Oak butt weight

[mr kipling]

Hi wondered if anybody could tell me how much a 3 foot diameter 3 meter long freshly felled oak butt would weigh also how many cubic foot it would contain many thanks Chris

[Big J]

Hoppus foot measurement is your friend here.

 

Measure the girth (circumference at mid point) in inches. In this case, it's 113.11 inches. Divide this by four, which is 28.28. Multiply this by itself (28.28 x 28.28) - the answer is 799.96. Finally, multiply this by the length in inches (which is 120) - so 799.96 x 120 = 95995.2, which is the volume in cubic inches. Convert this to cubic feet by dividing by 1728, and your answer is 55.55 hoppus foot.

 

In brief, to work out the volume of a log, it's quarter girth squared, multiplied by length (all in inches) and then divided by 1728.

 

To convert to tonnes (roughly) divide by 27 (the number of hoppus foot in a tonne of the heavier hardwoods), which a smidge over 2 tonnes.

[mr kipling]

Hi Big J thanks for that will take a bit of digesting all those calculations so is a hoppus ft a cubic ft the butt is about 12 m long with not a lot of taper its on the deck but down a bank the owners have said its mine for milling but going to cut it into 3 m sections to winch up the bank as access is not great cheers chris

[agg221]

Hi Chris, if you have an Alaskan then you may want to consider making life easier by running a single cut up the middle of the lengths to split them in half. This will make them far easier to winch up the bank. Although a Tirfor will easily handle the weight, it's very easy for the end of a heavy log on soft ground to dig in - if it's lighter you can skid more easily without it rolling (not so top heavy) and can use some bits of ply to skid up, which makes it very easy and does a lot less damage. You would need the extension uprights on the mill though.

 

Alec

[mr kipling]

Hi Agg yes it is an Alaskan mill did think about going down the middle but want to turn it into 8x8 beams and 8x5 beams as going to build a oak framed garage and going to mill and build it myself this is a hobby so not fussed how long it takes or if it would be cheaper / easier just to buy kit or beams i did read on here about boxing the heart but that seams wasteful from a log this size I have milled a 4 ft diameter oak before and just ran through and through at 8" then mini milled into beams and they appeared to be plenty strong enough,three are in my house and one over the inglenook fireplace we built, is there any reason for boxing the heart cheers Chris

[agg221]

Hi Agg yes it is an Alaskan mill did think about going down the middle but want to turn it into 8x8 beams and 8x5 beams as going to build a oak framed garage and going to mill and build it myself this is a hobby so not fussed how long it takes or if it would be cheaper / easier just to buy kit or beams i did read on here about boxing the heart but that seams wasteful from a log this size I have milled a 4 ft diameter oak before and just ran through and through at 8" then mini milled into beams and they appeared to be plenty strong enough,three are in my house and one over the inglenook fireplace we built, is there any reason for boxing the heart cheers Chris

 

Have you seen this thread:

 

http://arbtalk.co.uk/forum/woodcraft-forum/88433-green-larch-timber-frame.html

 

?

 

If you don't need to comply with building regs then nobody will want to see stress calculations, which means you can do what you like and either go for a calculated approach, 'that looks about right' or 'oops it fell down'.

 

If you do need to comply then you will need calculated sections based on species and grade.

 

Boxed heart is stronger so you can use a smaller section for a given grade and species. If you use non-boxed heart, e.g. quartersawn beams then you just need to allow for this.

 

Milling for your spec. I would take 5" slabs out near the centre so that when mini-milled to 8" widths they will be effectively quartersawn. I would take 8" sections further out, so that they can either be 8" x 8" or 8" x 5", as the timber allows. This approach also allows you to split the tree up the middle first, which has the advantages of showing up most major defects and taking out any stress (as well as making it easier to move where necessary).

 

Alec

[farmer rod]

Just in case it is useful, I am going to attempt to post a pdf log mass chart

Log mass charts.pdf

[ucoulddoit]

is there any reason for boxing the heart cheers Chris

 

There have been a few references to boxing the heart recently which has made me think about how relevant it is. Perhaps it was just the traditional way of squaring off a log by hewing the sides with an axe before bandsaws were invented and so now not needed but we continue to do it because it is the way it has always been done?

 

In terms of strength, visual grading is based on the visible defects on the outside of a beam or column and since the most significant defects tend to originate in the heart, a boxed heart section with the pith at the centre, milled from a small/medium sized log is likely to have fewer visible defects on the outside and hence, I would say this is likely to achieve a higher strength grade compared to a section milled with the pith on one face for instance. So that is an advantage.

 

Nowadays large diameter logs can be easily handled with machinery and milled so there is no need to be restricted to small/medium diameter logs. The outer parts of large logs are likely to have more closely spaced growth rings and might be completely clear of defects such as knots, wane and fissures. So I would speculate that this timber will have a high strength grade, maybe even higher than the boxed heart section. But as it dries, the original sawn squared section will distort into a diamond shape whereas the boxed heart section will remain nearer to a square shape. This probably doesn't matter for floor joists or beams, but in a timber frame, the beam to column joints need to remain tightly together, held by the oak pegs. So if the column distorts into a diamond shape the joints may open excessively. But this will be more of an issue on columns with a large cross section so not always relevant.

 

Another other issue that I think might be a problem is a beam or column warping along its length as it dries. I feel that a boxed heart column which has no intermediate restraints between each floor level is more likely to stay straight compared to a timber cut from the outer part of the log. A banana shaped column is obviously weaker than a straight one. But a beam or joist cut from the outer part of a log and used as part of a floor will be restrained by floorboards or other timbers which hold it in a straight line as the frame dries.

 

Andrew

[mr kipling]

Hi thanks for the replies very useful I now know the weight ,best way to cut how to move and how to grade this is a top forum cheers chris

[RealEstate]

Just in case it is useful, I am going to attempt to post a pdf log mass chart

Very useful, thanks!