Rebuilding MakerBot R2X, implications of E steps/mm
paralepsis last edited by paralepsis
I'm rebuilding a R2X with a DuetWifi board (my second build) and have it all working relatively nicely. One thing I've noticed is that the steps/mm with the stock (1.8 degree) extruder motor and extruder is very low with 16x microstepping: 96.275! From reading prior posts I get the impression that this is quite low, that I would ideally be in the ~800 steps/mm range (e.g., where a Titan Aero would be).
Because this printer doesn't have a very large build plate, I was thinking of trying to tune for relatively thin layers (0.05mm?) and more detailed parts. I'm concerned that that E resolution won't be adequate, but I'm neither sure how a problem would exhibit itself nor how I would detect it with Duet diagnostic information.
Beyond that, I'm interested in thoughts on use of higher levels of microstepping. From reading prior posts I understand that this creates more work for the Duet, but I suspect I can push this up to 32x+ in this scenario without worry? How would I know if I had asked too much of the Duet?
In the mean time I've found a Moons stepper with similar torque and 0.9 degree steps to get me into a better regime w/out leaving 16x microstepping. The PS has been upgraded and should be fine with the increased current requirements this entails. Of course this too increases the work for the Duet, but feels like an obvious first step.
Thanks in advance for your help!
Don't let the small number of e steps deter you. The Ender3 has similar ungeared extruder and 1.8 motor and a bowden system and can still achieve very nice detailed prints.
Though if you wanted to improve resolution you could swap the motor for a 0.9 degree one, or switch to a geared extruder system, or increase the microstepping which may help a bit. x32 or x64 should be fine.
So you're on the right track, but it may not make as big of a difference as you might think.
@phaedrux Thanks! Any hints on how I would tell if this was an issue?
During low layer height prints with small nozzle and low flow rates you may get uneven extrusion though I can't say if it would actually be noticeable in practice.
I would say that the extruder itself isn't really ideal for your intended application and replacing the extruder with a modern 3:1 geared design would be the best option.
The other thing to consider with tiny layer height is the z axis resolution and stability.
@phaedrux understood. I'll be looking around at alternatives for carriage / extruder but in the mean time will try 0.9 degree and 32x microstepping to see where things are.
Z is 400 steps/mm at 16x microsteps, not horrible.
Just to follow up on this, swapping in a 0.9 degree motor was a no brainer and helped things. However, when ironing 0.1mm layers, I was still seeing artifacts at 16x microstepping that I couldn't eliminate until moving to 32x microstepping, which appears to have done the trick.
Up to 64x microstepping seems to be fine on my Duet2 with these sorts of workloads, no hiccups reported. Haven't tried further as there appears to be no need.