Kate G. - June 26 2024
3D Printer Bed Mesh - Eddy Scanning Probe
If you have a really flat bed and a perfectly square gantry, you might be able to go without leveling probes, as the nozzle will maintain a constant distance from the build plate at all times. However, if your bed isn't flat or your gantry isn't square, you're likely to encounter both high and low spots in your layer. High spots can result in loss of adhesion, while low spots can cause the filament to glob up on the nozzle, leading to failed prints.
Using a probe, we can generate a mesh of points on the surface of our 3D printer bed, allowing the nozzle height to be dynamically modulated to maintain a constant distance, thus accounting for any high or low spots. On printers with independently driven Z motors, the probe also serves a secondary function: gantry leveling. By probing at the extremes, we can determine the orientation of the bed plane in space and automatically adjust the Z motor positioning to remove any tilt, ensuring the bed plane is perfectly parallel to the gantry. With the gantry leveled, the first layer will be much more consistent, and the mesh compensation will account for the bed's flatness. Thermal stresses introduced during the heating process can cause an otherwise flat bed to warp, making mesh compensation essential for achieving a good first layer.
What is Eddy Probing?
The new Eddy scanning probe from BigTreeTech, aptly named "Eddy," replaces the traditional mechanical or inductive bed probe on FDM 3D printers. Instead of probing a series of discrete points, Eddy probe scan the topology of the bed. This makes the process of generating a bed mesh much quicker and far more precise.
How Does It Work?
These probes operate using the electromagnetic principle of Eddy currents. The probe emits a magnetic field that induces a small electrical current in a nearby conductive medium, which in this case is the 3D printer bed. These currents, called eddies, emit their own magnetic field that can be detected by the sensor inside the probe. The strength of the magnetic field is proportional to the distance between the probe and the bed.
What Makes Scanning Probes Better?
Traditional probes collect height data at a discrete set of points. The more points collected, the better the resolution of the mesh, but this also slows down the process. Scanning probes, on the other hand, collect data continuously, allowing them to generate a very detailed mesh in a short amount of time.
Eddie: USB, I2C, & CAN
Eddie comes in three variants, which differ based on their connection mode: USB, I²C, and CAN.
1. USB Eddie:
· This standalone device connects directly to your Raspberry Pi or a similar computer.
· However, the USB cable isn't rated for use in a drag chain, so this version is only viable for printers with an umbilical setup for the tool head wiring.
Showing making procedure is a good way to guarantee product quality
2. I²C Version:
· This connects to one of BigTreeTech's CAN tool boards, such as the EBB 42 or EBB 36.
3. CAN Version:
· Currently unavailable but slated for release soon.
· The SB 2209 and 2240 boards, commonly used with the Voron Stealthburner, do not have an I²C port. Instead, they have a CAN port to which a downstream CAN device can be connected.
· The benefit of I²C and CAN is that no additional wiring is required between the tool head and the main board.
Eddy vs. Eddy Coil
· The Eddie Coil comes with a four-pin cable (JST-Z on the sensor side and Dupont on the toolboard side).
· The USB version is supplied with a 2.5-meter-long USB cable (about 8 feet), which should be long enough for even the largest printers.
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