0.9° extruder motor  

Re: 0.9° extruder motor

Thomas

I think that is all you need to change.

I wonder if you could do an experiment for me? I would like to know the maximum speed that this printer can retract filament at with a 0.9 degree stepper. If it can handle a high enough speed than I will replace the steppers on of my MM printers to get better resolution (min layer height is 70 microns but it can be a little flakey at that height...).

We need to get speeds of around 5600 mm/minute over a 50 mm distance.

G1 E-50 F5600

I think this will probably exceed what the printer with that stepper can do - I would expect maybe 3000 to 3600 mm/min.

Many thanks in advance

Peter

Re: 0.9° extruder motor

I would suggest to recompile the firmware with:#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,322.6}
inside the Configuration_prusa.h file.

so that loading and unloading the filament would be corrected as well (even after a reboot).

Re: 0.9° extruder motor

OK, Peter :

2500 OK
3000 OK
3500 OK
4000 OK
4500 OK
5000 failed !

Jeff, I know the problem with the filament load and unload, but it's not really a problem. Loading is OK you can say "color not clear" and load more. But unloading can be a problem. Pull the filament out just at the end of the unload function.

Recompiling the firmware ? 😮 "Meine Fresse !" 😉

Thomas

Re: 0.9° extruder motor

...Recompiling the firmware ? 😮 "Meine Fresse !" 😉

Thomas

it's a piece of cake, thanks to allen.d's script.

for your convenience: find the actual 3.0.12-RC2 firmware, compiled for 0.9° extruder stepper.

Re: 0.9° extruder motor

C:\Prusa\Get-PrusaFwDevEnv-master>Get-PrusaFwDevEnv.cmd
Deploying Prusa mk2 development environment to: .\Prusa-Firmware

This might take a few minutes, so while it's running check and make sure that
you have selected the correct RAMBo Mini controller variant for your printer.

This is currently set to RAMBo Mini variant 1.3a, which ships with all new
Prusa mk2 printers. If this is incorrect (say, if you upgraded from a mk1),
please cancel the script now and re-run it with the "-RAMBo 0" parameter.

Downloading latest Prusa firmware from GitHub
Invoke-WebRequest :
Access Denied (authentication_failed)
Your credentials could not be authenticated: "Credentials are missing.". You
will not be permitted access until your credentials can be verified.
This is typically caused by an incorrect username and/or password, but could
also be caused by network problems.
For assistance, contact your network support team.

Access denied ? To what ? 😕

Thomas

Re: 0.9° extruder motor

???
don't know. I've used allen.d's script only once a few months ago, primarily to get a proper arduino environment installed (requires a special version, with special libraries and path settings) which doesn't interfere with other arduino versions installed at the same computer (which I need for my tiny45 and nano projects).

all the latest firmwares I've downloaded (and archieved, even with several alpha interim versions) directly via browser through the github repository (-> Clone or download).

Re: 0.9° extruder motor

Thomas

Thanks for doing the test.

Can you not simply make the step change and save to EEprom (what is it - M500?)

Peter

Re: 0.9° extruder motor

Good question !

I will try it, but I suspect that it does not work with the filament load/unload.

Thomas

Re: 0.9° extruder motor

I will try it, but I suspect that it does not work with the filament load/unload.

It should be fine; once stored, the step value will be read from EEProm on power up.

Peter

Re: 0.9° extruder motor

good idea, but does M500 store the step values for the extruder permanently as well ?
I think there was a time where it doesn't.... don't know if it does now.

