jdowning - 11-14-2012 at 12:58 PM
For the serious luthier or woodworker always having a good supply of seasoned wood in stock is desirable.
The lowest cost way to build up a stock of wood is to cut and season the wood yourself.
This afternoon - weather being sunny and cool - I started work on converting some pine logs on my property into boards using a portable chainsaw mill.
I thought that the procedure might be of general interest to post here.
An advantage of a chainsaw mill is that it can be used to cut large diameter logs into boards that are too large for (more costly) portable bandsaw
mills to handle or where access in a woodlot is difficult. The chainsaw mill cuts a log where it lies on the ground without need for heavy equipment
to lift it.
There is often opportunity to obtain free access to storm damaged mature trees that can produce high quality lumber or to trees that must otherwise be
removed.
The basic concept is simple. A chainsaw is clamped to a frame that slides across the top of a log making a series of horizontal cuts. The thickness of
each cut can be adjusted by setting the saw blade higher or lower in the frame.
Chainsaw mills are commercially available although they are simple enough to be made. Mine is a 30 inch Granberg mill capable of cutting a 24 inch
wide board. The ripping action of the saw requires more power than cross cutting which is what chainsaws are normally designed for. My saw is a
powerful Stihl 084 - 122 cc capacity, now no longer available (replaced by the even more powerful Stihl MS880 of the same capacity). This saw is the
type used by lumberjacks on the West coast of Canada and the USA for felling very large diameter trees - capable of powering a saw blade (bar) of up
to 8 feet (2.4 metres) in length.
How these professional tree fellers have the physical strength handle these heavy saws in a days work is beyond me!
The work that I have in hand is less demanding. My pine logs are up to 15 inches in diameter (0.4 meter) - cut down last year to provide clear safe
access for electrical power lines to our property.
More to follow
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jdowning - 11-14-2012 at 01:14 PM
Here is an example of how these big chainsaws are designed to be used - for felling large trees.
Do not try this at home!
http://www.youtube.com/watch?feature=player_detailpage&v=HdgMcb...
jdowning - 11-14-2012 at 04:29 PM
.... and here is the same chainsaw power head with only a 30 inch long bar mounted in the chainsaw mill frame. Power to spare for the task in hand!
jdowning - 11-14-2012 at 04:37 PM
Logs being irregular and tapered in length, the first step is to set up a temporary straight platform along which the chainsaw mill can slide for the
first cut. Here i am using an aluminium ladder attached to two supports screwed to the log.
The height of each support is adjusted to compensate for the taper of the log - so that the saw cuts parallel to the centre line of the log.
jdowning - 11-14-2012 at 04:50 PM
Here is the first cut in progress. The saw bar depth has been set to safely clear the hold down screws supporting the temporary ladder supports.
So that the saw blade does not 'bind' or stick as the cut proceeds, temporary wooden spacers are hammered into the open cut (or kerf) at intervals.
The spacers are 3/8 inch thick in this case.
jdowning - 11-15-2012 at 05:21 PM
With the first cut completed the ladder guide together with the top slab of wood is removed to reveal a flat surface.
The depth of cut of the chainsaw mill was then set to 1 inch (25 mm) and the mill then slid over the flat surface for the second cut. This produced a
board 1 inch in thickness.
The process was then repeated - without changing the depth of cut - until six sawn boards were produced.
Other logs may be cut to provide sawn lumber of larger cross section dimensions.
The rough sawn green lumber produced from this log amounted to about 60 Board Feet. A Board Foot is a lumber measurement equivalent to a square foot
of wood of 1 inch thickness.
The boards are low grade lumber - useful only for shelving or repairs to the cladding of my out buildings. Nevertheless total retail value of the wood
is about $50. Not much for the time and effort involved but I hate to see these logs otherwise go to waste.
A better return may be realised by cutting hardwood species where value might be up to $10 a board ft.or more.
The green wood must now be properly stacked and air dried to avoid spoilage.
jdowning - 11-15-2012 at 05:41 PM
... and here for information is a video of a Granberg chainsaw mill being used to cut square beam lumber. The chainsaw power head in this case is a
Stihl MS660 less powerful than mine but still adequate for cutting softwood logs.
I like the design of the ladder guide rail system.
http://www.youtube.com/watch?v=m4a-56Pxic8
jdowning - 11-16-2012 at 12:53 PM
For those interested in using a chainsaw mill for making lumber the definitive work is "Chainsaw Lumbermaking" by Will Malloff - an excellent manual
on the subject. Now out of print it can still be purchased for about $30+ on line. It can also be read for free at Scribd:
http://www.scribd.com/doc/23255653/Chainsaw-Lumber-Making
For information, the saw chain that I used for cutting this softwood log is a standard skip tooth chain designed for cross cutting and felling trees.
This works but is not very efficient for cutting along the grain of a log (ripping).
For rip cutting of hardwoods I use a chisel tooth chain - specially modified from a standard cross cut chain - according to the design proposed by
Will Malloff in his book. This type of saw chain is much more efficient for heavier duty cutting requirements.
Modifying a standard saw chain can be done by hand with a chainsaw file but is easier, faster and more accurately achieved with a power chainsaw
grinder.
SamirCanada - 11-16-2012 at 01:01 PM
Thanks for sharing john. thats very interesting.
jdowning - 11-17-2012 at 01:21 PM
The freshly cut 'green' lumber must be properly stored to air dry and season.
The lumber must be stacked on a solid level surface and 'stickered' to allow air to circulate. The ends of each board should also be sealed with paint
or wax to prevent splitting of the ends of a board caused by too rapid drying.
My wood seasoning area is, conveniently, part of an old barn where there is level concrete flooring - protected from the elements but with less free
air circulation than might be otherwise be achieved with a covered stack of lumber outside.
The wood is stacked with strips of pine in between each board (stickered).
The pile of boards is then uniformly weighed down (to minimise distortion of the boards as they dry) with a heavy, straight hardwood beam.
In this case the boards have been cut to a thickness of only 1 inch so will be ready to use next year in their rough sawn state to be used as storage
shelving. It is better, however, to cut boards thicker than this so that any distortion on drying is minimised. A board thickness of at least 2 inches
is best although these take longer to dry (allow a year for each inch of thickness).
Another advantage of using a chainsaw mill is that they can easily convert short lengths of logs to boards - such as tree stumps or crotches of less
than a metre in length - where there might be spectacular grain figure of interest to to both luthiers and fine woodworkers.