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Removing vertical lines on prints

Posted by nebbian 
Re: Removing vertical lines on prints
May 27, 2017 11:54AM
Are you? I can see how these work in basic terms creating a smoothing effect by limiting inductance? But I'm fairly happy with my prints so not sure I'd buy them they must have a cost in terms of something or the driver manufacturer's would put these components on the driver IC.


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SJN
Re: Removing vertical lines on prints
May 27, 2017 04:25PM
Have tried smoothers on the 2100's, and they do nothing at all. They work great on the drv 8825
SJN
Re: Removing vertical lines on prints
May 28, 2017 12:33PM
ok...so I was looking at all my prints, and saw the bottom layer was looking realy nice.....and thats when it prints slowly

So I decided to do a complete print slowly at 20mm/s and see what happen, and it actualy looks much much nicer....... why is speed effecting this ?
I dont know if you can see the differences in the pictures, but in rea llife, it is quite noticable.

Left benchie is at 40mm/s, and right is 20mm/s both 0.3mm









Re: Removing vertical lines on prints
May 29, 2017 05:07AM
Errors related to too big blanking time (i.e. the errors we are fixing by selecting mixed/fast decay or by diodes (TL smoothers)) are always worse when printing slowly than when printing quickly. These are the errors which happen on the rising quadrant(*) of a sinusoidal signal going from drivers into the steppers.

Errors related to slow decay at the falling current quadrant(**) get worse with higher speed. But it is highly unlikely you get this problem because I doubt there is any stepper driver which would use slow decay in the falling current quadrant by default. But it is often possible to set slow decay even in the falling current quadrant. I doubt you have stepper drivers setup this way.

(*) the part of sinusoid where the value is increasing its distance from zero (regardless whether in positive or negative direction)
(**) the distance from zero is decreasing (regardless whether in positive or negative direction)

If you get nicer prints when printing slowly then it is probable you have some other problem. Besides the rare case I mentioned above, here are the examples of problems which improve with smaller printing speed and smaller accelerations:
  • loose belts or too elastic belts ("ringing" at the corners)
  • play in the printer (e.g. in the ball joints or between belt and pulleys)
  • overloaded MCU leading to segment buffer under-runs which lead to head movement slow-downs (decrease segment_per_second or ldc_refresh_rate)
Re: Removing vertical lines on prints
May 30, 2017 10:32AM
LV8729V and THB6128 use the same mixed decay scheme but are not the same driver. The datasheets use a lot of the same graphics and wording and both have Sanyo logos in various places. As far as I can tell, they both appear to have been designed and fab'd by Sanyo on behalf of other companies.
Re: Removing vertical lines on prints
May 30, 2017 10:44AM
Hi Ryan, do you know if you can adjust the decay on LV8729's?


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Re: Removing vertical lines on prints
May 30, 2017 03:11PM
My understanding is that the THB6128 and the LV8729 are the same chip in different packages. The LV is designed to be cooled via the PCB like normal driver chips, whereas the THB had the thermal pad on top instead of on the bottom to make it more suitable for use in plug-in driver modules with heatsinks fitted on top.


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Re: Removing vertical lines on prints
May 31, 2017 08:29AM
Do you know if LV8727 would be close to LV8729 performance?
SJN
Re: Removing vertical lines on prints
June 06, 2017 10:19AM
Strange. I just removed the chinese heatbreak, and 0.4mm nozzle, and installed original E3D parts instead......now I also get the wood grain texture in my pints.....could not replicate that before at any layer height with the old nozzle
Printed at 0.25mm 0.4nozzle






Re: Removing vertical lines on prints
June 06, 2017 06:53PM
Quote
SJN
Strange. I just removed the chinese heatbreak, and 0.4mm nozzle, and installed original E3D parts instead......now I also get the wood grain texture in my pints.....could not replicate that before at any layer height with the old nozzle
Printed at 0.25mm 0.4nozzle

That... does not compute. Gosh. Very interesting data point.
Re: Removing vertical lines on prints
June 06, 2017 11:30PM
Does nozzle diameter affect this pattern? Not many clone nozzles are exactly the diameter they are sold as. SJN have you verified the diameter of the nozzle?


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Re: Removing vertical lines on prints
June 06, 2017 11:36PM
I still see a pattern on the left cube like several parallel lines descending from left to right in a low angle ( 30°ish).
How did you secure the heatbrake in the heatsink? Was it tight or loose enough to blurr out the tree rings?
SJN
Re: Removing vertical lines on prints
June 07, 2017 06:02AM
Yes, it is strange. Sorry, did not mention, but the left cube is printed on the chinese nozzle, and the right is the E3D nozzle.
40 is stamped on the chinede nozzle, and 4 dots on the E3D.

