3D printers have made great strides in the past few years, but the process of leveling the bed is still a pain point. Let’s take a look at the different ways to solve the problem, and whether recent developments have successfully eliminated the trouble automatically.
Bed leveling and first-level calibration often trip up novices, because correct use requires experience and judgment, and errors mean printing failures. These are things that 3D printer operators have learned to deal with over time and experience, but they are still mainly manual processes, usually discussed in a way that sounds more like an art than anything else. No wonder there are many attempts to simplify the whole process.
Some consumer 3D printers are adopting a new method for bed leveling and first layer calibration. One of the printers is Arbitrary cube Vyper, It provides a one-click solution for novice and experienced users. We accepted the sample printer provided by Anycubic specifically to check this new leveling method, so let’s take a look at the latest attempts to automate 3D printer bed leveling, which is sometimes a stubborn task.
Why is bed leveling a problem?
In 3D printer terminology, bed leveling (or simply “leveling”) is a broad term, the end result of which is to deposit the first layer of the print on the build platform in an optimal way. A good first layer is the basis for successful printing.
For this reason, the nozzle needs to maintain a constant distance from the build platform over the entire range of motion. If the nozzle is too close to the bed in some places and too far away from the bed, it will cause poor quality and malfunction. Adjusting the printer base until it is parallel to the movement range of the nozzle is called leveling. (Machinists would correctly call this process tramming, because there is actually nothing that must be perpendicular to the earth’s gravitational field.)
The next step is the first level of calibration. This adjusts the Z axis offset, or the distance between the nozzle tip and the surface of the build platform. Sufficient space is needed for the critical first layer of plastic to be deposited uniformly in a uniform thickness and fully pressed into the build surface to maintain adhesion during the printing process.
What’s more complicated is that no build platform is completely flat. When counting fractions of a millimeter, even small defects can cause problems. High points or low points in the build platform are both a problem, because any tilt of the print bed cannot adjust them. This is one of the reasons why the leveling problem has always existed.
The various parts of the leveling bed are not particularly complicated, but many interrelated factors make it a complicated and tedious task. It is no surprise that people try different methods to make the whole process as simple and repeatable as possible.
Some solutions tried
The raft (a sacrificial build platform) was an early method of dealing with bed defects, but most solutions now revolve around Grid leveling.
Grid leveling is a way to compensate for imperfect print beds in software, but it requires a way to measure the build platform. By using sensors to measure, it is possible to create a software model that represents the build surface and its defects. The model modified the path of the print head when laying the critical first layer, adjusting for imperfect surfaces by trying to track these defects instead of moving as if they did not exist.
One way to achieve grid leveling is to use inductive sensors to sense the build platform without touching the build platform. Prusa The printer uses this method to measure with a 3 x 3 or optional 7 x 7 grid before each print. It is still up to the user to manually determine the appropriate Z-axis offset for a particular build table.
Another option is physical probes.this BLTouchFor example, it is a popular sensor that makes physical contact with the build platform. Its success as an aftermarket add-on, and the frequency with which it is copied, is a good indicator that how many beds are flat is still a pain point for 3D printer owners.
The latest method: integrated strain gage
This method uses the tip of the nozzle itself as a sensor. Not only can it be easier to measure from the point where extrusion actually occurs, but doing so also opens the door for automatically setting the appropriate Z offset.
One method is to integrate the strain gauge into the extruder itself, turning the hot end into a kind of load cell.We have seen this method in DIY projects that use SMD resistors as strain gauges, and this method is also used for Smart effector for delta printers.
Two recent consumer 3D printers, Anycubic Vyper and Creality CR-6 SE, have implemented their own factory-manufactured version.We accepted from Arbitrary cube Specifically to check this feature, so let’s take a closer look.
How does this work
Anycubic Vyper’s extruder assembly includes a fork-shaped metal bracket for the hot end, which has a built-in strain gauge.This turns it into a Load cell Similar to something in an electronic scale.
Any force applied to the hot end will slightly deform the mount, and the strain gauge converts this deformation into an electrical signal that can be measured and quantified. In this way, even very small pressures on the hot end can be detected.
Due to this function, the nozzle itself becomes a touch sensor. When the machine is automatically leveled, the extruder repeatedly descends toward the build platform until the nozzle touches it. Even a light touch can be reliably detected, so this process does not require much force.
By performing multiple measurements in grid mode, grid leveling can be achieved. In addition, since the physical distance between the nozzle tip and the build surface can be sensed, a reasonable Z-axis offset can be automatically realized, allowing the operator to only worry about fine-tuning.
The fork mount has a built-in strain gauge.
The strain gauge can be seen as a white patch under the base.
Remove the hot end from the fork bracket.
Touch the base to trigger touch sensing.
This is a very good idea, and the extruder is clearly designed around this function.
result?Perfect service
How’s the effect? I am happy to say that this feature seems to work as advertised, including automatically setting a valid initial Z offset.
Just install the build plate, make sure the nozzles and build surface are clean, and then instruct the printer to perform the automatic leveling process. The machine will warm up to ensure that the calibration is performed under the printing conditions and not in the cold state, and then the nozzle contacts the build platform in a 4 x 4 grid pattern, after which it will silently apply grid leveling and initial Z offset, which can be used if needed , Can be fine-tuned. In theory, unless the build platform changes, there is no need to repeat the process, but the user can trigger the process at any time.
limited
Auto-leveling works as advertised, but its functions are limited. First of all, the issues related to the quality or type of filament or the material from which the platform is built are separate issues that will still trip newbies. These are not fixed by the automatic leveling function.
Both the printing surface and the nozzle tip must be clean for best results, so it is best to remove the consumables from the hot end before auto-leveling. Since the machine warms up and touches each grid point twice, the loaded nozzle leaves a small amount of molten plastic at each point, and this extra material between the nozzle and the build surface will affect the accuracy of the measurement. In fact, this may be the Achilles heel of all nozzle-based sensors.
The content that can be sensed and modeled using 4 x 4 grid touch points is limited. Constructed surfaces with serious defects may not be accurately modeled. Before running the auto-leveling process, I briefly tested this by using shims to simulate mixed high and low points of up to 0.8 mm in the build plate. Unsurprisingly, a 4 x 4 contact grid is not enough to accurately simulate the exact locations where these defects start and stop, but I’m glad to see that the first layer generated is still usable at least if it’s a bit thin and Over-squeezed high areas. It is better to have an option to increase the number of measurement points, or to refine the mesh manually, as a way to better handle special situations.
Finally, the machine’s firmware is not very detailed about the details of its automatic leveling process. It seems that the sensitivity cannot be modified, the actual measurement results cannot be viewed, and anything other than the Z offset cannot be fine-tuned manually. The Z offset can be changed up or down in 0.05 mm increments.
Is this the way?
Vyper’s auto-leveling and initial Z-offset work as advertised and provide maintainable results, even though the firmware is a bit quiet about what is happening under the hood. It is very convenient, the strain gage integration looks very solid, and as a whole, it is a smart system, I am glad to see it in the factory products.
What do you think of this automated method of eliminating the boring chores of bed leveling and first-level adjustments? Is it the right way to turn the hot end into a load cell? We want to know what you think, so please let us know in the comments.