On 27 Dec 96  23:48:25 Roy McNeill typed to Niels Petersen ....

Hi Roy

 >  NP>  Using them at less than 20%
 >  NP>  moisture figure (used for kiln dried) will result in some further
 >  NP>  shrinkage after they are in situ which will leave noticable gaps.
 >  NP>  For a good finish you need them _fully_ dried.

 > I don't quite understand - do you mean that a too dry timber can
 > give problems similar to wet timber problems?

 Just my wording on a bad day.   Let me try gain......

Using kiln dried timber (~20% moisture) or timber with a greater moisture
content can result in further shrinkage in the finished product. This
will result in gaps where the timber has been joined as the moisture
drops to below 20% over time.

IOW If you want a good job, don't use kiln dried !!
    Use air dried where the moisture content has reached its lowest
    point.


 >  NP> For air drying, the timber needs to be stacked level and straight, with
 >  NP> at least a 1" gap between each board and each layer
separated by 1"
 >  NP> thick separators.  If the separators are laced about a foot apart and
 >  NP> the stack is of sufficient size, the weight of the timber itself will
 >  NP> reduce the warping and twisting to a minimum.

 > I heard a radio article on the subject just a few days before I
 > read this, kicked myself, went home and stacked the planks. I'd had
 > them just standing on edge, and two of the 13 were warping visibly.

 They will go in all directions as there is nothing to hold them still!
Tthe timber does not dry at the same rate along the length of the plank.

 > They're now in a spaced stack, with a few bricks on top.

 Put more weight on them


 > The garage
 > floor should be reasonably level over the 2 metre length of the
 > planks

 YEP

 > The spacers
 > are about a metre apart, though; I'll put in some more after
 > checking that the planks are reasonably even in thickness.

 The spacers need to be about a foot apart.


 >  NP> I found a rule of thumb figure was to get 30% more timber than required
 >  NP> and you will wnd up with enough straight stuff for the job.

 > Could be a bit tight; I'll need about 6 planks for the job, and a
 > few of the 13 are a bit thicker than the rest.

 Get them put through a thicknesser.


 >  NP> I know that 2 years seems a long time but it is worth the wait if you
 > are  doing something like laminated timber bench tops.

 > You've convinced me. I'll make a temporary top for the cupboard
 > while the good stuff dries.

It's the only way to go.
For some interim top timber, try dumpster diving at the local business
furniture manufacturer. I've got heaps of 3/4"& 1" laminated both sides
craft board that I have used for shelving etc at no cost :-).


 > I saw a program on telly about this quite a while ago - a
 > woodturning mob (a company or a school, I can't recall) found that
 > if they microwaved (as in microwave oven) newish timber, it would
 > become well-behaved timber, just as if it had been aged, and could
 > be safely lathed into bowls or table legs or whatever. I don't
 > think I'll find a microwave oven around here that can take 2 metre
 > planks, though...

 I knew about the microwaving. Somewhere there is a commercial setup
 that they feed the planks through, It's made up of about 50 Microwave
 setups end to end.  Goes in green and comes out dry.



 >  NP> in a later house and some 3x2's that were Blue Gum railway sleeper
 >  NP> offcuts.  (The Blue Gum HAD to be drilled just to get a nail to go in)
 >  NP> :-)

 > sounds familiar. Self drilling screws don't work in this stuff,
 > either.

 How many did you split before you came to that conclusion ? :-)


 >  NP> Best of luck ;-)
 > Gee ta. I have a secondary project now, a barbecue stand, that will
 > use some of the planks I can't use on the benchtop. I plan to cut
 > one plank into 500 x 60 x 15mm slats for the tops. I've seen thinner
 > offcuts of this stuff warp like crazy, I'm about to learn if 15mm
 > thick bits, screwed down at both ends, will warp...

 They will !!!
 I'd put a cross member at the 250mm mark or even 2 crossmembers at 1/3
 & 2/3 distance from the end. Even if they are only temporary to stop the
 warpage and are removed later.


 > Here's a semi-related question - is there an economical way of
 > buying or making a 2 or 3 metre long straightedge?

 Get some 25mm x 5mm aluminium rod (comes in about 5 metre lengths) or
 even 40mm x 5mm. Very light and does the job perfectly. 40mm x 3mm is
 also available but tends to bend too easily. (Two lengths screwed
 together would stop this of course.)  I got 4 lengths and that
 cost me $34 (wholesale) so it is about $8.50 a length on average. The
 sizes I got were a mix so the individual pricing is only a guess.  The
 25mm x 5mm takes a vice and all your weight to bend it permanently.

 Rob Young & I used it to build my back brace (1 day) and
 _it_doesn't_bend_ !  Quite a bit cheaper than the $600+ figure the
 professionals wanted to build one in 3 months :-(


 > Cheers, and ta for advice

 Not a problem!
 Why should you make the same mistakes that I learnt NOT to make years ago :-)

Regards
Niels

* OLR 5.1 *  Cut your own firewood and it'll warm you twice.

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