Little Monster calibration and configuration in 5 steps

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Little Monster calibration and configuration in 5 steps

Post by Xerxes » Fri Nov 24, 2017 8:14 pm

Little Monster calibration and configuration in 5 steps using Slic3r Prusa Edition and Pronterface

NOTE 14/8/18: *Since writing this guide for Slic3r PE I've also tried Simplify3d. It's a little easier, as the configuration is already available for the TLM. The calibration routine in here can be executed in Simplify3d instead of Pronterface. .But I encourage you to configure Slic3r PE as it is a really good alternative if you don't have access to Simplify3d or simply want to use an open source software. Both of them can get really good results.

Thought I might post this as it may help others get started with their TLM a bit quicker. I used ABS in this tutorial as it is one of the more difficult filaments to print with but has some advantages like temperature resistance when compared with PLA and it is cheap. It can also be post-processed easily for a gloss finish with acetone vapour. If you are after strength polycarbonate or nylon would be better choices. If you are new to 3d printing and care about your time and want easy print quality PLA will be the way to go because tuning and modifying your machine for these other filaments is a massive time sink. Any filament can be used just adjust these instructions for what you are using.

NOTE 14/8/18: *While you can print ABS, the object size you can do reliably without an actively heated enclosure in a cold room is going to be about 4cm x 4cm x 4cm. Bigger, maybe, if you live in a hot climate (30C+.) To get started please use PLA or if you want something stronger and more like ABS, use PET-G. It has the advantages of ABS and less downsides, but is only a little more expensive.

For the Little Monster to print anything meaningful you will first need to auto calibrate the printer, calculate the z-height offset (distance between the BLtouch sensor tip and nozzle tip), calculate the extrusion rate, and configure Silc3r PE for "Print Settings", "Filament Settings", and "Printer Settings."

In the stock printer there is an issue with salmon skin present on the print surfaces. This is an issue with the stepper drivers in the Smoothieboard, but it is correctable. The easiest and cheapest way is by installing four 8x diode tl-smoother boards in line with the stepper motor control lines (if you use 4x diode boards you need 8) for about ten bucks on ebay. http://web.archive.org/web/201712250723 ... steps.html

NOTE 14/8/18: *The TL Smoothers 1000% need to to have heat sinks on them or they will not work. Semiconductors like silicon (Si) loose their resistance as they heat, which is the opposite of what happens to conductors like metals (they increase resistance.) The smoother hack works because it reduces the voltage on the signal lines by 1.4V, when they get hot they do not provide this drop as they have no resistance. I have used mine without heat sinks and they got so hot they reflowed during printing (over 230C.) They survived this multiple times surprisingly!

Another thing worth mentioning are the layer heights that increase print quality/decrease salmon skin with delta printers. The "golden ratio" layer heights for the TLM are 0.0809mm, 0.1618mm, and 0.3236mm. I'd suggest using 0.1618 for high quality and 0.3236 for faster prints. http://forums.reprap.org/read.php?178,763881

NOTE 14/8/18: *Despite other reports I've heard of it not mattering, I can confirm these layer heights seem to work for me.

I'm sure there is room for improvement in this method and any suggestions are welcome.

+++++++++++++++++++++++++++++++
Steps to calibrating / post build tuning the TLM
+++++++++++++++++++++++++++++++


1) Auto-calibration via touchscreen menu

Auto calibration is in the touchscreen menu on the little monster. It will heat the bed to 100C then commence a calibration routine. Only press the button once as it will queue the calibration sequence over and over while it is waiting for the bed to heat before commencing.

2) Calibrate Z-axis height offset and note settings for Slic3r PE.

This process allows you to find the correct value between the BLTouch sensor tip and the tip of the nozzle. Every time the hotend, nozzle or BLTouch is adjusted or changed you should redo this process. The offset is independent of the bed surface position which is set by the auto-calibration, so you don't need to redo this step if you only change the bed surface and not the nozzle/BLtouch relative positions.

