Genesis V4 exhibits the following changes from Genesis V3
- Simplified track mounting brackets now have less screws for easier installation, less material use, and a cleaner look when attached to short wood posts or extrusions
- Track mounting bracket screw holes are re-positioned to allow attaching to 20x40mm V-Slot extrusion posts rather than 20x60mm
- A completely redesigned Universal Tool Mounting system utilizing magnets to secure tooling in place, a larger diameter while still being smaller in overall size, larger 5mm power and data screws, and optimization for 3D printing
- Changed the wire and trolley cable management systems to cable carrier/drag chains to prevent drooping of cables into the plants and provide a cleaner aesthetic
- Designed and integrated 3D printable electronics enclosures/housings for the motors
- Gantry main beam positioned in front of corner bracket to allow for more complete movement of the cross-slide, ease of taking the cross-slide on and off the gantry, more complete movement of the cross-slide in the farmable area, fixed interference between motor mount screws, and ease of cutting the gantry main beam to the correct length and adjusting the overall width
- Changed Z-axis to use a 20x20mm extrusion to save weight and space
- Moved the main power supply from the gantry to the corner of the tracks at the end of the tacks cable carrier
V4 tracks feature simplified connecting plates that are about half the size of V3 plates and use half the number of screws for each connection. This simplifiction reduces the number of components and assembly time significantly. Additionally the plates are flat on the top and flush with the track extrusions, creating a cleaner aesthetic for tracks mounted to short posts as seen in the renderings. Also different from V3 is that the mounting holes for attaching to the post are 20mm apart rather than 40mm, allowing the plates to attach to 20x40mm extrusions.
Also new in V4 tracks is the use of a cable carrier/drag chain for cable management along the tracks. This is less visually and spatially impactful than the wire and trolley system introduced in V3 hardware. Though it will be more expensive, it is more suited to smaller FarmBots such as Geneses. A series of light duty bent metal brackets are in place along the tracks to support the cable carrier.
There is the possibility of moving the cable carrier to alongside the tracks as seen with the gantry's cable carrier. This would allow the elimination of the custom bent brackets in favor of using more affordable screws and teenuts for support. For this to work, the track connecting plates would need to be lower profile, allowing the top half of the track extrusions to accommodate screws and the cable carrier. This would not work in situations where the track supporting posts extended upwards as in the case of using fence posts or the studs of a greenhouse.
Lastly, the tool holder has been modified to accommodate the new tool design.
There are five changes to the V4 gantry from V3:
- The main beam is now attached to the front of the corner brackets rather than behind them. This change was so simple and minor but it greatly improves the design. This allows the user to slide on and off the cross-slide without detaching the main beam from the corner brackets. This is hugely important from an ease of assembly and maintenance perspective. The change also allows the gantry width to be adjusted more easily because the extrusion can be longer than necessary and hang off the edges. Lastly, this change allows the cross-slide to more fully move within the farm-able area, rather than being stopped prematurely by the corner brackets. Looking forward, the new design allows for an extended gantry to be implemented that is two extrusions wide or more.
- The addition of a 3D printable housing for the gantry drive motor. It's fairly simple but should get the job done. There may be concerns with a 3D printed part being completely watertight, in which case a vaporized acetone process may be able to help, or an injection molded part may be used.
- A cable carrier/drag chain is used for cable management instead of the wire and trolley system of V3. This is more aesthetically pleasing and prevents hanging wires and tubes from interfering with the plants.
- The angled slots on the gantry/track plates have been reverted to plain holes and will use the eccentric spacers from OpenBuilds. The eccentric spacers were originally removed from the design because they were found to be so small that they would dig into the plates and wear them out. However, the OpenBuilds team has changed the design of them to be significantly larger, preventing this type of damage. They are still expensive at $2 per spacer, but they seem to provide a better experience for the user. Which design is better has yet to be determined but we figured we would try out the new spacers in this version.
- The power supply has been removed from the gantry and placed at the end of the tracks in order to conserve space and weight on the gantry column.
There are three changes to the V4 cross-slide from V3:
- The motor is slightly re-positioned to support the 3D printed housing
- The cross-slide plate is narrower to accomodate a 20x20mm Z-axis instead of the 20x40mm one in V3.
- Extra holes have been added for a 3D printable bracket to support the cable carrier.
- The Z-axis extrusion has been changed to a 20x20mm extrusion from a 20x40mm one in order to save space and weight
- A custom 3D printable or bent sheet metal bracket has been designed to hold the Z-axis motor
- A 3D printable motor housing has been added
- The 3D printed bracket is too weak at the points where the screws attach it to the extrusion. The print has the tendency to crack along the layers when screws are tightened. Increasing the thickness here and ensuring there is adequate clearance for the screw to fit in the hole will solve the issue.
Universal Tool Mount
The V4 Universal Tool Mount has been completely redesigned to be actuator-less, simpler, smaller, 3D printable, and more affordable to produce. The primary mechanism for holding the tool in the mount is a pair of strong ring magnets, one on the tool and one on the mount, each held in with 5mm screws. Both the tool and the mount are tapered to allow easy coupling an de-coupling of the components.
In addition to the magnet holding screws, there are three additional pairs of screws in the tool and the mount that make physical contact when the tool and mount are coupled. These three screws, along with the magnet holding screws allow for power and data to be passed from the mount to the tools, with the magnet holding screw being ground. The three screws have springs between the heads and the mount, enforcing them to make consistent electrical contact. In addition, the three screws act as keys to prevent the tool from rotating undesirably in the mount.
FarmBot will use the Z-axis's leadscrew to have enough mechanical advantage to pull the mount off the tool when the tool is in the tool bay.
- The tool mount has a lot of unnecessary volume on the top half. This causes it to take much longer to print for very little added strength or utility. The V5 tool mount will be slimmed down
- The body of the tool wants to make contact with the body of the mount at the same time the center screws want to make contact. Because tolerancing is not perfect, either the bodies contact or the screws do. If the bodies contact, then electrical connection is not made. If the screws contact, then the tool wobbles in the mount because of the small contact area.
- The magnetic connection works extremely well, tools practically jump into the mount. However, there is likely not enough magnetic holding power for tools any heavier than the "blank" tool used for testing. Swapping which screws have magnets and which screws have springs could solve this and the above issue. The center screw can have a spring and no magnet, while the three outer screws have magnets. Contact of the bodies can be prevented with different clearance, ensuring electrical contact is always made, and with the 3 magnet design, a larger contact surface will be made preventing tool wobble. For lighter weight tools not needing 3 pairs of magnets, 3D printed spacers can replace the magnets on the tool.
- The mounting flange should be made thicker for extra strength
- Support material had to be added when printing the tool in order to support the second flange. This material was difficult to get out cleanly without damaging the rest of the part. Adding a chamfer will prevent the need for support material.
The power supply has been moved from the gantry to the tracks to save space and weight on the gantry.
All of the plates can be CNC routed, laser cut, or waterjet cut and the motor housings, Universal Tool Mount, and Tool "Blanks" can be 3D printed. .STL and .DXF files for manufacturing can be downloaded here.
3D CAD Files
FarmBot Genesis V4 was designed natively in SolidWorks 2014. Using SolidWorks 2014 or a newer version will provide the most seamless experience if you are interested in viewing or modifying the 3D part files. For those without access to SolidWorks, we have converted the files to other commonly used file formats.
Files can be downloaded here.