Impressive Sawdust Briquette Machine

When you are a life long carpenter with an amazing workshop, you’re going to make a lot of saw dust, and managing its collection and storage poses quite a challenge. [Russ] from [New Yorkshire Workshop] built an impressive Briquette press to handle the problem.

It’s a hydraulic press that ingests  saw dust and spits out compressed briquettes ready for fueling his rocket mass heater. The build starts with a batch of custom, laser cut steel parts received from Fractory. The heart of the machine is a 300 mm stroke hydraulic cylinder with a beefy 40 mm rod. The cylinder had to be taken apart so that the laser cut mounting flanges could be welded, slowly so as not to deform the cylinder. The intake feed tube was cut from a piece of 40 mm bore seamless tube. A window was cut in the feed tube and funnel parts were welded to this cutout. The feed tube assembly is then finished off with a pair of mounting flanges. The feed tube assembly is in turn welded to the main feed plate which will form the base of the saw dust container. The hydraulic cylinder assembly is mated to the feed tube assembly using a set of massive M10 high tensile class 10.9 threaded rods. The push rod is a length of 40 mm diameter mild steel bar stock, coupled to the hydraulic cylinder using a fabricated coupling clamp. On the coupling clamp, he welded another bracket on which a bolt can be screwed on. This bolt helps activate the limit switches that control the movement of the hydraulic cylinder and the feed motor.

Next, he starts work on the hydraulic power pack, powered by a used Chinese piston pump coupled to a 7.5 kW motor, capable of delivering about 30 litres / minute. After a flurry of drilling, tapping, cutting, grinding and welding, he has the tank assembled with ports for the various connections, a motor-pump mount, an inlet lid and filter openings, a set of caster wheels and eye bolts and some angles to mount the  electrical panel. To check for leaks in the tank, he seals off all the openings, and pressurises the chamber with compressed air. Then, using soap solution, he identifies and fixes the various leaks. A heat exchanger to help cool the oil is attached to the power pack, with some of the rigid piping converted to flexible hoses.

He then proceeds to build up the electrical control panel, wiring up a custom relay PCB assembled on perf board, and a bunch of contactors, relays, MCB’s switches and the most important Emergency push button, doubled up with a remote E-stop pendant.

To stir up the saw dust, and push a handful down the funnel of the feed tube during each cylinder stroke, he used a set of rotating blades mounted to a hydraulic motor at the centre of the main feed plate. The rotating blades are 20 mm square section steel pipes welded to a central hub. To fabricate this, he first machined the central hub and a corresponding broaching sleeve, and then used a broaching tool to cut a key-way slot in the machined hub. With some effort, the broaching could be done manually, but why do that when he could use his powerful hydraulic cylinder to do it. The limit switches for controlling the motion of the cylinder and the motor were fixed on an aluminum extrusion and then [Russ] did a dry run to make sure everything worked as expected.

For compressing the saw dust in to solid briquettes, he used a 40 mm bore seamless pipe with two slits running along its length. By using a clamp to taper the open end of the tube, he could adjust the consistency of the briquettes – from soft and powdery to hard as wood.

Finally, he built the saw dust collector box using plywood and polycarbonate and assembled it on the main feed plate. Removing the old dust collection bags and fitting his new machine in place was quite straight forward, but there were several teething problems to be debugged before he could get briquettes of the desired consistency. Once everything was sorted, his machine was producing about 24 kg of briquettes per hour.

[Russ] might call himself a carpenter, but he sure has all the other skills needed to pull off this complex project. Check out [Russ]’s companion project where he rebuilds a shredder to help chop up card board boxes in to small strips, which can further be compressed using this machine in to briquettes.

Thanks to [Keith Fulkerson] and [Keith Olson] for tipping us off on this impressive build.


27 thoughts on “Impressive Sawdust Briquette Machine

    1. Not sure it’s overengineered if he is going to run it non stop, it makes 100s of lbs/kg a day!

      Nevermind the heating just from the pump and pellet forming tube 😆, 60C just from the pellet forming process, maybe add a thermal shutdown and/or fan!

    2. This does not look overengineerd. Just built properly to last a decent amount of time.
      Consider that things like a hydraulic press, cylinder and valves are relatively expensive parts. A bit of sheet metal does not cost much compared to that.

      These is also not much time difference between making it from thinner metal or thick metal and because a hydraulic press also generates a lot of force you do not want to have the thing breaking down and making a mess. Cleaning and repairing it is tedious to say the least.

    3. I am a little concerned from the description that it sounds a bit overboard on tolerance and precision when there will be pitch like saps being crushed out of the dust on the regular, and potentially making obsessive cleaning necessary such that it doesn’t jam up.

  1. didn’t watch the video, but I hope he works with only solid wood — the adhesives in plywood, OSB, engineered lumber, etc., would not only increase the chances of gumming up his nice press, but also you wouldn’t want to be burning them anywhere near where you’re breathing.

        1. Mind, the largest pollution output comes from lighting up the stove. It takes a while, especially if you’re running a big brick oven with heat retaining walls, for it to heat up enough so it won’t smoke. The same goes for catalytic stoves.

          You can reduce the amount of smoke by lighting it up correctly. You have to stack the wood just right and light it up from the top, but practically nobody does that because it’s unreliable. People just throw the logs in, scrunch up a bunch of newspaper in the middle and put a match to it, which belches up a ton of smoke from partial combustion before the firebox heats up.

          Coupled with cold spells which create inversion layers, which trap the smoke from rising in the atmosphere above some few hundred feet, you get that acrid smoke smell lingering about in any neighborhood that heats up with wood.

          1. People also like to burn old magazines and stacks of papers, which contain a lot of clay filler, which goes up the chimney as very fine ash and gets deposited everywhere in the neighborhood.

          2. I was going to say.. I wonder if you started your fire with plain wood then only threw in the sawdust pellets after it was good and hot would that result in less pollution?

            Maybe it’s still an unacceptable amount of pollution. I don’t know. But if people are going to do this regardless maybe suggesting that would at least reduce the damage.

          3. >Is fine clay ash going to hurt it?

            I’m sure the ground is fine. Your lungs on the other hand don’t necessarily appreciate it. Fine crystalline silica when inhaled is a known carcinogen, and the inflammation it causes contributes to asthma cases.

          4. The point being, when you burn a bunch of paper, there’s no rocket stove or catalytic converter that’s going to burn away what is essentially nano-sized sand particles. It’s going to smoke, and people will have to breathe that smoke.

            A gasifying stove might, though. There are some designs which heat up the wood in a well insulated box until it turns to gas, and then burn the resulting wood gas, first to heat up the box, then to heat up the house. All the ash stays in the box, and the gas flame burns with so much excess air that it doesn’t soot or smoke.

          1. That’s not an answer unless you define ‘second hand smoke’.

            Makes me think you’ve been reading BS.
            Remember: The press gets all science reporting wrong. Consistently for decades now.
            It’s as if they were all mouth breathing pretty morons selling blood and fear.

          2. PM2.5 concentration in cities varies between about 6 – 13 µg/m3 and wood smoke contributes up to 60% of that in places where heating with wood is common, such as Copenhagen. During cold spells and inversion layer conditions, the concentrations can jump 10x which makes them just about as bad as standing next to someone smoking a cigarette – the contents of the smoke is very similar.

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