Re: 0.9° extruder motor

Jeff

As far as I know, it reports (M503) what it stores:

Send: M503
Recv: echo:Steps per unit:
Recv: echo: M92 X100.00 Y100.00 Z400.00 E140.00
Recv: echo:Maximum feedrates (mm/s):
Recv: echo: M203 X500.00 Y500.00 Z12.00 E120.00
Recv: echo:Maximum Acceleration (mm/s2):
Recv: echo: M201 X9000 Y9000 Z500 E10000
Recv: echo:Acceleration: S=acceleration, T=retract acceleration
Recv: echo: M204 S1500.00 T1500.00
Recv: echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s), Z=maximum Z jerk (mm/s), E=maximum E jerk (mm/s)
Recv: echo: M205 S0.00 T0.00 B20000 X10.00 Y10.00 Z0.20 E2.50
Recv: echo:Home offset (mm):
Recv: echo: M206 X0.00 Y0.00 Z0.00
Recv: echo:PID settings:
Recv: echo: M301 P40.93 I4.88 D86.08
Recv: echo:PID heatbed settings:
Recv: echo: M304 P126.13 I4.30 D924.76
Recv: echo:Retract: S=Length (mm) F:Speed (mm/m) Z: ZLift (mm)
Recv: echo: M207 S3.00 F2700.00 Z0.00
Recv: echo:Recover: S=Extra length (mm) F:Speed (mm/m)
Recv: echo: M208 S0.00 F480.00
Recv: echo:Auto-Retract: S=0 to disable, 1 to interpret extrude-only moves as retracts or recoveries
Recv: echo: M209 S0
Recv: echo:Filament settings: Disabled
Recv: ok

Peter

Re: 0.9° extruder motor

OK, used Pronterface, do an PID and store the extruder steps in the EEPROM :

SENDING:M503
echo:Steps per unit:
echo: M92 X100.00 Y100.00 Z400.00 E322.60
echo:Maximum feedrates (mm/s):
echo: M203 X500.00 Y500.00 Z12.00 E120.00
echo:Maximum Acceleration (mm/s2):
echo: M201 X9000 Y9000 Z500 E10000
echo:Acceleration: S=acceleration, T=retract acceleration
echo: M204 S1000.00 T1500.00
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s), Z=maximum Z jerk (mm/s), E=maximum E jerk (mm/s)
echo: M205 S0.00 T0.00 B20000 X10.00 Y10.00 Z0.20 E2.50
echo:Home offset (mm):
echo: M206 X0.00 Y0.00 Z0.00
echo:PID settings:
echo: M301 P23.97 I2.54 D56.46
echo:PID heatbed settings:
echo: M304 P126.13 I4.30 D924.76
echo:Retract: S=Length (mm) F:Speed (mm/m) Z: ZLift (mm)
echo: M207 S3.00 F2700.00 Z0.00
echo:Recover: S=Extra length (mm) F:Speed (mm/m)
echo: M208 S0.00 F480.00
echo:Auto-Retract: S=0 to disable, 1 to interpret extrude-only moves as retracts or recoveries
echo: M209 S0
echo:Filament settings: Disabled

Looks OK, will reboot the printer and check again 😉

Geat, it works ! 😎

But I do an extrusion calibration and I get a value of M92 E375.7. A little bit high ? 😮 Is this possible ? I checked it twice. Yes, with this value, extruder is extruding 10cm of filament.

Thomas

Re: 0.9° extruder motor

Thomas

There is quite a lot of variance with the brass filament drive pulleys; I have one which was around 175 (350) steps, so your value is not far off that.

It also depends slightly on filament hardness so if your filament is quite hard, then expect higher values.

Peter

Re: 0.9° extruder motor

💡 yes, I can confirm that our MK2 usually is underextruding.
➡ due to the manufacturing process of the brass pulleys, they tend to be a little bit smaller in diameter as calculated.
at my genuine kit I had 93mm extrusion instead of 100mm, which lead to a value of about 173 steps/mm.
the prusa spare part (brass pulley) that I used for my own clone delivered about 95mm.

but I'm really looking forward to your experience with the 0.9° stepper, because I'm curious if it really improves printing. 🙄

I know that Peter is convinced...

