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 Sawing eucalypt with Mahoe multi-blade circular sawmill

The Mahoe is a cost efficient mill for production sawing. The main issue is movement off the saw, in particular crook. This, to some degree is compensated for by: 

  • Flatsawing of species not prone to drying degrade;
  • oversizing width cuts (e.g. 110 mm for nominal 100 mm boards);
  • cutting logs in long lengths and then docking boards off the saw into shorter lengths at knots.

After drying, shorter lengths of crooked boards can then be dressed twice through the four-sider, firstly blanked (i.e. square dressed) and then finished to size/profile. The machining straightens the boards, provided the four sider is fitted with straightening heads.

The longer log lengths also help to minimise degrade resulting from end-splits.

Note: Larger logs tend to move less off the saw.

Boards are easily graded off-saw according to sapwood content and quality.

Although to some degree the sawyer can choose to quarter or flat saw, there will always be a mix of the two along with riftsawn boards. For difficult to season species such as E. nitens the grade recoveries may be lower for the flat-sawn material (mostly due to surface and internal checking). For species which season well as flat-sawn boards this mill is fast and cost-efficient.

The corewood is generally boxed out as two 100x50 boards which may be used for firewood or sold as box grade for farm use. It may be very weak and riddled with shakes and has very little if any value.

Quite a few cuts are made to remove waste slabwood and produce a flat surface from which to saw boards. However, the mahoe sawmill is fast and efficient.

 

Flatsawn boards do not tend to move much, and mostly as bow rather than crook. Bow is not a serious problem because this should straighten in the stack, especially if weighted.

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Quartersawn boards tend to crook.
Movement can be unpredictable sawing boards off a log, here a flatsawn board is crooked.

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Half way through the log the log position is changed to compensate for taper and the face is recut before cutting more boards.
Nearly finished, the remainder will be slabwood.

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The core. This needs to be boxed out of product.
Boxed out 100mm x 50mm corewood separated out as "box grade".

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Cutting crooked boards at the knots.
Crooked boards have been cut at the knots and block stacked awaiting filleting.

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