Brian, I’d try one with smaller holes.
Jakob North had a similar problem in his downdraft and he found the jets were too big. Too big a jet and it makes more CO2 than CO.
6 Likes
Thanks Cody. Right now I have just a single open nozzle with the opening 3/4" inside at the fire but still just 1/2" going in.
Next time I take it apart I’ll try grinding and pounding a 1/2" pipe in the end. That should give it an even thicker nozzle in the hottest zone.
It’s working pretty good but it runs good at very low loads but takes a little while (few seconds) to get to full power when a bigger load like the compressor or miter saw is turned on. Maybe the bigger nozzle is letting more air flow when the draw increases than it can handle until more of the charcoal is burning.
The other possible problem could be too big of charcoal. I need to make a new charcoal grinder that will process it faster and make more of the smaller pieces. Mine is slow (hand crank powered) and has too much space for the larger pieces to get through.
I’m happy with it and keep using it but it could still work better. I never did rip the engine apart and try to adjust the timing a little and have considered taking the head off and either shaving a little off or trying to find a thinner gasket. I still use it and it works so I hate to mess around too much and risk messing it up though.
I keep looking at the sawmill so close and want to try running it on the gasifier. Just don’t have the pipes to get the gas closer to it and then add a flexible hose that could travel with the carriage and engine. It’s about the same size engine as the generator but needs to spin fast enough to keep the clutch engaged. I would need to build another adapter to fit that engine and have a good filter so it doesn’t suck up the fine sawdust it throws while cutting.
4 Likes
While reading older threads, I found Building a KISS Gasifier and am still going through that one but I found a comment from @SteveUnruh
For the longest time I was insisting from experiences that woven fiberglass stove rope would seal airtight. It just took using the larger diameter rope; with a made rope holding channel; and opposing raised compressing bead. Ha! Ha! Most ignore the opposing squeezing bead. Versus a flat surface squeeze. These will unevenly squeeze. And with use, wear, leak.
I don’t understand the “opposing raised compressing bead”
I have a feeling this could fix my leaking lid problem if Steve or someone could help me understand how this is made.
6 Likes
On almost all modern no-leak sealing systems the tightened down components are metal to metal.
The actual sealing bead; elastomer bead/woven rope, is ~50% compressed in a grooved channel between the major components.
So in-use vibration; old-way constant compressing clamping forces do not squish, flatten, wear the sealing member; then resulting in a loosening gap.
Those cover bolts that aways seem to have gone loosen . . . NO. The gap shrank. Paint dab mark the bolts . . . they did not move.
You find this metal to metal system now very common on cam covers. Intakes gaskets. Automatic transmission covers.
S.U.
9 Likes
I stopped using big refilling lids a while ago. I tested and found out that engine grade charcoal will have no trouble “flowing” trugh an opening more thain about 5" wide. Its a hell of a difference refitting and sealing a 5 or 6" wide lid or a 55gal drum lid each time you refuel…
All else, like Steve sayd. Metal to metal. Threads, specialy plumber parts wich are conical, work exelent as cleanout openings. I never ever use any seals anymore (except on the filling lids), l have been hurt many many times…
10 Likes
Thanks for the no leak ideas. I think my lid leaks a little but not sure if it does under vacuum. My clean out hatch is sealed with stove rope with a flat plate bolted on. I have tried to see if it was leaking but never noticed any leaks.
I wasn’t happy with the chimney flapper pattern I made so I made another one that is thinner. The pattern is now 1/2" thick instead of 3/4".
Besides making it thinner, I extended the piece that will be hinged. I also used some auto body spot filler to put a bit of a radius in the gasket pocket so the sand releases.
I wanted to try engraving the pattern but my test piece doesn’t look like it would cast right and I didn’t want to mess up the pattern. It isn’t very big and the wood has too many fuzzy strings in the V-carved engraving so the sand would never release clean enough to make a good casting.
I haven’t made it to pick up my foundry tools and don’t know if the pattern is good enough (or my skills are good enough) to turn it into aluminum.
It only has about a 2-1/4" inside diameter so wouldn’t be good for loading the fuel but should make a nice chimney/safety pressure release in case of a hopper poof.
Yesterday I ground up some charcoal to smaller pieces and filled the hopper full. It started and run good with little to no condensed liquid and the hopper and lid stayed cooler with the smaller charcoal.
I’m hoping to pick up my foundry stuff this weekend but it could take a while before I actually build and install this. The gasifier works as it is so I don’t want to start modifying it until I’m pretty sure it will work.
13 Likes
Not done yet but was messing around with the idea of casting the cover for the chimney.
The green sand could use some more time to get the moisture distributed better.
Next I needed to make sure I could actually melt the aluminum. I used a soup can in the house furnace along with some smashed cans as the source of aluminum. The soup can is one time use but it heats and melts fast for the small amount I should need.
I guess I didn’t take a picture of the actual mold I poured but the pattern came out of the sand pretty good.
This is the top of the cover. Doesn’t look too bad for a first try.
Unfortunately, the back side where the stove rope pocket is formed must have broke a piece off the sand.
I think the main problem is that I wasn’t able to find my parting powder so this was done without any. I wasn’t going to pour it until I got the parting powder but the mold looked like it would work and I wanted to see if my estimate of the amount needed and the way I gated the mold was going to work.
I should have more parting powder (diatomaceous earth) here but it will need dried.
I think that first casting could be cleaned up and used but I’m going to call it practice and make a better casting. As far as I can tell, the casting didn’t shrink too much so the gasket pocket fits the pipe I hope to use.
12 Likes
Looking good Brian. I often use the very fine sawdust from MDF as parting powder. I put it in an old sock.
Rindert
7 Likes
Tried casting the cover a couple more times.
