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    Oddly shaped holes?

    Scheduled Pinned Locked Moved
    Tuning and tweaking
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    • Surgikillundefined
      Surgikill @arhi
      last edited by

      @arhi This is the start of one of my gcode files. I forget exactly what I had to do, but I think I wrote something special in there because I'm using 4 independent z motors to tram the bed.

      M107
      M107
      M104 S235 ; set temperature
      G32 ;home and level
      G28 ;home
      G21 ; set units to millimeters
      G90 ; use absolute coordinates
      M82 ; use absolute distances for extrusion
      G92 E0
      ; Filament gcode
      M109 S235 ; set temperature and wait for it to be reached
      
      G21 ; set units to millimeters
      
      G90 ; use absolute coordinates
      
      M82 ; use absolute distances for extrusion
      
      G92 E0
      
      G1 Z0.200 F7800.000
      
      G1 E-2.00000 F2400.00000
      
      G92 E0
      G1 Z0.350 F7800.000
      G1 E-2.00000 F2400.00000
      G92 E0
      G1 X91.390 Y102.905 F7800.000
      G1 E2.00000 F2400.00000
      G1 F1800.000
      G1 X93.026 Y102.689 E2.11451
      G1 X117.999 Y102.489 E3.84808
      G1 X179.410 Y102.488 E8.11097
      G1 X207.724 Y102.689 E10.07646
      G1 X208.948 Y102.812 E10.16187
      G1 X209.906 Y103.069 E10.23068
      G1 X210.823 Y103.463 E10.29994
      G1 X211.673 Y103.985 E10.36920
      G1 X212.434 Y104.621 E10.43802
      G1 X213.273 Y105.598 E10.52746
      G1 X215.387 Y108.621 E10.78349
      G1 X215.889 Y109.505 E10.85410
      

      I'm going to try adding your code in with the prime on the extruder. I usually use a skirt, so that's my priming.

      1 Reply Last reply Reply Quote 0
      • Surgikillundefined
        Surgikill @arhi
        last edited by

        @arhi Yea I just ran the updated Gcode and it's still printing in air and not extruding anything. This is what I have for the gcode.

        
        
        M107
        M107
        M104 S235 ; set temperature
        G32 ;home and level
        G28 ;home
        G21 ; set units to millimeters
        G90 ; use absolute coordinates
        M82 ; use absolute distances for extrusion
        G92 E0
        ; Filament gcode
        M109 S235 ; set temperature and wait for it to be reached
        
        G21 ; set units to millimeters
        
        G90 ; use absolute coordinates
        
        M82 ; use absolute distances for extrusion
        
        G92 E0
        
        G1 Z0.200 F7800.000
        
        G1 E-2.00000 F2400.00000
        
        G92 E0
        G1 Z0.350 F7800.000
        G1 E-2.00000 F2400.00000
        G92 E0
        G1 X91.390 Y102.905 F7800.000
        G1 E2.00000 F2400.00000
        G1 F1800.000
        ;...
        G21       ; millimeters
        
        G90       ; absolute XY moves
        
        M83       ; RELATIVE extruder move
        
        M200 D0   ; no volumetric extrusion
        
        G0X0Y0Z10 ; go to 0,0,10
        
        G1E50F100 ; extrude a blob of plastic in the air to prime the nozzle
        
        G1X0Y20Z0.25      ; go to start position, 0.25mm layer
        
        G1X10Y10
        
        G1X50Y50F600E2.352 
        
        G1X80Y10F600E2.352 
        
        G1X100Y30F600E1.176
        
        G1X70Y70F600E2.352 
        
        G1X50Y50F600E1.176
        
        G0Z20
        
        ;...
        
        ; shut everything down here
        
        G92 E0
        M107
        ; Filament-specific end gcode 
        ;END gcode for filament
        M104 S0 ; turn off hotend
        
        M140 S0 ; turn off bed
        
        G28 X0 Y0  ; home X axis
        
        G1 Z310  ;move Z to max
        
        M84     ; disable motors
        
        
        
        arhiundefined 1 Reply Last reply Reply Quote 0
        • arhiundefined
          arhi @Surgikill
          last edited by

          @Surgikill said in Oddly shaped holes?:

          still printing in air and not extruding anything

          the extrusion, you can try increasing the E values in those codes
          but "in the air" .. no idea, it must be at z 0.25 .. that is very close to table πŸ™‚ .. no clue how it messes up

          Surgikillundefined 1 Reply Last reply Reply Quote 0
          • Surgikillundefined
            Surgikill @arhi
            last edited by

            @arhi This might help. The circles on the bottom of the picture are closest to Y max, and the circles at the top of the picture are closes to Y min. X min is right side, X max is left side. It definitely look like the circles get worse as it goes towards Y max.

