Category: nema 17

nema 17: essential component of the new motor

nema 17 and six controllers of different industrial Ethernet protocols, absolute multi-loop encoder, closed-loop and M12 connector compose the new ServoStep integrated stepper motor. This new nema 17 is based on the latest microprocessors and cooling technology and advanced design than before.
All the necessary electronic components in the stepper motor system are integrated in the motor itself, and are similar to other JVL motor concepts, so they are easy to use in various motion control stepping motor or servo motor applications. New nema 17 contains everything needed to solve modern control tasks, whether as an independent and self-programmable motion controller or from external PLC or PC control.
Industrial Ethernet:
Profinet, EtherCAT, Powerlink, EtherNet/IP, Modbus TCP or SERCOS III can be used, and synchronization and driver profiles of EtherCAT and SERCOS III can also be used.
MACtalk can use Ethernet to debug the motor, so there is no need for RS232/RS485 converters or extra cables.
Because of scalability, the JVL industrial Ethernet module is also a “proof of the future” because the new version of the protocol will always be suitable for design. New nema 17 is equipped with two Ethernet connectors and a built-in switch, so that the circuit topology does not require any additional expensive hardware.The new nema 17 can be upgraded at any time by using other protocols or updated versions of the same protocol.

nema 17: what’s the impact on a project

nema 17 is used in a new project. This is a 3D printer based on the standardized production process. Yes, building a “unified” 3D printer will require a lot of capital investment to get the first printer offline. Once done, however, Tiko printer creators will have a viable product that costs far less than their competitors. Tiko has made many innovations in their haplotype framework. Unfortunately, they decided to extend this innovation to other parts of printers. Even a week ago, Tiko Kickstarter had a question about Tiko printers on the 3D printer forum. In 3D printers, the common method of linear motion is stepping motor. nema 17 is the standard process.
The historical pricing of nema 17 itself is interesting: it was not unrealistic to spend $40 on a single nema 17 long before the 2008 RepRap project was implemented. Now you can buy the same parts at less than half the cost. Tiko chose to go his own way instead of relying on an ecosystem that allows very cheap printers to emerge. They used a cheaper but lower torque stepper motor on the printer. This will lead to serious problems with printers. Of the more than 4,000 units delivered by Tiko, there are too many reports of layer transfers and missing steps that exceed your expectations. In the worst case, Tiko printer can’t print a simple cube. Deciding to use inexpensive nema 17 directly leads to a very poor final design.

nema 17: what is the speed limit of it

 nema 17 has a speed limit, it is essentially the maximum speed set by the user, beyond which the nema 17 can not move forward. Why is this useful? It is mainly because the speed of nema 17 can cause vibration when it reaches the resonance frequency. This may cause the stepper motor to become unstable and overshoot. This is also the reason why it loses its torque. Sometimes it is very fast.
In order to control speed correctly, actuators should achieve maximum speed and acceleration. If you try to accelerate at a faster speed than possible, the stepper motor will stop moving. In this case, sports should start afresh. This is because the commutator loses track and should be restarted by slowly increasing the commutator frequency.
Other factors also affect stepper motor torque. The low speed torque of the stepper motor varies directly with the current. The speed at which torque drops at higher speeds depends on many factors, such as winding inductance and drive circuit, including drive voltage.
Setting speed limits will prevent nema 17 stall. This is because the torque decreases with the increase of nema 17 speed. Speed limits can be set on stepper drivers or controllers.

nema 17: used in a plotting robot

Nema 17 is used to Build a free-standing, autonomous robot capable of creating an accurate plot from a set of Cartesian coordinates.
Pen plotters work by precisely moving either the plotting head or the plot medium or both. The size of plot that can be created is limited to the platen size of the printer. This project mounts the print head on an autonomous robot capable of precise movements in two orthogonal directs: x and y. Because it is freestanding, plots can be drawn directly onto floors, sidewalks, and other smooth concrete surfaces. The basic design can be scaled up for a machine capable of plotting on roads, runways, etc.
Finding a pre-made, small, rugged, adaptable chassis for the project proved difficult. Selection was further complicated because the print head needed to be centrally positioned and be able to access the print surface, The VEX Robotics 15×16 Chassis Kit (Small) was usable but not perfect (Figure 1). The primary problem with this chassis is that the spacing of mounting and connecting holes are based on Imperial units and many of the connected components use metric spacing. Mount holes had to be drilled or extended, weakening the chassis. The best but expensive solution was to have a custom chassis fabricated.







