The coolest thing is invisible when it's assembled: I tried a new type of joinery, with dowel holes aligning with slots rather than matching dowel holes. It eliminates setups and allows for staged assembly:
The coolest thing is invisible when it's assembled: I tried a new type of joinery, with dowel holes aligning with slots rather than matching dowel holes. It eliminates setups and allows for staged assembly:
do the dowel-receiving slots create more "wiggle" in the construction? And is it tough to cut in the threads for the jar?
Excellent questions, as always.
The dowel slots are tight against three sides of the dowel, but definitely completely loose on the fourth. So that's a difference. But in the constrained directions they're very tight. Part of that is that the bit used to cut those slots is somewhat dull, so there was extra tear-out, which tightens the fit :-)
There is a sacrifice in glue area: when dowels are in circular holes you can glue them in and count on getting some decent fastening contact surface. In these slots I'd be less confident. However, we're not relying on glue here, because...
...We're actually not cutting threads to mate with the jar, we're creating a little liner that holds the jar lid in place. The fasteners that hold the liner are actually long bolts that come up from the bottom, so they'll hold the whole sandwich together, pulling on the liner - which pulls on the lid - which presses the walls down against the base.
In other devices of this sort, the lid/ring is often held on with little nails (!!) so you have the double risk of nails mixed in with your candy (yum) and lid-ring contact with your candy. That ring really shouldn't touch food: in the original Ball jar, that ring is only used to press the little rubberized lid down onto the glass. That's the food contact lid (though these days people are quite concerned about the BPA in the lid's coating... uh oh). We're replacing all that with polypropylene, like a yogurt tub, safe as can be and washable.