Tevo Little Monster scratches print

Phaedrux

I've moved to the tuning and tweaking forum, might get more eyes.

I'm not a delta user, so I haven't got much insight, unfortunately. If the first layer is perfect, that would seem to indicate the calibration is good.

Please share your config.g and config override and bed.g and your slicer start gcode. Include the results of a M122 for good measure.

Are you using mesh compensation?
What does your height map look like?
What does the print surface of solid infill look like?
Does the Z axis move the expected amount? If you command to go to Z0, does it touch the bed? If you raise it to 100mm does it actually move up exactly 100mm?

With 2a motors, the current should be set to 1500-1800ma for printing ideally.

x16 microstepping with interpolation to x256 is recommended.

And finally, have you been through this? https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer

My first instinct is that it's either over extrusion, or a mechanical issue.

justus2342

Thank you, @Phaedrux for moving my question!

@Phaedrux said in Tevo Little Monster scratches print:

Please share your config.g and config override and bed.g and your slicer start gcode. Include the results of a M122 for good measure.

config.g and config-override.g can already be found in my first post.

Here is the bed.g:

; bed.g
; called to perform automatic delta calibration via G32
;
; generated by RepRapFirmware Configuration Tool v3.1.1 on Wed Jun 03 2020 19:59:35 GMT+0200 (CEST)
M561 ; clear any bed transform
; Probe the bed at 12 peripheral and 3 halfway points, and perform 9-factor auto compensation
; Before running this, you should have set up your Z-probe trigger height to suit your build, in the G31 command in config.g.
G30 P0 X0 Y109.9 H0 Z-99999
G30 P1 X54.95 Y95.18 H0 Z-99999
G30 P2 X95.18 Y54.95 H0 Z-99999
G30 P3 X109.9 Y0 H0 Z-99999
G30 P4 X95.18 Y-54.95 H0 Z-99999
G30 P5 X54.95 Y-95.18 H0 Z-99999
G30 P6 X0 Y-109.9 H0 Z-99999
G30 P7 X-54.95 Y-95.18 H0 Z-99999
G30 P8 X-95.18 Y-54.95 H0 Z-99999
G30 P9 X-109.9 Y0 H0 Z-99999
G30 P10 X-95.18 Y54.95 H0 Z-99999
G30 P11 X-54.95 Y95.18 H0 Z-99999
G30 P12 X0 Y54.9 H0 Z-99999
G30 P13 X47.54 Y-27.45 H0 Z-99999
G30 P14 X-47.54 Y-27.45 H0 Z-99999
G30 P15 X0 Y0 H0 Z-99999 S9
; Use S-1 for measurements only, without calculations. Use S4 for endstop heights and Z-height only. Use S6 for full 6 factors
; If your Z probe has significantly different trigger heights depending on XY position, adjust the H parameters in the G30 commands accordingly. The value of each H parameter should be (trigger height at that XY position) - (trigger height at centre of bed)

And here is what the M122-Command says (after startup and calibration, not printed yet):

