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

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

I ran e-corr recently on 3.7.2 to fine tune my skelestruder. No issues.

Posted : 29/06/2019 9:56 am
CybrSage
(@cybrsage)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: guy.k2

Cybersage,

I'm going to have you follow some instructions exactly to execute gcodes. Please refrain from opening the gcodes to check them with your editor. I want to fully remove the editor as a remote, but possible cause of problems.

Please follow the instructions exactly and without interpretive deviation. Your system is acting in a bizarre manner and we need to greatly reduce the number unknown variables.

The cube is 0.89mm thick on every side and 25.28mm wide and perfectly square.  Admittedly, I do not know if I am pressing too tight or not, I tried to close the micrometer until it lightly touched the sides, then moved it to each side to make sure it slid onto them easily yet I could hear it lightly scraping so I know it was touching.

It looks VERY good to me.  I took a picture of the outside (the side that appears to have a seam on it) and the inside bottom.  What settings did you use to slice it, I want to mimic them.  As a note, I kept having issues with things sticking to the textured PEI plate, possibly because I had been cleaning it with acetone like they said but now say will damaged it.  I am now using the smooth PEI plate and everything is sticking like it was glued.

This post was modified 5 years ago by CybrSage
Posted : 29/06/2019 5:17 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

CyberSage, the walls are much thicker than they should be. They should be 0.45 mm thick.

By using my gcode, we have eliminated slicer settings as the root cause.

There is something physically different about your printer that  we are not aware of. 

Let's have a look. Could you post picts of your extruder, nozzle tip, and extruder motor (the model number label)

Posted : 29/06/2019 7:07 pm
CybrSage liked
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Let us also eliminate your compilation of the firmware as a cause. You settings looked correct. So this is very remote possibility. Let's have you flash with firmware compiled here and repeat printing of the extrusion calibration cube.

The attached firmware is MK3S, 3.7.2 with 0.9 motors on x and y, BMG geared extruder.

unzip and flash to printer.

Attachment removed
Attachment removed
This post was modified 5 years ago 2 times by Bunny Science
Posted : 29/06/2019 7:28 pm
CybrSage liked
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

After flashing the firmware, please also do printing of my "set BMG esteps" gcode, printer off/on sequence before repeat printing of the extrusion calibration cube. 

When you post image of cube, I am most interested in an image with its TOP edge well focused.

Posted : 29/06/2019 7:36 pm
CybrSage liked
AnatomicFlack
(@anatomicflack)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Trying to add a video with the "Add Media" option.  Hopefully it's high enough resolution to see the benchy in good detail.  

https://forum.prusa3d.com/wp-content/uploads/2019/06/55Xa2R0.mp4

Printed in PRUSA PETG (It's the end of a scrap roll, so it wasn't very dry).  I need another set of eyes on my prints.  I think I'm still seeing some very fine VFAs, but maybe I'm just seeing stuff that can't be eliminated. On some more organic models I've printed I think I'm confusing actual surfaces for VFAs.  

This post was modified 5 years ago by AnatomicFlack
Posted : 29/06/2019 7:59 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Yes, I agree there are some fine VFA's in the print. Easiest place to look without getting confused is on the FLAT surfaces. Looking where only one x or y motor is running is easiest place to detect them without confusion by other other artifacts. Their characteristic spacing (doesn't vary) also makes them easier to identify. 

They won't completely go away with the 0.9 motors. Maybe with the zero detent motors, but I have none of those to test.

Posted : 29/06/2019 8:28 pm
AnatomicFlack
(@anatomicflack)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: guy.k2

Yes, I agree there are some fine VFA's in the print. Easiest place to look without getting confused is on the FLAT surfaces. Looking where only one x or y motor is running is easiest place to detect them without confusion by other other artifacts. Their characteristic spacing (doesn't vary) also makes them easier to identify. 

They won't completely go away with the 0.9 motors. Maybe with the zero detent motors, but I have none of those to test.

Thanks.  Are we looking at the same thing... the fine fast repeating pattern in the filament layers? I ran a few XYZ cubes, but it was harder to catch that pattern.  I'll scale one up and run it.  

I just swapped out my Prusa X pulley for another Prusa one I bought with the new EISNY.  The original one was out of round by just a tiny bit and it would cause moving the extruder along the axis to get slightly harder than easier.  I don't believe that was contributing to this particular VFA, but it certainly couldn't be helping things. The new one is smooth along the entire length at the same belt tension.  Prusa missed the boat on that one during QC (especially since mine was an assembled printer).  Running another benchy now for comparison.  

The real trouble with all this fine tuning is you quickly discover your less than ideal parts. 🙂

I still have my Misumi pullies and belts coming in about a week to swap in. 

