Lessons in Accuracy – Reworking Frame C

With the MDF extension in place, I went ahead and started marking the top side of Frame C. That’s when things got... interesting.

Unlike Frame B, which is open at the top, Frame C is a closed frame, and that makes accuracy on the upper section even more critical. Once I marked all the points and stepped back to check, I quickly saw that something was off—the top corner points didn’t align symmetrically with the centerline as they should. There was a noticeable error, and no amount of re-measuring or adjusting seemed to solve it.

After several frustrating attempts, it became clear what was going wrong: measuring distant points from the origin (0,0) isn’t very reliable. When you’re working across a board that’s more than two meters wide, it’s natural to measure in multiple steps, and even a few millimeters of error in each one start to add up fast.

So I decided to stop, erase everything, and go back to the method I probably should’ve used from the beginning.

I started fresh: carefully redrew the waterline and centerline, then took the time to draw a full 10x10 cm grid across the entire board. It might sound tedious (and it was), but it’s a game-changer. Even drawing the grid was tricky—keeping long lines straight over such a large area isn’t easy. I ended up using one of the straight MDF offcuts from the extension I built earlier, relying on the precision of the table saw cuts to act as a makeshift long ruler.

Using the MDF offcut as a long ruler

Even after all that, not every square on the grid ended up being exactly 10 by 10 cm. But the key advantage is that the grid lets me reference coordinates directly from the plans without relying on long, error-prone measurements. For every point, I’d measure from multiple adjacent squares to get an average position. That not only improved accuracy, but also gave me a better sense of which grid areas were slightly off—kind of like triangulating your position from multiple bearings on a chart.

Grid Completed

In the end, I managed to redraw Frame C with great precision. This time, the top left and right corners matched perfectly with the centerline and the plan's measurements. A big win.

So, what’s the takeaway here? Draw the grid. It takes time, but it pays for itself by eliminating a lot of measurement headaches later. And don’t blindly trust any one line—cross-reference everything, just like you would when navigating at sea.

The best news? My pine wood arrives tomorrow, so I’ll finally be able to start assembling the first frames. Can’t wait to move from pencils and rulers to glue and clamps.