Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)  

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Hello, just got 17HM15-0904S for X and Y axis. I run over this thread about linearity correction but I did not find any information, how do you test proper value for X/Y linearity correction. Is there any test pattern similar to that tower for extruder linearity correction?

Btw, is that extruder linearity correction working for anyone? I tested and all parts of the tower have that pattern, none is clean.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Hi @guy-k2

I've tested many many steppers now on other printers and now also on my Prusa MK3S.
But at the Moment i have a Problem with your Firmware for 0.9deg Steppers.
With your Firmware i get no sharp edges.

I modifyed the stock Firmware only with steps to 8, homing Speed and the sensorless thershold.
And with this i get better edges.

Lefts side in the Picture is stock Firmware and Right your Firmware … i have Nothing changed in Hardware, only changed the Firmware. After Firmware Change i run the komplete wizard and also erase the data.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

@michael-1

Looking at the bottom edge and the lower left hand side of the Z, it looks like your K factor is well out.

In Prusa Slicer did you change the K factor from the higher Prusa values to the much lower LA1.5 values as used by Guy's firmware?.

(I'm at work so cant open Prusa Slicer to get exact details)

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Both cubes are the same gcode file. I must check LA but i think it is off. Also in the FW it is set to 0. I tought the FW 3.8.1 can handle both LA values.

Left cube Looks than with LA and the Right without LA or not?

I will go back to 0.9deg Steppers and FW from GUY and check the LA function. Maybe you can tell me the important Points.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I installed OMCs 0.9deg stepper with Guy's FW again. 

The cube looks the same whether I put M900 K30 or K0 in the start code.

When I do M900 K2 it is very strange. Very thick straight lines and the corners are missing. And the extruder accelerates audibly and brakes like "bubble gum".

If i use stock 3.8.1 or the Bontech Version the Corners are better but the stepper noisier.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Yikes. K30 vs K0 for linear advance 1.5 is fantastically wrong. You are plugging in values that are bonkers for LA 1.5.

Use the test generator at http://marlinfw.org/tools/lin_advance/k-factor.html to create a test file from 0 to 0.3 in 0.02 steps to measure on your printer.

Under LA 1.5 the value is going to be a small, fractional value. My printers are best around M900 K0.075 or K0.10. 

BTW never confuse linear advance with linearity correction in the Prusa setup menu. They are completely different things.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

If it helps, here is what my printer settings custom start g-code for BNBSX with an E3DV6 hot end. (Mosquito needs slightly lower, M900 K0.075)

M83 ; extruder relative mode
G28 W ; kuo MUST FIRST home all without mesh bed level or else risk nozzle crash!
G0 X70 Y70 Z0.2 F2000; PINDA warms faster near bed
M140 S[first_layer_bed_temperature] ; set bed temp
M104 S160 ; preheat extruder to no ooze temp to help warm PINDA
M190 S[first_layer_bed_temperature] ; wait for bed temp
M109 S160 ; wait for extruder temp
M860 S36 ; wait for PINDA temp. For most stable PINDA temp during mesh, measure your actual PINDA temp at end of mesh call and enter a temp here 1-2 deg below that value.
M104 S100 ; drop extruder to lower temp to minimize PINDA temp rise during mesh
G80 N7 R3 ; mesh bed leveling
G1 Y-3.0 F1000.0 ; go outside print area
G92 E0.0
G1 Z3 ; raise head safely clear of bed before heating extruder
M104 S[first_layer_temperature] ; we heat extruder AFTER mesh to minimize ooze
M109 S[first_layer_temperature] ; wait for extruder temp
M900 K0.1 ;set LA 15 kfactor
G1 Z0.7 ; kuo move slightly above bed for easy clean intro line
G1 X60.0 E9.0 F1000.0 ; intro line
G1 X100.0 E12.5 F1000.0 ; intro line
G1 E-0.8 F2100; bobstro anti-stringing retract and wipe
G1 X99.0 E0 F1000.0 ; -1mm intro line @ 0.00
G1 X110.0 E0 F1000.0 ; +10mm intro line @ 0.00
G1 Z0 ;kuo lower head back to normal Z after intro line
G92 E0.0
M221 S{if layer_height==0.05}100{else}95{endif}

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Thanks alot @guy-k2

I've now a K value of 0.04 and it is almost the same as with stock FW.

But why is there such a big difference? The Stock Firmware also use LA1.5?

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Posted by: @michael-1

 

But why is there such a big difference? The Stock Firmware also use LA1.5?

No, it doesn't. (yet, it's coming in 3.9.0)

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Exactly the information I’ve been googling for. Thanks!

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

So with 44 pages, there's a LOT to root through here.   Is there any particular place where some finality was achieved?  Considering buying new stepper motors to achieve the better surface finish.  I've edited firmware before so shouldnt have too much of an issue adjusting voltage and such, but some guidance would be great.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I have now installed the Skelestruder and all other Taurus Mods. The X and Y axis work well and the extruder starts to click when loading the parliament. All motors except z are 0.9.
I looked with the M503 command and it took the steps correctly.
"Recv: echo:Steps per unit:
Recv: echo: M92 X100.00 Y100.00 Z400.00 E490.00
Recv: echo:UStep resolution:
Recv: echo: M350 X8 Y8 Z16 E8
It also looked as if he either extruded too much or did not lift Z properly on a new layer.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I wonder. Last time I couldnt use my LDO motors because the drivers just cant handle them.