This post was modified 5 years ago by AnatomicFlack
Posted : 29/06/2019 8:44 pm
CybrSage liked
CybrSage
(@cybrsage)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

The cube printed the same thickness again.  I have included a direct top down view of the cube and a slightly angled one as well.  There is a little bit of elephant footing going on.

 

Posted : 29/06/2019 10:51 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Cybersage, yes the top edge verifies it was printed as a single shell with double the extrusion specified in the gcode. Easiest explanation is a 1.8 degree extruder motor being driven as a 0.9, but the configuration file snippet appeared correct. I don't know there are a garbage characters in the file or a bad Arduino build environment. Hence, the need to flash with firmware compiled by me instead of you.

I am quite frustrated. It is impossible to help you without any indication which of my instructions you actually follow. There is ample indication that something is wrong. Knowing which steps you followed is essential to ruling items out. 

I will ask in exacting detail because each piece of information is needed. PLEASE answer or provide each item requested. Without good feedback, we may as well let you figure it out on your own.

---

Did you flash your printer with the firmware "firmware mk3s for cybersage.hex" I uploaded in my prior post?

After flashing with the firmware I provided, did you print my "set BMG esteps.gcode" file from SD?

Did you turn the printer off/on after printing "set BMG esteps.gcode"

What size print nozzle are you using? Is it a 0.4 mm nozzle or a large one?

Still need pictures of your extruder.

Still need picture of your extruder motor including its model number.

Please zip and attach your entire firmware folder used for your Arduino compile.

 

 

 

 

Posted : 30/06/2019 12:02 am
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

AnatomicFlack, scaling up the cube won't scale up the VFA's. VFA's are fixed in size and 2Dspace. I use the term VFA very strictly because doing otherwise invites confabulation with other artifacts. That quickly becomes impossible to sort out what people are looking at or trying to fix.

Think of VFA's as a piece XY cartesian coordinate graph paper. Each little square on the graph paper is where non-linearity of a microstep causes the carriage to change its travel velocity. Because our belt system is synchronous, any particular XY location always has the motor shaft positions in the same microstep position. Hence VFAs are fixed in space.

If carriage motion slows, more plastic is deposited at that XY coordinate. If carriage motion accelerates, less plastic is deposited. We see these deviations from uniform delivery of plastic as fine vertical lines. I call them Vertical Fine Artifacts. Remember that they recur at the same xy coordinates. The VFA's align in same xy locations for each layer. End results are fine vertical lines with a spacing that is directly related to how far motor moves during microstep cycle. Period stays constant. XY location stays constant.

Going to 0.9 degree motors but keeping the number of effective microsteps/mm constant allows the motor to be more linear. The motion disturbances at the XY coordinates become smaller. VFA's decrease in amplitude.

Note however, the spacing of the lines in our XY graph paper does not change. Scaling up an object merely makes it larger cross more of the XY lines. The VFA's don't get magnified by scaling up an object. The underlying XY "graph" of motion deviation locations remains the same.

Posted : 30/06/2019 12:18 am
CybrSage
(@cybrsage)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)
Posted by: guy.k2

Cybersage, yes the top edge verifies it was printed as a single shell with double the extrusion specified in the gcode. Easiest explanation is a 1.8 degree extruder motor being driven as a 0.9, but the configuration file snippet appeared correct. I don't know there are a garbage characters in the file or a bad Arduino build environment. Hence, the need to flash with firmware compiled by me instead of you.

I am quite frustrated. It is impossible to help you without any indication which of my instructions you actually follow. There is ample indication that something is wrong. Knowing which steps you followed is essential to ruling items out. 

 

Did you flash your printer with the firmware "firmware mk3s for cybersage.hex" I uploaded in my prior post?  YES

After flashing with the firmware I provided, did you print my "set BMG esteps.gcode" file from SD?  YES

Did you turn the printer off/on after printing "set BMG esteps.gcode"  YES - waiteed 10 seconds before turning off, then kept it off for 10 seconds.  Comes up with Bunny XYE9 BMG OK

What size print nozzle are you using? Is it a 0.4 mm nozzle or a large one? 0.4mm normal everyday nozzle, a little dirty on the sides, a little left over from an old blob.

Please zip and attach your entire firmware folder used for your Arduino compile.  I deleted it when I used the new firmware you sent me.  But if you like, I can recreate it (following the steps in the read.me file) and it will be the same as the one I made before.

Not sure what you want to see with the extruder, so I took a pic looking up at the nozzle and one from the side.  I have extra nozzles, I can replace it just in case something happened to a sleeve inside it or such and it is all kids of messed up.

