Cutting on a marked line

xabi

Let’s say I want to cut a 12” piece of wood, I measure 12” mark and square it. For precision, do it cut to remove the pencil line, or leave the pencil line visible after the cut. If I cut on the line am I not losing the saw width from the 12”?

phormium

Depends a bit on the saw you are using, I have a couple of different type saws and the thickness of the cut line varies. For the circular one I use I would always go slightly to right of pencil and that will leave most of the line there, if I cut it directly on the line I would definitely be short a tad for the 12" . Do a test cut on a scrap and see which gives you the most accurate result.

xabi

I don’t have stable saw but watching a video got me thinking, you measure from the fence to the closest tooth and set it, in that case the the whole line would be visible. With a hand saw isn’t it the same principle?

tabby aspreme

Cut to the line, if you remove the line you have nothing to work to.

dathi

cut to the line it is easier to plane off a millimeter than to add one back on.

my3cents

You could write a book on this and the consequences it has on the design of what you are making.

In the OP's case it also matters a lot where he draws the line in the first place.

For example if the straight edge is exactly on the 12 inch mark then the middle of the pencil line is going to be either a tad bigger than 12 inches or a tad less depending if the straight edge is on the part that is left or the part that is to be cut out. Now we have introduced the magic difficult to describe often ignored "tad" - its a bit like Schrodinger's cat.

If I want something an exact size I'd always mark out with the straight edge on the part I'm cutting to length (12inch in this case plus a tad) and cut (on the opposite side of the piece we are cutting out) so I just remove the line as I cut (removing the tad with it). For better accuracy that I'd rarely need I'd mark out with a marking knife which has less thickness than a pencil and pre-scores the cut. Even then you need to take certain precautions for to be really accurate.

Where items need to be fitted together the tad can be used to make sure that something fits first time by making sure the tads add up in the right way. One part may be cut accurately with little or no tad error and another part that has to fit can be a tad smaller. The tad can be the thickness of your pencil line, half the thickness of your pencil line, the thickness of the saw blade half the thickness of the saw blade or anything that has a thickness that is used in the measurement or cutting.

I make the odd shed and chicken coop, I embrace the tad. When cutting out shiplap sidings in most cases I don't want them to be bigger than the frame they are going on (otherwise the frames won't fit together) so the tad is the full width of the saw blade. Very few components need massive accuracy apart from the roof framing where exact angles are used and the tad is eliminated wherever possible.

This all reminds me of a very old boat building joke. A cabinet maker works to the nearest 1/16th of an inch a joiner to the nearest 1/8th of and inch and the boat builder to the nearest boat. If you get that then you understand a bit about measuring and cutting.

dathi wrote: »

cut to the line it is easier to plane off a millimeter than to add one back on.

While a good point I find if you take that attitude its not long before every cutting job becomes a two part job cutting first with a saw and then planning off any excess. You need to cut accurately with a saw and no excuse nowadays with power tools.

policarp

My best method so far is to scribe a cut line with a sharp blade or knife.
Then cut along one side of the score mark.

jmBuildExt

I measure from left to write (i.e. so the line i want to cut is on the right)
Then with a sharp pencil (thin line) I mark the timber in line with the mark on the tape.
Draw my square line with same thin point pencil.
Then try to cut along the right half of the line

my3cents

jmBuildExt wrote: »

I measure from left to write (i.e. so the line i want to cut is on the right)
Then with a sharp pencil (thin line) I mark the timber in line with the mark on the tape.
Draw my square line with same thin point pencil.
Then try to cut along the right half of the line

If I'm cutting a lot of lengths I find it easier, quicker and more accurate to do similar except I don't make the first mark. Instead I hold a roofing square (the triangular ones) on the wood and slide it up under the correct dimension on the tape then draw in my line. Then I measure to the line to double check I haven't cocked it up.

jack of all

For really accurate work mark with a marking knife, which creates a shallow "vee" cut, then run a pencil in the "vee". Cut along the mark removing half of the "vee".