Just published a YouTube video of my machine's current state of evolution if anyone is interested. https://www.youtube.com/watch?v=IG3AGKDzdH4.
I've attempted to explain the machine without using words - hope it works. It's best viewed on something a bit bigger than a 'phone and better still with reasonable speakers. It'll take 10 minutes of your time to watch it.
I've attempted to answer the question in the title by putting a thermocouple inside a nozzle (as opposed to just measuring the hot end temperature). Then running various tests to evaluate the further effects of deflected (as opposed to direct) part cooling air on nozzle temperature with both brass and hardened steel nozzles. The results might surprise you (or at least give food to thought) - especially if you use (or are considering using) hardened steel nozzles.
I've made a bit of progress on this if anyone is interested - details on my blog here
https://somei3deas.wordpress.com/2020/02/24/my-6-input-51-mixing-hot-end-version-2/
A quick update for anyone who is/was following this thread. The repairs to the printer after the crash (RRF 3.3.beta1+1) were all completed within a couples of days. We don't really know the cause but @dc42 thinks it may have been due to something called a "race condition". Anyway, long story short but I've done lots of test prints and I'm now running 3.3.beta2. With that, I got three good repeats of the part I was printing before - not perfect prints (mostly due to a lack of retraction) but they were consistent so I finally had a baseline to work with. The problems I had with pressure advance seem to have gone away so I've re-enabled that. I've moved on to printing other things (because I really don't want to make any more of that same part) and have just completed 3 collet holders which take a tad under 7 hours each. They are quite respectable prints with no significant variations in print quality between all 3.
So confidence has gone up a couple of notches..........
This is a follow on from my earlier multi-input mixing hot end designs. I believe it might be the worlds first hot end capable of printing multiple materials at up to 350 deg C whilst maintaining the temperature of other loaded filaments at less than 200 deg C. That is to say with this single hot end, I could potentially print a 6 part object with each part made from a different material ranging from say PLA at around 200 deg C up to PC at around 320 deg C or higher and the PLA would not get "cooked". It also has the capability to combine filaments with similar thermal characteristics and because it has 6 melt chambers, it could also be used with very large nozzle diameters requiring very high flow rates.
Link here if anyone is interested (and there is a bit of an appeal at the end). https://youtu.be/1j0UH6ctTDI
I've taken a few more tentative steps along what I'm sure will be a bumpy road and which may even end up in a cul-de-sac. But anyway, I've started to document the journey on my blog if anyone is interested https://somei3deas.wordpress.com/2019/06/06/my-modular-multi-input-multi-material-mixing-hot-end-part-1/
For anyone watching this thread, and for those who have contributed, I just want to say that the Duet team and I have opened up the communication medium that we used at the very start (when Gen 3 was still at the pre-production stage), in order to work together to resolve these issues. That's nothing personal - just that these forums are maybe not the best way to post messages rapidly back and forth between us.
I thought it important to state that fact, in case anyone got the impression that I had been abandoned by the Duet team - that isn't the case and we are working together to try and get to the bottom of wtf is happening.
I thought that I would post a couple of pics of my printer as it stands right now - although I can't get back far enough to get the full 1.7 metre height in the pics.
So this is a CoreXYUVAB with 6 extruders. XY is the lowest gantry and currently carries a Diamond 5 colour hot end. UV is the next gantry which moves in sync with the XY apart from when homing. It carries 6 Bondtech BMGs and two Duet gen 3 (prototype) expansion boards. This is the heaviest gantry and is driven by 2.8 Amp Nema 23s. AB is a uppermost gantry and does the opposite moves to the lower two gantries. It carries nothing more that lumps of lead to cancel the forces of the lower two gantries. XY and Z are connected to the 3rd expansion board (not visible in those pics). UVAB are connected to the main board mounted at the back of the printer along with the RPi. Eventually these will have covers.
