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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 I did all of that. I took start and end gcode I have for my slicer and pasted it in there. Not sure what the issue is. I changed the F value as well because I think it was a little too low. I had 1800 in my setup.

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

        @Surgikill I used 10mm/sec as "safe" πŸ˜„ .. you can increase .. you can try to increase the E values, maybe I was too conservative and put too low values

        but it can't be printing in air

        the first line after M83 (M83 just set extruder to relative positioning) is

        G0X0Y20Z0.25

        that's move (G0) to X=0 (X0) Y=20 (Y20) and Z=0.25 (Z0.25)

        Z is not set after that so all moves here needs to be on Z=0.25mm

        till the last code G0Z20 that moves Z straight up 20mm

        The E value is maybe to low and maybe you need to prime it first, something like this:

        ;bed temp, extruder temp, home..
        M190 S60  ; bed 60
        M109 S230 ; nozzle 230
        M106 S0   ; fan off
        G28       ; home
        ;...
        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
        M104 S0 ; turn off extruder
        M140 S0 ; turn off bed
        M106 S0 ; turn off fan
        ;...
        ; shut everything down here
        
        Surgikillundefined 2 Replies Last reply Reply Quote 0
        • 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
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