working duet 0.8.5 with new folding portable corexy design: sandwich200
Posted by lkcl
|
working duet 0.8.5 with new folding portable corexy design: sandwich200 April 16, 2016 07:45AM |
hi, i just wanted to let people know that i've managed to get a successful first print - at rather "cute" speeds well below what i have been operating at with arduino-based boards - and it came out beautifully.
the sandwich200 is a standard corexy design currently with a geared 53:13 bowden using 3mm filament, with a split box for transportation purposes that joins together at the bottom and the main assemblies are bolted onto it. with the box being aluminium extrusion filled in using hardboard it's extremely rigid. the main differences between this design and the "default" corexy configs (many many thanks to dc42 for all your work btw), are that there is no z-probe on this design and the x endstop is at the "high" end not the low end.
the configuration process was hair-raising to say the least: learning on-the-go with a finger on the mains power switch, i only had to do an emergency off just the once
that was when researching how to disable z-probe detection and use z-stops instead. the bed hit the glass and there was this "creaaaak" sound from the plastic supporting the printbed before the capacitors ran out of juice in the 300W PSU...
for those people who may be thinking of converting their corexy printer to a duet 0.8.5, the configuration files are available here: [hands.com]
now, my only annoyance was that the documentation on the duet 0.8.5 was in absolutely no way clear that software-control of micro-stepping down to 1/8th was impossible, or that setting 1/4 (or 1/2) micro-stepping was only possible by carrying out soldering of the board. the amount of pressure needed on a 3mm bowden is rather extreme, and the only way i've found it was possible (with the previous electronics) to avoid motor skipping was to set 1/8th microstepping and to increase the current to 1.1A. i also had to spend a week experimenting, increasing the initial gear ratio through 2.5:1, then 3.54:1, then finally to 4.07:1 with a 53:13 herringbone gearset. i was... not happy to be learning on-the-fly about needing to solder the board.
that having been said, the different packaging of the stepper ICs used means that the heat dissipation is better, thus the current can be much larger, which is a key reason why i picked the duet in the first place. in addition, the inclusion of ethernet (on an embedded board!) is awesome, and i really like being able to sit at a table a good 2-10 metres away, maybe consider watching a film comfortably on the sofa, and still monitor what's going on, instead of being tied to a USB cable which might cause an EMF spike at any time. that's a really, really nice feature.
anyway i've got it all working now. many thanks to the people who've put so much design effort into this board, and into the rather quirky software - software which, as a software engineer, i would, if i ever was to start a printer controller firmware project, it would be pretty much exactly the kind of design that RepRapFirmware is: none of this "edit a source code header file and recompile" nonsense! being able to use the power and features of the faster ARM Cortex M3: none of this "timing loops" stuff that goes on in the arduino... wheurgh what i also love about it is that there are no thermistor "tables", there's enough horsepower on the ARM Cortex M3 to *calculate* the temperatures based on the information from the thermistor datasheet and the resistor values of the voltage divider circuit. that, and other sensible little additions - time-based event-driven software design - means that i'm pretty happy and impressed. it all... "resonates" with me, if you know what i mean.
the only thing i have to resolve is, the extruder whipped out 250mm of filament at the end of the print, which is all rather odd. there's a relative "extruder retract" command in the end.gcode of the cura config that i'm using - it says "E-1" but what actually happened was "E-250" or so, which tells me that, possibly, the G91 command just before it isn't being listened to (or does something different from Marlin firmware) - maybe G91 doesn't set relative *extruder* moves or something, i don't know - i'll experiment and find out.
anyway. yeah. thank you to everyone who's put so much design effort into this board and its software.
-- sandwich200: compact portable folding corexy printer [reprap.org]
the sandwich200 is a standard corexy design currently with a geared 53:13 bowden using 3mm filament, with a split box for transportation purposes that joins together at the bottom and the main assemblies are bolted onto it. with the box being aluminium extrusion filled in using hardboard it's extremely rigid. the main differences between this design and the "default" corexy configs (many many thanks to dc42 for all your work btw), are that there is no z-probe on this design and the x endstop is at the "high" end not the low end.
the configuration process was hair-raising to say the least: learning on-the-go with a finger on the mains power switch, i only had to do an emergency off just the once
that was when researching how to disable z-probe detection and use z-stops instead. the bed hit the glass and there was this "creaaaak" sound from the plastic supporting the printbed before the capacitors ran out of juice in the 300W PSU...for those people who may be thinking of converting their corexy printer to a duet 0.8.5, the configuration files are available here: [hands.com]
now, my only annoyance was that the documentation on the duet 0.8.5 was in absolutely no way clear that software-control of micro-stepping down to 1/8th was impossible, or that setting 1/4 (or 1/2) micro-stepping was only possible by carrying out soldering of the board. the amount of pressure needed on a 3mm bowden is rather extreme, and the only way i've found it was possible (with the previous electronics) to avoid motor skipping was to set 1/8th microstepping and to increase the current to 1.1A. i also had to spend a week experimenting, increasing the initial gear ratio through 2.5:1, then 3.54:1, then finally to 4.07:1 with a 53:13 herringbone gearset. i was... not happy to be learning on-the-fly about needing to solder the board.
that having been said, the different packaging of the stepper ICs used means that the heat dissipation is better, thus the current can be much larger, which is a key reason why i picked the duet in the first place. in addition, the inclusion of ethernet (on an embedded board!) is awesome, and i really like being able to sit at a table a good 2-10 metres away, maybe consider watching a film comfortably on the sofa, and still monitor what's going on, instead of being tied to a USB cable which might cause an EMF spike at any time. that's a really, really nice feature.
anyway i've got it all working now. many thanks to the people who've put so much design effort into this board, and into the rather quirky software - software which, as a software engineer, i would, if i ever was to start a printer controller firmware project, it would be pretty much exactly the kind of design that RepRapFirmware is: none of this "edit a source code header file and recompile" nonsense! being able to use the power and features of the faster ARM Cortex M3: none of this "timing loops" stuff that goes on in the arduino... wheurgh
what i also love about it is that there are no thermistor "tables", there's enough horsepower on the ARM Cortex M3 to *calculate* the temperatures based on the information from the thermistor datasheet and the resistor values of the voltage divider circuit. that, and other sensible little additions - time-based event-driven software design - means that i'm pretty happy and impressed. it all... "resonates" with me, if you know what i mean.the only thing i have to resolve is, the extruder whipped out 250mm of filament at the end of the print, which is all rather odd. there's a relative "extruder retract" command in the end.gcode of the cura config that i'm using - it says "E-1" but what actually happened was "E-250" or so, which tells me that, possibly, the G91 command just before it isn't being listened to (or does something different from Marlin firmware) - maybe G91 doesn't set relative *extruder* moves or something, i don't know - i'll experiment and find out.
anyway. yeah. thank you to everyone who's put so much design effort into this board and its software.
-- sandwich200: compact portable folding corexy printer [reprap.org]
|
Re: working duet 0.8.5 with new folding portable corexy design: sandwich200 April 18, 2016 11:14AM |
the "volcano" set arrived with the new 0.4mm nozzle, this was the first print. compared to previous results, i'm really happy with it, warts an all.
Sorry, only registered users may post in this forum.