Sawdust Log Press

Why?

For personal reasons. I rid myself of the wood stove the year I moved in here, also the oil stove and heater. This house is all-electric now.

I am building a sawdust log (briquette) press as a hobby activity over the winter. As well it is a prototype for a small business start up . A briquette press can double as a cider-press, or a press for any number of fruit or vegetable juices.

The Structure

On the left hand side of the image we see a scissor-jack (you could use a hydraulic jack, or even a lever-beam).

The lower plate exerts a force on a piston in a cylinder to compress sawdust, wood-chips from chain-sawing, or even a fluid pulp of scrap cardboard and paper. Water is squeezed out, the pellet is ejected to dry out, then can be stacked and burnt as fuel.

On the right hand side we see a vertical frame made of 2x4 timber. The jack and piston module sits within the strong beam frame, and during operation, fluid drains from a drop-tray into a container.

The Process

Collect your sawdust, saw chips, cardboard or paper in a pail; add in a weak solution of wood glue, flour, or whatever binding agent you have that, when burnt, will not release toxic fumes. Mix well.

The process operates one cylinder at a time, but with sufficient man-power can be worked up to a batch process.

Pour the mixture into as many cylinders as you have, or that you think you can press in one work-session. Too many cylinders and a short session means that your gluey pulp will solidify in the cylinders before you get around to compressing it.

Tamp the mixture down by hand; the maximum force you can exert by standing above the cylinder and pressing down with a shovel-handle will be less than your body weight, 150 pounds at most, but this will enable you to fill the cylinders to a standard density.

Place the cylinder in the jack frame and compress to the full extent of the jack.

This should produce pellets compressed to a standard density and hence pellets that will burn for a standard period according to the type of material.

This means that a load of pellets is assured of providing a given amount of heat. Good for client relationships.

Enhancements

(1) A frame that can accommodate two jack-frames will allow you to double-buffer your operations. While you are preparing to fill and jack the second cylinder, the first cylinder is draining the last of the fluid, and the jack will offer a few more last-minute turns. Result: a pellet that dries a little sooner. (Is this true? The more compressed the cylinder, the fewer avenues for the moisture to escape)

(2) A horizontal lever-beam – another piece of 2x4 set out to the side – will allow your weight (you swing from the beam by your hands) to act as a huge lever, applying a compression force more quickly than cranking the jack. A cinder-block or similar weight hung from a hook on the outer end of the beam will allow a force to be maintained for ultimate squeezing.

(3) The tray that collects excess glue-solution allows you to reduce the waste of materials. Tip the drainage bucket into your next pulpy batch.

(4) The cylinders can be old cans from apple- or tomato-juice. Coffee cans might work, but they would make larger diameter pellets, perhaps suitable for burning overnight.

(5) The cylinders could be made from wooden slats, hinged at four corners, with the fourth corner being stage hinges so that the pellet can be ejected quickly. The slats could be oiled or lined with sheet tin or plastic to reduce absorption of the glue solution.

(6) Consider slitting the can cylinders vertically and using hose-clamps to close the can. Releasing the clamps makes for fast and sure ejection of the pellet.

(7)  A raised brand slid under the top plate of the jack will identify your pellets and distinguish them from inferior products.

(8) The machine can be mass-produced and sold as a kit anywhere on the island.

(9) If you can source large-diameter tubes, you can use those directly as combustible molds.

(10) Different materials may require different formulas of binding solution.

(11) I like the idea of a prototype that fits completely in a 5-gallon pail. Any bonding fluid is caught in the pail. A double-buffered system allows for 24-hours of soaking between each log.

Friday, January 05, 2024

I measured the range of my old car jack. Closed at four inches; opened at fourteen inches.

Two pails of off cuts from David’s garage.

Two of the longer pieces will form a side-panel; I could make a 3-sided to an 8-sided container.

The two short pieces are fishplates, used to hold the two pieces of wood together, making a wider panel.

The longer parts will make collars, joined at each end by hinges with drop-pins

The panels will be thirty-one inches tall. With ten inches of travel, the car jack can make 31-10 gives a 21-inch briquette.

Scraps of plastic siding can act as a liner making easy removal of the briquette.

Thin strips of plastic siding placed between the ribs of each panel can be removed after screwing the fishplates, providing a good gap for extrusion of water from the slurry.

The briquette “cylinder” and be laid horizontally, with plastic-siding strips used to partition a single load into two or more smaller briquettes.

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Tuesday, January 23, 2024

I now think about a lever, anchored to the heavy workbench, and the plunger can be bolt-slotted anywhere along a ten-foot lever to provide the force to quickly squeeze the briquette. This would have the advantage that my body weight (180 lbs ahem!) is used as the energy source. Fast.

