External perimeter speed?
-
You can still control, the volumetric speed is only the maximum, so yo do not make a mess. That way you v can set infill speed to let's say 200mm/s and it will still be OK
-
@OBELIKS yeah I appreciate that thanks.
-
@DocTrucker said in External perimeter speed?:
.............................. I'm assuming the really high print speeds that are occasionally mentioned (150mm/sec+) only really come into play when you run with much lower layer thicknesses, or running a long heat zone hot end (e.g. volcano) with a comparatively small nozzle - something that I want to try for TPU once I'm happy that I understand my test bed well enough!
I'm a bit tired of saying this but if you want to print fast, best of all is to use a mixing or multi input single output hot end such as a Diamond. For two reasons. Firstly you have multiple melt chambers so vastly increased surface area through which the heat can be transferred to the filament. Secondly, each filament passes through each melt chamber at fraction of the speed of a single melt chamber/single filament design. So for example, with a 3 input hot end, with mixing ratio set to 33.3% each individual filament takes 3 times as long to pass through it's respective melt chamber. So greater time in contact with a greater surface area = greater throughput.
With a 5 input diamond and mixing ratio set to 20% for each input, using a 0.5mm nozzle and 0.3mm layer height @ 195 deg C, I managed 240 mm/sec before any signs of under extrusion. Which equates to a flow rate of around 36mm^3/sec. Bumping the temperature up to 210 deg C allowed me to print at 300mm/sec which equates to a volume flow rate of 45mm^3/sec. And with a great big 0.9mm nozzle and 0.6mm layer height, I managed 100mm/sec at a flow rate of 54mm^3/sec. All with a single 40 watt heater cartridge I might add.
Write up here https://somei3deas.wordpress.com/2018/10/14/real-3d-printing-at-high-speeds-and-even-higher-melt-rates-with-a-large-nozzle/ .
Accompanying video here https://www.youtube.com/watch?v=rUV5IZxfAxU&feature=youtu.be
-
@deckingman said in External perimeter speed?:
I'm a bit tired of saying this but if you want to print fast, best of all is to use a mixing or multi input single output hot end such as a Diamond.
True, but then you're flinging a lot of weight around, which causes other problems... but you know that, and have fixed it, already!
Ian
Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth
-
@deckingman said in External perimeter speed?:
I'm a bit tired of saying this but if you want to print fast, best of all is to use a mixing or multi input single output hot end such as a Diamond.
So in other words yes:
...or running a long heat zone hot end (e.g. volcano)
This thread is mainly trying to establish if the behaviours I am seeing on my machine are typical or if I still had some serious issues to overcome. For a 12V machine running on a v0.6 board I think this machine is approaching the limit on balance in returns to effort spent, and so I am happy with it.
I do intend to fire up the three way again at some point but I've concerns about swinging the weight of a direct extruder from the 8mm smooth rods at this stage which comes before my interest in colours as I have an interest in a TPU application. The rods are bouncy and I would like to swap to a v-slot extrusion before doing much more heavy head stuff.
Edit: My comment on ultimate speed was merely a curiosity. My main interest was main vs external/perimeter speeds when you are trying to get a consistent part finish.
-
@DocTrucker I take your point - you are unlikely to be able to fully exploit high melt rates unless you have a sturdier frame. But the Diamond isn't a direct extruder - you still have Bowden tubes. And to get the same size melt zone you'd need a Volcano that is 3 times as long as a std V6. I've never compared the weight of a (super) volcano with a Diamond but I guess the Diamond would still weigh more because of the multiple heat sinks. But then again. one long melt chamber still has the filament speed disadvantage compare to multiple (parallel) melt chambers. And of course, you need multiple extrudes (in my case 5) which probably cost more than many people spend on an entire printer.
But surface finish is a function of both speed and temperature IMO. If you run high temperature to get high flow rate, then you really don't want to slow it down too much on perimeters. TBH, with those high speed tests I did at up to 300mm/sec, I didn't slow down the perimeters at all. The surface finish wasn't all that shiny but not too bad at all.
-
@droftarts said in External perimeter speed?:
True, but then you're flinging a lot of weight around, which causes other problems... but you know that, and have fixed it, already!
Ian
What problems?
-
@deckingman said in External perimeter speed?:
...Diamond isn't a direct extruder....
Direct extruder is a requirement of the TPU, I'll be running that into an E3D hotend on these machines.
@deckingman said in External perimeter speed?:
But surface finish is a function of both speed and temperature IMO. If you run high temperature to get high flow rate, then you really don't want to slow it down too much on perimeters. ...
Generally agree with you a few posts before yours External perimeter speed?. But definable need to slow a reasonable amount on my system. This is likely to be largely do the larger time the the polymer stays molten in your system. I suspect the polymer is there long enough in yours to reach a stable temperature, and hense why you have said in the past you are able to run (and indeed the 3 way did before I broke it down) at lower temperatures.
In a crude sense in my system the melt is out of control due to the very short residence time for the melt and the polymer melt temperature being largely effected by changes in process rates and hot end temp. At 230C if the head stays still it will leak a significant amount of polymer in a short space of time. Without the high temp the process rates need to be slowed down significantly to avoid patchy parts.
Essentially I'm talking myself into trialling a volcano soon with a small diameter nozzle!
Edit: Requirement for direct extruder comes from trial work I did on Duet 2 Ethernet core XY with direct mounted genuine BMG. It was utter crap before I used direct.
