Upgrading to higher torque extruder motor creality ender3
So according to E3D customer service, the V6 is designed to have higher back pressure than the MK8. This leads to underextrusion with PLA and all kinds of problems unless you increase the temp by 30 - 50 °C so it will heat the filament faster and reduce the back pressure. They recommended getting a geared extruder such as the titan when I contacted them. Why none of this is mentioned on the V6 product page I have no idea, but I am not about to spend the cost of the V6 again on an E3D extruder unless it is truly the only option. I would imagine one could just replace the stock extruder motor with higher torque.
Does anyone know the max amperage motor you can replace the stock extruder motor with?
Is a 2 A NEMA 17 too much?
Will a 2 A stepper give any more torque than the stock one (I know it is rated at a higher oz-in but does that actually translate to more torque)?
Finally, where are the specs for the Ender 3 stepper drivers listed?
"oz-in" is actually the torque rating itself. "oz-in" is comparable to "lb-ft", only it's a lot less. It's a measure of twisting force. **1 lb-ft = 192 oz-in**. Use this and not the Amps to determine if the new motor has more torque than the old one. While looking up NEMA 17 motor specs, I've seen "high torque" ones listed with much less power draw than 2A (0.63A is what it was rated at). I'm sure depending on how the motor is built internally will dictate how much Amperage it will draw and thus the torque output.
@Pᴀᴜʟsᴛᴇʀ2 Indeed, you shouldn't look at the current rating to identify higher torque steppers, although a higher current produces stronger magnetic fields, the geometry of the stepper determines the torque. Higher torque steppers have a larger overall height to house increased sized electromagnets.
@Oscar amps x turns, the magnetic path inside the stepper, the radius of the rotor, ... Steppers (and other motors) can be wound with more turns of finer wire to run at lower current and higher voltage, or fewer turns of heavier wire to run at higher current and lower voltage, with the same end result provided other factors are unchanged. More turns does increase the inductance, so a proportionately higher voltage is required to slew the current through the windings in the same amount of time.
So the 'obvious' answer to this problem is to run a slower print speed, so it isn't so much as a case of information being missing, as there being a non-trivial trade off between speed, quality and cost.
Using the E3D products as examples, a double length NEMA17 can indeed deliver twice the kg×cm as a standard one, and a slimline a little less. E3D suggest that 'standard' A4988 drivers are capable of supplying 2A, but this is right at the limit of their performance (and you would certainly want to consider heatskinking/forced cooling).
E3D also list a standard stepper motor with a 5.18:1 reduction gearbox. This should give a good 4x increase in driven torque, and if you can find just the gearbox, that might be the cheapest option. You don't need such a high reduction, but this is limited by the physical size available.
In the absence of any better specs, a physically similar motor might be a good reference. You can check this by comparing various parts from different manufacturers. Regardless of the current capacity, more torque generally means a larger sized part.