😕 but does it really make a difference when we have a calculated retraction/extrusion resolution of about 3µm per step instead of 6µm/step ?
in my opinion this is a little bit "oversampled", because of the friction of the pulley, the variance in diameter and surface properties of the filaments that we use, even 6µm seems to be more resolution than we need.
acutally I simply can't believe that if we retract the filament 0.8mm and extract it afterwards the same calculated length, that we have a repetitive accuracy below 6µm in reality.

:ugeek: it's a little bit like asking: should we sample an analog signal with 24 bit/sample when we know that the S/N ratio is only 85dB and we only use it for simple record/playback purposes (I'm not thinking about mathematical signal processing here, to improve S/N at the cost of bandwith).

Re: 0.9° extruder motor

Jeff

The biggest issue is with the MM upgrade with only 140 steps/mm which reduces the minimum resolution of the printer to 70 microns (realistically 100 microns) due to the inability to consistently extrude (retain a constant pressure) at the lower layer heights.

Currently the minimum extrude volume with 140 steps/mm is around 0.5mm^3/second while maintaining the consistent extrude (that's only around 28 steps per second) and that is simply not enough; the print has to be speeded up, leading to poorer quality.

Basically only just over 1 extruder step is issued for 100 X or Y steps; any extrude path less than 1mm long will generate 0 (or 1) extruder steps.

If it were possible to double the extruder steps, that would help all round, but I need to experiment with filament changes to see if slower speeds work OK.

Peter

Re: 0.9° extruder motor

OK guys, go ahead with the dicussion: I'm learning to understand my printer 😛

But : Is this value not too high for an 0.9° stepper ?

M201 X9000 Y9000 Z500 E10000

In my opinion, the value should be halved.

Thomas

Re: 0.9° extruder motor

Is this value not too high for an 0.9° stepper ?

M201 X9000 Y9000 Z500 E10000

Yes it is way too high, but then so are the other values.

The maximum X and Y acceleration are in the region of 1500, but this is all handled within Slic3r; there is no need to worry about it.

The only time E acceleration values will come into play are generally during retracts (ie where there are no other axes movements). And acceleration is about accelerating a mass, and that mass has not changed, so I think acceleration should not require a change.

@Jeff - just one thought I had overnight (which has revised my thinking on 0.9 degree steppers) is that the extruder continues to ooze when the extruder motor is not turning. So forget what I said in the earlier post (pressure is not constant; i't all about the flow...).

Peter

Re: 0.9° extruder motor

...@Jeff - just one thought I had overnight (which has revised my thinking on 0.9 degree steppers) is that the extruder continues to ooze when the extruder motor is not turning. So forget what I said in the earlier post (pressure is not constant; i't all about the flow...).

yes, I've read your post last evening... but didn't respond immediately because I wasn't sure if I understood it completely.

so lets do some math: 😀
if we use an 1.8° stepper at the multi-material kit and the given pulleye, we have a value of 140 microsteps/mm (just checked that it's per millimeter not per centimeter).
this means that we do have a retraction or extrusion per microstep of approx. 7.14µm.
the tip of our standard mk2 nozzle has a diameter of 0.4mm, so the radius is 0.2mm and the round extrusion area of our nozzle is about 0.125 mm².

😐 but I still can't see the point why you've estimated the minimal layer height to about 70 - 100µm at a 140 microstep/mm rate.

---------------------------

update: anyone (beside Peter) noticed my error in reasoning ?

forget my calculations above ! i made the mistake to calculate the extracted volume per microstep by the area of the nozzle hole, not by the area of the filament cross section, where the pulley works to produce the propulsion 😳
so it's in fact only 11.6 microsteps at my 10mm purge !

Re: 0.9° extruder motor

What I did not understand : What's the difference between the MM and the non MM in case of the extruder ? Are not all printers the same ? Yes, I know, MM has 4 extruder motors, non MM only one.

So, it's not the worst to upgrade to an 0.9° stepper ? 🙄

Thomas