September 2003
The first job this month was to finish off the lofting table.
Now I need to create some long sheets of ply, ~20' long in fact.
Researching 'scarffing' techniques shows that there are two popular methods involving jigs
fitted to power tools with a third elementary method which involves stacking the plywood
to form a staircase with the tread depth equal to the scarf length and then planing away the
tread and riser until the surface is flat.
I've chosen the power tool approach and invested in a
'West System' scarffing attachment for a circular saw.
Which when assembled onto my Hitachi C9U looks like this.
The manual supplied is very thorough although full of contradictions, like drilling
1/4" holes for 5/16" bolts and then only supplying 4 bolts after asking for 5 holes.
In practise it's very easy to use. The 1250W C9U just rips through 3/8" ply effortlessly and
produces results like this.
I've experimented with the depth of cut. The recommended stand back
of 3 5/8" leaves an edge ~0.050" thick which is clearly not feather edged enough. I should
probably reduce the blade to plate dimension but that would involve filling holes. However,
adjusting the stand back dimension to 3 15/16" when the machine capacity is 4"
gives a nice 0.015" edge which is probably the minimum you can practically work with.