This is the first and second tries. The inside gasket pocket turned out better but the top was shrunken in a little. I’m guessing that was from not having a big enough gate to feed the molten aluminum into the part. It isn’t real bad and could probably be used.
The third try is probably going to be the final one unless I mess up drilling and finishing it. I might use the second one as the practice for drilling the holes and getting it to open and close while staying lined up.
The top isn’t as smooth as I would have liked on the last one but it is good enough.
The bottom has a little sunken in shrinkage but the gasket pocket looks OK. Better venting might be needed.
It will take some filing and sanding to clean up all the flash around the edges and I still need to drill it for the pivot point and a way to hook a spring on it to hold it closed.
I don’t think any of the left over gasket rope I have is going to be the right size (too big) and I still need to design and build a way to attach it to the piece of pipe.
I’m not in a big hurry to get this done since the gasifier works without it and I haven’t run the gasifier for a few days because of the weather and other projects.
This part didn’t take very much metal but the house furnace easily melted the aluminum. I was going to set up the actual foundry and use some of my charcoal but using the furnace instead meant none of the heat was wasted.
9 Likes
You could use water glass to make one side “form” to the other. It wouldn’t take very much and it can handle the heat.
8 Likes
I changed my design of the chimney cap and tried casting it repeatedly. The new design has ears for 2 springs instead of one as a hinge. Mostly just to make it easier to build although probably not as nice as one attached with a hinge.
The pattern has a deeper gasket pocket which also made the part thinner. I was having trouble getting the mold to fill before cooling. I knew what the problem was but was trying to avoid another riser or vent.
This was my last attempt. Hopefully I can clean this one up good enough to use. My sand might not be the best mixture or I’m just not good enough to get perfect molds. I might need more clay but I had too much clay in my green sand years ago when I was trying to cast metal and it made lumps of sand that were like bricks every time I made a mold and needed forced through a screen to be usable again. My mixture now breaks up fairly easily by hand.
10 Likes
Hey BrainM.
Can you cast in bronze alloys too?
The early gas plants works found that bronze alloys were much more gasworks corrosion resistant than any other. Acidic on one end. And high alkaline/basic on the other. SS’s and acid-proofs not yet then developed.
Britannnica has the best short one-page article on bronze’s, and non-tin bronze alloys. History to modern usages.
Regards
Steve unruh
8 Likes
Aluminum bronze would be an excellent candidate I think. Not terribly hard to cast, and is used in corrosive environments like marine applications.
8 Likes
this was also my thaught…for renew worn out bronze bearings…
7 Likes
I’ve never tried melting anything except aluminum or lower temperature metals like lead, zinc, or pot metal.
I doubt the soup can crucible could handle higher melting point metals. I burnt through one when I tried remelting some sprues and failed parts. I used a coffee can years ago and a glowing and bulging can of molten metal was scary. I have a real crucible and somewhere there should be a homemade pipe crucible but the soup cans have been working for the tiny amount of metal I need for this part.
I’m hoping the aluminum part lasts long enough to at least test the idea of having the chimney for venting off moisture and as a pressure relief port. It’s giving me a lot of practice and all the failed parts should make cleaner metal for future projects than the aluminum cans they came from.
I have watched some videos on aluminum bronze but never tried making or melting any. I’m still trying to perfect my mold making on the lower temperature metals. The temperature where I want to put this part should stay fairly low. Might even be able to coat the casting with paint or silicone if corrosion is a problem.
The gasifier works as it is so I’m not in a hurry to add the chimney but I still hope to eventually. I think it would allow me to bolt the lid of my gasifier solid.
I didn’t try casting another one of this part but I did some more sanding on the pattern to get the draft a little better. I think that was part of the reason I was getting so much flash around the outside of the part. I also added some more clay to my sand which gave it a little more strength.
7 Likes
You could powder coat the aluminum lid that you’ve made, that would basically be encasing it in plastic. Take an old toaster oven that you won’t use for food again, we had recently retired one so I use that for powder coating my cast lead bullets.
It takes about 350-400°F for 20 minutes to cure. Since the lid won’t get that hot I think, you shouldn’t worry about it melting again.
The plastic texture might help with sealing as well.
7 Likes
I don’t think it can. You need a ‘real’ crucible.
Anodizing and electroplating are two options. Anodizing is probably easier. but nickel will electroplate to it. And nickel is commonly used as a base for electroplating other metals like gold. 
5 Likes
I haven’t done anymore with this idea. It’s been cold here and I’ve only used the gasifier a couple times recently. It works as it is and I don’t want to start cutting and welding on it until I have everything ready to build so I only need to run the generator on gasoline for the final welding on the lid.
I might give up on the cast aluminum cover and just make it all out of steel or just stick with what I have and add a couple more springs to try to hold the lid down more evenly. I only notice the leaking lid when I shut down or when I’m starting it and forcing air into the nozzle. While the generator is running I can’t tell if it is still leaking at all or if the vacuum helps seal it. The back opposite the nozzle still gets warm but the lid and most of the hopper area is staying cooler but the weather probably has something to do with that too.
The last few runs I haven’t collected any water so I’m guessing my ashes dried out and it is working as it should now. I haven’t been letting the charcoal level drop low enough to check on the thicker nozzle but got some more thick walled pipe to use if/when the one in it now melts.
Basically I’m happy with it. Before every run I poke the charcoal down and refill it if needed. I’ve only cleaned out the ash chamber a couple times and just screened the ashes out and dumped the charcoal back in.
10 Likes
I no longer ever seal off a gasifier on shutdown. It needs to vent as it will still produce gas for a minute after the draft is relieved. The best way is to open the flare cup valve and let it vent out there. It will still shut down. Once the venting has stopped the gas inside will be static, reguardless if you seal it off or not air can not get inside as there is nothing drafting it.
12 Likes