Using a low-cost 3D printer like CTC DIY I3 Pro B (Geeetech I3 Pro B clone) with M8 threaded rods as Z axis with loose or floating ends is what you get – and so also some wobble or banding on the X axis due slightly bent M8 threaded rods – they barely come straight. I hesitated to use lead screws due decrease of resolution (M8: 1 cycle = 1.25mm height, lead screw like TR8x8 (8mm dia, 4 starts, 2mm pitch, 8mm lead => 1 cycle = 8mm height) but otherwise gaining pretty straight lead.

Anyway, I searched Thingiverse for Z mounts for the CTC DIY and found a few, and adapted one design and made a remix Geeetech / CTC Prusa i3 DIY – Z Axis Bracket Remix with printable Bearing:

• changed structural holes (larger hole -> smaller holes)
• bearing hole widened to have more floating
• printable bearing added to restrict end (optional)

New Z bracket mounts (black), without/with printed bearing (white):

And I did a few tests:

Left to right (close-ups photos below):

1. original Z bracket (wood) apprx. 4mm play
2. new Z bracket without printed bearing, apprx. 10mm play
3. new Z bracket with printed bearings (with loose tolerance)
4. new Z bracket with printed bearings (tight tolerance)

Now comes the surprise, the best surface (best to worst):

1. no bearings / open floating: gives the smoothest surface, most straight Z edge
2. tight bearings: gives very good surface, slightly worse than with no bearings
3. loose bearings: noticeable artifacts / wobble, Z edge wobbly
4. original bracket: worst wobble of all, Z edge wobbly

Which means, either give it a lot of space so the upper end of the Z threaded rods can float, and thereby the X gantry can stay fixed (and not wobble) – or – fix the threaded rods and suppress wobble (there is still wobble but restricted).  Giving it some space on the top means the inherent wobble of the rod is distributed between top and X gantry – giving wobble artifacts on the print . . .

The issue isn’t simple: with or without fixation gives good results, some fixation gives more bad print results.

Open Ends / Floating

The new Z bracket provides more space for the threaded M8 rods than the original wooden bracket:

Printed Bearings

You may print two bearings (OD 22mm, ID 8mm), make sure to test inner diameter, so the threaded rod slides smoothly – if required use a 8mm drill to widen the inner hole.

Conclusion

Worst Z wobble was with original Z mount with ~4mm play or the loose bearing with apprx. 1-2mm play.

Best results I achieved with floating ends or with tight bearing – in other words, either leave it open or make it stay close, but worst is to give it a little play and threaded rods will show their unevenness on the prints.

I would also guess, the unevenness of the threaded rods and their position to each other also matters, e.g. whether left and right go the same way or cancel each other wobble out. What I noticed was, once I used the printable bearings for a print, and removed it, the threaded rods wobble already less – but as said, best results I achieved with no bearing and wide floating ends or with the tight bearings.

Recommendation: print the mounts, print the two bearings, and print the XYZ Calibration Cube or whatever reference item, and see yourself which option works better for you.

Addendum: M6 Z Axis Conversion

I made a small package Geeetech / CTC DIY I3 Pro B M6 Z Axis Conversion to use M6 threaded rods instead of M8. It made little difference:

• less wobble, but still wobble despite of “straight” M6 threaded rods
• wobble seems mostly introduced by the couplers (either printed or PVC pipe):
  • out of center alignment = wobble
  • tilted mounted rods = wobble

It is hard to mount the rods perfectly with the couplers, a little misalignment and one introduces wobble (X/Y wiggle).

Anyway, M6 gives slightly higher resolution in Z axis with 0.005mm per motor step.

Printing with different layer heights with the same nozzle diameter (e.g. 0.4mm) gives quite a range of printing quality and printing time – the higher the quality or lower the layer height the more printing time it takes, the 20mm height XYZ Calibration Cube as an example:

0.05mm layer height / 398 layers / 1.38 hrs

0.1mm lh / 200 layers / 0.73 hrs

0.2mm lh / 100 layers / 0.37 hrs

0.3mm lh / 66 layers / 0.25 hrs

0.32mm lh / 62 layers / 0.23 hrs

0.32mm layer height is 80% of the nozzle diameter, and supposed to be the maximum of layer height.