The total moving mass, excluding the load balancing gantry and now that I have upgraded from 5 extruders to 6 as well as fitted the expansion boards to the extruder carriage, is a tad over 5 Kgs (up from about 3.5 kgs). I used to run non-print moves at 350mm/sec with acceleration set to 1000 mm/sec^2 and see no reason why I won't be able to continue to use those settings with the larger Nema23s driving the now heavier UV gantry (but we'll see)....
I'm posting this here in the "Gcode meta commands" section because these files contain many of these type of commands which might serve as practical examples. But the files might also be useful for anyone setting up a tool changer.
I'm slowly getting to grips with meta commands and the object model but I've had a lot of help along the way from others on these forums and from DC42, so a big thank you to all who have helped me out.
I don't have a tool changer as such. That is to say, I do have multiple tools and print multiple filament types but with a 6 input, dual heat zone, single nozzle hot end. So switching between filaments means moving the print head over a "chute" and purging, wiping etc as well as changing temperatures and filament specific parameters for things like pressure advance, retraction settings, speed multipliers etc. There are a lot of other things going on such as when changing from a high temperature filament to a low temperature one, I need to purge out the high temperature filament with low temperature filament but before I change the temperature. Otherwise, the nozzle will still be full of high temperature filament which won't extrude at the new, lower, temperature setting. Then I need to do a second purge with the new filament at the correct temperature.
Anyway, here is what I have for tfree0 but you'll see that with the use of conditional statements and meta commands, it's a "universal" file. So I could wrap all the commands into a single macro called something like "toolfree" and use a one line M98 in every tfree file. Likewise tpre and tpost. The files are all annotated so shouldn't need any further explanation.
echo "Running tfree",state.currentTool,tools[state.currentTool].name
; in this case will print "Running tfree 0 PLA"
G10 ; retract
All this file does is to retract the filament but note the "universal" echo statement which uses the current tool number and current tool name.
Here is tpre
echo "Running tpre",state.currentTool,tools[state.currentTool].name
; check if axes homed and if so, move to purge position, if not, abort
if !move.axes[0].homed || !move.axes[1].homed || !move.axes[2].homed || !move.axes[3].homed || !move.axes[4].homed
abort "One or more axes not homed - aborting"
G1 X{global.left} U{global.left} Y{global.rear} V{global.rear} F18000; move to "bucket"
In tpre, I need to move both the print head (XY) and the extruder gantry (UV) to a position over the purge bucket (chute) which is defined by the global variables. So it's important that the printer has been homed before attempting the G1 moves. Hence the check which will either do the move or abort. Again I use a "universal" echo statement which will tell me which tpre file is being run as well as the tool name.
Here is tpost which has a bit more going on like additional purge but only if going from high temperature filament to low temperature, force cooling but only if going from a high temperature to a low temperature, waiting for temperatures to settle, wiping the nozzle etc.
echo "Running tpost",state.currentTool,tools[state.currentTool].name
;state.currentTool is the current tool number, so in this case will print "Running tpost 0 PLA"
; When switching from a high temperature filament to a low temperature filament
; it is necessary to purge out the old filament with the new filament
; at the high temperature. No tool is active at the start of tpre
; so I need to do the purge here in tpost.
; By doing it first, the hot end won't have had time to cool
; heat.heaters[1] is the nozzle heater
; tools[n] is the tool number
; active[0] is the nozzle active temperature
if heat.heaters[1].current >= tools[state.currentTool].active[0]-5; 5 degree tolerance - no point purging if both temps close to each other
echo "Purging out high temperature filament"
M98 P"0:/macros/SinglePurge.g" ; purge nozzle
;the following will force cool the nozzle to within 4 deg of the active temp if it's too hot
while (heat.heaters[1].current > heat.heaters[1].active+4)
echo "Force cooling nozzle now at ", sensors.analog[1].lastReading ; show current hot end temperature
M106 P2 S255; turn on force cooling fan
G4 S1 ; wait a sec
M106 P2 S0 ;turn fan off
; the following will wait for the nozzle only to heat to within 3 degrees of it's active temp if it's too cold
; it won't wait for the combining block temperature to change
while (heat.heaters[1].current < heat.heaters[1].active-3)
echo "Waiting for Tool",state.currentTool,"to reach temperature" ; will print "Waiting for Tool 0 the reach temperature"
echo "Now at",sensors.analog[1].lastReading
G4 S1
; load filament specific parameters from macros/Filaments
echo "Loading ",tools[state.currentTool].name," specific parameters" ; will print for example "Loading PLA specific parameter"
M98 P{"0:/macros/Filaments/"^tools[state.currentTool].name^".g"} ; will load the macro with the exact same name as the tool - so be careful!!