------------------------------------------------
:!: NOTE: Unless you know what you are doing, make sure you issue these exact commands and not out of order or with a jump to much larger values (increment by more than 0.2 or 0.3) because there is a high likelihood that it will cause a Z crash. If that happens pull the power to the printer, then remove the USB power to the Smoothieboard to reset it. If you don't remove the USB power it will continue to execute the Z crash when the printer power supply is turned back on.

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

Install Pronterface OR Repetier host and the Smoothieware USB drivers, then setup and connect the printer by USB serial from either Pronterface or Repetier host.

Pronterface seems to work for me: http://www.pronterface.com/
Smoothieware USB drivers: http://smoothieware.org/windows-drivers

To calibrate the Z-axis offset, issue the following g-code commands via "Manual Control" console within Pronterface/Repetier host.

Note: You don't need the bed to be heated for this process as the value between the BL-Touch probe and the tip of the nozzle is independent of the expansion of the heated bed.

Begin routine & calibration test

Code: Select all

G28		; Homes all axis
M280 S10.6	; Clear BL-Touch errors . After this command it should not flash
M280 S3		; BL-Touch extend probe
G1 Z55 F2500	; Move to 50 off the bed speed 2500
G1 Z10 F250	; Move to 10 off the bed speed 250

G30 Z0.1	; Set a small offset between the BL-Touch tip and where the printer thinks the nozzle ends

G1 Z10		; Get some height (reuse last speed)
M280 S10.6	; Clear BL-Touch errors.
M280 S7		; BL-Touch retract probe
G1 Z0		; Test the new zero (feel for slight drag with a sheet of paper under the nozzle)
Notes:
After G1 Z0 the nozzle tip will be where the machine now thinks Z0 is.
Use a sheet of normal printing paper to feel for resistance between the bed and nozzle.
Make sure the paper is only under the nozzle, not under the BL-Touch sensor when the G30 Zx.x is issued.
If you get some light drag then you have your Z offset value.
If not go on to calibration loop below (which reiterates some of the code above)


Calibration Loop (g-code to check z values until you are happy with the G30 Z offset value)
----------------

Code: Select all

G1 Z10		; [top of loop] Get some height (reuse last speed)
M280 S10.6	; Clear BL-Touch errors
M280 S3		; BL-Touch extend probe

G30 Z0.2	; Set Z offset value ++increase this value by .1 each loop, ie G30 Z0.3, G30 Z0.4, ...

G1 Z10		; Get some height
M280 S10.6	; Clear BL-Touch errors
M280 S7		; BL-Touch retract probe
G1 Z0		; if there is resistance on the paper after this command then we 
		; have the final G30 Z value to go into the Slic3r PE configuration
		; if there is still too much space, go back to [top of loop] and try again
----------Done calibrating Z height------------

3) Calibrate extrusion rate and note settings for Slic3r PE.

A simple method to work out under extrusion is to mark 100mm on the filament then see how much is left after extruding 100mm.

The method I use is to add an offset to the 100mm so I can work out either under or over extrusion. Use a ruler/calipers and sharpie to mark 120mm (100mm plus a 20mm offset) on the filament back from the top of the extruder. Use the touchscreen to heat the hotend to the printing temperature of the filament (ie 245C for ABS) and then extrude 100mm.

Now measure the new distance to the mark on the filament from the top of the extruder. Subtract the distance found from the 20mm offset to find the value of the under/over extrusion.

For example: If you mark 120mm back, request 100mm, and the line is now 26mm from the top of the extruder, the filament is under extruding by 6mm per 100mm as:

26mm - 20mm (offset) = 6mm

To work out how much filament is fed into the machine for the 100mm requested just subtract difference from 100mm.

100mm (amount requested) - 6mm = 94mm (filament consumed)

Do this 3 times (or more) and then average the result to improve the accuracy.

ie 100mm requested = first 91mm, second 93mm, third 92mm, fourth 92mm.

