Kitchissippi Gemini 3D Printer
Project Description
This is an in-progress design for the machine – the source may change frequently and is not currently stable. Any questions can be directed to novakane on the freenode IRC channel #reprap
The Gemini is a CoreXY based 3D printer with dual extrusion capabilities and a large print volume. The machine is capable of depositing layers of filament from both extruders over it’s full print volume of 300mm x 300mm x 400+mm.
Initial object models were designed to minimize initial print time; test the underlying design theory; and finally, identify stress points in assembly. This makes the parts more fragile than a production model, however the initial K02.2 prototype successfully made several prints of decent quality. Most print failures may have been explained by early bed mounting and filament pusher mounting – these were done mostly as hacks to test the electronics and basic mechanism.
Current design work is aimed at producing a more robust mechanism with a polished look and feel.
Dual Material Printing
Many 3D printers can only deposit a single material per print. This limits the shapes of objects you can create without using difficult to remove same-material supports. Same-material support requires greater effort in post-print finishing and is impossible to use internally within an object.
With a second extruder you can use dissolvable filament such as HIPS or PVA which makes post-print removal of support material easy and clean.
Newer materials such as electrically conductive or carbon fibre filaments open up a world of possibility to embedding dissimilar materials within each other in the same print.
The Kitchissippi Gemini 3D Printer aims to make these possibilities a reality.
Large Volume Printing
Typical consumer 3D printers can only make small objects due to their limited print bed size and physical limitations. Scaling many of them up to the size of the Kitchissippi Gemini 3D Printer will introduce speed penalties due to the increased moving mass.
The larger the print area, the faster you want to be able to print to cover the increased volume. It is counter productive if the machine has to slow down to accommodate a larger mechanism.
The Kitchissippi Gemini 3D printer is scalable without compromises – the base prototype has a 300mm x 300mm print area with very little moving mass, allowing it to produce large objects in less time. The print bed itself only moves once per layer, vertically driven by precision lead screws. Only the extruder carriage is in constant motion and the heavy stepper motors for pushing the filament remain stationary.
CoreXY Linear Motion
Although there are many ways to achieve a stationary XY gantry, the Kitchissippi Gemini 3D Printer uses the CoreXY concept.
Instead of moving heavy hardened steel rods, the Gemini uses light-weight 9mm miniature linear slide rails which provide smooth but rigid linear motion. CoreXY eliminates the potential binding issues seen with HBot designs allowing for large-span guides without the bulk.
Recent Blog Entries
Gemini 3D Printer End Stops
As I discussed in my previous post, work is being done towards creating an OpenSCAD parametric version of several key complicated assemblies within the Gemini 3D printer. Things are going well - I have designed a basic syntax and part numbering system to keep...
Project Overhaul and Reorganization – Gemini 3D Printer
While reviewing certain aspects of the Revision 2 design for the Gemini 3D Printer a few minor design issues have come to light. Unfortunately for this project, I was busy doing other things over the course of the Summer and needed to take a break from this machine....
Slow weeks for Updates
It's been a slow week or two for updates on the Gemini 3D printer project, I have not as much time to dedicate to the project as I would have liked, such is life. I have been putting what time I've been able to spare on optimizing the electronics configuration for the...
Electronics Mounts for the Gemini rev. 2
The latest test build of the second revision of the Gemini 3D printer is coming along well. Shown in this photo (sorry for the bad lighting) is the mounting of the fans (only one shown) along with the 24v power supply, motors and of course the Smoothieboard. The print...
Test Build of Gemini 3D Printer Revision 2
I have been working hard at the 2nd revision of the Gemini 3D printer prototype. The new version has a sturdier frame assembly which is easier to put together and more straight forward in it's construction. This is a work-in-progress of the new design: The Z axis has...
Gemini 3D Printer Revised Gantry Test Assembly
As per my posts over the previous days, there is a new gantry in the works for the Gemini 3D printer. Last night the motor mounts were printed and attached to the frame. These have a lot more strength than the previous version and have slotted holes for the for M3...
Gemini 3D Printer Gantry Continued
Things are progressing fairly well with the second revision of the Gemini 3D printer's CoreXY gantry. The new corner pieces assembled well the first time and the resultant frame is quite strong and rigid. The former corner bracing scheme was fraught with issues of...
New Top Idler Corner for Gemini 3D
As part of the redesign and strengthening of the Gemini 3D, working towards a more production-like model instead of the flimsy proof-of-concept prototype I have printed and assembled one of the new top idler corners. This is made as a two piece assembly in order to...
Flat Bar X Axis for Gemini 3D Printer
As I mentioned in my previous post, I am experimenting with a revised gantry for the Gemini 3D printer. Here is a test assembly of the new idler ends assembled with the flat aluminum bar support and the 9mm hiwin rail for the X axis mounted. This design is proving to...
Experimental Revisions to the Gemini Gantry
The previous prototype of the Gemini 3D printer gantry worked effectively however there are many aspects that I have been working on revising. Plastic parts in use on the x-end/y-carriage were not designed to be robust in the prototypes - it was assumed that they...