Sawmilling - hints, tips, do's and don'ts.

[Big J]

Guide for buying logs:

 

Things to look out for with all species:

 

When buying logs (or indeed deciding what goes into the firewood pile or what you are going to mill, if you don't buy your logs) there are criteria that apply to all species. These are some (though it's not an exhaustive list!):

 

* Ring shake: This is where you find cracks that run along the growth rings of the tree. This is the most serious form of shake, and seriously ring shaken trees are not worth milling due to fractured boards. This is what ring shake looks like:

 

 

I've found it to be most prevalent in Sweet Chestnut - I've looked at many SC logs and only milled one.

 

* Star shake: Not as serious as ring shake, but severely shaken trees can still be a lost cause. Seems to be worst (in my experience) in oak up here. I wouldn't automatically disregard a star shaken log, but I'd look carefully at both ends. If you can't easily see the top end of a log, look at any larger branch stubs as the shake will still be visible through the branch stubs if it is present.

 

 

* Twist: Very few trees grow completely straight. It's the degree of twist that causes the issue. The best way to judge twist is to follow the pattern of the bark. Severely twisted trees tend to come from sites that are exposed or subject to other stresses. As such (for this moment ignoring the fact that the twist will result in boards that will twist the moment they are cut), trees like this should be avoided.

 

* Off centre heart: If you haven't seen the tree standing, you can still get a very good idea of how it grew by the position of the heart. In an ideal world, you would only mill logs with a dead centre heart, as these trees will yield boards that are most stable. A severely miscentred heart will mean huge tension in the log and result in boards that move a huge amount both on the mill and in drying. This is accentuated with softwoods - you won't believe the movement in milling larch with off centre hearts.

 

* Rot: Don't automatically disregard logs with rot. It might not extend as far as you think, and in some species (like elm) it's thought that rot can cause more colourful figure further up the tree. That said, on commonly available, lower value timber, firewood a half rotted log as it's not worth the effort.

 

* Metal: Metal is sometimes obvious, usually not. Look for usual lines across the butt (this often means fence wire), look at the position the tree grew in and look at the butt for discolouration (blue stain from metal is only really apparent in oak, but other species can give metal away sometimes). Accept that garden trees nearly always have metal in them, pray it's not too severe and don't bother with a metal detector as they really aren't that good.

 

* Branching: The number of acceptable branches on a log depends on your customers. If you are selling quartersawn oak, the number of acceptable branches is zero, or as close as is damn it. Garden furniture is the other end of the scale. Sometimes branching results in stunning figure - the difficulty comes later in getting it to dry flat and machining it. Very branchy logs at my yard usually end up as mantle pieces.

 

* Amount of time felled: For some species, a tree that has been down for a couple of years is better (oak for instance). For others (sycamore and pine mainly), it can be disastrous. Sycamore is very prone to grey staining and will grey within a couple of months of being felled, even if felled in winter. Pine goes blue. Get the right tree at the right time of year, and make sure you don't sit on it for too long if you can. Spruce is another one - dries fairly quickly in the round and becomes very hard to cut flat once part dried.

 

That's about all that springs to mind at the moment - do add to it!

[Mountain man]

Is shake in oak due to soil type?

[Big J]

Is shake in oak due to soil type?

 

No one is certain what causes it. Elm from sandy soil is supposed to have major problems, but I had 50 tonnes last month from a sandy site and it was fine

[Mountain man]

Ok cheers, does a tree have to be felled to assess the presence of shake (last question!)

[devon TWiG]

As a general rule trees grown on deep fertile soils tend to be shake free , but on coastal and upland areas with stony ,free draining soils are not so good , often a local timber merchant will express an interest ( or not ) after telling them where the wood is !

[Mountain man]

Thanks Twig, that has been my experience, at least when trying to sell wood to a sawmill.

They have also pointed out faults in the bark which point to its likely presence.

[openspaceman]

Thanks Twig, that has been my experience, at least when trying to sell wood to a sawmill.

They have also pointed out faults in the bark which point to its likely presence.

 

One can sometimes see a sign of star shake in the bark but I've not seen any evidence of ring shake showing in the bark.

 

Ring shake is often in larger butts of sweet chestnut, normally present after the bark has chequered, younger fast grown trees with smooth bark are normally ok.

 

Often with older butts the ring shake is in a cone and can appear to be sounded out by cutting rings off. striking a narrow ring to split it and looking at the split surface will often reveal a greyness showing an undetectable de-lamination.

[agg221]

Some useful thoughts on this thread (particularly agree with Jonathan over not bothering with a metal detector). A few more thoughts from me:

 

For those with budget/space constraints, log handling presents an issue. You can move and roll a surprising amount with a 2 ton engine hoist from Screwfix or similar. You can even edge stuff over rough ground a couple of feet at a go by letting it dig in and dragging in steps. A big toe jack is also very handy for rolling large lumps around and lifting them clear of the ground if you want to run a mini-mill down them for quartering.

 

Stickers - a standard pallet is a good source of well dried material. Sawing through the slats, close up to the nailing points. This will produce a series of lengths of around 16" which can be ripped down with a standard circular saw or bandsaw to make a good number of stickers per pallet - around 100.

 

I break down a log with a sawmill that runs on a rail fixed to the log (e.g. an Alaskan) in the following order:

1. Rest the rail on the top of the log measuring up from the centre at each end and propping it so that the two heights are equal and work out where the rail is resting, and how much needs to come off where to get it stable.

2. Knock any knots or lumps off the top first - I find a decent side axe is quicker and easier for this than a chainsaw by the time you have had several goes to get it secure. 3. Once the rail rests well on the log and is wedged so that it won't dip, take the first cut thin, just enough to create a continuous surface to run the mill down.

4. The next cut is dead up the centre of the log as this takes out the maximum amount of stress.

5. Either quarter by sawing each half vertically, or through and through saw boards off the two flat surfaces. If different thicknesses are needed, take the thickest sections furthest out from the centre as they will be more stable.

 

Alec

[morten]

Guide for buying logs:

 

Things to look out for with all species:

 

...

 

That's about all that springs to mind at the moment - do add to it!

 

Birch: Mill within a few weeks of felling. If left for months in the round, it will rot and become useless. If left for a year in the round, it will not even be worth cutting up for firewood.

[wardenjohnny]

is there a good web site one can get spares for the Alaskan mill?