I have worked in the foundry business. They usually make patterns out of RenShape. But for just a few castings I usually use MDF. Do you have a CNC? Also we have a whole thread dedicated to metal casting.
Rindert
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Yes, I have a homemade CNC router. That was part of the thought behind this especially the text.
A lot of the pattern could be made as sections and glued together. Even Styrofoam could be used either as the pattern for sand molding or as a one time use lost foam pattern.
My main thought was that the cover wouldn’t need any welding and could likely have a pocket or groove cast in to put the gasket.
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I would change the lid to have a central post on top, where you could attach a coil spring from maybe an overhead valve, and a bar with a hinge on one end and a latch on the other.
Something like what Gary has on his Ranger
Edit: note how the bar has a hole running through, this allows the lid to jump up in a puff event.
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Thanks Cody, I’m not sure how I missed that video. Looks simple enough if I can find the right spring.
That’s one of the problems with my design. The lid isn’t sealing good enough especially if I’m blowing air into the nozzle to get it burning good or for flaring.
Today I did hook it back up after drilling the holes out bigger. The nozzle is getting thinner so it isn’t going to last a long time but that helped a lot. I was able to refill my air compressor tank all the way without loading the generator down much. I tried the miter saw and same thing, it ran fine.
I was going to pump some power into my 12 volt battery but the sun is hitting the solar panels and that battery is charged.
Only ran the generator about 15 or 20 minutes using the same charcoal I had in it last run. The only change was the holes in the nozzle enlarged and more of the moisture had been removed from the last run. I still got about 2 more ounces of water out of it in this short run but it’s running as good as the simple fire now and has larger charcoal and there’s still a piece of two of raw wood that hadn’t fully converted.
The weather got a lot colder and I’ve been using the house furnace and getting some charcoal out of it about every time I reload it with wood. There isn’t a lot yet but probably an hours worth of charcoal from it.
There’s a little bit of ashes mixed in and some of the pieces need broken up smaller but doesn’t seem as wasteful as just burning the wood in a barrel to get the charcoal. Once I take my good barrel near the furnace room and start heating continuously I could see that keeping enough charcoal produced to run my generator and I hope to stockpile the charcoal over the winter.
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I forgot about the other change but I don’t think that had anything to do with the generator running better.
I got a mesh laundry bag to put my grass/straw filter material. The bag wasn’t quite big enough so I blocked the space with more felt but that should make cleaning or replacing the filter material easy.
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Ever think about using the heat from a tlud to heat the house, while making charcoal? Very cool Aussie Bio retort - #7 by d100f Too many ideas.
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With your CNC router, you can probably just cut aluminum directly. most ones designed for wood, you can also do soft non-ferrous materials. So then, you just need to cast a block. It skips making the pattern and trying to cast it perfectly, and dealing with shrinkage, etc.
If you are dead set on making a pattern, another way, would be to do spin forming. you make the pattern, and take a sheet metal, and press it against the form while it spins. It is an art all by itself, but then you could use stainless or another material.
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That TLUD looks nice but I couldn’t put something like that in the house. Might be perfect for use in a workshop or greenhouse though. I couldn’t find any actual drawings or plans for that device but the comments made it sound like the hopper is just a stove pipe:
The fuel container is made out of stove pipe. The primary air is forced down one of the vertical square tubing supports that holds the heat exchanger. The heat exchanger can be removed and replaced with a cooktop. It only takes between 2 and 3 watts to run the primary air fan which is a 12 volt computer fan with a speed control added to the circuit.
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When the pyrolysis front burns out the charcoal starts burning and produces more heat that trips the thermostat that shuts the fans off.
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I know this is an older video but i’m just now seeing it. To answer your question oxygen (air) enters through the bottom of the fuel can and migrates up through the fuel until it reaches the fire. The fire depletes the o2 and leaves the char behind, migrating down the can as it burns. The spent gasses go up the fuel can. At the top where more O2 is introduced the hot gasses reignite and go up the stack. The key to this is stopping the the burn when it gets to the bottom of the can. Otherwise the char that is left behind will burn from the bottom up leaving nothing but ash behind. If all you are after is heat no problem if you want the char you have to stop the burn. Hope this helps.
The top looks similar to something sold as “Magic Heat” but probably bigger.
Mine isn’t rigid enough and it would need to be run very slow to cut. Even hardwood I can’t go real deep or real fast.
Back in high school I did a tiny bit of metal spinning but haven’t tried to set up any way to do that myself. That’s a good idea though. My sawblade cover is working but I added a piece of felt (in addition to the stove rope) to help it seal better. So far that hasn’t gotten too hot.
Doing a little more studying, I still think my main problem was the moisture in the ashes but the raw wood even mixed with the charcoal was probably creating a lot of the moisture too. The last run had very little raw wood and it run pretty good.
I don’t regret trying the raw wood and it looks like I could get away with at least some less than perfect CHARCOAL but I don’t want to add a monorator hopper or all the heat exchangers that would be needed to use raw wood. Not on this one anyway.
I had already used some of the charcoal salvaged from the house furnace but this was what I was able to collect from a couple days without really trying. That should be enough for over an hour run time for the generator. The colder it gets here, the more charcoal I could potentially collect and purposely feeding smaller chunks of wood would speed up converting it into coals.
I’m not happy with how my cyclone is turning out so I think I’ll stick with the radiator I made and use the filter to collect any moisture like I have been doing. This down draft gasifier is starting to work about as good as the simple fire but holds more fuel and shouldn’t need as perfect of charcoal. It probably won’t hurt if a brand or even a tiny bit of raw wood slips in but the rocket fuel idea looks like it adds too much moisture if not some tar.