Figure 1. Plotting robot built on the small chassis kit from Vex Robotics to which Mecanum wheels are mounted to roll in parallel but the roller axes are perpendicular to the two adjacent wheels.
Omni versus Mecanum Wheels
There are two different types of wheels used for moving vehicles in two orthogonal direction: omni wheels (Figure 2) which can roll in one direction and be pushed on their rollers in the orthogonal direction (available from RobotShop), and mecanum wheels (Figure 3) that, when mounted in sets of four, can be powered to roll in one direction and, when the front and back wheels are rotated in opposite, directions, will move in the orthogonal direction (also available from RobotShop).





Figure 2. Omni wheels rotate in one direction and the rollers move in the orthogonal direction.






Figure 3. Mecanum wheels rotate in one direction but when mounted in pairs and rotated in opposite directions, moves the wheels in the orthogonal direction

To enable movement in two orthogonal directions, omni wheels may be mounted in two sets perpendicular to each other to roll in orthogonal directions (Figure 4). When using mecanum wheels, all four wheels roll in the same direction but the roller direction is perpendicular to the direction of the rollers across and in line with it. To move obliquely, the robot moves a minute distance in the x and then in the y directions (Figure 1). Nema 17 is uniquely able to make the precise, minute movements necessary. Many of the STEPPERONLINE nema 17motors have ¼” D-shafts ideally suited for the attachment of either wheel type using hubs with 8mm diameter mounting holes (Figure 5). Mounting brackets available from STEPPERONLINE are ideal for mounting the stepper motors because the motors are held precisely and tightly and the mounts are very strong and inflexible.






Figure 4. Omni wheels are mounted in two sets to roll in two orthogonal directions.







Figure 5. These hubs, available from RobotShop, can be attached to either omni or mecanum wheels and mounted on the ¼” D-shaft of stepper motors.

Microprocessor control
A variety of microprocessors can be used to move the wheels. Both Arduinos and Raspberry Pis have been used successfully. Although the wheels can be turned simultaneously using parallel processing or multiple microprocessors, it was easier to move each wheel successively a minute amount. Because space on the robot was limited, it was not practical to use the digital stepper drivers available from STEPPERONLINE . Drivers based on the L298 H-bridge driver were tried initially (Figure 6). Because these can only drive whole and half steps, stepper motors with a 0.9° step size were used to achieve the resolution necessary. Because of its limitation to half steps and because all wheels must be moved as close to simultaneously as possible and the L298 is relatively slow, faster and more sophisticated drivers from Allegro MicroSystems and Texas Instruments (TI) were tested. The TI DRV8825 was found to work best (Figure 7). The DRV8825 on a board from Pololu was mounted so that the step size the step size could be changed by the microprocessor.







Figure 6. L298 H bridge




Figure 7. The TI DRV8825 is fast, provides a up to a 1/32 step size, can easily handle currents up to 1 amp and above






Figure 8. To keep the weight over the wheels roughly equal, the robot is powered by two lead-acid batteries wired in parallel.

Yaw correction
The system worked well but, with larger plots, the robot rotated about its vertical axis (aka yawed) about its vertical axis. A Bosche BNO055 absolute gyroscope was used to measure and correct for this rotation. Because the BNO055 requires clock stretching and the Broadcom BCM2836 microprocessor used in the Raspberry Pi has problems handling this, the BNO055 was run by Arduino Nano which was read via serial by the Raspberry Pi over the USB connection (Figure 9).




Figure 9. Rotation of the robot about its vertical axis was measured by a Bosche BNO055 absolute gyroscope run by an Arduino Nano connected to a Raspberry Pi.

Initially, to reduce weight, a NiMH battery was used for power. This arrangement worked but not well. A design using 12V lead-acid storage batteries was used instead. Because the battery is quite heavy, to keep the weight over each wheel roughly equal, two batteries were used wired in parallel. Because the robot weighed in excess of 53 Newtons, nema 17 geared steppers motors from STEPPERONLINE were used.

nema 17: a suitable option for 3d printers

nema 17 is widely used in 3D printers. Though stepper motors are the main components of all projects, gearboxes are often required, especially in applications such as CNC machines and linear drives for 3D printers. Among these mechanisms, a high torque, low backlash gearbox may be the most suitable option, and a 3D printed, separable planetary harmonic driver for nema 17 may be better.
We suspect that any plastic gearbox will not bounce back as Sirek SBurom claims. But we can see the benefits of design. It has some good functions. Its perfect combination with nema 17 is also a very good feature, and the design on Thingivers should not be too difficult, so it cannot be stretched up and down. Nema 17 drives a solar gear with two planetary gears, each with a 56-tooth stationary ring and a 58-tooth output ring. Each rotation of a planet around a fixed ring causes the output ring to rotate one tooth, resulting in a reduction of nearly 100:1.
We think the term “harmonic” on this gearbox is a bit of a misnomer, because the definition of harmonic driver seems to be characterized by periodic deformation of the bent spline, no matter how you call it, this nema 17 is pretty cool and can be a convenient tool for all kinds of construction.

POWERED BY automation-blog