(95mm + 93mm + 94mm + 94mm) / 4 = 94mm

Now calculate 100mm as a percentage of 94mm to find the extrusion rate multiplier

100mm / 94mm = 1.064

So in that example the extrusion rate multiplier for Slic3r PE is 1.064


4) Configure Slic3r PE for the TLM

I've tried Slic3r, Cura, and Slic3r PE. I find Slic3r PE the easiest to configure as it includes configuration files for Prusa i3 printers with various nozzle sizes and configurations for various filaments. These configurations are within the ball park of something that might work with the TLM and various filaments so use them as a starting point.

Download Slic3r PE from Prusa website: https://www.prusa3d.com/slic3r-prusa-edition/

Pick a configuration for "Print Settings", "Filament", and "Printer" that is similar to the configuration of your TLM. Modify each file and save as a version with TLM in the filename. Don't edit the original configurations as you can save those for reference later. For each filament, nozzle, or printer configuration save a different TLM version of each file and tweak the settings for yourself after examining calibration prints.

Note the nozzle size on the TLM is 0.4mm by default, though you may want to change to 0.6mm to get faster or more reliable prints (less clogging) at the expense of resolution.

You will want to change at least the following in those 3 configurations:

Print settings
Start with configuration named "0.15mm Optimal" and save as "TLM - 0.1618mm Optimal 0.4mm", or
start with configuration named "0.15mm Optimal 0.6mm" and save as "TLM - 0.1618mm Optimal 0.6mm"
Change:

Layer height = 0.1618 (0.0809, 0.1618, 0.3236 for 0.4mm nozzle, or 0.1618, 0.3236 recommended for 0.6mm nozzle)
First layer height = 0.1618


Filament
Start with configuration named "Generic ABS 1.75mm" configuration and save as "TLM - Generic ABS 1.75mm.", or
if using PLA, PET-G or another filament choose the relevant "Generic XXX 1.75mm" file to save.
Change:

Extrusion multiplier = x.xxx (calculated at step 3)


Printer Settings
Start with configuration named "Original Prusa I3 MK2" and save as "TLM - Tevo Little Monster 0.4mm", or
start with "Original Prusa I3 MK2 0.6mm nozzle and save as "TLM - Tevo Little Monster 0.6mm"
Change:

Bed shape "Circular" (diameter: 340mm)
G-code flavor Smoothie
Use relative E distances [ ] (unchecked)
Nozzle diameter = 0.4 or 0.6
Layer height limits = 0.0809 min (0.4mm nozzle, or 0.1618 recommended for 0.6mm)
Layer height limits = 0.3236 max
Lift Z = 0mm (turn lift Z off as it hurts quality)
[ ] Retract on layer change (unchecked as it hurts quality)


Custom g-code ; XXX edit the "G30 Zx.xx" line from the value you calculated at step 2! IE "G30 Z1.20"

Code: Select all

;Start G-code (insert this g-code with your G30 value set)
;-----------
M280 S10.6 ; clear bl-touch errors after this command it should not flash
G28 ; home all axis
M280 S3 ; bl-touch extend to probing position light on pin out
G1 Z50 F25000 ; move to 50 off the bed speed 25000
G30 Zx.xx ; bl-touch trigger point in mm below nozzle tip - increase will lower nozzle closer to bed
M280 S7 ; bl-touch to idle position light off pin in
G1 X0 Y0 Z100 ; lift nozzle
M42

Code: Select all

;End G-code (insert this g-code)
;----------
G92 E0
G1 E-8.0 F9000
M104 S0 ; turn off temperature
M140 S0 ; turn off bed
G28  ; home  axis
;M84     ; disable motors


5) 0.6mm nozzle (optional)

I found using a 0.6mm nozzle is a massive upgrade. Good quality, faster prints, and no clogging. 0.6mm is wider, but still prints well at 0.1618mm layer heights so you don't loose resolution for all but the thinnest of walls. About $1 from ebay including postage. Don't forget to re-calibrate everything (auto, z-axis, extrusion rate) when you change nozzles.