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Rocket Fuel is really only meant for a raw wood gasifier when you have a bunch of overly wet wood or just need a boost in efficiency.
Mixing in raw wood I think could really only work in something like the Double Flute if it’s sealed off like with Don and Bob’s versions, or with a Mako style charcoal gasifier. Something with a perifery of jets. Even then I’d only mix maybe 10% raw wood in a quick charring form like wood chips.
Rocket Fuel for a wood gasifier is usually 90/10 wood/char I think.
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That’s my understanding too. I’ve tried it only a couple times but it seems a wood gasifier gets easily consipated if you overdo the char.
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Is that because of the charcoal soaking up the tars and gets sticky?
Does that mean a WOOD gasifier don’t work on all charcoal?
This gasifier still isn’t dropping the charcoal down real good and I poke it down after almost every run and the level drops. The same thing happens with my simple fire and it has never had any raw wood. I assumed it was just too big of charcoal or maybe my flute nozzle blocking the charcoal from dropping. Not usually a big deal since I mostly only run an hour or less but sometimes a couple hours.
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Brian, I think it has to with tar to a point. It turns to soot. Also, all the soot, char and ash from above have to pass a restriction in a wood gasifier.
Small fuel, extreemly dry fuel and char - they all contribute to a denst charbed. They all chatter down to small bits faster.
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Hello Brian .
All what JO said plus a couple thoughts of mine .
Char along with small dry wood will catch fire and react much faster than raw wood blocks. As this char or dry small fuel burns it consumes the oxygen and leaves the wood gas flowing down through the remainder of the char bed and because of no oxygen in this gas the lower char will stay dormant and start packing up and get constipated.
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I think I understand but don’t know how much I can explain because I found the information in the premium section.
https://forum.driveonwood.com/t/choke-plate-variables/709
Since I’m using just charcoal, I don’t know if it fully applies to me. I don’t really have a choke plate. I’m considering my stack of brake rotors as the fire tube with the nozzle right above it. I’d have to empty it out to get actual dimensions but should be around 5 inch diameter but maybe up to a foot between the nozzle and the grate.
I haven’t run it a lot and usually only an hour or two maximum at a time. My generator is only a 212cc engine so probably not a lot of pull. I haven’t gotten enough ashes or dropped char to bother cleaning out yet. MAYBE the distance/diameter is not allowing the oxygen to get close enough to the grate to purge the ashes?
I might be overthinking it. Charcoal only wasn’t supposed to need a restriction plate and it works good enough.
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Yes to tight of a Charcoal bed is not good, I use popcorn size for my smallest Charcoal size, I like to use bigger Charcoal because it does reduce down in size quickly and fills in the voids in the brands above the nozzles. The charcoal picks up moisture quickly. Then when it burns it makes extra Hydrogen. But this is what I experiences with my WK Gasifier. We all know the gasifiers are all different in operations.
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If we are talking just a charcoal gasifier bridging , then you will always have a collapse of fuel after stopping the machine as there is a cavity of sorts above the nozzle that falls once you poke down after stopping , over the years various contraptions have been thought of to over come this and also to move the funnel effect of the charcoal not flowing from the outer edges .
This is why its a good idea to get your fuel as small as possible smaller pieces flow better
Dave
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I second what Cody says. You MAY get by by using a bit of torrefied wood but raw wood might be too much. Only the periferal nozzles will prevent tars sneaking trugh by the walls.
Raw wood and bridging is a recepie for tar. Imagine. A cavity forms because of a bridge. It collapses sooner or later, and now you have peaces of raw wood dangerously close to the grate… l have tared up engines before by just that phenomena, in a dedicated raw wood gasifier…
Speaking of bridging, a stiff connection from your generator to the gasifier shuld produce enaugh vibration to help it.
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That is my experience as well.
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Another hour+ run today.
Trying a different path for the gases and added the water trap.
Charged all my drill batteries and did some grinding and welding on the cyclone.
It run good but I found some leaks when I shut down.
The water trap didn’t catch any liquid but had some leaks which I kind of knew the jar didn’t seal tight. I have a rubber Fernco adapter ordered that I hope to use in place of the jar lid.
The lid still isn’t sealing right probably because the little springs aren’t strong enough. Didn’t seem to be a problem with vacuum on the system but leaks when there is any pressure. I didn’t check around yet to see if I can find an old valve spring to make a different hold down.
The rubber connector from the gas output to the cooler was stopping some of the water and not sealing tight. Probably not enough slope on that pipe which also explains why the jar didn’t catch any water.
The filter did catch some water but I didn’t measure how much.
I tested the cyclone with a shop vac and some dirt and it did catch the dirt. Not sure if it caught all of it because I had wood shavings in the vacuum container which I didn’t realize was there. The plastic Cyclone either missed some or I used it without that filter. I’m not sure if I will add the cyclone to the gasifier or not but it was nice to see the design might work.
I thought the water problem should be going away. It is getting a lot less but still getting some. The generator is running good and the charcoal didn’t get the big pocket like it had been even though the level dropped noticeably on this run. It wasn’t completely full when I started though.
All in all, I’m still happy with it but there is still work to be done to improve it.
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Pressure brings smoke and vapors to the outside where we can see it; vacuum brings it to the inside and I’m not crawling in there to watch. 
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