Hello, I am a researcher and I developed a paste extruder machine to do the basic test of biocomposite materials. I also shared the STL models of the machine parts and the code on my account page at Prusa.com (Printables). I am using Arduino 2560 board and Ramps 1.4 with a stepper motor NEMA 17 at 43.1 Ncm torque and DRV8825 Stepper Motor Driver Carrier. However, my torque is not enough for pushing the materials. I want to increase the torque as much as possible. I was looking for geared NEMA 34 with TMC drivers. Before ordering them all and make some tests with my Arduino 2560 board and Ramps 1.4, I wanted to be sure about, whether it is a good idea or not? Besides, since NEMA 34 are a bit big, I am not sure the amount of weight of the motor can damage the process or not? If yes, I can get a geared NEMA 17 with TMC drivers too. Do you have any idea about this?
What mechanism are you using to apply the stepper motor torque to your extrusion project? Have you measured the actual amount of torque required? Can you provide a picture or a drawing of the mechanical connection between the motor and the extruder?
NEMA tells about the mechanical interface like screws, mounting hole pattern, and tells nothing about the torque. Okey, big usually has place for more power but there are "long NEMA17" that has more torque than a "standard" "NEMA23".
To get the maximum torque out of a stepper the driver must be set regarding the current limit. Using a gearbox increases the torque but also the time to actuate the mechanics.
Supply voltage is interesting.
looks interesting!
Only you can determine how much is possible, by experimenting with the possibilities.
No, I did not measure the actual torque required but I can do it easily by my hand. You can see the extrusion mechanism from the images of the linked I shared in Prusa above. [Printables].
Thank you, as I mentioned I was already using a NEMA 17 at 43.1 Ncm torque. It is already quite good compared to pancakes. However, I would like to increase it more because it is not enough for pushing the material. I am using 20 amp power supply with DRV8825 stepper drivers. I want to upgrade my motor and the stepper to increase the torque but I need to shop wisely, I guess I do not have enough budget for buying different steppers to experiment the highest torque with these setup.
That's an important figure for You. The most engineering way is to measure the needed torque and check the stepper specifications if the motor will manage. The amateur way is to crank up the stepper driver current until either the project works or the stepper is toast, producing smoke. Check the driver capacity.
More powerful drivers can be stuff like TB6600 etc.
You need to find out the torque first, its the basic initial step in selecting a motor or gearmotor. Do you know the linear force required and the thread-pitch of the leadscrews?
Hello Again,
Thank you for the replies. Yes, I am aware that I need to measure my required torque. However, my required torque changes depend on the viscosity of the materials that I push and the nozzle diameter that I try to extruder. For example, if I do not try to push the material with a motor but a pressure, I apply up to 6 bar pressure to the nozzle. On the other hand, as I say sometimes only 2 bar pressure is also enough for me too.
That's why I want to have a motor with a high torque and later to change it based on the material accordingly. Another thing is, for my long term research line, I am planning to do more tests, but now I just need an quick solution just for an educational project.
All in all, I found a geared motor ([https://www.robotshop.com/es/en/12v-17a-667oz-in-nema-17-bipolar-stepper-motor.html] on this link which can produce 480 Ncm= 48.9 kgcm (which is almost 10 times higher than my current motor), with using up to 2 Amp current value.
Moreover, yes TB6600 is very good driver and offers long time solution and adjustability, however, for this educational project I need to hold things as simple as possible. I found this stepper driver (Driver Pololu A4988 paso a paso stepper), which is easy to assemble with the necessary 2 pins, one for the direction of rotation (DIR) and another to take the step (STEP). Furthermore it can work up to 2 Amp. I guess these to can be the most easy and quick solution for now to upgrade my extruder that I powered with 12 V DC 20 Amp power supply, and controlled with Arduino Mega 2560 and Ramps 1.4. What do you think?
The A4988 modules cannot handle 2A - that's the chip limit (assuming infinite heatsink).
The DRV8825 modules might get you to 1.7A or so, the A4988 isn't going to cut it I think even at 1.7A.
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