; in this case, it will load 0:/macros/filaments/PLA.g
echo "Purging Tool", state.currentTool,tools[state.currentTool].name ; will print "Purging Tool 0 PLA" in this case
M98 P"0:/macros/SinglePurge.g" ; purge nozzle
echo "Wiping nozzle"
M98 P"0:/macros/Nozzle wipe" ; wipe nozzle
M400 ; wait for moves to complete
G1 R2 X0 Y0 U0 V0 Z0 F18000 ; return gantries to whence they came prior to tool change
G11; unretract
The comments within the file should explain what's happening but if not, I'll happily answer any questions.
So hopefully you'll see that by using meta commands and conditional gcode, I've ended up with "universal" files that can be used with any tool. As stated earlier, the entire thing could be wrapped in another macro so each and every tpost file would simply have the same single M98 to call that macro. Without those meta commands, I would have specifically reference say the active temperature for the specific tool, so every tpost file would be slightly different. I have 9 tools defined so that's 27 separate tool change files which would otherwise need to have slight differences between them.
There is just one thing I still need to address which is this....
M98 P{"0:/macros/Filaments/"^tools[state.currentTool].name^".g"}
This will extract the current tool name and add it to the path for the macro. So for example with tool named "PLA" the macro must also be named "PLA.g". I need to add error checking to catch cases where the macro is incorrectly named or missing.
This was great help https://docs.duet3d.com/en/User_manual/Tuning/Tool_changing. Especially the section on tool change sequence. There is one thing I found slightly quirky which is that the old tool gets deselected after tfree, but the new tool isn't active until after tpre. So no tool is selected during tpre which means that if you want to do anything with extruders, you'd have to do something like pick up and save the active temperature of the previous or next tool in a variable, set the temperature to the correct value for the old tool, do what you need to do, then restore the correct active temperature.
Anyway, I hope the above may be of use or at least give you some ideas.
It's been a long and bumpy road but I've finally developed my 6 input hot end to the point where I can now print and switch between, almost any filament type from Carbon fibre Nylon, to flexible filaments such as TPU, whilst retaining the ability to combine similar filament types for multi colour printing.
Link to YouTube video here if anyone is interested - it'll take 23 minutes of your life to watch it fully. https://youtu.be/5VG_r_b00sY
I guess the sub title could be - "My crazy printer is now completely insane (like it's owner)"
Just a quick pic if anyone is interested - blog post and YouTube video coming soon
This is the top 600mm of my CoreXYUV with additional dynamic force cancelling\load balancing gantry (7 axis or 3 CoreXY gantries plus Z). There is another 1000 mm of printer below the build plate, not shown in this pic.
This is nothing to do with anything really, hence the reason I've put it in the "Off Topic" category.
I've always kind of regretted choosing the user name "deckingman". It mostly stemmed from the current career path that I had chosen at that time. I have had a long and varied career, mostly in the automotive industry and always in engineering in one form or another. It has only been the last few years that I decided to earn a living by doing something completely different by designing and building garden decks and associated structures. So "deckingman" was never a reflection of my training or background. But I have a presence on the internet as deckingman (various forums, my YouTube channel, Thingiverse etc) so I'm kind of stuck with it.
Anyway, age and a couple of health issues have taken their toll so I've come to the decision that I can no longer build decks. Also, I am now in receipt of the state retirement pension, which takes up most of my personal allowance, meaning that the taxman wants a huge chunk of anything I earn.