The fan cable slipped out of hits holder when I was moving things around for a better shot, normally it is safely in its run.  The motor comes up as a 1.8 degree stepper, which is too bad...I was hoping they sent me a 0.9 by mistake and that would answer a lot of questions.  I bought the full kit from Bondtech even though I did not need it all - I wanted it mostly assembled and it gave me a spare set of gears.  I have an MMU2s but it is unplugged and I am running the MK3 in stand alone mode, completely bypassing the MMU2s until I get everything else figured out, so it is not part of the issue at all...the printer does not even know it is there.

This post was modified 5 years ago 2 times by CybrSage
Posted : 30/06/2019 2:57 pm
CybrSage
(@cybrsage)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

So I decided that if it is doubling the thickness at 830 esteps, what would it do if I edited the gcode to make it 415 esteps.  The result is fantastic...but I have to wonder WHY it is!  The cube thickness is 0.49mm (give or take a tiny bit, it is a $20 caliper) and looks VERY smooth.  What could it mean?  I followed the Bondtech instructions to the letter (easy enough to do when it was mostly prebuilt).  This is the exact one I purchased from them.  https://www.bondtech.se/en/product/prusa-i3-mk2-mk2s-extruder-upgrade/

Posted : 30/06/2019 5:33 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Thank you for getting that all back to me. It rules out a host of zebras. Your physical setup cannot be causing this doubled extrusion rate. No need to recreate your firmware file. Having certainty that my compiled file also creates this issue rules your compilation / editing out as the problem. This is bizarre and yes, your halving the esteps does solve it, but you should not need to do so.

Based on all information, I have to conclude my firmware is doing something weird when BMG extruder gets defined. Looking through, but nothing obvious. There HAS to be something. Just don't see it yet. 

Posted : 30/06/2019 7:00 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

I just don't see anything in the firmware. Just weird.

Can we see a pict inside your extruder (with idler door open)?

Is there any way to assemble a BMG with 1.5:1 gearing?

This post was modified 5 years ago by Bunny Science
Posted : 30/06/2019 8:20 pm
Dave Avery
(@dave-avery)
Honorable Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

could the g-code have an e-step opcode embedded?

Posted : 30/06/2019 8:26 pm
AnatomicFlack
(@anatomicflack)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Oh I wasn't suggesting to scale up prints to magnify the VFAs, I was only trying to get a few larger flat area to more easily spot them.  🙂 

I printed a couple single wall cubes in black PETG, but the wall buckled a little at the size I printed (so they weren't flat enough to get a good bounce of light).  I need to print something with some structure to keep the planes flat. 

I'm just trying to diagnose where my small fast repeating VFAs are coming from.  What pattern were you getting using the Prusa pullies?  It's tough to tell if I'm getting the same VFAs on both X and Y or mostly X and a little Y.  

I'm just a bit unsure what to check next.  

 

Posted : 30/06/2019 8:45 pm
AnatomicFlack
(@anatomicflack)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

Here are three videos to try and highlight what I'm seeing on an XYZ.  

https://forum.prusa3d.com/wp-content/uploads/2019/06/AMWjuX9.mp4

https://forum.prusa3d.com/wp-content/uploads/2019/06/zxTjcGH.mp4

https://forum.prusa3d.com/wp-content/uploads/2019/06/NA1eBKM.mp4

Posted : 30/06/2019 9:32 pm
Bunny Science
(@bunny-science)
Noble Member
Topic starter answered:
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

AnatomicFlack, those look really very nice. There is a little bit of residual VFA, but your results are already about the best we can get out of the 0.9 motors we are using.

The pulley belt artifact is VERY faint, broader vertical bands with 2mm horizontal spacing - which is consistent with our 2 mm spacing of belt and pulley teeth. Usually needs a flat surface about 5 cm or longer before you reliably find it. 

-------

Still have no explanation for CyberSage's machine acting so weird. Is anyone else using my 0.9 firmware with a BMG extruder?

Posted : 30/06/2019 9:47 pm
Evan
 Evan
(@evan-2)
Eminent Member
RE: Stepper Motor Upgrades to Eliminate VFA's (Vertical Fine Artifacts)

For @cybrsage, I hesitate to throw this out there since I can't really explain it, but I had some weird behavior this week as well. Changed back to 0.9° steppers and flashed new firmware. When I started a print, the both X & Y axes traveled exactly half distance at half speed. I tried several different iterations of firmware, setting steps with gcode, etc. Nothing made a difference.

Eventually, I did a factory reset and selected the option to delete all data. It didn't work...until I turned the machine off and back on. Then it worked perfectly. No explanation, but I'm happy with the result!

Posted : 30/06/2019 10:05 pm
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