Tuesday, March 05, 2024

A design for a jack-less press – if you don’t have a car jack to deliver a mechanical advantage, obtain the advantage from a lever.

In the sketch above the mold is outlined heavily, and above that is a piece of timber – an eight-foot length of 2”x4” that acts as a level . Place the pulp in the cylinder, haul down on the ever, and Presto! The piston at the top of the cylinder is pushed down by the level.

To the right of the cylinder are two pairs of uprights. The inner pair guides the lever and piston in a straight line between the fulcrum and the piston.

The rightmost pair of uprights form the fulcrum.

The pivot point is shown by a small circle which represents ¼” holes drilled through the lever and the uprights. There will be a series of holes in the uprights which can be used to adjust the fulcrum-end of the lever. A ¼” bolt slips out, adjust the lever, slip the bolt back in.

A similar series of holes is available on the piston rod; again represented by a single hole.

At our left-hand end of the ;ever is a hook; no need for you to swing from the lever for twenty minutes. You can hang a weight and eave the pulp to compress overnight. Or you can hang a pail and fill it with water from the garden hose.

A couple of cross-braces are sketched in for the uprights.

A thick base of wood provides the setting; a sheet of plastic, such as a garbage bag, can be laid down t channel the pressed liquor into a container for re-use. Let’s suppose that each pail of slurry has added to it a teaspoon of wood glue. The strength will tend towards a point of stabilization.

Various proportions of sawdust and cardboard can be used on trial.

Procedure

(a) Build the piston – a rectangular cylinder using door hinges as the corners. The cylinder opens out for removal of the log. Mar-25 through

(b) Build the piston – a rectangle of wood fixed flexibly to the bottom of the piston rod

(c) Build the base

(d) Build the guide posts

(e) Build the lever.

(f) :Put it to use.

Monday, March 25, 2024

Armed with two packets of wood screws …

I assemble four pairs of palings. Each pair of palings is held together by two fishplates. At this time the screws are screwed in almost-flush, because I may well dis-assemble and re-assemble in a day or two. We’ll see.

I had three old door hinges. Again a trial. I may instead use string T-hinges. We’ll see. Hinges because I want to be able to open out the cylinder and obtain the log with no fiddling about.

On the inside, no hinges, just planks, flush, but with a slight gap between the planks/palings which are not finished (planed) timber, but bits of old pallets and fences.

Tuesday, March 26, 2024

As the construction season gears up, I’ll be doing carpentry; In Swyers here in Bonavista I can buy 700 1¼” wood screws for $22 plus tax (3.14¢/screw). Canadian Tyre in Clarenville sells a 1200-pack of 2” screws for $53 plus tax (4.42¢/screw).

Yesterday I paid $11 for a pack of 100 (11¢/screw).

Moral: shop around, buy in bulk.

I bought six T-hinges then decided to drop the old door hinges and use three Ts per joint, so back to Swyers tomorrow for more hinges.

My current method has the hinges on the inside. This will produce drag/friction while compressing, but I think not so much as to prevent it working.

Here I have joined three panels with two sets of hinges,

From the outside you see quite a gap between panels. This should result in a fast compression.

The third set of hinges will be like the first two sets, but the fourth set will have the hinge pins knocked out and replaced with drop-pins, which is what I learned from scenery work at St Anne’s Music And Drama society many years ago.

Wednesday, March 27, 2024

Down to Swyers for six more T-hinges; but this time I know that they are useful in the T-configuration.

On three hinges I used my drill-grindstone to grind of the heads of the bolts of three hinges; only one end of each hinge pin.

When I tap the screwdriver against the right-hand side of the hinge pin, the pin will POP out of the left-hand side; same for the other two hinge pins.

The three hinge pins are popped out and that frees up the “opening” corner of the cylinder.

Here the three hinge pins have just been popped out. I use a long nail, thinner that the pins, to reach into the hinge and pop the pin right out; or to dislodge the screwdriver that I used to push the pins out.

Here the cylinder is assembled. I need a too to pop out the pins. Right now the fitting is tight. I might use a wire coat-hanger to make pins with a finger-loop at the upper end; that would make it easier to pull out the pins.

None of the hinge screws is fully tightened. I want to make the piston head and shaft next. Only when the whole device is in working order will I return and fix everything in lace. Sloppiness (in setting up and fitting) is my friend.

Monday, June 10, 2024

Two and a half months pass …

I chose the wrong hinges, but since they represent capital I was determined to use them.