0.14mm – 0.39mm lh / 64 layers / 0.21 hrs

using the Adaptive Layer Height feature of Cura.

0.4mm lh / 50 layers / 0.18 hrs

obviously too high layer height with 0.4mm on a 0.4mm nozzle, some layers have gaps.

0.4mm w/ 0.6mm nozzle / 50 layers / 0.11 hrs

using 0.6mm nozzle on E3D Volcano clone – not quite tuned with under extrusion on the top (90% flow, with 100% flow the X/Y surfaces were terribly over extruded).

All printed with

• 60mm/s print @ 190C
• 80mm/s infill
• 150mm/s travel
• 1st layer: 20mm/s print @ 200C

on

• a heavily improved CTC DIY I3 Pro B (Geeetech DIY I3 Pro B clone) with
• Bowden setup and E3D V6 clone hotend,
• sliced with Cura 3.4,
• printed with white PLA-R (recycled PLA) by Fabru – it was a custom extrusion based on recycled white PLA, they usually sell only black recycled PLA as of 2018.

While reviewing all the samples, I noticed I could improve the Z banding issue, which still showed a bit – addressed in 3D Printing: Fixing Z Banding; done after all my layer tests.

Conclusion

Layer height 0.05mm and 0.1mm look very alike with this XYZ Calibration Cube – so it’s not really worth 0.05mm but 0.1mm would be sufficient. The Adaptive Layer Height turned out quite well, near the same speed as 0.32mm layer height.

The top surfaces of 0.05mm and 0.1mm are very nice, whereas 0.2mm already shows significant artifacts – best choice would be to print the last layer at 0.1mm layer height.

If one prints large volume, it’s worth to consider a larger nozzle, e.g. 0.6mm nozzle diameter, which outputs 2.25x more material already yet direct drive recommended – I struggled with complex prints with retractions with the Bowden setup.

I usually print at 0.2mm layer height, and if a larger piece is required I increase to 0.3mm – for the future I might switch the Adaptive Layer Height feature in Cura in that case.

The CTC DIY I3 Pro B, a Geeetech I3 Pro clone, is the very low-end of 3d printers – quality and pricewise, and uses a direct drive to feed the filament aka “MK8 Extruder”.  I ordered an E3D V6 clone with 0.2mm-0.4mm short nozzles with optional Volcano hotend for larger diameter nozzles (0.6mm – 1.0mm) from China, at EUR 9 price, as I wanted to

• print faster, above 100mm/s if possible
• print thicker or larger layer height to reduce print time for larger volume prints, e.g. 0.6mm – 1.0mm nozzles

and E3D V6 hotend seemed to be the remedy.

First I tried the Bowden setup, then printed an adapter so E3D V6 works with original extruder as well, e.g. direct drive is recommended when printing with flexible filament.

2-in-1 Fan Setup for E3D V6

I used the 2-in-1 fan duct: extruder and filament cooler for E3D V6, it’s low complexity and low mass makes it quite suitable, yet, since only one fan is used, it cools at the first layer already and likely reduce adhesion – not optimal but for now an acceptable compromise. The cooling otherwise is excellent, as good as my “duck beak” fan I had with original setup.

To secure the fan better, I used some rubbery-like glue (when dried) and put it on the end of the clamp of the fan adapter (let it dry first before using), to increase the grip on the hotend – as the fan once fell off while printing when it ran off failed printed filament which was cool and hard already – which would have caused quite a chain of dangerous events (hotend no longer cooled, melting the mounts, falling on the heatbed and heat whatever lies on the bed if the print(er) would have let be unattended).

E3D V6 Radial Fan Fang

After some time I switched to E3D V6 Radial Fan Fang, which uses 5015 radial fan, which turns on at 2nd layer – I used a remix which uses 40x40x10mm fan for the heatsink and replaces the small E3D V6 fan.

If you choose this, file the grip a bit so it attached smoother to the heatsink – my first print broke while attaching.

 

Quality of E3D V6 Clone

Before I go into the details, let me comment of the overall building quality of those E3D V6 clones: you get what you pay for, a compromise. My hotend leaked like crazy, at the junction of heatblock & nozzle, and heatblock & heatbreak – which is most annoying, and that did not happen with the original MK8 Extruder.

