Compressed Sawdust

[openspaceman]

I agree but it's a way of selling softwood logs to the punters I suppose.

 

Of course I was only meaning to demonstrate that the lignin got hot by the wasted energy pushing the wood through the die.

 

Wear on the die and auger is high too and in Asia where the press originated they have to be resurface with stellite type material regularly.

[Steven P]

8 hours ago, DocMustard said:

Back to the post subject, Fox Blox are made by a Lancashire timber moulding company from all their shavings. Their website states that the shavings are compressed using a load of 1700kg per square centimetre, in order to force the lignin to bind the wood fibres together.

So based on a block surface area of, say, 20 x 10 cm (or 8 by 4 inches) this equates to a load of 340 metric tonnes compressing it. (200 square cm @ 1700 kg). That's a fair piece of machinery!

I'm going to need a bigger car jack then.

 

So... coffee didn't work,. and sawdust didn't work in that set up, going to put it down to an interesting experiment - worthwhile I think to record it here because I wasn't the first to wonder if it would work and no doubt won't be the last. Not viable for the expense of a real machine either.

 

Interesting stuff about how real briquet and pellet machines work and the physics of how the pellets are stuck together.

 

 

 

 

 

 

Experiment 2 then, I wonder if this will work...... I have a car scissor jack, and a load of saw dust...... Inside the mould from before the dust was quite compacted as you'd expect, so bean tin, dowel down the middle, filled with saw dust and compressed with the jack to make better sawdust burner - should contain more sawdust than just hand filling, should burn for longer, and the kids might be able to make them to play with.... but that is for another day.

[sime42]

Do you know any local blacksmith's with a Drop Hammer, or even better a power drop hammer? One of those might be capable of providing the force required to soften the lignin to fuse a block of sawdust together.

[Steven P]

9 hours ago, sime42 said:

Do you know any local blacksmith's with a Drop Hammer, or even better a power drop hammer? One of those might be capable of providing the force required to soften the lignin to fuse a block of sawdust together.

Had one of them once... 

[Stubby]

On 28/04/2022 at 17:48, openspaceman said:

Yes that is my understanding too. Similarly when one steams wood in order to bend it it works because the cellulose fibres are the tensile strength of the wood and the lignin is the stuff that binds them all together ( like glass fibre in polyester resin). Heat the lignin and it loses some stiffness and can flow and reform as it cools.

 

My boss sold his briquette making machine before I could see it working but that hammered a wadge of sawdust through a 2" die and, again, it was the heat generated from the friction of the sawdust binding in the die that caused the softening of lignin.

 

If you watch pictures of the shimada screw press working you can see both steam and smoke rising from the emerging briquette from this friction generated heating, often the briquesttes emerge with a charred surface. About 2:30 below.

 

 

I have one of those at home ! Don't know why I did not think of it ...😀

[renewablejohn]

Have been wondering if there is any mileage of having a mobile briquette and wood pellet service. Already have both machines but mothballed as at one time imported briquettes and wood pellets were so cheap. Now that prices have gone up it looks like it could be viable.

[difflock]

No fuss, no mystery, as long as the stove is hot and there are still some reasonable chunks of embers left.

Zero draft, and will burn out entirely if left. Also good if I really wanted to keep the fire in overnight, acts just like wetted slack on an open coal fire.

I only burn the sawdust in the autumn and spring when the heat requirements are minimal.

2 nd image only a minute, perhaps two? after adding the sawdust and closing the door.

[Steven P]

I can never manage to get it in the fire without some spillage!! (which is what I was wanting to do).

 

 

(as an update, my experiments have paused at the moment for sawdust burning, last one was a stack of 3 bean tins for The Boys to play with, lower one has air vents at the base, drop twigs in the top, it burns OK for them but has no use otherwise - too top heavy to put a mug on, too small to heat any real area, but for the boys playing it does OK.))

[Justme]

3 hours ago, Steven P said:

I can never manage to get it in the fire without some spillage!! (which is what I was wanting to do).

 

 

Pack in paper bags outside.

Throw on as needed.

 

[Steven P]

That's what I have tended to do really, used boxes from the groceries - but this plan was to do something different than that