There are many ways to move a printhead around a XY coordinate system, the most common kinematics are:
I have choosen to go with the Crossed Gantry style kinematics. But why?
Most people familiar with 3d printers will recognize this motion platform from the ultimaker machines. I always admired ultimaker for the print quality they could produce, but at the same time thought their machines were hugely overpriced, and their close sourced/hard to mod mentality also don’t help my view on them, after all I like to tinker and mod stuff. I personally would never buy a ultimaker simply because I believe the same amount of money can be spend better elsewhere. The crossed gantry mechanism consists of 4 stationary smooth rods and two moving smooth rods. The two moving rods are then connected via two bearing/bushings on the print head(.
Researching for this project I came across a open source design team called annex engineering. I never heard of them before, but they make some pretty impressive designs! Go check them out. I also found a machine called CroXY on GitHub
These two projects take on the crossed gantry mechanism (Lets call it CroXY – Brilliant name!) is much more elegant than ultimakers I think – mainly due to two design choices:
While ultimakers method is undoubtedly the cheapest method and obviously good enough when well implemented, there are no doubts that the CroXY style is superior when you want to make larger machines and push the limits of acceleration. The CroXY design is far superior to any of the other common designs out there, the most popular ones being CoreXY and bedslingers. Here are some of the major benefits
All that being said. A properly designed CoreXY machine can perform more than good enough. Just take a look at what Simon Vez is doing with his VzBot:
That thing is crazy! But he is also using 4 motors on this design – Not a common thing to see on coreXY machines.
Of course CroXY is not just a dance on roses, there are three main disadvantages over let’s say a classic CoreXY when building a tool changing machine.
So why CroXY? I do believe it is the ultimate motion platform for 3D printers due to the points listed above. And.. it looks cool!