Tuning new build DBot Bowden E3D v6 - First layer problems

I've started tuning my DBot build, and I'm having a problem with the first layer intermittently leaving gaps of fairly large size on lines of extrusion. I'm printing on blue painters tape, and I've used a gap gauge to set the bed height to 0.11mm. Filament is PLA

Here is a sample picture:

I tend to think that the regular nature of the gaps points towards the extruder / hotend not getting plastic out, as opposed to the plastic not sticking.

I have tried some extrusions into thin air just to see the behavior and when I extract 10mm or 20mm at a speed of 1mm, it seems that there is a significant lag between the extruder starting to feed filament and plastic coming out the nozzle. Additionally, once the extruder stops, plastic comes out for what seems like an extended amount of time. Some of that I'd expect due to compression / filament shifting around in the Bowden tube, but the gaps in the image seem to point to another issue. I've tried fiddling with the spring holder on the extruder, but quickly bounce between not feeding at all and starting to grind the filament on the hobbed bolt.

Here is the overview of config and tuning to date:

"D-Bot Blue" D-Bot build 300 x 300 x 300
Hotend: E3D V6 (full)
Nozzle: 0.4mm
Extruder: D-Bot standard
Print Bed: Mic6 Aluminum (8 x 325 x 325)
Print Bed Heater: Keenovo Silicone heater (300 x 300) (120v, 750w)
Controller: DuetWiFi (firmware 1.19)
Steppers: 1.8 degree, 2.0 amp, 84 oz
Leadscrews: 8mm x 400mm - single start, 2mm / turn - w/anti-backlash nuts
Filament width: 1.75mm

Slicer: Simplify3D
Layer Height: 0.2mm
Extrusion Multiplier: 1.0
Extrusion width: 0.5mm

Tuning To Date:
- X, Y, Z steps / mm
- Extruder steps / mm
- Autotune PID Extruder
- Autotune PID Bed
- Pressure Advance: M572 D0 S0.1

Config.g is:
; Configuration file for Duet WiFi (firmware version 1.17 to 1.19)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool on Sun Oct 29 2017 15:26:10 GMT-0500 (Central Standard Time)

; General preferences
M111 S0 ; Debugging off
G21 ; Work in millimetres
G90 ; Send absolute coordinates...
M83 ; ...but relative extruder moves
M555 P2 ; Set firmware compatibility to look like Marlin

M667 S1 ; Select CoreXY mode
M208 X0 Y0 Z0 S1 ; Set axis minima
M208 X296.5 Y295 Z298 S0 ; Set axis maxima

; Endstops
M574 X1 Y2 Z1 S0 ; Define active low and unused microswitches
M558 P0 X0 Y0 Z0 H5 F120 T6000 ; Set Z probe type to switch, the axes for which it is used and the probe + travel speeds
G31 P600 X0 Y0 Z2.5 ; Set Z probe trigger value, offset and trigger height
M557 X15:265 Y15:265 S20 ; Define mesh grid

; Drives
M569 P0 S1 ; Drive 0 goes forwards
M569 P1 S1 ; Drive 1 goes forwards
M569 P2 S1 ; Drive 2 goes forwards
M569 P3 S1 ; Drive 3 goes forwards
M350 X16 Y16 Z16 E16 I0 ; Configure microstepping without interpolation
M92 X100 Y100 Z1600 E137.25 ; Set steps per mm
M566 X900 Y900 Z12 E120 ; Set maximum instantaneous speed changes (mm/min)
M203 X900000 Y900000 Z300 E1740 ; Set maximum speeds (mm/min)
M201 X1500 Y1500 Z250 E259 ; Set accelerations (mm/s^2)
M906 X1200 Y1200 Z1200 E1200 I30 ; Set motor currents (mA) and motor idle factor in per cent
M84 S30 ; Set idle timeout

; Heaters
M143 S260 ; Set maximum heater temperature to 260C
M301 H0 S1.00 P10 I0.1 D200 T0.4 W180 B30 ; Use PID on bed heater (may require further tuning)
M305 P0 T100000 B3950 C0 R4700 ; Set thermistor + ADC parameters for heater 0
M305 P1 T100000 B4138 C0 R4700 ; Set thermistor + ADC parameters for heater 1

