I’ve become a bit dissatisfied with my current charcoal crusher. I’m finding that it lets long pieces slip between the teeth and isn’t purchasing on the big pieces to break them.
I’m going to make a few different crushers to compare them. My next one will be using these cheap saw blades I got on eBay. I bought 10 blades for about 60 dollars.
Using two lengths of 5/8" allthread rod, washers and nuts I’m going to see if this design will work.
One side will be spun and the other just freely rotating.
Waiting on some pillow block bearings to arrive,
Between the nuts and washers I think the blades will be spaced apart about an inch, and with each blade between the other, maybe a half inch spacing.
I know Bruce has made something similar, his Ab Roller design and the saw blade plus hammer mill. I don’t know if he tried making a double saw blade crusher, though.
Don’t forget to bring your spacers between blades out to just clear the blades on the other side. I used gears for counter rotating by hand. Maybe I should have just let one side freely rotate like you suggest. If you find that you need counter rotation, using motors powering each shaft separately might be easier than gears.
I’m looking forward to seeing how yours works.
You might put a pipe or wedge under the rotating drums to help keep the long stuff from slipping through as well. It is just to make sure it bends, and breaks. But it may also increase jamming.
One thing I could do is put a 1/2" or 3/4" screen cupping the underside, so if a piece does get beneath it could give the blades a chance to grab again.
You could just make a hammermill. I saw one that shells corn, it was a barrel or metal 5 gallon bucket and then just a shaft with chains on it. then I forgot what they used for hammers. They use them for biochar a lot. but you would just need a bigger screen.
This is actually a pretty good, cheap idea. he is using pvc pipe for the barrel.
I would actually use screens instead of slots in it. so you can switch them out… worst case scenario, you have a machine that can process grains. It is pretty much the same design as the others I have seen. Usually you put the feed shoot offset so stuff doesn’t fly out the hole. If you use a larger barrel, you could have a larger feeder that could process sunflowers with it as well.
With a 5/8" rod, a wash on either side of the blades, and a 5/8" nut on either side, in a confined box with a small hopper: I’m getting engine grade charcoal with minimal dust.
I need to tighten the heck out of these bolts some more, when it slips the blade that’s caught freely spins. Brands will just simply get cut instead of smashed.
I have a 1/2" square mesh screen beneath the blades with maybe a 1/2" gap, I should probably try to tighten that gap.
This setup wants speed and a lot of char in the hopper. The more you have the more it helps in the crushing. I have a 2000 RPM motor that I might try to use, with a 3:1 reduction.
I will probably take this apart and put some wooden spacers inside as well to prevent char from getting stuck between the blades, but the way I see it the jams clear themselves with higher speed.
Now I need to make a 1/8" sieve so I can stop wasting some of the fuel. This grinder makes more finer sized fuel than the big stuff. This was all sifted using 1/4" mesh.
@sbowman do you want the other axle I made? All you’d need to do is make a wooden box to place it in with some bearings. To attach a pulley I just used two more of these nuts and jammed it on. I used 1/2" hardware cloth stapled to the bottom as my screen.
Hi Cody, that seems like a good design, i’ve read about some war-time charcoal crushers with blades, both like saw blades, and smooth edged, very sharp, they all worked at, around 1500 rpm, and was said to produce much less fines than ordinary crushers.
Can you just spin it with a electric hand drill?
Shame on me for not having two wrenches big enough for these nuts, I noticed when the blades would jam on something they’d freely spin until the blades next to them managed to break it apart. I think at a higher speed this wouldn’t happen.
When my wrenches come in the mail I’ll really crank all the nuts down, also ordered some right angle brackets. Going to mount the crusher and motor together on a wooden platform so I can place it over a bucket.
I have an idea for a charcoal sifter that uses a concrete agitator/vibrator motor so you don’t need it to be too long or at a dramatic angle. Maybe it’s just me but if I have a sifter at an angle, it tends to not sift fast enough. Agitating even a little bit makes it go more efficiently.
My sieve won’t be very different from how others make theirs, imagine the classifier sieves that have multiple exits for different sizes. I like to pre-sort my charcoal to reduce dust in my grinder and also make less work.
There’s some videos on YouTube that use old drill motors or reciprocating saws, but they require a rail system or a bunch of pivots. I reckon just vibrating the sieve is enough if there is already a downwards slope. Vibration is just to prevent blockage in the grid holes.
After I grind my char into a Wheel barrow I just sift it through quarter inch screen. I usually get about a gallon of fines per five gallon bucket of char which I use for bio-char so I’m happy to get it. If I wanted to refine it further I’d use the dust for water purification. It’s all good. I just sift it in a half bucket with a screen in the bottom like you would pan for gold. I can do a 30 gallon WB full, ground and sifted, all by hand, in 15 to 20 minutes. Lately I have been washing the dust off the fuel and then drying it. I never used to and didn’t have any issues with it but now I don’t have to deal with the black hands syndrome.
If you weld the head of a 3/8 bolt to a 5/8 nut you can put it on to the threaded rod and fit it to the electric drill and easily take it off if you want to.
Very interesting. Can you give us anything more on these war-time machines? Pictures or descriptions for the “around1500 rpm” “saw blades, and smooth edged” charcoal crushers?
Ill try to find some, i don’t know where the pic’s is to be found, i know i read a description of a charcoal crusher that used thin, very sharp discs to cut the charcoal, one drawback was they get blunt pretty fast, especially when charcoal was made the old way, in “mounds”, a lot of sand and dirt contaminated the charcoal.