=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.1.1 running on Duet WiFi 1.02 or later
Board ID: 08DLM-*****-*****-*****-*****-*****
Used output buffers: 3 of 24 (12 max)
=== RTOS ===
Static ram: 27980
Dynamic ram: 93152 of which 44 recycled
Exception stack ram used: 552
Never used ram: 9344
Tasks: NETWORK(ready,384) HEAT(blocked,1224) MAIN(running,612) IDLE(ready,80)
Owned mutexes: WiFi(NETWORK)
=== Platform ===
Last reset 01:14:58 ago, cause: power up
Last software reset at 2020-06-05 18:54, reason: User, spinning module GCodes, available RAM 9632 bytes (slot 2)
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0441f000 BFAR 0xe000ed38 SP 0xffffffff Task MAIN
Error status: 0
MCU temperature: min 28.8, current 32.5, max 34.9
Supply voltage: min 24.1, current 24.3, max 24.5, under voltage events: 0, over voltage events: 0, power good: yes
Driver 0: standstill, SG min/max 0/1023
Driver 1: standstill, SG min/max 0/197
Driver 2: standstill, SG min/max 0/198
Driver 3: standstill, SG min/max not available
Driver 4: standstill, SG min/max not available
Date/time: 2020-06-10 22:08:11
Cache data hit count 4294967295
Slowest loop: 884.98ms; fastest: 0.12ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest read time 1.8ms, write time 309.9ms, max retries 0
=== Move ===
Hiccups: 0(0), FreeDm: 169, MinFreeDm: 163, MaxWait: 319042ms
Bed compensation in use: mesh, comp offset 0.000
=== MainDDARing ===
Scheduled moves: 1634, completed moves: 1634, StepErrors: 0, LaErrors: 0, Underruns: 0, 0  CDDA state: -1
=== AuxDDARing ===
Scheduled moves: 0, completed moves: 0, StepErrors: 0, LaErrors: 0, Underruns: 0, 0  CDDA state: -1
=== Heat ===
Bed heaters = 0 -1 -1 -1, chamberHeaters = -1 -1 -1 -1
=== GCodes ===
Segments left: 0
Movement lock held by null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
Daemon is idle in state(s) 0
Autopause is idle in state(s) 0
Code queue is empty.
=== Network ===
Slowest loop: 1220.40ms; fastest: 0.00ms
Responder states: HTTP(2) HTTP(0) HTTP(0) HTTP(0) FTP(0) Telnet(0), 0 sessions
HTTP sessions: 1 of 8
- WiFi -
Network state is active
WiFi module is connected to access point 
Failed messages: pending 0, notready 0, noresp 0
WiFi firmware version 1.23
WiFi MAC address **:**:**:**:**:**
WiFi Vcc 3.35, reset reason Unknown
WiFi flash size 4194304, free heap 20992
WiFi IP address 192.168.1.15
WiFi signal strength -56dBm, reconnections 0, sleep mode modem
Socket states: 0 4 0 0 0 0 0 0

@Phaedrux said in Tevo Little Monster scratches print:

Are you using mesh compensation?
What does your height map look like?

Actually I tried with and without mesh compensation – no difference. But indeed the mesh itself is quite interesting. It seems to change more than it should from calibration run to calibration run.

Here are two runs of G29 (without homing in between or Delta Calibration):

First run

Second run

@Phaedrux said in Tevo Little Monster scratches print:

What does the print surface of solid infill look like?

To my understanding the first layer is quite perfect.

@Phaedrux said in Tevo Little Monster scratches print:

Does the Z axis move the expected amount? If you command to go to Z0, does it touch the bed? If you raise it to 100mm does it actually move up exactly 100mm?

The tower axis move exactly the expected amount, measurement-Limit 0,02% (80cm movement, 1mm measurement precision). G0 Z0.3 brings it repeatable to 0.3mm height, measured by feeler gauge.

A word more on that. The repeatability I am talking about is not really consistent. Measuring repeatingly one XY-Coordinate yields quite good results. But when moving the effector in XY and then moving it back again it is not that consistent anymore. It seems a little like the Z-height is dependent on the direction of the last move in the XY-plane.

But I cannot think of any reason for this. Backlash should be no issue, at least not between the motors and the carriages.

@Phaedrux said in Tevo Little Monster scratches print:

With 2a motors, the current should be set to 1500-1800ma for printing ideally.

Thank you for this clarification. I testet it, no change so far.

@Phaedrux said in Tevo Little Monster scratches print:

x16 microstepping with interpolation to x256 is recommended.

So nothing to change in my config concerning microstepping.

@Phaedrux said in Tevo Little Monster scratches print:

My first instinct is that it's either over extrusion, or a mechanical issue.

I also think that it really behaves like a mechanical issue. But I have to Idea what to check or what to change.

@Phaedrux said in Tevo Little Monster scratches print:

And finally, have you been through this? https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer

Yes, I have been through this multiple times. The only thing that makes me think a little is the statement on Carriages must not be rotated or warped about the Z axis. In fact the joints on the carriages are not perfectly on the same height. But we are talking about less than 1 degree.