Oh and the other reason why I had been known as "deckingman" stems from a bit of a wild time in my younger days - I'm far too old to deck anybody now.
So deckingman is no longer a decking man. I have some ideas to do something with 3D printing to supplement my pension. I'm not exactly sure what yet but watching a machine do the work is a lot easier than carrying 4.8 metre lengths of timber and 20kg bags of concrete around (and I don't need to wear thermals and waterproofs).
Some of you might find this reasonably interesting https://www.youtube.com/watch?v=rOP9QYAlhZU
@mikedc While the suggestion by @Stephen6309 will work to prevent homing if one or more axes are currently homed, there are a couple of caveats. Firstly, if one axis had been homed but you wanted to home the other axes, then the boolean "or" will prevent you from doing that using homeall.g. Secondly, if you had made some adjustments to the physical position of an end stop or some such, you might at some time want to home the printer even though it has already been homed.
As an alternative suggestion, you could instead use something like this at the beginning of your homeall.g...
if state.status != "processing"
That means if the status does not equal "processing" i.e. a print is not running, then......(carry on with the homing macro).
I'm by no means an expert on conditional gcode so someone more knowledgeable than I might say it won't work - but I use that in one of my trigger macros so I think it will work.
I'm up to Part 6 now and have made a start on the actual build if anyone is interested https://youtu.be/th-wwZF8akw.
If the video is of no interest, here are some pics
Maybe we should have a "look what I made" section? In the absence of such a thing, I thought I'd post this here. If anyone is interested, I have replaced the previous fixed speed, fixed voltage, geared (noisy) motor with a stepper motor, driven by a TMC2208 driver module which has made it silent (at least to my ears). I've also replaced the LEDs with new, WS2812 addressable LEDs and use a Wemos D1 mini running ESP home to simulate a flickering candle effect. Finally, I have made a new drive shaft to replace the previous threaded rod. This is in sections for easier storage and along with redesigned rotating discs, allows tool free assemble.
A short YouTube link is here https://youtu.be/olKgEr6VtaM
Just resurrecting this because an error in my files has come to light. It's a result of the (IMO) slightly quirky behaviour that no tool is selected when tpre is run. That is to say, the previous tool is deselected prior to tpre, but the new is not selected (made active) until after tpre. So this line...........
echo "Running tpre",state.currentTool,tools[state.currentTool].name
...........throws an error (because "currentTool" will be something like -1) and the macro will then not complete.
The fix is to use "nextTool" instead of "currentTool" in tpre. So this works and will echo the name of the new tool which is about to be selected and which is associated with the tpre# file being run.
echo "Running tpre",state.nextTool,tools[state.nextTool].name
Following on from this thread where I asked for help to write the conditional gcode macro, https://forum.duet3d.com/topic/19541/yet-more-conditional-gcode-help-required/18
I've now got this up and running. It enables me to jog multiple gantries in sync on my CoreXYUVAB machine, using a simple, cheap, switch type joystick. But the code could easily be modified to suit the sort of 3 axis machine that most sane people have.
I chose to mount the joystick onto the machine but it could just as easily have been mounted in a small box to make a sort of pendant.
Explanation and demo here if anyone is interested https://youtu.be/wCR5Ao0iH-c
I'm posting this under the Duet Web Control wish list.
Here is a screen shot of my configuration using 6 tools, each with 2 heaters.
I can't see the last tool , let alone the axis homing and movement buttons unless I scroll down a fair way. I thought that if I change the the heater names so that they fit on one line, it would help to bunch things up a bit. But it doesn't - the 12 rows that I saved are simply padded out with useless blank space thus.......
If I want to get at the fan controls, I have to scroll down so far that I lose the tools altogether.
Now I appreciate that not many people use 6 tools and 7 axes. In an ideal world I'd like to see a much more customisable GUI but in the meantime, reducing the amount of padding would be a big help.