; Tools
M563 P0 D0 H1 ; Define tool 0
G10 P0 X0 Y0 Z0 ; Set tool 0 axis offsets
G10 P0 R0 S0 ; Set initial tool 0 active and standby temperatures to 0C

; Network

; Fans
M106 P0 S1 I0 F500 H-1 ; Set fan 0 value, PWM signal inversion and frequency. Thermostatic control is turned off
M106 P1 S1 I0 F500 H1 T45 ; Set fan 1 value, PWM signal inversion and frequency. Thermostatic control is turned on
M106 P2 S1 I0 F500 H1 T45 ; Set fan 2 value, PWM signal inversion and frequency. Thermostatic control is turned on

; Custom settings
;Endstop set to Active Low
;Geometry refined (X, Y, Z max)
;Z home trigger height at z axis = 0.1
;Motor milliamps = 1200
; Selected preset thermistor coefficient (e3D)
; Extruder - 137.25 steps / mm (calcuated)
; X and Y motor steps / mm set to 100 (calculated)
; Z steps / mm = 1600, set Extruder fan to 100%
; M501 to load override params
; Keenovo Bed parameters - P0 T100000 B3950 C0 R4700
; no network

;Enable Pressure Advance
M572 D0 S0.1

; Miscellaneous
M501 ; Load saved parameters from non-volatile memory
T0 ; Select first tool

Any guidance or help would be greatly appreciated.

Thanks

Its hard to tell from the pic what the first layer that hits the bed is being squished like, but for what I can see it looks like its not.

I also see what I would think is under extrusion.

1) Have you calibrated your extruder feed rate?

2) What temp is the hot end at? Is your extruder skipping?

I have gotten a mess like that when I error on my H.E. temp and its too low, the extruder motor skips as it cant feed because the hot end is not hot enough so the filament needs way too much torque to push it thru.


The E3D V6 hotend does ooze its molten load as it cools down, you can add a post print retraction of 3 or so mm to cut that back and then do a pre print extrude of 3.5 to 4 mm to reload it.
This would be setup via Gcode in your slicer.

I often print with a skirt to prime the HotEnd b4 the part is printed.

Edited 2 time(s). Last edit at 10/30/2017 04:36PM by JustSumGuy.

I calibrated the extruder feedrate, basically following Sanladerer's technique and measuring the filament pushed out the end of the feed tube without going through the hotend.

I've been printing at 220c to 225c, and it looks stable on the Duet web console.

I haven't had the "clicking" of the extruder, but do have situations where the filament appears to stop and the extruder grinds some of the filament.

Just before this print, I did disassemble the hotend and clean it out, since I thought the bowden tube wasn't getting all the way down the heatbreak. My focus on the cleaning was the heatbreak. I might need to go back to the nozzle, but this is all brand new, so there shouldn't be much built up -- This is literally the 3rd or so print off the machine.

hmm, I am not familiar with the Duet...
I run marlin, could the thermistor be out of wack maybe? so your colder than you think?

Any chance you mixed up filament... maybe that's ABS?

I am kinda grabbing at straws

I agree it appears your not getting enough extrusion from the hotend tho......


hmmm, check your slicer setting for the nozzle size, maybe its set to a smaller one than your useing?
increase the extruders 'grip' on the filament.....

i dont know what else to think of....

You could raise the extruder stepper current from 1200 to 1600mA.
Is the drive gear aligned with the filament path? You also should clean it after grinding through the filament.
Keep the Bowden tube as short as possible.

225°C is a lot for PLA, no wonder it oozes like hell. You might even see it expand ( foaming )?

Q to all: Is a full metal E3D the right choice for PLA?

Edited 1 time(s). Last edit at 10/31/2017 02:44AM by o_lampe.

The full metal H.E. is more for higher temp filaments but I have used them with PLA fine.
With the higher temp setting tho the heat could travel up more and cause jams as PLA will of cource melt at a much lower temp, so yes a PTFE tubed H.E. would be better for PLA imo.

For the record I Print PLA at 190c ish and ABS at 245c So ya 225c is HOT for PLA...... but a little cool for ABS.....

Thanks. I'll dial back the temp to 195 - 200 and see if things look better.

I also have some Matchbox and Atomic PETG that I can use. Any general recommendations for temp on that?

