Thickness

[MichaelMouse]

The 3/4" is just a convenient number. Boards rough sawed at 1" (fractionally over to meet grading specs) should shrink as they dry, and still allow enough to plane down to 3/4". So plans and jigs / tools are made with this in mind. Here we rough saw to 25mm (0.984"), and plane to 19mm (0.748"). But no one normally measures that close, because next week the numbers will have changed

Of note, though not here, hardwood is supposed to be surfaced to 13/16 per NHLA.  Softwood standard is 3/4.  Not sure of NZ standard.

[Bill Tindall]

I have some plans for a barristers bookcase. The plans call for quartersawn white oak, 3/4" thick. I finally located some, but of course had to plane it down. I have it at .753". When planing boards to size, what do yo consider close enough? + or - .005, or do you strive for perfection, every time? Would you rather be slightly over or under?
I'll probably have a lot of stupid questions like this. I really appreciate your patience.

Thanks Greg

The specification in the plans was arbitrary.  Depending on details of the mill logs are sawed between 1 and 1 1/8" thick to make the lumber you used. The lumber shrinks some during drying and winds up about 1" thick in the rough.  If commercially planed it will be sized to 13/16".  In almost all cases stuff gets built from this 13/16" thickness.  In all the years we sold lumber I don't recall a customer adjusting the size of the planed lumber we sold beyond finish sanding.  

If starting with rough lumber an individual can usually squeeze out a 7/8" thickness.  A lot of furniture looks better made from this thickness.  

A caution about plans. They can have errors.  They can be created by someone not skilled at woodworking.  Before starting always go through the plans to confirm reliability.  

Here is the one of the best pieces of advice you will get on building stuff.  Do not cut a piece of wood to size until you need it.  Then take the dimension needed off the piece under construction, not relying on the plan to predict a door will be exactly 18.00", for example.

[CStan]

I have some plans for a barristers bookcase. The plans call for quartersawn white oak, 3/4" thick. I finally located some, but of course had to plane it down. I have it at .753". When planing boards to size, what do yo consider close enough? + or - .005, or do you strive for perfection, every time? Would you rather be slightly over or under?
I'll probably have a lot of stupid questions like this. I really appreciate your patience.

Thanks Greg

That's probably about the thickness of the lines on a folding ruler.  You're fine.  Carry on.

The shop standard has long been 7/8" out of 4/4 but you don't walk up to a board that basically contorted itself into a propeller and expect that. It's a shop standard assuming an adequate lumber inventory, and sense enough to not put what is obviously reaction wood into a furniture project.

[EdL]

I just make everything a uniform thickness.....if its .005 off, who cares.

On my own designs, if the stock finishes at 7/8, thats what gets used.

Ed