I havea actually updated the firmware to another version now that I think about it......
The steps in the config file, and arm length and radious and steps has changed since I made the old cube.

New firmware and config was provided by TEVO to level the bed better. A new probe pattern with the bl touch was added.

I wonder if this has caused it...must have ?





Old config :

# Arm solution configuration : Cartesian robot. Translates mm positions into stepper positions
# See [smoothieware.org]
alpha_steps_per_mm 80 # Steps per mm for alpha ( X ) stepper and tower
beta_steps_per_mm 80 # Steps per mm for beta ( Y ) stepper and tower
gamma_steps_per_mm 80 # Steps per mm for gamma ( Z ) stepper and tower

# Delta configuration
# See [smoothieware.org]
arm_solution linear_delta # Selects the linear delta arm solution
arm_length 396.9419 # This is the length of an arm from hinge to hinge
arm_radius 156.5621 # This is the horizontal distance from hinge to hinge when the effector is centered







"New config"


# Arm solution configuration : Cartesian robot. Translates mm positions into stepper positions
# See [smoothieware.org]
alpha_steps_per_mm 79.765 # Steps per mm for alpha ( X ) stepper and tower
beta_steps_per_mm 79.765 # Steps per mm for beta ( Y ) stepper and tower
gamma_steps_per_mm 79.765 # Steps per mm for gamma ( Z ) stepper and tower

# Delta configuration
# See [smoothieware.org]
arm_solution linear_delta # Selects the linear delta arm solution
arm_length 397.1900 # This is the length of an arm from hinge to hinge
arm_radius 157.0741 # This is the horizontal distance from hinge to hinge when the effector is centered

Edited 1 time(s). Last edit at 06/07/2017 06:09AM by SJN.
Re: Removing vertical lines on prints
June 07, 2017 08:04AM
Changing the steps per mm value will do that.

You probably didn't do a cube at 0.202 layer height (at your old 80 steps/mm value). If you had, you would probably have seen the tree ring U shaped pattern.

Changing the steps/mm down will have the same effect, when you print at 0.2mm layer height.


It's all making sense to me now.
SJN
Re: Removing vertical lines on prints
June 07, 2017 09:34AM
Yea, allways a reason for things :-)

Well, removed the TMC 2100, and installed LV8729`s. ordered 4, but one of them had a broken VREF pot.
So installed 3 on the XYZ, and a TMC on the extruder.

First cube at 1/16 stepping looked very similar to the TMC
Other cube at 1/32 looks way better.
TMC`s are silent, LV`s make some noise, and the DRV8825 are noisy.

Printed at 0.25mm height.

Tmc left, LV 1/16 middle, and LV 1/32 right



4 sides of te 1/32 cube







Re: Removing vertical lines on prints
July 09, 2017 01:15AM
All I can add is that I built my Sintron Kossel out of the box, didn't modify anything at all. Running standard Marlin, using the original hotend, binned the alloy bed and installed a glass one. I only print using the cheapest PLA that I can find, and do not have a part cooling fan. I use a PVA glue stick, and don't get any lifting.

I almost sold it after I built it as I was convinced that it was never going to print properly, but I stuck with it, and kept searching for configuration info. Then one day, bingo! It worked as nature intended, and has done ever since. It is fast, smooth and produces top quality prints. The nozzle never clogs, it just keeps running. The only things that have happened are blown thermistors and wires snapping on hotend heater cartridges. I fit the cheapest Chinese replacements that I can find. 12v/25w or 30w.

The only thing I would wish for is a larger print bed due to the size of some items I need to print. I also have an old Smartrap that I can use as that has a 200x200 bed. I am thinking of using the parts from that to build a Hypercube, with a 400x400 bed, which means that between them the two printers would give me the best of all worlds.

The standard Sintron is quite an amazing piece of kit, the problem is that Delta's are, as I learned, an absolute pig to configure. I would guess that many think that as it is cheap, it doesn't print well due to cheap parts, so they keep buying more expensive 'upgrades'. The printer in standard form, as many will testify, is capable of some wondrous things. The issue is that whereas a Cartesian printer will print pretty well when not perfect, a Delta needs to be tweaked to perfection or it won't produce the goods.

The Ramps board is my only weak point, I think the thermistor circuit is about to give up the ghost as it keeps losing the temperature, gets to the start print stage, and then drops up and down drastically. It's had a lot of use, and I always keep a spare so that I can swap it out.
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Re: Removing vertical lines on prints
July 09, 2017 06:44AM
Very interesting read. I thought i read this before, but that was in relation to ball-grove rods... i will have to make an adjustment and watch for gains,


From what i've gathered her the drivers on the duet wifi are already in fast decay mode?
SJN
Re: Removing vertical lines on prints
July 09, 2017 08:14AM
I doubt it, otherwise it would ve very noisy......and that is not the case.
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