I’ve always wanted a flapper valve exhaust but never found the right engine to put one on. I thought the chimney might be a good reason to get/build one so I drew up an idea.
Then I thought this could just be overcomplicating things especially when my gasifier is stationary. Now I’m thinking just a pipe plugged with something maybe held down with a spring or springs or maybe just a big cork and a chain to keep it from getting lost or becoming a projectile if/when it poofs.
Having a separate safety exit for the gas would allow me to clamp my lid down tight without worrying about leaks or worse. Being able to easily vent the smoke and steam should help dry out the damp charcoal.
I found a pipe about 2-1/4" ID but I’m worried I will just end up with another place for a leak. The lid hasn’t gotten too hot to touch but it does get hot and I’m not sure how to seal it good enough but not too good.
I’m just going to leave it alone for now.
I think, if there was a poof, the nozzle is going to shoot glowing charcoal out instead of (or in addition to) pushing the lid up. That wasn’t a big deal when the gasifier was outside but glowing pieces of charcoal would be a bad thing where it is now. I usually put the cap on it to kill the generator now because it shoots flames out that nozzle if I just shut off the generator.
Had a new idea for the chimney cap. Thinking about casting one out of aluminum which I’m not really set up to do right now but would like to be.
This has taken several tries to get the size right to fit the pipe I have. The idea is to have a pocket for a stove rope gasket.
While it should be possible to make a pattern with hand tools alone, I have a CNC router that hasn’t been used in a while so I thought I’d try using that to make the pattern. It isn’t as rigid as I’d like so I kept the depth shallow and figure I can cut it out by hand following the outline.
The block of wood is programmed as a 4" wide x 5" tall block and all the depths are set to cut only 1/8" deep. The starting block of wood can be bigger than that but the zero point is set at the lower left corner of that size block.
The estimated cut time is 10 minutes but that isn’t always accurate. My tool (a 1/8" bit) won’t cut the draft for the pattern so that will need to be done by hand.
Loading the Gcode program into the software it estimates only a little over half the time at 5 minutes 19 seconds but that isn’t always accurate either.
Testing the fit it looks like it could work. It will need cut out, sanded, and probably a coat of shellac before it can be cast. Of course, my casting sand, crucible, and other foundry tools are 10 miles away right now. I’ll also need to cut and weld some pieces as the hinge and some way to attach a spring but I’m closer than I was this morning.
I won’t be surprised if I mess up and need to rebuild the pattern or run into other problems but getting a foundry set back up and figuring out how to use it should open up a lot of possibilities like the ash clean out cover I was thinking about before.
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.
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.
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.
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…
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.
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.
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.
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.
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.
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
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.
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.
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.