-
@DocTrucker I think we must have been talking at cross purposes. You mentioned something about being concerned about swinging the weight of a direct extruder and I assumed that you were referring to the diamond - hence my mentioning the fact that it isn't.
And yes, filament is funny stuff. It's generally a poor heat conductor so one can get the situation where it is fully molten on the outside but only partially molten on the inside. Which is why I think that time in the melt zone is as important if not more so, as the surface area of that melt zone.
-
@deckingman I meant to add a comment saying I think we are talking at cross purposes. To many things going on at once here!
Edit: I have said many times on here polymer is weird!
-
I mention the E3D products regularly. In order to avoid sounding like a fan boy I'd like to pojnt out I am checking out the other options like Micro Swiss, Dzyne, Mosquito, and any others that I find which are substantially different to the J-head and E3D V6.
-
@DocTrucker If I was looking for a single input hot end, I'd put my money on a Mosquito. I just like their approach to the heat break.
-
@deckingman said in External perimeter speed?:
@droftarts said in External perimeter speed?:
True, but then you're flinging a lot of weight around, which causes other problems... but you know that, and have fixed it, already!
Ian
What problems?
Lots of weight on axis + fast speeds = backlash
That's why I said you'd fixed it; by separating the weight out onto independent axes.Ian
Bed-slinger - Mini5+ WiFi/1LC | RRP Fisher v1 - D2 WiFi | Polargraph - D2 WiFi | TronXY X5S - 6HC/Roto | CNC router - 6HC | Tractus3D T1250 - D2 Eth
-
@droftarts I guess that depends on your definition of "backlash". For me it's a varying clearance between mating components depending on the direction of travel, so unaffected by mass. Even though I've separated the mass onto two gantries, I still have 2Kgs on one and 3Kgs on the other which most people will say is very very bad.
-
@deckingman said in External perimeter speed?:
@droftarts I guess that depends on your definition of "backlash". For me it's a varying clearance between mating components depending on the direction of travel, so unaffected by mass.
Lovely description, makes it sound so positive, almost intentional!
Ian
-
@DocTrucker said in External perimeter speed?:
@Phaedrux said in External perimeter speed?:
Some of the filaments I use don't like to change speed very often, so print speed is held constant. Polyalchemy elixir for instance.
What are the symptoms of a polymer that doesn't like to change flow rate?
With the polyalchemy for example, it's a very spongy filament. When extruding into free air it creates a glob that sticks to the nozzle and keeps expanding rather than a single drawn out filament. When printing if the speed changes abruptly it can leave gaps at the transitions where not enough plastic is deposited.
With some PETG I find that it gets blobby and sticks to the nozzle unless speeds are consistent. If the print speed changes from 40 to 60 at different areas I get blobs. If I run the same print at 70mm/s it's nice and clean.
-
MAX flowrates in slicers don't mean ANYTHING unless you calibrate the printer with a filament at a given temperature and even PID tune too properly at that temp.
IMO filament melt rates are non-linear and vary significantly between materials and physical hardware setups. Even the slightest draft on your printer will throw the numbers off for the same material and temp.
Here is a video example of what KISS does for flow tuning. Not my video, but pretty descent for the concept. It changes print speed to vary the extrusion rate. The gaps and bad surface finish on the print is basically the printer falling flat on its face. It intentional failure- pushing the limits until you can find it.
Jumping ahead to the resulting print-
https://youtu.be/c5xcAjdjYhI?t=326the author picked the elevation of the best looking part of the calibration object and computed that for the filament and temp, best flow was 3.7 mm^3/s. You might scoff at the final answer but the procedure gives consistent results.
3.7 is a far cry from the theoretical max of 10mm^3/sec for v6. But the truth is that for that printer, under those parameters, that was the authors interpretation of 'best quality'.
As an aside, we calc'd out the extruder filament speed to maintain the throughput of the E3D to yield 10mm^3/sec. It was surprisingly low, like on the order of 2mm/sec for 1.75mm filament.
EDIT: I use KISS and Slic3r PE depending on the print. I use the calibration process in KISS to get printing parameters for Slic3r to get close to the dialing in spots. Doing temp, flow and destring (retraction) takes about an hour of print time total with a couple of iterations.
-
@sinned6915 agree with most of that, I'll have a look at the link later. Have they calibrated for linear/non linear extrusion correction and got pressure advance set up before doing that?
I tend to limit my max speeds to either 10mm3/sec, when the extruder stepper skips, or when the plot of the required extrusion corrections takes a sudden jump for the sky!
Yes filament speed at 10mm3/sec is low, 3.6mm/sec. The melt zone on the V6 is little more than 2mm long, but those to figures next to each other elequently demonstrate a reason why I am interested in longer melt zone.
I really want to do destructive pull tests at some point because I don't think dull parts are poor parts. Geometrically they are still good aside from a little more ringing.
-
i don't understand your question about linear advance. i don't see how its relevant for this calibration.
if you are skipping steps, then you have found you limit. but is that number reproducible or repeatable? how predictable is it?
i don't use any of the linear advance / pressure advance. i think its folly and band aids over scabs to try and go faster when you are already at the point that the hardware cant keep up.
-
He wasn't talking about linear advance / pressure advance but rather non-linear extrusion which makes adjustments to the extrusion speed/rate at different print speeds.
