Geological Sample in Presentation Case

A geologist friend left a small rock sample in my car when he visited.

So I could have

1. thrown it away
2. wrapped it up and send it to him
3. hand-crafted a needlessly complex presentation case for it.

I chose option 3).

To protect the sample, and to hold it securely, the case was going to be made from solid chunks.

A small scrap 3/4" (18mm) plywood was found which was large enough to form both the base and the lid of the case.

A holesaw large enough to contain the sample was used to cut two holes in the ply.

The edges and inside of the holes was given a quick tidy-up with 80 grit sandpaper and then a thin sheet of nice plywood was glued across the two holes and left clamped to cure.

The layered plywood was cut in half and the two halfs were aligned using the holesaw bit to orient them together.

Once the two parts were mated correctly, they were held together with screws and fixed to piece of scrap. This allowed the two pieces to be cut to the correct size with a circular saw.

A table saw would have made this much easier as a jig to hold the pieces safely would have been easier to make.

One cut line was drawn on the wrong side of the ruler, so the two halves of the box were left as shown in the last picture.

The two pieces of the case were cut too close to the storage space.

A scrap of hardwood laminate was glued to the short side of the wood, and once the glue had cured the excess hardwood was trimmed off to leave the edges flush with the ply.

Then the accidental offcuts were glued to the other side of the hardwood.

Disaster avoided.

The wood was sanded with 120, 180 and 240 grit paper, then dusted off and wiped clean.

Two coats of Danish oil were applied, with a very light 240 grit sanding between coats.

By orienting the hinges with the pin on the inside, the comb of the hinge acted as a prop for the lid when opened, and the back was smoother.

To fit the pin and housing of the hinge, a tiny (1/16", 1mm) rebate had to be cut out of most of the width of the hinge. The first photograph shows the rebate after it was cut. The second and third are sadly out of focus, but they show the surface veneer of the ply being scored deeply with a craft knife, and then a narrow chisel being used to chase out the rebate. This was all done by hand, but a tiny router (like a Dremel router attachment) could be used too.

The hinges were attached with matching brass screws, and then the catch at the front was fitted. Once the upper part of the catch was mounted, the box lid was clamped shut and then the lower part of the catch was matched and fitted. This meant that there was a tiny bit of tension in the catch when it is closed, and so the lid gives a nice little "pop" when the catch is released.

Using a compass cutter, two discs of self-adhesive felt were cut the correct diameter of the holes.

Two strips of felt as wide as the holes were deep (i.e. 3/4" or 17mm) were cut.

Once the felt had been fitted to the base of the recess, and the strip glued around the inside circumference, they were given an extra-hard push by thumb to make sure that they stuck well.

A label was printed out from Libre Office. I've obscured the location of the samples just in case picking up rocks in nature reserves is frowned upon. Since this is for a present, I sprung the 50 cents to have the file printed onto 250gsm paper at a copy shop.

The thick paper proved rather hard to cut cleanly with the compass cutter, so the tear marks on the edge were covered up with Sharpie (other felt-tip pens are available).

Centering the compass cutter was hard. I printed several poor-quality discs on 80gsm paper on my home printer and cut those for practice until I was able to determine the precise point for the centre pin of the compass cutter.

The finished box looks really nice, and took only a couple of hours of actual work (apart from drying times).

Marking on the wrong side of the ruler, and therefore cutting the box in the wrong place was a bit bone-headed. The recovery mechanism of gluing a sliver of hardwood in between the box and the offcut worked really well, and the result actually looks better. I may use a similar technique on a future box, but deliberately. How close I came to breaking the holesawn circle can be seen in the second photograph above, where the glue from the hardwood sliver is actually being forced through the end-grain plies of the plywood.