What does a cube of dry logs weigh? Test

[Woodworks]

I have been meaning to double check this for some time so I have just been out to check. The logs are about 80% beech with a snaffle (phrase on loan from TCD) of other hedgerow trees including oak, sycamore and hazel.

 

The only scales I have suitable are some sheep scales so first I checked their accuracy with a couple of feed sacks. For some old scales I was pretty impressed as they read exactly 50 kg.

 

An IBC crate was filled to 1.01 m3. Close enough for me

 

I put the logs through the scales in batches.

 

Split and tested 10 logs from the crate with the highest being 26% and lowest 20% interestingly the sycamore was the wettest. Average from the 10 was 23%.

 

Total weight was 366 kg.

 

And then a picture of a cube in the back of a Defender 90.

[Hanser]

Interesting. As a bit of an experiment to check on the outdoors seasoning of some milled green walnut I dried a piece (left near the stove) and over 2 months and it has lost some 38% of its weight.

[luke_mclachlan]

Woodworks, I see that your 1m3 crate is filled very neatly, because according to some official statistics a loose filled 1m3 hardwood load should weight about 300kgs with a moisture content of 23%. what are you charging for these loads?

[Woodworks]

Woodworks, I see that your 1m3 crate is filled very neatly, because according to some official statistics a loose filled 1m3 hardwood load should weight about 300kgs with a moisture content of 23%. what are you charging for these loads?

 

The logs have only been thrown into the crate but have had about 10 months to settle. I think 300kg would be a pretty mean cube of dry hardwood or very dry.

 

"What am I charging?"

 

More than my customers want and less than I would like

 

 

 

 

 

 

Ownly messing with you. £95 per cube.

[luke_mclachlan]

The logs have only been thrown into the crate but have had about 10 months to settle. I think 300kg would be a pretty mean cube of dry hardwood or very dry.

"What am I charging?"

More than my customers want and less than I would like

Ownly messing with you. £95 per cube.

 

you must have a very good throwing technique then

 

I've worked out that your £/kWh is 0.0675, which is very competitive indeed! I'm basing this on a calorific value of 3884 kWh for a moisture content of 23%. yes, i'm a bit of a geek . I've simply averaged statistics from sources such as scotlang.gov.uk, aebiom.org & biomassenergycentre.org.uk, and performed a linear interpolation to give me calorific values for any (wet) moisture level.

hope this helps.

[logmanfuels]

I'm getting similar results

 

I also find that a builders bag weighs about 1/4 ton as they tend to only hold around .7m3

[Woodworks]

you must have a very good throwing technique then

 

I've worked out that your £/kWh is 0.0675, which is very competitive indeed! I'm basing this on a calorific value of 3884 kWh for a moisture content of 23%. yes, i'm a bit of a geek . I've simply averaged statistics from sources such as scotlang.gov.uk, aebiom.org & biomassenergycentre.org.uk, and performed a linear interpolation to give me calorific values for any (wet) moisture level.

hope this helps.

 

You need to check your maths there Luke

[luke_mclachlan]

are you sure? i adjusted the weight of 366kgs so that it was for 1m3, not 1.01m3. that brings your cost per tonne to £262. now you're making me paranoid

[Woodworks]

are you sure? i adjusted the weight of 366kgs so that it was for 1m3, not 1.01m3. that brings your cost per tonne to £262. now you're making me paranoid

 

 

"are you sure"

 

Not in the slightest

I have made a balls up of my kWh to pounds sums. Don't be paranoid my school boy error

[luke_mclachlan]

I'm getting similar results

 

I also find that a builders bag weighs about 1/4 ton as they tend to only hold around .7m3

 

I'm gonna have to find a better resource for my statistics. AEBOIM say that hardwood, freshly stacked, 20% moisture, per m3 should weigh 450kg. I suspect this is a little high and should be around 430kg. But in any case, if we use a conversion factor of around 0.64 for stacked to loose, you should be getting ~ 275kg.