Now that chris got a cloned prusa firmware running on a proper 32 board with 2209s. You guys think the chance of them working now got much bigger? I am going to do a full bear rebuild with the skr 1.4 anyway. Figure I might as well try to get the 0.9 LDOs working

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

i think i found the error.
Because I have the Skelestruder I noticed that the configuration in the description of the Skelestruder shows  3.0 ratio,
although the 3.5 ratio is most used with 56/16.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

//====== Kuo Uncomment ONLY ONE or NONE of below for geared extruders
//Don't forget to also send gcode to set e-steps as detailed earlier
//Reversion back from geared extruder requires sending M92 E280 & M500 to printer
//
#define SKELESTRUDER // Uncomment if you have a skelestruder. Applies the patches for load distances and Z height.
//#define BONDTECH_PRUSA_UPGRADE_MK3 //Kuo Uncomment for Bondtech MK3 extruder upgrade. 3:1 extruder. This also sets Z_MAX_POS 205.
//#define BONDTECH_PRUSA_UPGRADE_MK3S //Kuo Uncomment for Bondtech MK3S extruder upgrade. (Note the S!!!!) 3:1 extruder. This also sets Z_MAX_POS 205.
//#define EXTRUDER_GEARRATIO_30 //Kuo Uncomment for extruder with gear ratio 3.0. 
//#define EXTRUDER_GEARRATIO_3375 //Kuo Uncomment for extruder with gear ratio 3.375 like 54:16 BNBSX.
//#define EXTRUDER_GEARRATIO_35 //Kuo Uncomment for extruder with gear ratio 3.5 like 56:16 Bunny and Bear Short Ears or Skelestruder.

There are to section for skelestruder and only one should uncomment. So if i use the EXTRUDER_GEARRATIO_35 section does it also applies the patches for load distances and Z height?

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

With the Taurus Y axis mod (Motor in middle of printer not at end), I found homing with the OMC 0.9 Deg motor unreliable and causes skipping, this is due to belt stretch and tooth jumping since the Y axis mod, the belt is only in contact with the pulley for about 1/3 its surface, whereas with a motor at the end it is at least 1/2 the way round the pulley.

Also from the end stop to the motor is approx quarter the belt length, whereas at the end it is what, about 1 cm, maybe less, even with stretch, this is hardly going to make any difference, but 1/4 of the whole belt length will.

This is one of those where the original motor mounting position is better than the Taurus Y axis mod, don't get me wrong, it is a nicely engineered mod, but I found it problematic when moving to 0.9 Deg motors. YMMV.

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Uncomment only the

#define SKELESTRUDER

That does set it up for 3.0 gear ratio and all the other move distances for Skele.
If you are on a different ratio Skele, you'll need to edit the step valuess. Search for Skelestruder later in that config file.

I probably should remove the 2nd skele mention. That was originally the only Skele mention. The 1st one listed was added later to implement the special move distances.

 

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I have now looked at the other lines and found that both defines are identical.
At a 3.5 ratio it is 960 e-steps and by setting to 8 microsteps it becomes 490. Or I get something wrong.

#ifdef SKELESTRUDER
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,490} //Skelestruder 3.0 geared extruder 
#define TMC2130_UNLOAD_CURRENT_R 20 //higher unload current than stock for M600

#elif defined(BONDTECH_PRUSA_UPGRADE_MK3)
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,415} //Bondtech upgrade MK3 approx 3:1 geared extruder
#define TMC2130_UNLOAD_CURRENT_R 20 //BMG unload current for M600

#elif defined(BONDTECH_PRUSA_UPGRADE_MK3S)
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,415} //Bondtech upgrade MK3S (Note the S!!!!) approx 3:1 geared extruder
#define TMC2130_UNLOAD_CURRENT_R 20 //BMG unload current for M600

#elif defined(EXTRUDER_GEARRATIO_30)
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,420} //3.0 geared extruder 
#define TMC2130_UNLOAD_CURRENT_R 20 //higher unload current than stock for M600

#elif defined(EXTRUDER_GEARRATIO_3375)
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,473} //3.375 geared extruder like 54:16 BNBSX
#define TMC2130_UNLOAD_CURRENT_R 20 //higher unload current thans stock for M600

#elif defined(EXTRUDER_GEARRATIO_35)
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,490} //3.5 geared extruder like 56:16 BNBSX
#define TMC2130_UNLOAD_CURRENT_R 20 //higher unload current thans stock for M600

#else
#define DEFAULT_AXIS_STEPS_PER_UNIT {100,100,3200/8,280} //default steps/unit e-axis
#define TMC2130_UNLOAD_CURRENT_R 12 //lower current for M600 to protect filament sensor with stock extruder
#endif

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

You're right. It IS 3.5 ratio for the SKELESTRUDER define. 

Will have to come back round and fix up the comment. Still on list is firmware 3.9 when I get a breather from work

RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Okey then the extruder has another problem that it extrudes so much. i'll try to make a video later, maybe one of you knows what it is.