Nozzle fitting volcano e3d hotend block will fit. Specs:
Length:21mm (approximately)
Material:Copper/Brass/Steel
Filament size: 1.75mm
Nozzle size: 0.4mm/0.6mm/0.8mm/1.0mm/1.2mm
Screw diameter: M6

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

Well hopefully you now have a printer that can make good quality small prints in ABS. Larger prints will require an enclosure due to the temperature differential between the bottom layers of the print and room temperature causing warping. The easiest way to mitigate warping to enclose the printer as the heated bed will elevate the ambient temperature around the whole print and reduce the difference.

NOTE 14/8/18 *Experience has learned me that an enclosure by itself will not help much, you need active heating to 50C for ABS. The best bed temperature is 110C (all layers,) the best surface is heated glass, and best adhesive for ABS is ABS juice applied by pouring a small amount of acetone on the bed and rubbing with an ABS puck.

I'd also recommend staying away from after-market bed stickers such as PEI. They are all consumable and an expensive learning curve. Once the original Buildtak one expires due to blistering, just go to using the glass bed and a purple glue stick or ABS juice.

NOTE 14/8/18 *The best surface is always heated glass. Use a temperature and adhesive that works for your filament. Most filaments will work very well with readily available household substances. Watered down PVA based adhesive works well as well as purple glue stick for PLA and many others. Some filaments like PLA can print straight onto heated glass very successfully if you clean the glass thoroughly (until it squeaks) with glass cleaner or vinegar.

Most print quality issues arising from printer settings can be troubleshooted using this guide, however I've found the Slic3r PE's Prusa I3 configuration to be a fairly good start: https://www.simplify3d.com/support/prin ... leshooting
Last edited by Xerxes on Sun Oct 14, 2018 5:18 am, edited 14 times in total.

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Re: Little Monster calibration and configuration in 5 steps

Post by Xerxes » Sun Oct 14, 2018 1:34 am

I need to add some information to the guide: As my experience increases I've learned a few things worth noting.

While you can print ABS, the object size you can do reliably without an actively heated enclosure in a cold room is going to be about 4cm x 4cm x 4cm. Bigger, maybe, if you live in a hot climate (30C+.)

To get started please use PLA or if you want something stronger and more like ABS, use PET-G. It has all the advantages of ABS and less downsides, but is only a little more expensive.

In order to go to full bed sized prints with ABS you need a at least of 50C inside. 80C would be better, 50C is sufficient, but don't exceed 50C without water cooling of the heat break or you can expect problems with jamming!

Also the smoothers 1000% need to to have heatsinks on them or they will not work. Semiconductors like silicon (Si) loose their resistance as they heat, which is the opposite of what happens to conductors like metals (they increase resistance.)

Since the smoother hack works because it reduces the voltage on the signal lines by 1.4V, when they get hot they do not provide this drop as they have no resistance. I have used mine without heat sinks and they got so hot they reflowed during printing (over 230C.) They survived this multiple times surprisingly!

Once they have heat sinks on them, they work extremely well, they are a real solution to upgrading the stepper drivers, and no salmon skin is visible on the prints at all.


I'm going work this information into the above guide for people who have yet to read it.

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Re: Little Monster calibration and configuration in 5 steps

Post by Xerxes » Sun Nov 18, 2018 2:15 pm

Another follow up.

The way Slic3r is configured above using the Prusa i3 files results in acceleration values of 2000mm/s/s movements, and 800mm/s/s external shells, which is very safe and should get decent results on external shells with minimal ringing.

The default acceleration is 6000mm/s/s from the factory in the TLM's firmware configuration file.

Not an issue with Slic3r, as this should be overridden. But other software packages may not allow you to set it outside of putting gcode into the startup script, which isn't obvious. To improve quality on all software control packages, consider updating your firmware's configuration.

A sane default is 1500mm/s/s to 2000mm/s/s.

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