in the next week or two. All of the sculpting needs to go into one master mold so I've been working on each project a little at a time, which is not really the most efficient way to do things. I did manage to finish up a set of seated Hell Divers for Clear Horizons Miniatures and the command pack for my Space: 1889 Martians.

     Coming off the table in the next week are some figures for Rebel Minis, some aliens for Loud Ninja Games, another set of Hell Divers, a few pieces for Pictor's and the long awaited minions in white to go with my space pals. These will be heading to my mold maker as soon as they are done. I'll post pictures of these later.

     I have tons of things on the painting table. Actually they've been sitting there for a very long time during my ten month hiatus from painting. The absolute minimum got finished for releases, but most projects just sat while I moped about failing eyesight. It's finally time to think about bifocals. The doc says, at this point, it's probably better to just remove my glasses altogether when I work close. That seems to be working. Sometimes a combination of glasses and optivisor works out. But it has all been a depressing development that I was hoping would just go away.

     Anyway, I did start painting again late in December. Here are a few of the items I was playing with.

     Some 08 15mm sci-fi and a couple of Rebel Minis Tomcat walkers.

     I still play fantasy skirmishes and RPGs in 28mm. Here are a few Chainmail elves.

     Slightly converted Games Workshop Necromunda rats.

     And a Ratman sculpted by Bob Charrette.

     The larger stuff gave my eyes a much needed break while getting me back into painting. I also like the fantasy skirmish games because I can paint a few figures that interest me without trying to field whole units or armies.

In the Meantime

     I'll write a bit about the sculpting and painting projects in a few days. I'm still gathering parts for the foundry and a larger brake drum forge. But in the meantime, here are a few of the other projects that I have going on at the house.

     First up... the soup can forge.

     Or in my case the coffee can forge.

     Here are the gathered parts. A 1 lb. coffee can, 2 L straps, a 1/2" x 2" black iron nipple, and 2 nuts and bolts. I followed the instructions and assembled the forge shell. Total cost of materials was $5 plus the coffee and a scrap block of wood.

     The refractory liner was a bit of a problem. I used the plaster of paris and sand mix the video recommended. The first batch was way too dry and wouldn't stick together. The second was way too wet and wouldn't hold its shape.

     The third was just right. Or so I thought. Once it was in the can it still had trouble keeping it's shape so I put a PVC form inside and let it cure a while.

     Then I placed it in the oven for a slow drying cure at about 250 degrees. I took it out 2 hours later to check on it and there were several cracks in the lining. It seems that a combination of cold basement temperature and too much water in the mix allowed for a lot of shrinkage. So I chipped the liner out, cleaned up the can and let the project sit for a day.

     My next liner was made of a 50/50 mixture of sand and scratch coat plaster. I mixed it to the specifications of the foundry liner and used a Paul Mitchell hair product bottle for the form. Thanks, Susan. :)

     That seemed to work out well. I have a solid refractory liner with no cracks or shrinkage. I let that cure for a day and headed to the basement for a slow burn with the torch.

     All seemed to be going well until the torch started sputtering and I removed it to check things out. Evidently the shutoff valve hasn't survived the test of time. Imagine my surprise as flames started shooting out of it while I was turning it off. I haven't moved that fast in years.

     Ok. Off to Harbor Freight later to grab some new equipment.

     The second project is to make bio-fuel briquettes for any time of low fuel consumption stove. Here's one of the two rocket stove models that I want to make this month.

     There is another larger version that uses a 5 gallon bucket as a form for the shell, but that one will have to wait a few weeks.

     Anyway... back to the fuel. Briquettes of fuel can be made for these stoves by compressing waste paper, sawdust, etc. One of the projects on my honey-do list during December was to shred a mountain of Susan's old bills and other sensitive documents. I ended up with 2 1/2 garbage bags full of shredded paper that we usually take to the local recycling center.

     Enter.... the bio-fuel press!

     A standard caulk gun outfitted with a PVC tube and a few end caps becomes becomes the press. Holes were drilled into the tube to allow the excess water to escape. The caps are round furniture sliders. One has a groove ground in it to cover the front end. The other is ground to fit inside the tube and press from the back end. Simple enough and it uses a tool I already had and $2 of extra materials.

     The idea behind the briquettes is pretty similar to paper making.

     The shredded paper is soaked in water for a week. Then an optional binder like flour is added and the resulting slurry is pressed into the tube. I'm trying the first batch without binder to see if it is actually necessary. The briquettes are then set aside to dry for three weeks. Before they are burned.

     Today is the last day of the soak. I'll be pressing the fuel later today or maybe tomorrow. I'll add pictures of them when I have them done. Actual burn tests will need to be done next month.

     The cool parts of these projects are that they cost nearly nothing and they're mostly made from things I had on hand. We'll see how well it all works out in a few weeks. If you have any questions, comments or suggestions please send them along.

    Update: I did my first pressing tonight. It took about an hour and a half to make 30 6"-7" briquettes, start the next bucket of slurry and clean up my mess. I'm hoping for about an hour burn time for each one, but even 20-30 minutes each would be time well spent.