Extrude issues, too much force needed

My extruder drive block broke today so I had to print a new one. It went fairly well, I had to file up the hole a bit where the big gear is sitting. Anyway, it's re-installed but now I have problems extruding. For some reason I had to use a lot of force to extrude while re-inserting the filament. The weird thing was, if I retracted filament I could easily extrude again up until the point where I haven't extruded yet. Until I came all the way to the nozzle. The last bit of extrude to get filament out of the nozzle is always hard and the motor doesn't have enough torque to turn the gear. Both gears themselves turn nicely. This is also verified by retracting and extruding again which works fine up until I reach the final bit of the nozzle.

Why could this be?

Edited 1 time(s). Last edit at 08/16/2015 02:18PM by bitfield.

Of course there is a difference as the hobbed insert grabs a profile into the filament. If you retract and move forwards this procedure did not have to be repeated. It sounds like the distance between the hobbed insert and the counter bearing is too short for some reasons. Which material are you using? ABS can shrink so I often print ABS and scale it up to 101%. Also if you use a spring loaded extruder the tension may be too strong or as you filed up the hole you maybe decentered the whole so the space between the hobbed insert and the counter bearing decreased and so on. I also had trouble with the herringbone gears. Did you check the diameters and distances of your printed parts? And normally I do not have to file up the whole for a gear that sounds strange. Maybe overextrusion? Wrong settings? Which slicing software?

---

Slicer: Simplify3D 4.0; sometimes CraftWare 1.14 or Cura 2.7
Delta with Duet-WiFi, FW: 1.20.1RC2; mini-sensor board by dc42 for auto-leveling
Ormerod common modifications: Mini-sensor board by dc42, aluminum X-arm, 0.4 mm nozzle E3D like, 2nd fan, Z stepper nut M5 x 15, Herringbone gears, Z-axis bearing at top, spring loaded extruder with pneumatic fitting, Y belt axis tensioner
Ormerod 2: FW: 1.19-dc42 on Duet-WiFi. own build, modifications: GT2-belts, silicone heat-bed, different motors and so on. Printed parts: bed support, (PSU holder) and Y-feet.
Ormerod 1: FW: 1.15c-dc42 on 1k Duet-Board. Modifications: Aluminium bed-support, (nearly) all parts reprinted in PLA/ ABS, and so on.

I'm using PLA. Pardon me but I have no idea what a spring loaded extruder is . It's Ormerod 1 but I picked this extruder drive block this time: [forums.reprap.org]

I had to file up the hole where the bearing and hobbed insert goes. It's not very uncommon for me to have to file up holes and I wouldn't be surprised if I could fix that with some calibration somewhere. But I'm still in a mode where I try to tweak things (like better bed level which I still suffer from I believe).

For this drive block I was using Slic3r 1.2.9 with the Ormerod configuration from here: [github.com]. Using the 0.5mm Nozzle setting in "Print Settings" and "PLA" under "Filament Settings" and "Ormerod PLA 0.5mm Single Nozzle" under "Printer Settings", with the modified start code:

T0
M107
M190 S57                                    ; Set bed temperature
;G28 ; home all axes
M83
G10 P0 S195 R160                       ; Set tool 0 operating and standby temperatures
M109 S195 ; wait for temperature to be reached
G21 ; set units to millimeters

Edited 1 time(s). Last edit at 08/16/2015 02:44PM by bitfield.

Quote
bitfield
I'm using PLA. Pardon me but I have no idea what a spring loaded extruder is .

[www.thingiverse.com]

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

You were right about distance between bearing and hobbed insert. I disassembled it and filed up the hole even more and now the problem is gone.

I used this block some times ago and I used Slic3r for generating the G-code. I used this block with Herringbone gears and I had serious trouble to move the motor by hand. So I printed the block scaled up by 102% and every was fine. I am not sure if this is a designing fault but I more believe this is a problem caused by Slic3r. Later I repinted that design and I had not these problems. These normal extruders are not very tolerant regarding printing issues and so on. These spring loaded extruders (thanks dc42 for linking) are much easier to handle but getting the filament into the extruder is a little bit difficult. maybe I will redesign my remix to guide the filament better. If you want to use Herringbone gears (like dc42's improved design of iamburny's Herringbone Extruder Gears) I only cann suggest to use a spring loaded extruder as it is much easier to mount the gears plus it is very easy to clean. But I only uses remixes and not the original in this case.

---

Slicer: Simplify3D 4.0; sometimes CraftWare 1.14 or Cura 2.7
Delta with Duet-WiFi, FW: 1.20.1RC2; mini-sensor board by dc42 for auto-leveling
Ormerod common modifications: Mini-sensor board by dc42, aluminum X-arm, 0.4 mm nozzle E3D like, 2nd fan, Z stepper nut M5 x 15, Herringbone gears, Z-axis bearing at top, spring loaded extruder with pneumatic fitting, Y belt axis tensioner
Ormerod 2: FW: 1.19-dc42 on Duet-WiFi. own build, modifications: GT2-belts, silicone heat-bed, different motors and so on. Printed parts: bed support, (PSU holder) and Y-feet.
Ormerod 1: FW: 1.15c-dc42 on 1k Duet-Board. Modifications: Aluminium bed-support, (nearly) all parts reprinted in PLA/ ABS, and so on.