Strange Layer Quality

I've recently built a Prusa i3 MK2 clone, everything has gone nicely and I've found a lot of resourceful websites to help me on my build. While printing where my layers are bumpy and separated, it does not look like my extruder is skipping steps. Although I've never worked with a direct drive system, I don't think it would make that much of a difference. I have calibrated my extruder several times, and still haven't gotten any differing results. Any input would be appreciated, Thanks!!!!!

Please provide the follwoing:

• Filament Type
• Break Type (All Metal or...)
• Temp
• Layer Height
• Speed

This will give me a better idea of where to start. Thanks!

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

I have a Hotend with a nylon tube down the heat break. I'm working with PLA from SeeMeCNC printing at 210. My layer height is .25mm with a .4mm nozzle diameter. my highest speed is 45mm/s. I talked with a fellow today and I'm starting to think it is my acceleration settings. I started a print just now and will update with my results tomorrow.

Sounds good, let me know what you find out on that end.

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

What I have discovered is that yes, my printer was jerking around way to much. I lowered my acceleration values and that got rid of my bumpy layers, but not the gaps. I found out that writing to my eeprom from mattercontrol does not work. When I change a value and save, close, then open again it doesn't write. So when I calibrated my extruder it never was written to the printer. So, my next task is to calibrate and change the value in the firmware.

Well hopefully that solves the issue, if not let me know.

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

By now I've "fixed" everything that I thought was wrong. After changing my acceleration values I was still getting the same results but a tad bit better. My extruder is definitely skipping steps, so I changed out my extruder body because I have the MK8 drive gear. Thingiverse Link After putting that on, my filament path was exceptionally better, but my extruder is still skipping steps if I tug on the filament, while the motor is moving, it pulls out easily. I've tried upping the current on the motor till it gets hot and the stepper driver quits out because of too much heat. I'm thinking to get a new stepper motor with a higher torque. The one I have now is .42 NM. Here are some pics of the latest print.

What drivers are you using and what are the rated amps for your steppers?

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

1.7 amp motors and A4988 Stepper Drivers with 2 amp output. I have 1/16th stepping set for that step stick, if that helps any.

Besides your stepping problem it looks like the object is too hot. You may try to increase the part cooling and/or decrease print temp.

First verify that your extruder Vref is not in excess of .68, this should be your top end for the motor so you can run lower. I'm not sure how you calibrated your extruder steps, but assuming you have a MK8 with an 11mm drive gear and 1.8 degree step (200 steps per revolution) your e-steps should be 92.59. This can be found using the following formula if something is different on your machine...

(Steps per turn * microsteps) / (gear diameter * pi) = steps/mm

example...

(200*16) / (11 * pi) = 92.59

You should be able to print a benchy without part cooling and based on the temps you have given I don't believe a lack of part cooling is the issue, also with the extruder missing steps I believe feed rate is the issue (I am not saying you could't use some additional cooling ... I honestly don't know at this point but I think it's best to move in one direction at a time). You did mention that the thermal break you are using has a PTFE tube inside, it's worth noting that although the temp range you are at is well within the capabilities of the PTFE even a short period of higher temps can permanently damage that tube causing feed issues. In our testing we have found that generally, 250c and over immediately compromises the tube where temps of 245 remain stable for around 50 print hours before damaging the tube.

It's difficult without knowing a lot about your build, and I'm also unaware of your background so I do apologize if I covered something already checked.

Let me know... I hope this is helpful.

Edited 1 time(s). Last edit at 05/07/2017 04:51AM by 3dGriff.

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

How would I measure my vref? What spots on the stepper stick would I use my multimeter? From my research I found this "- The A4988 does NOT come with an internal power regulator to be used for Vref, so it needs +Vdd (and GND) from the Arduino." from the Arduino Forum.

These are the Stepper Drivers that I have.

Update: I have changed the VRef value to .68 and my filament does not seem to be slipping at all. To me, that's strange to me because I spun that potentiometer so many times and did not notice a difference. My infill and top layers are more full (yay progress!!!!), but my perimeters don't seem to be smoothing out, granted I can only see a portion of the print so far.

Edited 3 time(s). Last edit at 05/07/2017 03:47PM by jmargush.

It looks like you have already made the adjustments but we have a quick guide on this here if it helps at this point: [github.com]

Good to hear you are feeding well at this point, do you have auto bed level or a z probe on this machine?

Let me know how the print turns out at this point. Thanks.

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Hooklet3d/Bad Code LLC
www.hooklet3d.com

I bought a new motor with a higher torque. It works perfectly and way more quietly than the other one did. I suspect it may have been a defected motor. Sorry it took so long for a reply.

All good. As long as you are up and running. Happy printing!

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Hooklet3d/Bad Code LLC
www.hooklet3d.com