            2020-04-03 20.02.44.jpg

            1 Reply Last reply Reply Quote 0
            • arhiundefined
              arhi
              last edited by

              Sorry mate, I'm lost here. You really need someone who actually has experience with coreXY machine. With the CNC this type of error is always backlash. No clue how backlash on each motor affect this at all. Normally you can tweak backlash compensation in the firmware of your CNC machine, but AFAIK there is no support for that in RRF (not sure any 3d printing firmware supports it, I know there was try to implement it in marlin but I think they gave up, never entered master branch).

              Surgikillundefined 1 Reply Last reply Reply Quote 0
              • Surgikillundefined
                Surgikill @arhi
                last edited by

                @arhi My theory here is that the igus bushings are binding up near Y max. This is causing 2 things:

                1. I lose microstepping, which causes a loss in resolution
                2. My belts stretch more (it's a pretty large printer, so the belts are pretty long) and that creates the "backlash" issue

                I'll have the LM16UU bearings in this coming week. Those will get installed and hopefully this issue will be resolved.

                1 Reply Last reply Reply Quote 0
                • arhiundefined
                  arhi
                  last edited by

                  It is a good theory as any. I see even on large printers ppl go with 2mm belts which is weird to me, the only reason to go with 2mm pitch is tight bend radius, but if you are on big printer you can design so that you don't need tight bend radius and go with 5mm pitch where for much less $$ you can get higher quality belts .. but ..

                  Surgikillundefined 1 Reply Last reply Reply Quote 0
                  • Surgikillundefined
                    Surgikill @arhi
                    last edited by

                    @arhi If I still have an issue, I'll re-design for 5mm pitch. I think the 2mm should be fine. I might need to upgrade to a non chinesium belt.

                    arhiundefined 1 Reply Last reply Reply Quote 0
                    • arhiundefined
                      arhi @Surgikill
                      last edited by arhi

                      @Surgikill even chinesium ones at 5mm work nice, the 2mm prc belts stretch, while a lot of ppl online try to say they don't my experience show different, also no proper reinforcement... 5mm you can chose if you want glass or steel, last a long time, only issue is if you go 180 degrees it has to go over large diameter (18 or 20 5mm pitch teeth is rather large circle) .. so the idea is to design motor to sit on the "straight" path of the belt with some idlers (3 point setup) rather then doing 180 around the motor forcing you to use large diameter driving pulley making 1 step of the motor move too many mm of belt πŸ™‚

                      also, using 5-6mm wide belts on big printers... IMO 5mm is ok on something like 200x200mm print surface, you go over you need to step up to 10mm or more .. if you look at professional machines it's not hard to find belts that are in 10cm width class πŸ™‚ ... I remember some stratasys printer I was repairing back in the day motor was linked to extruder with belt that was 4-5cm wide, X and Y belts were both 6-7cm wide πŸ˜„ 5mm pitch belts ...

                      1 Reply Last reply Reply Quote 0
                      • mwolterundefined
                        mwolter
                        last edited by

                        @Surgikill said in Oddly shaped holes?:

                        LM16UU

                        I think you’re on the right path regarding the igus bushings causing the oddly shaped circles. I bought into the hype of the polymer bushings but had print quality issues. In my case the sticktion could be felt when manually moving the axis with the belts removed. Either they were loose to prevent sticktion and had excessive play or they were tight and caused the oddly shaped circles like you are experiencing. Also found that the rods need to be completely dry and cleaned regularly. Not worth it, went back to LM16UU bearings and the issue went away.

                        Surgikillundefined 1 Reply Last reply Reply Quote 0
                        • Surgikillundefined
                          Surgikill @mwolter
                          last edited by

                          @mwolter Yup. I've had the same issues where they're either too loose or too tight. Hopefully the LM16UU fix that issue.

