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I bought a 5.2:1 geared stepper motor (http://www.kysanelectronics.com/Product ... ordID=8318) and the funny thing is it is performing worse than the standard 1:1 motor that came w/ the RMAX so I think I need to change a setting or two because a geared motor s/ print better than a non-geared motor as far as I know.

It's running w/ the current set to 110 in config.h because at 135 the motor was getting too hot to the touch. It's hooked up to the EZStruder and is running w/ an 11 mm diameter (at the valley of the hob) hobbed pulley. I changed the steps to 480.5 so I can extrude the correct amount of filament, but I'm getting perimeters starved for filament:
The stock 1:1 motor does not show any perimeters starved for filament when I print this vase. Any ideas what else I need to change to get the geared motor working properly?

Can I ask what your motivation was for moving to the geared extruder motor?

There's a lot of variables requiring a fast, strong motor so as I increase print and retraction / prime speeds and shorten retraction / prime distances and try to shrink the difference between retraction / prime distances, etc I wanted to make sure my motor was the best one for the job. I guess there's other variables as well that could benefit. I realize filament material, temp, the EZstruder itself, etc also play a big role, but I'm working on one variable at a time.

To get best performance out of the current stock Nema 17 1:1 connected to the extruder some people probably run it too hot and I've seen others on the forum go to the Kysan 5.2:1 motor so I thought I'd try to eliminate one potential limiting variable as I try to increase print speed and quality by also going to the geared Kysan.

inventabuild wrote:I bought a 5.2:1 geared stepper motor (http://www.kysanelectronics.com/Product ... ordID=8318) and the funny thing is it is performing worse than the standard 1:1 motor that came w/ the RMAX so I think I need to change a setting or two because a geared motor s/ print better than a non-geared motor as far as I know.

It's running w/ the current set to 110 in config.h because at 135 the motor was getting too hot to the touch. It's hooked up to the EZStruder and is running w/ an 11 mm diameter (at the valley of the hob) hobbed pulley. I changed the steps to 480.5 so I can extrude the correct amount of filament, but I'm getting perimeters starved for filament:

Filament Starved Rows.jpg

The stock 1:1 motor does not show any perimeters starved for filament when I print this vase. Any ideas what else I need to change to get the geared motor working properly?

When you tell the extruder to extrude a specified amount of filament does it extrude the correct amount? In other words, have you calibrated this extruder?

From my experience, and from my past investigations, stepper motors can run much hotter than most will think is safe, and if you don't like the temps, put a fan on it.

I guess your response doesn't clarify the motivations for me. By using a geared stepper, you now need more steps to push/pull the same amount of filament, which means that trying to extrude faster will require this motor to run even faster than the 1:1 motor (5.2 times as fast). It will require less torque from the motor due to the gearing, but the torque requirement on the filament drive won't change. I guess I don't understand how more steps allows you to go faster.

Stock setup would be better for retracts than a geared stepper. The reason I'd go with a geared stepper is to get more consistent extrusion, especially at low speeds. You can feel individual pulses on the extruder motor if it's going slow enough, and the constant oscillation between accelerating and stopping may result in slightly uneven extrusion width. More steps per degree would smooth out a lot of that.

I would think that a 2:1 or 3:1 transmission would be a decent tradeoff. If I ever go this route I'll probably print a planetary gearset with the right ratio and sandwich it between the stepper and the EZstruder plastic parts. I can remember the old Steve's extruder (the geared one from some months ago) and every time it would do a retract the motor would have to spin like crazy. I can get the EZstruder to retract at 300mm/sec (limited by the acceleration settings, of course) without barfing.

I'm not an expert on motors so I don't know which motor would get up to speed the quickest, etc; although it seems to me a geared motor would get up to speed the quickest (up to a point) similar to the way you could start from a dead stop quicker in 1st gear vs the 10th gear of a bicycle. Of course if the 1:1 motor has overwhelming power for the task at hand then it would get up to speed the quickest since it needs to turn less to spin the extruder gear.

I do know that at one point in time I was getting sporadic layers starved for filament and that's when someone told me to get a geared stepper motor and it would help w/ a host of variables. It turns out that I had extra friction in my system due to a bad threading connection between the effector I was using at the time and the push to fit connector. Although I can't prove one caused the other the problem went away when I changed the effector. Unfortunately I did not have my geared stepper at the time so I don't know if it would have powered through the bad threading connection or not. And my starved layers only got worse as I boosted my speed.

Several people including Berry Werner of berrybot fame also upgraded to the same geared motor last I heard, but if your prints are coming out fine and you've never felt like maybe your extruder motor might be under powered at certain speeds then it's not necessary to upgrade to a geared motor I guess.

The 5.2:1 ratio means the motor has to revolve 5.2 times for the output shaft to revolve once. In other words, it isn't faster - it's slower. You sacrifice speed for increased torque and accuracy.

Can retraction / extrusion be mimicked by using a bike analogy, namely is it like pedaling a bike forward and backward for say only 5 ft and if it is a good analogy would you rather ride a bike in 1st gear or 5th gear for these 5 ft?

To follow your analogy, doing fast retracts with a geared stepper would be like trying to get on the freeway in 1st gear. You sacrifice speed in order to gain torque, but you're going to hit the redline well before you hit 65. 5.2:1 is remarkably short (real slow with LOTS of torque.) In a car, 1st gear might be around 3:1. Dunno what it is for a bike.