Data collection is not so difficult, but starting printing calibration 3DBenchy ‘s is a bit to complex to start with.
I do not know how much impact the filament force sensor in this build has on the printing properties and measured values, but is certainly not neutral.
The distance from coldend to nozzle is extended by the sensor with 42mm and works for force/vibrations as a lever , but also bending of the load cell will be transmitted to the nozzle because that’s the way of measurement of the applied force.
There are other full bridge load cells with a much smaller build as in some luggage scales which may be more easy to integrate in the extruder body later and a pair (two) to reduce the motion in only slight movement in z-axis direction.
At this stage, there are still a large number of combinations for the extruder, even we start with only 5 different feedstock gears , two transmissions ( herringbone / GT2 ) , two different diameters, four filament types ( PLA , ABS, PETG, HIPS) two different hotends , 3-5 nozzle diameters and a whole bunch of parameters such as temperature, acceleration , etc.
Would give a big armada of 3DBenchy’s.
First , limit the possible combination with starting only with ABS 3mm .
ABS 3mm filament is the only filament type were I more colours from same production batch date have, September 2014, a bit old and what is already noticeable at printing.
A rule of thumb for me is to use ABS filament within 2 years after production date , the experience is that after 3 year it hardly anymore printable is, but the quality of filament improves also every year.
The hope is that the filament sensor here here also helps, so that filament is consumed in time
Limiting the nozzle diameter for the time to only 0.4mm reduce also.
Based on this and this blog, I have calculated a maximum continues flow for 100mm/second.
In practice, there are not often long periods (30 seconds) of continuous flow during printing unless you print spiralized vases and cylinders, but it is a first target
Slippage at 15 & 20 ul/s from herringbone gear set
When the driving forces go above 10kg , the first slip niggles appear, the printed small herringbone gear has only a single setscrew which slips and by use of a pit or small flat D profile on stepper motor axis, the small gear breaks after some time. From experience I print by default already 2-3 small gears to one large gear.
The herringbone gear transmission is replaced with a 6mm 188mm GT2 94 tooth closed timing belt (16Tooth pulley / 80 tooth printed big gear for M5 head bolt) and gave no problems , despite a couple of times we were over 20kg.
The used Wantai 42BYGHW609 stepper motor is too strong and the filament slips before it is clear that steppen motor is lossing noticeable steps and how this looks on chart for that we need to redo this with a smaller gear ratio or weaker stepper motor.
Despite same production batch date, there are obvious differences between various colours, with ABS dark colours which the most force needs and with black being the most divergent.
All measurement are with the same temperature setting of 250C, a different approach might be the optimal temperature of this calibration print for ABS but with an average flow of only 2.5 ul/s the layertime is already below 15sec.
There are some difference, but hardly to see at this low speed, also are there other visual items with the selected filament.
Esun ABS silver(left) needs the least force in the graph above, but apparently has also the most of low boiling additives which gives a very inconstant extrusion quality at higher flow rate
This is not the sensitive to moisture (hygroscopic) from ABS, like all filament spools these go direct from vacuum package into a drybox with silica for use and ABS silver and black shared all times the same box.
Above 10 ul/s, it is not only mechanically but also heat transfer can be an item.
ABS has considerable advantage of a longer melting zone , but also more (half) molten mass must be moved which can have influence on the acceleration.
The feedstock gear’s just like all other parts for extruder are from eBay, with the exception of the T26 (26tooth) feedstock gear all other have only one grub screw and where two grub screw is desirable.
Slipping feedstock gears may also be less inconspicuous at first as MK7-02 (light blue) in the above chart, blackening the shaft with a stylus is helps so that slip is visible on the material shaft (M5 DIN931 hexagon head bolt) also afterwards
At higher flows, there is a pressure peak in front, a clear indication it’s more difficult to get the semi-molten mass in motion
Especially for PETG, PLA is this much higher then for ABS and HIPS and the long melting zone of the volcano clone has so lesser benefits these two.
I can do some minor adjustments before the 1.75mm filament and redo the first comparison between the feedstock gears, but until now no big differences.
Only that T36 still sliding , which I have missed during measurement.