2x scaling of Monoprice Mini Select v2 Firmware v30.50b after factory reset?

1

About a year ago, a bad print encased my hotend in PLA and I broke the wires due to my impatience trying to get the glob of PLA off.

I don't remember the details of the disaster print, but generally the printer was working fine except I now know I was heating the bed too high and causing warped prints that I was trying to avoid by raising the bed temp.

I'm trying to salvage the printer now, I bought a new hotend and build plate sticker. I don't want to name the supplier because I'm pretty sure these parts are irrelevant and I don't want this to seem like an advertisement. Anyways, install was pretty easy, I didn't disconnect any of the axis or feeder steppers control wires - just the hotend heater and thermistor.

I don't think it should have anything to do with the bad print or the replacement parts, but now when I print I'm having major calibration issues. My entire print seems to be 2x scaled up. This is causing skipped stepper steps, grinding, etc for completely bad prints.

I ran at least part of a factory reset program before any trial prints because it was recommended online somewhere (which displayed weird 50 % complete message and that's all). I most suspect the factory reset as my problem. After the reset, I needed to flip the Y axis with an additional G-code instruction before it would home to the correct corner instead of grinding to the top-back-left.

M502 ;     Restores default settings
M562 Y ;     Reverse Y  -- I had to add this to even get it to work as well as it does.
M500 ;     Saves the settings to EEPROM

I have read that I can adjust the axis scaling by an arbitrary factor with additional G-codes, but since I didn't mess with the printer other than the program above, I don't expect my scaling factor to be off by a random value, but more a common value that ALL mini select v2s need that I erased. But I am not finding info about this.

I am using Cura 4.5 and Cura knows I'm using a Mini Select v2 and the model I've loaded is known to Cura to be the right dimensions.

In the picture, you can see that Cura shows it is centered on the bed, but it actually prints off center. Also, the finished print is about 2x scaled in all three axes and lacks the material density of a correct print - it's printing only enough plastic for the correct size print, but spreading it over the scaled-up volume. The steppers are also skipping steps (I guess) so there are a few layer shifts in this print. What a mess! (It's supposed to say it's dimension on the top - "23 mm" but it actually measures about 46 mm but hard to say exactly due to the other print issues)

enter image description here

Jason Kleban

Posted 2020-03-07T04:42:16.830

Reputation: 131

2

Hi welcome to 3DPrinting.SE! It sounds that the steps per mm are off in the firmware. You can set or see them with M92. With M503 you see all settings. You do need to connect to a console.

– 0scar – 2020-03-07T07:25:24.827

1supplier is usually not any issue, but you want to tell us the style of Hotend. e3d v6 style has other issues than the Makerbot Mk8 or Mk10. – Trish – 2020-03-07T09:11:50.497

Answers

2

Thanks for the comments! They led me to find this solution using PuTTY on Windows as my serial (COM) terminal. I guess one of my resets put the settings to 1/16th stepping whereas my hardware has 1/8th stepping.

> M115
NAME: Malyan    VER: 3.0        MODEL: M200     HW: HA04
ok N0 P15 B15

> M503
echo:Steps per unit:
echo:  M92 X93.00 Y93.00 Z1097.50 E97.00
echo:Maximum feedrates (mm/s):
echo:  M203 X150.00 Y150.00 Z1.50 E50.00
echo:Maximum Acceleration (mm/s2):
echo:  M201 X800 Y800 Z20 E10000
echo:Accelerations: P=printing, R=retract and T=travel
echo:  M204 P1500.00 R3000.00 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 X20.00 Z0.40 E5.00
echo:Home offset (mm):
echo:  M206 X0.00 Y0.00 Z0.00
echo:Invert axis: M562 XYZE
XYZABCD++-+-+-
echo:PID settings:
echo:  M301 P20.00 I0.02 D250.00 C100.00 L20
echo:  M304 P10.00 I0.02 D305.40
echo:Filament settings: Disabled
echo:  M200 D1.75
echo:  M200 D0
ok N0 P15 B15

> M92 X46.50 Y46.50 Z548.75 E48.50 ; from https://www.mpselectmini.com/howto/steps_per_unit_mm
> M562 Y ; Invert Y because it was Homing to the wrong corner
> M206 X0.00 Y-2.00 Z0.00 ; Inverting the values from M114 once good Home manually found.
> G0 X0 Y0 ; testing the range of motion
> G0 X0 Y120 ; testing the range of motion
> G0 X120 Y120 ; testing the range of motion
> G0 X120 Y0 ; testing the range of motion
> M500 ; this saves the new values to EEPROM
```

Jason Kleban

Posted 2020-03-07T04:42:16.830

Reputation: 131