3D printers - do you really need one?

We don't quite know where its gone, but the knob fell off the kettle, so no problem I just designed and printed out a new one. It was only after I finished the repair it dawned on me that after several years of owning a 3D printer its the first time I've actually needed to print a repair piece. I remember the decision process behind getting hold of my printer kit, even seeing articles saying that a 3D printer would pay for itself in no time at all! The main problem with this idea is that while you can make some interesting and occasionally useful things, the sad fact is that a 3D printer is simply not a Star Trek replicator, that said looking at some of the designs on the 'net you'd be forgiven for thinking this. Just because you buy a new hammer it doesn't mean everything is a nail, and the better way of thinking of a 3D printer is that its a tool just like any other piece of kit in your tool chest. Printing is slow, even a small item like a knob can take quarter of an hour to print, and if you're making something more complex and or larger you are easily looking at an hour or more print time, which can really suck if something goes wrong 80% through the print! fortunately I've got a good quality kit with a decent strong frame and arguably over spec'd motors, so I'm lucky that prints rarely go wrong (yeah I know tempting fate!). Even a simple small item like a bag clip to keep food fresh is possibly not the best use for a printer, you can pick up a bag of 10 for probably less than a quid, even just printing one could easily take 20 minutes or more, and due to the lack of malleability of most printable plastics, you may well find yourself with a worse clip in place of something costing not much more than 10 pence or less. Really careful consideration needs to be taken when designing for a 3d printer, while large overhangs just won't work sometimes just turning an object upside down can be enough, sometimes you might need to design in pieces and assemble them after printing. Other things to look out for are tolerances, while you probably won't be surprised that a 4mm peg won't fit into a 4mm hole, you often need to make much larger allowances than you'd think. To get the best out of a 3D printer you really do need to be able to do your own designs, if you rely solely on other peoples designs you can look forward to a load of wasted time and plastic, that said you can pick up the skills you need with something like OpenSCAD quite quickly, learning what you can and can't do with your printer might take you a little longer however. So do you really need one ? Almost certainly not! many people manage to survive quite happily without one, however if you are in anyway creative, they are a great tool, do you want one? well there's a good chance this is a rabbit hole you may well enjoy but only if you ignore the hype and keep your expectations realistic.