More accuracy in cuts

[chrisknight67]

Hi. This is going to seem like a basic question, but can people help me make more precise cuts?

Today, for example, I was cutting Sheetrock and each cut was just a little bit too long. I think that, from the time I mark the cuts with the measuring tape, trace the marks along the length of the Sheetrock and then cut the Sheetrock, I am losing a bit of accuracy in each step.

I know I am losing a little precision with the measuring tape. Is there a better measuring tape out there to help people make exact pencil marks? My measuring tape changes slightly, for example, depending on whether I stretch it tightly or just lay it down and mark the cuts.

What I would like to have is a good method of measuring a piece of wood, marking the measurements, drawing or snapping a line and then cutting it to the exact size, whether I am using a handsaw or table saw.

Also, the cutting of the blade removes a certain amount of wood as well, changing the measurement slightly. How do we factor this in?

Sincerely,

Chris Knight, Paris, France

[dwacker]

In the shop I use a sharp 2.0mm mechanical pencil and keep it sharp. For furniture and things that need to be precise I use a marking knife.

Don

[Beechwood Chip]

The blade removes a certain amount of material (turns it into sawdust so it's no longer part of either piece after the cut). That's called the kerf. Also, your pencil line has a certain thickness. So, you need to line up one side of the pencil line with one side of the saw blade, so the edge of the blade lines up with the edge of the line. When marking, people often indicate which side the kerf is one with a squiggly line.

As Don pointed out, using a fine pencil or a marking knife gives you a thinner line. Also, a marking knife can give you a cleaner cut.

[Darnell Hagen]

I seriously love that your getting super precise for drywall. No joke, that's awesome.

Your tape could be worn, or the tounge bent. If it moves more than it's thickness the rivet holes are wallowed. Measure with the tounge engaged, then to the same mark starting at the 10" line. The measurement should match. Do this with an inside corner, as well.

If you're measuring floor to ceiling, make a mark 60" up from the floor, measure down to the mark, and add the two together. You can't get an accurate read from a bent tape, and could be the cause of your overlength panels.

[chrisknight67]

Hi, everyone. Thanks for the help. My cutting will be much better now. I think the rivets are, indeed, bad on my measuring tape. I appreciate your time. Chris

[Bombarde16]

Drop the pencil and start using a blade. (An X-acto, a utility knife, a scribe or whatever) It's more precise than the sharpest pencil and is easier to see on darker species of wood.

[CessnaPilotBarry]

I was taught to split the line with one side of the kerf, with the rest of the blade kerf going to the waste side, regardless of marking with pencil or knife. Even with a reasonably sharp pencil, this makes for a seriously precise cut. I prefer a knife when hand sawing, on chippy woods, and when transferring marks from other pieces, as the knife doesn't have the offset like a pencil.

If using multiple marks with a tape, mark the edges first, then add some internal marks. If you lay a straight edge across the work, from edge mark to edge mark, you may notice that some of the internal marks won't align. Each measurement from the reference edge needs to be 90 degrees. The farther you deviate from 90, the more imprecise those marks will be. I would not snap a line on wood, draw it with a ruler. In my experience, the snapped line is fine for aligning rough carpentry parts, but can bow or belly too much for finer woodworking.

Ditto on the Sheetrock comment! That's such a difficult material to cut precisely, most folks will get close enough and let the tape and mud to the rest...

[bois]

I'd also suggest using referential measurement whenever possible. I lay out most components against the pieces they will fit against to avoid problems transferring measurements. I usually put away my measuring tape after laying out basic height, with, and depth dimensions. And I then use a marking knife to transfer from one piece to the next. Also you can use stops on your miter saw or table saw to ensure you are cutting equal length pieces exactly to the same length. Just a few suggestions among many tricks out there.