Phaedrux

@justus2342 said in Tevo Little Monster scratches print:

Measuring repeatingly one XY-Coordinate yields quite good results. But when moving the effector in XY and then moving it back again it is not that consistent anymore. It seems a little like the Z-height is dependent on the direction of the last move in the XY-plane.

That would definitely indicate backlash. Unfortunately I'm not sure what exactly to check at this point.

justus2342

I managed to solve my Problem. I switched to a Smart Effector, Haydn Huntleys Magballarms and light self-printed carriages (Thingiverse).

Actually the problem is not entirely gone. But it became so faint that it does not really matter at all anymore.

giostark

@justus2342
The frame of this printer is really crap. I'm managing to rebuilt it with a CNC machine for eradicate all the mechanical issues.
Those of the the Tevo really steal nonsense amount of time to so much people. By the way after 2 years on the delta I could build it by my self and it will be !

dc42

@justus2342 said in Tevo Little Monster scratches print:

I managed to solve my Problem. I switched to a Smart Effector, Haydn Huntleys Magballarms and light self-printed carriages (Thingiverse).

Actually the problem is not entirely gone. But it became so faint that it does not really matter at all anymore.

If you haven't already done so, lubricate the magnetic joints with some light grease to reduce the backlash.

giostark

@dc42 said in Tevo Little Monster scratches print:

light grease

With "light grease" What do you mean?

I'm using this grease of Teflub (PTFE) : http://82.185.148.242/B2C/SchedeTecniche/Cat_Generale/Cat_Gen2016_ristampa/CatGen_ristampa016017_15.pdf
Is it good? Or I should use the silicon one instead?

dc42

It probably doesn't matter exactly what lubricant you use, as long as you use one.

justus2342

@giostark Why do you consider the frame "really crap"? What exactly did you change/rebuild with your CNC machine?

giostark

https://forum.duet3d.com/topic/6951/not-yet-solved-tevo-little-monster-duetwifi-errors/139
1)In my case the top frame had holes not aligned with the extrusion holes same as the bottom frame.
2)the 3 extrusion (tower) are bended.
3)bars have different length (six time the maximum allowed)
4)the glass bed is not glued planar in the aluminium socket.
I'll redraw with Freecad the top/bottm frame and some lateral connection for make the build very rigid. (all will be CNC milled)
Also I'll use the 8x2 extrusion for leave the linear rail the right space to be mounted...
I'm building a pretty amazing (for my standard) CoreXY 300ZL and at the same time I'll rebuild my delta.
I'll post all the stuffs here

Manuel

Hello folks,
I'm a real newby in the "world of codes".
Lately i bought a tevo little Monster (occasion) to build some bigger parts i need for my gollowing project.
Now: i had to make several changes to make the printer work again. Additionally a added 3 springs under the bed for manual leveling.
This set the bad heigher than before.
Auto calibration still works with this height of the bed.
BUT now: I'd likd to add a new plate onto the bed. Again 4mm of material.
These 4mm would make the hotend crash into the bed while auto leveling.

What/Where can I change a Z-setting, so this could be fixed?

Thank you very much for your help!

giostark

@manuel
Hi ,
At this page you can find the delta printer calibration full explanation:
https://duet3d.dozuki.com/Wiki/Calibrating_a_delta_printer

If you are sure about the numbers that you added (thickness of the glass) you can just modify the "System > config-override.g" file in the M665 line at the H parameter (subtracting the mm you added).
If this will go fine you can change the H parameter also in the config.g

In general for see the height of the printer:
1- power on the printer
2- home the printer
3- lower the head till the glass
4- when you are at the zero send in console G92 Z0 (to define the new zero level)
5- home the printer and read the new height value in the duet dashboard (Status > Z position) after the endstop are triggered. Keep in mind that the home position is lowered of 5mm (you can find your value in the homedelta.g , so you have to add also those mm to the height value you read in the Status > Z position.
6- write this new height in the config-override.g (and config.g)

If you dont have changed also the nozzle height modifying the head of the printer , should be enough adjust the height as above.