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Nov 2016
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Nov 2016
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levitaylorprusa
Nov '16

Hey Guys,

I am not exactly new 3D printing, I have been in it for about 3 years. I have built my Prusa i3 rework after I started with my little Printrbot Simple Wood. My i3 is a very sound structure. It is very rigid, and it is extremely reliable. However, I am having a little problem I have not been able to solve. I have very rough edged prints. I cannot seem to get the prints to look like a solid piece. Each individual layer doesn’t seem to line up 100% with the previous layer. I am not sure if this is an extrusion problem, although that is the conclusion I have come to. I have completely tore down, resquared, and rebuilt my printer to try solve the problem. I CANNOT seem to get a nice clean print where all the sides are nice and smooth.

Advice PLEASE. I am desperate to fix this. I just want clean, nice looking prints.

I have all Sainsmart electronics. Geared extruder using an E3D hot end.

I have attached pictures.

20161102_204347.jpg
20161102_204347.jpg2988×5312 2.27 MB
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20161102_204358.jpg2988×5312 2.11 MB
20161102_204420.jpg
20161102_204420.jpg2988×5312 2.17 MB

shahramrobotics
Nov '16

First make sure the filament you are using has at least 0.05mm accuracy, otherwise whatever change you make is just waste of time. Take a few feet of the filament and measure as many points as you can, make sure they vary less than 0.05mm in diameter and print a tall cylinder with it. Once you get a smooth and lined up cylinder then go for a cube for corner stops and see if you get that right as well. Don’t let the print head pull the filament and make sure spool is turning freely. There are many things that can cause this to happen but you need to first make sure what you are feeding to the printer is a good quality filament.

wirlybird
Nov '16

A little info would be helpful. What is the filament, bed temp, extruder temp, print speed, layer height etc.!! What slicer?

levitaylorprusa
Nov '16

I havd checked that on every filament i have used. So far so food. I am currently sing octave ABS, but i have used Matterhackers, Jet, Makerbot, Gizmodorks, Hatchbox, all with same result. Also, i will try the cylinder for sure. How tall would you recommend?

wirlybird
Nov '16

From your other comment I am guessing this is ABS.

First I would cut the print speed in half and see how it goes. Also try the print with one shell and no top/bottom or infil and see how the sides come out.

I think 230 is good for ABS and I run about 100 on the bed (different printer)

If the printer is not enclosed ABS is going to give you problems. But, your print isn’t that bad considering. More tuning I think.

Nebbian
Nov '16

Things to check:

  • Nozzle doesn’t have any clicking or wobble when you grab it and try to move it
  • Grub screws on pulleys are all TIGHT. This one is very difficult to see, and can cause this sort of issue
  • Belts are tight
  • Bed doesn’t have any wobble when you grab it and move it
  • Extruder hobbs are concentric to shaft (again, very difficult to check), you’ve got to watch the idler pulley as the extruder bolt goes through a revolution to see if the idler pulley moves slightly in and out

Check to see if the layers are offset, or if the extrusion is fatter for one layer. This will tell you whether it’s a mechanical positioning issue, or an extrusion issue. The way to check this is to pick a layer that pokes out on one side of the cube, and see if it pokes in or out on the other side of the cube.

shahramrobotics
Nov '16

Print as tall as you can, make it tiny like the size of the Z shaft and you’ll see if the bed is moving to the sides while going down for each layer or not. If the shaft is not fully straight or the bed attachment is loose or misaligned you will see different patterns on the print. You can also exchange the step motor drivers to see if they are causing this issue.

Perry_1
Nov '16

Looks like over-extrusion to me. You are laying too much plastic down, that is squishing out.

Lower extrusion width %.

levitaylorprusa
Nov '16

Yes, It is ABS. Thanks for the quick reply. The parts are usable, but I really prefer to have clean, parts that are aesthetically nice as well. Do you think it is possible to have a poorly machined hobbed bolt, and going to a direct drive would fix this?

levitaylorprusa
Nov '16

Thanks for the quick reply!!

I have checked the nozzle, and made sure everything was snug, and there was no play in everything.

I will however, check the set screws on the pulleys. I never thought of that, and i don’t think that’s it. But, it never hurts to try.

Also, with the hobbed bolt, are you saying I could have a poorly machined hobbed bolt?

Is it possible a direct drive extruder would fix this?

levitaylorprusa
Nov '16

Thanks for the help. Unfortunately, I have tried that. It remains the same, It just adds air pockets when i lower extrusion rate.

levitaylorprusa
Nov '16

Does anyone think that I may just have a poor extruder setup, and going to an aluminum direct drive would help?

levitaylorprusa
Nov '16

Currently using Repetier, and slicing with CuraEngine. But again, i have tried using Slicer and Pronterface, as well as Cura Software. Octave ABS Filament. Print speed: 50 mm/s Extruder temp: have tried anywhere 215C to 2550C. Currently at 220. Bed temp: 80C Layer height: .2mm Nozzle size: .3mm Using a geared extruder with an 8mm hobbed bolt.

levitaylorprusa
Nov '16

If the layers on the tall cylinder aren’t lining up very nicely, (Also, it is SUPER brittle. Possibly a key to part of the problem) what kinds of things can I try? My Z-axis doesn’t appear to have any wobble. But, the layers on the cylinder look just like the layers on the cube, however, they lined up a little better. Thoughts?

wirlybird
Nov '16

Again with a .3 nozzle have you slowed down the print speed a lot. You seem to be at 3000mm/min, that is pretty fast. I would try a single wall cube no top or bottom no infill at 230 temp and 1000-1500mm/min and see how it comes out. Then measure the height and side thickness and see how close to the measurements they are. This will tell you where to start some settings.

You have to get to basics to see where the issue is.

levitaylorprusa
Nov '16

I went down to 2400mm/min. I will try going slower tonight. Along with measuring my thickness results.

shahramrobotics
Nov '16

Slow your print down to 15mm/s this time print a short (like 5 to 10 layers) but very wide cylinder (max bed size) if you still see the same issue then it’s probably the motor driver(s) or like a power issue that fools the drivers. Have you tried a UPS?

Nebbian
Nov '16

It’s certainly possible that the hobbed bolt is at fault. You can check your print to confirm, see if the layer is fatter all the way around the print, or if the layers are offset from each other. If the layer is fatter all the way around, then a new extruder will help.

3DFlying
Nov '16

To me it looks like your hot end temperature is varying too much. You may need to look up some information on how to do PID tuning.

shahramrobotics
Nov '16

Uninterruptible power supply, it has many filters that removes all the noises of the power grid and will give your printer a very clean and stable 110v 60hz/220v 50hz , also some of them have internal batteries so you can continue printing for a while even during blackouts.

levitaylorprusa
Nov '16

Still working on my problem. I have done large and small cylinders and cubes with not top or bottom, 1 wall, and 0% infill. I have the same look of prints at different layer heights too. The wall thickness measures out okay. I have tried extrusion rates both directions, temperatures in both directions. I tried a z axis backlash fix with a nut above x ends a spring in between, tightened all belts and grub screws, checked extruder tension, checked for z wobble, (VERY minimal), and I have autotuned my PID settings. Nothing is fixed. I can’t seem to fix it. Anyone have any other ideas? Direct drive aluminum extruder?

Does anyone have any personal experience with one type of an extruder printing better than another? Thoughts and comments appreciated.