.11 should be a good bed height setting, but the print looks to me like the height was too high on the first layer for a .4 nozzle. Since you are running the Duet controller on its web interface, I'd recommend clicking on the Z Baby stepping down button when the print starts and that will lower the height by a .05 mm offset to see if it makes any improvement. This is a very handy feature as you can quickly offset the bed height while printing if needed.

I suspect that your extruder may also be slipping a little too. I've had terrible luck with direct extruders and recommend a geared one like the E3D Titan or the one for the Ormerod.

Its my observation that ideal PLA melting temperatures vary quite a bit depending upon the manufacturer. I am fond of Atomic filament and usually use its upper limit of 230 and it performs well at that temperature. 230 is really too high for most PLA. I occasionally use Hatchbox filament which has an upper limit of 210 and it prefers 195 on my printers.

Whenever I get new filament that I've not used before, I'll slice a test piece (usually a whistle) into four sections each using a lower temperature and see which temp looks best.

ayudtee - Thanks for the tip on the Z baby stepping, I was wondering what that did.

I've been thinking of going to something more substantial for the extruder since the "stock" build one seems to a little sparse. I was looking at the Titan as an option. I'll have to look and see if I can find a d-bot v-slot frame mount for that.

The Titan can support direct drive as well as bowden configurations with the E3D V6, can't it?

For your PETG question, look at the manufacturers recommendation and then aim right in the middle.
run a small test print and go up or down 5c to dial it in.

here is a cute tower for dialing in temp on PETG

[www.thingiverse.com]

And one for PLA

[www.thingiverse.com]

This one looks right for ABS

[www.thingiverse.com]

Found a new temp tower setup that I intend to use from now on...

[www.thingiverse.com]

Edited 2 time(s). Last edit at 10/31/2017 05:30PM by JustSumGuy.

Webdad, I misspoke and used the wrong term about the extruder. By "direct" I meant that it is a 1 to 1 drive with no gears. Sorry for the confusion. The Titan can either use a bowden or mounted directly. The Ormerod extruder is bowden only.

Its likely that Thingiverse will have a Titan mounting option that will work for your D-Bot. Good luck.

So, I upped my extruder power from 1200 to 1600 and set the temp to 200.

After heating to 200 I then just extruded 10 - 20 mm to move the filament forward (I had left the filament loaded over the past few days). That seemed to be going ok, and the extrusion seemed to be more responsive.

I tried doing a few prints, but nothing seemed to be extruding much at all, or sticking to the painters tape. I tried the baby stepping but that didn't help. Seemed that there still wasn't much coming out of the hotend. The extruder wasn't missing steps, but it was grinding the filament.

Keeping the heat at 200, I tried to retract but the filament seemed stuck and wouldn't come out of the hotend.

Tried to remove the PTFE tube at the hotend, but it would not come out, no matter what I tried.

So, wound up disassembling the endstop and pulling everything apart. The PTFE tube still wouldn't come out, so hit the heat break with a heat gun and then the PTFE tube came unstuck. At that point the filament is still stuck in the heatbreak but the PTFE tube is out.

More heat gun and was able to pull out the filament.

The heat break is still blocked - no light passing through so a little more heat gun and out popped a plug of filament, not burnt but melted and expanded.

Here's the picture. BOTTOM is the first piece of filament that came out, and the TOP is the plug that came out after getting the filament unstuck.



So, I'm guessing that the high temp at 220 caused heat creep that melted the filament while still in the PTFE tube, which then solidifed or at least impeded extrusion?

Once I put everything back together I'll try a totally new print at 200 and see if things work better.

Regardless, I ordered a titan extruder and will plan on replacing the stock extruder, since through all of this, the stock extruder just seemed to be difficult to work with. Worse comes to worse, I can mount the titan to the print carriage and go direct, but hopefully I can get the bowden set up to work out.

ayudtee - I know what you meant. I'm hoping the Titan will help me with my overall problems. I also ordered some of the blue translucent PTFE tube that is narrower and slicker.

JustSumGuy - Thanks for the links. Always looking for a good index print. I've printed with PETG before on my original Prusa i3 Mk1, but that just has an E3D Lite and it blows out the PTFE tube after a few prints.

Thanks everyone for the continued feedback.

While waiting for the Titan, you might want to exchange the heatbrake with a PLA friendly version?