Remedy: I used teflon thread tape used to seal threads of the heatbreak, on both nozzle and heatbreak thread – this is really suboptimal. The teflon thread melted over time (not right away but after days/weeks), so I didn’t keep it.

Update 2: the real problem of leaking was the PTFE/teflon inliner, the end toward the nozzle wasn’t perpendicular sufficiently and likely a bit too short (by less than 1mm) and it was too narrow tube with 3mm OD instead of 4mm and be more tight – so the PLA leaked between the inliner and the threads of the heatbreak and nozzle – so the real remedy is to pay close attention of the length of the inliner (in case the E3D V6 clone comes without it as in my case), and give it 0.5mm to 1mm extend with a clean cut and preferably a conic end which presses then toward the nozzle.

Further, I had to use again a teflon inliner/tube – this wasn’t an all metal hotend, means, I am still limited with limited material choices, staying below 240C to preserve the teflon tube.

But on the upside, the quality of the extrusion was excellent, there was an significant improvement of print quality compared to the old “MK8 Extruder” setup, and I seemed to increase printing speed as I desired:

E3D V6 with Original Extruder

I used an adapter but altered it so it prints without support Simplified E3D V6 mount for CTC Prusa i3 Pro B with original extruder, fortunately it maintains the similar Z and Y distance to the bed as the original hotend, so there is little to change.

And the usual XYZ calibration cube at 60mm/s and 120mm/s:

Since I didn’t upgrade or customize my firmware yet, my thermistor likely reported wrong temperature, as the possibly new type wasn’t properly assigned in the firmware – and I had to reduce print temperature, too much stringing otherwise occured:

The tests reveals that stringing is mainly a problem of nozzle temperature, and much less of retraction length.

XYZ Calibration Cube

Left to right: 60mm/s, 120mm/s and 150mm/s:

Surprisingly it still performed quite well with 120mm/s and 150mm/s, although I doubt 150mm/s were really achieved at this small print.

E3D V6 MK 7 Extruder Settings

• Printing speed: 60mm/s – 150mm/s
• Infill speed: 100mm/s – 150mm/s
• Motion speed: 120mm/s – 150mm/s
• Retraction distance: 1.5mm

E3D V6 with Bowden Setup

With the Bowden setup one uses a teflon/PTFE tube to put the extruder motor stationary aside and push from there, reducing the moving mass on the X axis and so faster printing speed is possible – but as I found out, with faster printing speed more pressure in the hotend and if the hotend isn’t properly sealed, it will leak quickly.

The first run with Bowden setup, the extruder stepper motor not yet mounted but sitting aside:

With the direct drive I printed at 60mm/s as default, now printing at 80mm/s the XYZ Calibration Cube:

and the results are impressive, left 60mm/s, right 120mm/s:

The two E3D V6 bowden adapters I first printed and used required quite some change in Z height, bringing my Z stopper screw to its limits and also were off in the Y axis – so I designed a more suitable adapter with multiple mounting holes: CTC Prusa I3 Pro B E3D V6 Extruder Adapter V2.2 with a simple extruder motor mount at the top left-hand side of the XZ frame.

E3D V6 Bowden Settings

• Printing speed: 60mm/s – 150mm/s
• Infill speed: 100mm/s – 150mm/s
• Motion speed: 120mm/s – 150mm/s
• Retraction distance: 2.5mm – 4mm (really depends on the length of the Bowden tube)

Conclusion

Using E3D V6 with a low cost and low quality 3d printer:

Faster printing with improved overall print quality.

Aside of the leaking, which was fixed with teflon thread tape, the E3D V6 clone is a great addition to the CTC DIY I3 Pro B – true added value, but comes with more cumbersome handling with sealing threads when exchanging nozzles.

Btw, in this setup I still use M8 threaded rods in the Z axis, and you see no Z wobble artifacts, the linear threads for the Z axis are overrated – it works with simple M8 threads, if you let the couplers flexible enough, like with this “cheap” clear PVC tube, and not fasten the threads on the top, they have to stay floating.