Since it's Christmas, it must be time to inflict home-made marmalade on my friends.
Giving people two jars on the big day means that they have to juggle, which is funny, but not very kind, so I decided to make small cases to hold the jars together.
A couple of prototypes produced a design which I felt could be mass-produced quickly, and that is what is presented here.
Experiments showed that two plates of plywood with holes slightly larger than the jam jars, connected by a webbing strap-handle and with rails on the base as feet, and over the top as a lid, held the jars securely, while keeping them safe from breakage.
Making ten cases used about a square yard of 1/2" ply (about a square metre of 12mm) and about five yards (4.5 metres) of webbing.
Step 1: Cutting the Pieces
The wooden plates which have the jars embedded in them need to be large enough that there is sufficient strength even after the holes have been cut. I needed pieces about 5" by 8" (120mmx220). I also needed thin strips to fix across the top of the upper plate and the underside of the base, which needed to be about an inch wide (25mm).
I used a jig to rip four one inch strips from the edge of one of the pieces of plywood, and then cut the remainder of the ply into 8" (220mm) strips.
Leaving the thin pieces aside for the nonce, I stacked the wider pieces up and cut them (four at a time) into 5" lengths, giving the 5x8 I wanted.
All of these plates were stacked together and then the circular saw was set to do a 45degree cut. Running that along the four edges of the stack of plates left a pile of small triangles and an irregular octagonal prism comprising of the plates, each with a chamfered corner.
Step 2: Holes and Slot
I took a holesaw slightly larger than the jars would be, and fitted that to the arbor including the pilot drill.
I marked the required center point for the two holes, and built a jig on the platten of the drill press to hold each plate in the correct location. This was adjusted until the pilot drill in the holesaw was perfectly aligned with the center of the hole location.
With the drill and jig set up, I removed the pilot bit from the holesaw so that the circular pieces would be removed without a central hole.
Then I drilled forty large-diameter holes using the holesaw. This is a very cheap and not very good saw, so I had to stop after each hole and wipe the holesaw down with a damp rag to remove some of the waste heat. This was a bit of a nuisance, but it meant that I didn't have to keep waiting for the saw to cool in the ambient air.
Once the holes were all cut, I smoothed all of the outside edges of the plates with a fairly coarse sandpaper on a machine, and also removed any frayed bits left by the holesaw using a sanding block.
Then I used a jigsaw to join up the two holes with a straight cut at the closest approach. This cut has to be wide enough to allow a double-layer of the webbing through, but narrow enough that the webbing is slightly pinched.
For the blade which I had in my saw, this required two passes. If you have a wider kerf on your jigsaw, or choose to use a padsaw or other handsaw, then please check on a piece of scrap that you aren't leaving too wide a gap.
Step 3: Making and Fitting Feet and Lids
Returning to the inch wide strips cut earlier, I measured the length needed to bridge the holes while not encroaching over the edge of the plate.
The strips were stacked up and cut at a 45 degree angle to produce trapezoidal prisms and shown in the fourth photograph above.
Once they were all cut, they were glued in place with a single drop of PVA wood glue (Elmers) at each end and then stacked up and clamped overnight for the glue to cure.
Since I was using really poor quality plywood, I had to be careful to ensure that the "better" (i.e. less worse) side was upright, so that the plates which would form upper pieces were fitted with a bar which also showed the "better" side uppermost, and similarly for the lower plates.
EDITED TO ADD:-
No fewer than five of the feet/tops lost adhesion during transit. The boxes did an excellent job of protecting all the jars from the vicissitudes of airline baggage systems (no jars broken!), but five of the feet/tops separated from their plate. They were clamped with my usual enthusiasm during curing, so I am going to suggest that an additional mechanical fastener might be needed on these parts, unless the boxes are redesigned to have a larger contact area for this joint.
Step 4: Sand and Oil
Once the glue had cured, I hand-sanded all of the pieces and then applied a coat of Danish oil.
Since these are just packaging, I did not bother with multiple coats and inter-coat sanding. The end result is fine and doesn't feel or look too bad.
Step 5: Making and Fitting Handles
The prototype had shown that 16" of webbing (400mm) gave a good length of handle for most of the jars I was using.
It works out at about eight inches (220mm) more than _double_ the height of the jar. That gives a nice amount to grip in the hand, and three-quarters of an inch (20mm) to fasten to the lower plate.
The webbing was cut into the relevant lengths, and then each end was heat sealed with a flame.
The doubled-over webbing is slid into the slot of the lower plate, then opened out underneath so that each end is spread flat against the wood.
I used an air-stapler to fasten the webbing securely, but a hand-operated staple-gun would probably be fine, or screw/clamp/knot/sewing.
Then the doubled over strap is slid into the slot of the upper plate, the jars are inserted and the upper plate is slid down the webbing to trap the tops of the jars.
Step 6: Labels and Finishing
So that people know what they are eating, I printed labels for the jars.
A couple of tests using plain paper showed that I could fit enough little labels for all jars onto a single A4 sticky-label. I have attached the file which I used, but you'll probably be faster starting from scratch. If you lack a printer or full-sheet labels, then I'm sure that your local copy-shop will be able to do the print-to-label for not much money.
The individual labels were cut out using a craft knife, and then the corners were rounded using a corner punch.
Then the sticky labels (title on one end, ingredients on the other) were wrapped around the edge of a piece of stiff cardboard, and pressed hard to ensure good adhesion.
Punching a single hole and cutting into a classic luggage-tag shape produced some very nice-looking labels.
I looped a colored rubber band through the hole and then stretched that around the neck of the jar just below the lid.
The end result is a home-made gift which looks a bit more impressive than a jar with a Dymo tape on it.
If you make something similar, I'd love to see the results in an "I made it".