Difficult to see in this photo but I had to chamfer the edges to make a tapered fit, and since I didn’t have a chamfering tool, I had to do the work on the bench with a circular saw and an old chisel. And since the bench was too cluttered, well … two and a half months.

Above we see my rectangular cylinder and in front of that, a rectangular piston rod and plate. The plate fits in loosely with about a half-inch gap. I am looking for the opposite of water-tight here, and whatever and wherever I can squeeze out water, that water will run away under the influence of gravity.

Here the press is assembled. This is a prototype made from scrap timber, and may well collapse on its first use. So I took these photos while everything was still in one piece.

Well, three pieces, actually. The piston is separate from the cylinder, and the cylinder has a fixed base and is separate from the bigger part of the press.

One pair of hinges on the cylinder boasts drop-pins. In theory the pins pop out and the hinge falls apart, exposing the compressed material inside the cylinder. Now let’s see it in practice.

These two images suggest that I need to tack strips of wood along the lever. As the volume in the cylinder rises and falls, I move the cylinder along the platform to get a good angle-of-attack, but in each case, the top of the piston rod might slip along the lever.

Strips tacked along the underside of the lever will inhibit slipping.

Over winter I loaded scrap cardboard into an empty compost bin. The snow melts, the rain falls, the dry cardboard is softened and settles.

Today I haul a stack of cardboard in the barrow and use the log press piston to push the scraps underwater. I leave them to soak for an hour.

In practice I will try to reclaim my squeezed water and re-use it; if I can do that, then I can add a binder agent (a teaspoon of wood glue?) to the water to help keep the pressed logs intact.

While I wait, I slide a second sheet of duct steel under the exit lip of the sheet attached to the rack.

This second sheet arrests the movement of most of the rocky material.

As a bonus, I can lift the second sheet and funnel the collected material straight into the wheelbarrow then truck it across the street to David’s driveway.

Meanwhile, the Holyrood Radar station enhancements are in place. This device, I am convinced, is now so sensitive that from one hundred kilometres away it can detect my entry into the garden, and trigger rain to fall on me. How do they DO that?

After 50 minutes I start loading cardboard into the cylinder.

(1) The cardboard is in bad condition; there is much plastic adhesive tape, labels and so on. Not suitable for a domestic fire. But it should still work for me as I create and try burning some of this stuff.

(2) Likewise we don’t want embedded gravel, exploding after ten minutes of being on the living-room fire.

(3) I need a shorter piston rod; that, or a selection of lengths. The current rod is too high when I have the cylinder close to the lever pivot. Thinking of different lateral positions for the cylinder may be a waste of effort.

(4) I slid the lever away and used the back of an axe to pound the top of the piston rod for the initial compression.

(5) I need a place at the far end of the lever to hand a 5-gallon pail of water, to continue compression over night.

(6) The cylinder tends to rotate about the base. The base itself doesn’t move, but the top of the cylinder sways back and forth, pivoting about the foot of the cylinder

(7) The swaying may be resolved by a shorter piston rod.

(8) That said a set of strips along the base of the lever should reduce the chance of the base shooting off the end of the lever base.

So now the piston rod is roughly half the previous length.

I load more cardboard, press down, and the device slops sideways still.

Aided, no doubt, by the flex at the bottom of the upright. This upright is held with at most three screws, and is not a rigid fixture.

My idea was to use the fabricated slab of wood as a trunion of some sort. Perhaps a diagonal strut on each side …?

(later)

The right-hand side (in this view) sports a single diagonal brace, which makes that right-angle junction for the vertical more secure.

But the downside of such a brace on such a narrow platform is that there is not enough room for the hinges and fishplates that hold the cylinder together.

I screwed four tabs along the base to reduce slipping of the base of the cylinder along the base.

I have yet to screw strips along the underside of the lever; I am considering replacing this initial, 2x1 lever with an eight- or ten-foot length of 2x4.

Note that the piston rod is away out of its supposedly vertical alignment.

I must thing about caging the cylinder in a vertical cocoon.

(later) Now I am wondering if the mobile cylinder and piston might be a good thing. Use the lever for fast compression of a log, then move the cylinder into a jack-press (my first idea) to do the final compression.

Five months ago I began this diary with a car scissor-jack, …

Friday, June 14, 2024

“I must thing about caging the cylinder in a vertical cocoon.”

But why am I making this a vertical cylinder? Why not horizontal? Vertical has the benefit of simple lever that could be loaded to exert a force overnight.

Horizontal has the benefit that there is not gravitational force encouraging the cyclinder to stray out of alignment.

Here is the vertical system. I have slid the cylinder out of the humble frame, and my feeble lever (only 2x1) has dropped to the ground.

Here is (roughly) how it might look in a horizontal arrangement.