How to work out m3 of a round log.

[WeeDee]

Brilliant many thanks for your help

 

You're welcome.

 

Remember, that's a calculation for total volume.

 

It doesn't account for wastage as the hoppus formula does.

[Celtictimber]

Yea ok.

[difflock]

For some reason I use:

Pi * D * D / 4 for the area of a circle.

And using 3.0 for Pi, would both make for easier sums, and make some little allowance for saw kerf.

m

[wisewood]

Thanks for explaining that, think I've got it now

Is there a contemporary hoppus pricing guide for species of woods?

[John in Scotland]

You're welcome.

 

Remember, that's a calculation for total volume.

 

It doesn't account for wastage as the hoppus formula does.

 

also doesn't account for the gaps between each log.

cubic meter of wood isn't the same as a cubic meter of split logs.

 

as I'm sure you ae aware.

 

but you did say from the customers point of view?

[WeeDee]

For some reason I use:

Pi * D * D / 4 for the area of a circle.

And using 3.0 for Pi, would both make for easier sums, and make some little allowance for saw kerf.

m

 

Pi * D * D / 4 = area

I can't make this work unless D is always 2. Pity, because it very tidy!

 

 

 

" And using 3.0 for Pi, would both make for easier sums, and make some little allowance for saw kerf."

I think this is a great idea! I would like to see how it actually compares to a real situation. Nice one.

[difflock]

Pi * D * D / 4 is the same as Pi * r * r

 

Pi * D * D / 4 wus wot we wus taught at the Poly on the C Eng course.

Perhaps because pipe sizes etc were/are always specified by their diameter

 

4*4/4=4

or 2*2=4

 

6*6/4=9

or 3*3=9

 

8*8/4=16

or 4*4=16

Edited January 20, 2014 by difflock

[harvey b davison]

My head hurts

[WeeDee]

Pi * D * D / 4 is the same as Pi * r * r

 

Pi * D * D / 4 wus wot we wus taught at the Poly on the C Eng course.

Perhaps because pipe sizes etc were/are always specified by their diameter

 

4*4/4=4

or 2*2=4

 

6*6/4=9

or 3*3=9

 

8*8/4=16

or 4*4=16

 

Yes - I get it now. Sorry for my misunderstanding.

 

Nicely explained. Thanks.

[openspaceman]

Pi * D * D / 4 is the same as Pi * r * r

 

 

Possible better writ as

 

=Pi()*(d*d)/4 and bunged in a spreadsheet or =Pi()D^2/4

 

Hoppus is an interesting measure. Hoppus was the chap that bought timber for the dockyards and his system was based on the measuring tools readilly available.

 

I imagine the average yard would only have one accurate measure (a steel yard??).

 

Hoppus would have the middle of a log girthed with string, this length was then folded twice to give a quarter girth which was measured off against the steel yard. Similarly a piece of string would measure the log and be held against the steel yard repeatedly to get the length.

 

The calculated volume would then have been read off pre calculated tables.

 

Now whilst you cannot cut a 50ft3 beam from a 50Hft log you will get approximately 50ft3 of pieces in total including bits of scantling cut from the slabwood, so it was an intuitive measure, unlike m3.

 

Another nicety of using the string to girth an oak log was that you could fold the string into 8ths, discard one 8th and then fold the remaining 7/8 into 4 and use this as the qg, the answer then was a good approximation to the underbark volume.