On the importance of precision

Dremel 4000 blueprint - Bento BoxOn Saturday, I started working on the Bento Box / Zen Garden. By evening, I got as far as finishing the tray box. It was a long day.

I mentioned before that my work has been suffering from unintentional sloppiness – crooked cuts, imprecise sanding angles, etc. Luckily or, perhaps, unluckily, I have been getting away with it on the small scale of the Hello Kitty café furniture – the tables and countertops were OK without perfect corners or balance, and glue held everything together in the end. This by-the-seat-of-my-pants approach came to a screeching halt with the Bento Box.

I started making the frame out of the 4.5cm-wide wooden corners, measuring two 30cm and two 50cm pieces. To join them at the corners, I wanted to make all cuts at 45° angles – a classic fit seen in most picture, window etc. frames. I vaguely remembered seeing sawing guides for cutting at an angle, but thought that I could do without. The protractor imprinted into the tabletop of my workbench is not particularly useful, and so I resorted to basic geometry: measure e.g. 2cm in one direction, measure 2cm perpendicular to the first, draw a diagonal by joining the two measures, and you’re good to go, right?

Well, practice turns out to be a bit more complicated than theory. For one, the edges of the wooden corners were rounded, and so measuring by eyeballing the ruler’s 0 to the edge was inconsistent. Secondly, as I have mentioned, my amateur jigsaw technique leaves a lot to be desired. 4 pieces × 2 ends each = 8 cuts. Multiply that by the uncertainty of the measurement and poor cutting, and you can predict the result: bad fit all around. Some angles were not 45°, elsewhere the cuts weren’t perfectly vertical, and all of them were not straight enough. I briefly tried putting it all together, but it became clear very quickly that this time such lack of precision simply wouldn’t fly.

Of course, I did try to use my Dremel 4000 to make things better. From the beginning, though, I suspected that I was wasting effort. Sanding waves and bumps out of a cut with a 432 sanding band is not likely to work well, and it’s very easy to make things worse by adding even more grooves and imperfections. Also, without a guide to maintain a perfect 90° angle, my Dremel technique suffers from the same problems as my jigsaw technique. So I took a break.

Now, a sawing guide that I mentioned earlier became a necessity. The tricky part was that it’s not called a sawing guide or any such thing, it’s called a mitre box – a fact that it took me around 30 min of internet browsing to figure out. With a little bit of new knowledge, I set out to build one. The only suitable material on hand was the same wooden corner, so I cut two ~15cm long pieces and glued them face-to-face on a piece of plywood. The 90° guide slot was the easiest one, and I cut it with the two pieces clamped together before they were even glued to the base. The 45° guide slots were tricky: I measured the angles as best I could with the bench-top protractor, and then went nice and slow with the jigsaw, constantly checking both sides of the mitre box to make sure I stayed on the lines. The end result was less than perfect, but it was enough to let me re-cut the corner pieces and put together the base tray, with a sheet of plywood serving as the bottom and PVA glue holding it all together.

Dremel 4000 - mitre box

I made all cuts with the pieces secured to the mitre box with C-clamps

This mitre box will be, no doubt, short-lived. It is too shallow and is made of very soft wood (pine, my guess), which means that the saw will cut into the sides of the box almost as easily as follow the guide slots. Nevertheless, it did it’s job today and may yet come in handy once or twice. If were lucky enough to have a garage or a workshop, I would almost definitely invest in a power mitre saw like this one or, if money were no object, in this Cadillac of mitre saws 🙂 .

The Bento Box project is now on hold as I’ve used up all the wooden corners and have nothing out of which to make the inner dividers.

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5 comments

  1. Pingback: Quick weekend project: kitchen tray « The Dremel Amateur
  2. Pingback: “Frame” earring rack « The Dremel Amateur
  3. Pingback: Made: Bento Box « The Dremel Amateur

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