                          1 Reply Last reply Reply Quote 0
                          • bondusundefined
                            bondus
                            last edited by

                            Those IGUS bushings have pretty tight tolerances on how they are supposed to be mounted. There is a lot to read on their website.
                            I have tried them a few times, but as many of you say they either bind or have play.
                            They seem to be popular in the industry, "lubricated by dirt".

                            zaptaundefined mendenmhundefined 2 Replies Last reply Reply Quote 0
                            • zaptaundefined
                              zapta @bondus
                              last edited by

                              Igus has plastic bushings that are encapsulated in a hard shell. This way you can clamp it without increasing the binding on the rod. E.g.

                              https://www.amazon.com/gp/product/B00QZ7YJ7W

                              Linear bearings are available in double length but I couldn't find double length igus bushings and installing two one after the other creates non co-linearity that increases the binding.

                              Surgikillundefined 1 Reply Last reply Reply Quote 0
                              • mendenmhundefined
                                mendenmh @bondus
                                last edited by

                                @bondus Yes, the Igus bearings are built to quite tight tolerances, and to not like any mounting error or rod misalignment. Industrial equipment, which is what they are designed for, usually is toleranced more closely than 3d printers. I designed a bearing mount: https://github.com/mendenm/hemera_mount_plate which has a self-aligning lower bearing block which avoids this problem.

                                1 Reply Last reply Reply Quote 0
                                • Surgikillundefined
                                  Surgikill @zapta
                                  last edited by

                                  @zapta Yea I was looking at those but I wasn't going to pay 20-30 dollars a bushing when I need 8 of them. I'll just stick with the regular bearings. Are there any recommendations on good bearings? I have all chinesium ones right now, but if I find out that it does end up fixing my problem, I'll most likely upgrade to better bearings.

                                  zaptaundefined 1 Reply Last reply Reply Quote 0
                                  • mrehorstdmdundefined
                                    mrehorstdmd
                                    last edited by

                                    I used to use Thomson Super8 bearings when I was still using 1/2" round guide rails. I was buying them new on ebay for $5-8 each. They allow adjustment of preload and the races can tilt a little to compensate for slightly inaccurate mounting.

                                    Make sure your rails are hardened- ball bearings will cut grooves into unhardened rails.

                                    https://drmrehorst.blogspot.com/

                                    Surgikillundefined 1 Reply Last reply Reply Quote 0
                                    • Surgikillundefined
                                      Surgikill @mrehorstdmd
                                      last edited by

                                      @mrehorstdmd @zapta @mendenmh @mwolter @arhi I just replaced the Igus bushings with the LM16UU I ordered. No more issues. Now I have no idea what to do with all these Igus bushings I have.

                                      arhiundefined 1 Reply Last reply Reply Quote 1
                                      • gtj0undefined
                                        gtj0
                                        last edited by

                                        I'm a little late to the party I know but I started down the carbon fiber/igus route back in 2017 and although it "worked" it was way too finicky. The plain igus bearings MUST be press fit into a very specific hole diameter to be usable with the specified diameter diameter rods. Most of the carbon fiber rods I bought needed tuning with 1000-1500-2000 grit sandpaper to get them to have constant and reasonable friction in the bearings. Some could never be tuned properly because they were too narrow to begin with. Also, while most of the roll-wrapped ones were spot on for straightness, some were not which made trying to get matched sets almost impossible. In the end, I gave up.

                                        zaptaundefined 1 Reply Last reply Reply Quote 0
                                        • zaptaundefined
                                          zapta @Surgikill
                                          last edited by

                                          @Surgikill said in Oddly shaped holes?:

                                          Are there any recommendations on good bearings?

                                          When I need good quality bearings and rods I get them from Misumi. They have a large selection and they sell them also in small quantities, including but to length rods.

                                          1 Reply Last reply Reply Quote 0
                                          • zaptaundefined
                                            zapta @gtj0
                                            last edited by

                                            @gtj0 said in Oddly shaped holes?:

                                            I'm a little late to the party I know but I started down the carbon fiber/igus route back in 2017

                                            The lure of light weight moving mass. πŸ˜‰

                                            I tried bowden, igus bushings and carbon and aluminum rods but after a lot of trial and error realized that a solid design with stainless steal rods, real ball bearings and a direct drive give me the best print quality.

                                            Time to adopt this term from the bicycling world πŸ˜‰

                                            https://www.urbandictionary.com/define.php?term=weight weenie

                                            gtj0undefined 1 Reply Last reply Reply Quote 2
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