While the SolidCore design is still a work in progress it’s slowly but surely materializing. For now we decided to go with a simple but funtional design but still have many plans that will later be adapted for additional tools and configurations. We recently moved the z-axis motors to the bottom of the printer and are setup to either use three independent driven z-axis motors or a single driven motor with the belt path connecting to three z-axis lead screws.
- Modular / Scalable
- All Metal or 3d printed
- Linear Rails
- Balanced Carriage Pull
- Triple Z-Axis: Independent Driven or Shared Belt Routing
Belt Path And Tensioning
If you want accurate motion, you need a CoreXY 3d printer design with straight and parallel belt paths. Belt tensioning can change when the belt length changes as the gantry moves. Otherwise racking or belt tensioning issues may occur. Belt segment that changes length must be parallel to the axis as it moves to avoid racking or other undesired motion that can occur. Belt thickness must be taken into account when laying out your pulleys. The belt sections between motor mounts and idler mounts need to be parallel with the axis as the gantry travels across.
Bowden vs Direct Drive
A Bowden setup will let you have higher acceleration but a direct drive extruder will give you higher feedrate. The difference in acceleration is in print time and can make a noticeable difference.
- Direct drive gives you more control over the extruders and better print for flexible materials .
- Bowden gives you a lightweight carriage design and is better for higher acceleration.
The moving mass from a direct drive extruder from the size or weight at higher print speeds. Reverberations that happen with fast accelerations and jerk rates. A heavier carriage also increases these artifacts. missing steps, that happen with fast accelerations and jerk rates and increases these artifacts.
Our long term goal is to is to build a modular platform, not just a printer. Think of it as an ecosystem of parts that can be arranged in different configurations and adapted for unique applications.
- Customized Parts
With the motor and idler mounts placed on the inside corners of the frame gives us clearance to easily mount an enclosure. This configuration also eleminates any design constraints of overall length and width which maker the machine completely modular and scalable.
Eventually we would like to have a spreadsheet or configuration tool that will allow you to input the current frame or linear rails that someone already owns and output length and rail options. Or if you’re aiming for a specific build area, you can input the data and it will output the frame and rail length options.
All Metal Parts
The SolidCore is designed to be a highspeed workhorse for repeated use. All-metal-parts and components will give us the durability and repeatablility needed. But we want people to have the option to use 3d printed parts so they can upgrade later on. Solid all metal parts are durable and less likely to deflect at high printing speeds. The aluminum components are also less likely to breakdown over time when introduced to the forces and heat from repeated use.
Belt tensioning is done with the XY motor mounts. The XY mounts have slots to allow the belt tension to be applied by pulling the motors back.
- High Speed
Carriage / Gantry
The carriage and gantry are designed to be light weight and strong. We currently use c-shaped aluminum stock because it reduces machining time. The reduced machining time and minimized waste helps but it’s a compromise. Thats going to change soon. We’ll probably make some changes such as reorienting the the y-axis linear rail into a vertical position similar to the RailCore but the current horizontal version will be easier to adapt an E3D Toolchanger.
The top plates or motor/belt mounting plates that mount the idler pulleys have recently changed as well. The motor/belt mounting plates shown position the z-axis motors on top vs the bottom of the machine. When I first designed the plates I thought it would look cool with the motors on top but after I machined everything I realized that moving the bed up and down could cause deflection in the main plates.
The left motor plates are going to be re-machined to give room for a tool changer setup.
The overall footprint of the machine relative to print volume is somewhat excessive. In order to have a solid enclosure design I had to move the motors inside the frame boundary. This sacrificed the overall printer size to print volume ratio.
We’re aiming to balance the pull to the center of carriage instead above it or below. It seems to be more rigid and minimize deflection. The belts are somewhat within the same plane of the three linear rails to avoid rocking cantilever loads that other designs may have with the belts up high or down low.
The original prototype was about 350mm x 350mm x 350mm print area but we now have a 200mm x 300mm and 400mm x 400mm build volume.
This design was inspired by the RailCore, HEVO, D-Bot, Mike Fisher’s QuadRod and Maarten van Lier’s corexy build.
Triple Z-Axis: Independent Driven or Shared Belt Routing
With the build plate removed the single z-axis stepper motor with shared belt routing is shown.
The SolidCore has two different z-axis designs to move the print bed. The SolidCore picture shown on this page has the z-axis motors at the top of frame.
- Independent Driven Z-Axis Motors
- Single Z-Axis Motor (Bottom)
Both z axis designs use 3-point bed leveling. The image below is of the prototype build which uses 12mm ball screw. The new design (yet to be shown) uses lead screw.
Three Point Kinematic Bed Mount
Although the implementation of the kinematic bed coupling is till in progress, we are designing a mechanism that works for us. Three point bed leveling uses three independently driven lead screws to automatically level the bed and compensate for a bent bed plate or dips .The three z-axis lead screws are used as the three points that make up a triangle and define a plane. 3 points define a plain.
The advantage of a kinematic bed mount is that the defined plane of the bed can raise or lower without binding or twisting, keeping the bed flat. 3-points define a plane, therefore you will need to take into account the synchronization of the lead screws that raise and lower each point of the plane.
We’re using a mic6 tool plate for the bed. Cast Aluminum tool plate is a good solution because it has good thermal conductivity and heats up evenly without warp or twist. The bed needs to be flat and remain level. In three point bed leveling, the three z-axis lead screws are used as the three points that make up a triangle and define a plane.
Since 3 points define a plain 3 screws, evenly placed in a triangle will raise and lower that plain without imparting any twisting forces so the bed will stay flat. A mechanical bind can cause the bed to tilt over time. The advantage of a kinematic bed is that the aluminum plate can expand without causing anything to bend or flex.
Download 3D Model
Crossed Belts vs Offset Steppers
The corexy motion system uses crossed belts instead of offsetting the stepper motors giving the belt path a clean run. Simpily offsetting the motors may give a much better alignment path.
The belts don’t have to cross if the pulleys are at different z-levels, I always thought that was bv the difference between the hbot corexy was the corexy belts crossed at the m segment. But the difference between hbot and corexy is that hbot has a single belt on a single plane, corexy can have either 2 “non-intersecting planes” or a single plane + idlers on different levels to keep the belts from touching.
Hypercube for example doesn’t have that “x” because the belts are on different planes. The Railcore has the crossing belts but the belts are on different planes.
Motors at differing planes = straight belt paths
Motors at same plane = Crossing belts
Steal our files! We encourage designers and builders of any diy 3d printer project to use our designs. You can download the open source STEP and STL files at:
New Motor Mount Design
Download 3D Models
Download 3D Models