On Fri, 19 May 2017 01:42:52 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
On Fri, May 19, 2017 at 12:35 AM, Neil Jansen njansen1@gmail.com wrote:
<snip>
now, neil, this is the kind of speed at which an arduino 2560 *cannot cope*, and, also, where the design flaws inherent in RAMPS - using prototyping Evaluation Boards (polulu-style drivers) - start to show up.
Could you be more specific? Why can't the arduino cope?
david crocket (dc42) has specifically designed the duet series so that you can consider exceeding PWM rates of 150 khz, which is what you need if you want to sustain 500mm/sec for example (and do not want problems to occur at speeds well below that).
Link?
also i forgot to mention that i've been using the E3Dv6 "volcano" which, when you use a 0.5 to 0.8mm nozzle can easily do flow rates of something mad like.... 200c^3/min - particularly when combined with the huge 40:1 gearing of the flex3drive which can *accurately* deliver the kinds of torque needed. the volcano basically turns the heat chamber round, so that the heat area is 20mm long instead of the usual 10mm.
Torque for what? Again, maybe a link would help us stay on the same page.
none of this stuff i knew about, the 18 months before i began designing the laptop's parts. oh well.
I researched 3D printers thoroughly before I bought mine. I even started asking questions at a forum, and I'm still not too certain if I got what I sought. According to this list, I did worse when looking for hacker boards. So, you are not alone.
<snip>
welcome to the list neil. really good talking with you.
l.
Indeed.
Sincerely, David
--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Mon, May 29, 2017 at 3:44 PM, doark@mail.com wrote:
On Fri, 19 May 2017 01:42:52 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
On Fri, May 19, 2017 at 12:35 AM, Neil Jansen njansen1@gmail.com wrote:
<snip> > now, neil, this is the kind of speed at which an arduino 2560 *cannot > cope*, and, also, where the design flaws inherent in RAMPS - using > prototyping Evaluation Boards (polulu-style drivers) - start to show > up. Could you be more specific? Why can't the arduino cope?
there are more experienced people who know the precise details. bottom line: an 8-bit 16 mhz processor is simply not fast enough to be able to send the data to the stepper motors in a way that they will remain properly synchronised.
example: X axis gets changed direction/speed, and Y needs to be changed at the exact same time. but because it takes e.g. 50uS (0.05 ms) to get round the "compute" loop, the print head has moved on (say) 0.2mm in that time, it's going so fast, so X and Y are no longer properly synchronised.
only by going to a 32-bit processor running at say 100mhz can you get the timing synchronisation back.
david crocket (dc42) has specifically designed the duet series so that you can consider exceeding PWM rates of 150 khz, which is what you need if you want to sustain 500mm/sec for example (and do not want problems to occur at speeds well below that).
Link?
google it please.
also i forgot to mention that i've been using the E3Dv6 "volcano" which, when you use a 0.5 to 0.8mm nozzle can easily do flow rates of something mad like.... 200c^3/min - particularly when combined with the huge 40:1 gearing of the flex3drive which can *accurately* deliver the kinds of torque needed. the volcano basically turns the heat chamber round, so that the heat area is 20mm long instead of the usual 10mm.
Torque for what? Again, maybe a link would help us stay on the same page.
google them, please. i have a lot else to take care of.
none of this stuff i knew about, the 18 months before i began designing the laptop's parts. oh well.
I researched 3D printers thoroughly before I bought mine. I even started asking questions at a forum, and I'm still not too certain if I got what I sought. According to this list, I did worse when looking for hacker boards.
well, if you are only looking to print a few trinkets at below 50 mm / sec then whatever you have is perfectly fine.
if on the other hand you're looking for something that you intend to take seriously, then yes you have been through an important learning experience.
actually after looking at the design of TMC2100 postage-stamp-sized driver boards, i believe these may actually be okay. in these particular boards they've put the TMC2100 *ON THE OTHER SIDE OF THE PCB*. what that means is that you can put a heatsink on the TOP of the PCB, where it will actually be effective at taking heat away.
l.
On Tue, 30 May 2017 03:51:01 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Mon, May 29, 2017 at 3:44 PM, doark@mail.com wrote:
On Fri, 19 May 2017 01:42:52 +0100 Luke Kenneth Casson Leighton lkcl@lkcl.net wrote:
On Fri, May 19, 2017 at 12:35 AM, Neil Jansen njansen1@gmail.com wrote:
<snip> > now, neil, this is the kind of speed at which an arduino 2560 *cannot > cope*, and, also, where the design flaws inherent in RAMPS - using > prototyping Evaluation Boards (polulu-style drivers) - start to show > up. Could you be more specific? Why can't the arduino cope?
there are more experienced people who know the precise details. bottom line: an 8-bit 16 mhz processor is simply not fast enough to be able to send the data to the stepper motors in a way that they will remain properly synchronised.
example: X axis gets changed direction/speed, and Y needs to be changed at the exact same time. but because it takes e.g. 50uS (0.05 ms) to get round the "compute" loop, the print head has moved on (say) 0.2mm in that time, it's going so fast, so X and Y are no longer properly synchronised.
only by going to a 32-bit processor running at say 100mhz can you get the timing synchronisation back.
I understand now. I thought that the arduino was faster...
david crocket (dc42) has specifically designed the duet series so that you can consider exceeding PWM rates of 150 khz, which is what you need if you want to sustain 500mm/sec for example (and do not want problems to occur at speeds well below that).
Link?
google it please.
This looks like it: http://forums.reprap.org/read.php?147,33082,471483
also i forgot to mention that i've been using the E3Dv6 "volcano" which, when you use a 0.5 to 0.8mm nozzle can easily do flow rates of something mad like.... 200c^3/min - particularly when combined with the huge 40:1 gearing of the flex3drive which can *accurately* deliver the kinds of torque needed. the volcano basically turns the heat chamber round, so that the heat area is 20mm long instead of the usual 10mm.
Torque for what? Again, maybe a link would help us stay on the same page.
google them, please. i have a lot else to take care of.
<snip>
I thought you were waiting for the PCBs to get done (which was going to take another week I think), and had nothing better to do than play with that oh-so-giggly-and-fun little girl in the youtube vids?
Thanks, David
On Tue, May 30, 2017 at 9:02 PM, David Niklas doark@mail.com wrote:
only by going to a 32-bit processor running at say 100mhz can you get the timing synchronisation back.
I understand now. I thought that the arduino was faster...
neeeh. they're.... well... not very good, basically. also the arduino base code.... *sigh* it does timing loops to get accuracy by hand-coding them in assembler with NOOPs (no operation).
as a programmer, you know what that means... :)
david crocket (dc42) has specifically designed the duet series so that you can consider exceeding PWM rates of 150 khz, which is what you need if you want to sustain 500mm/sec for example (and do not want problems to occur at speeds well below that).
Link?
google it please.
This looks like it: http://forums.reprap.org/read.php?147,33082,471483
yehhh that'd be about right - a good example, and really highly technically informative and insightful. good find.
also i forgot to mention that i've been using the E3Dv6 "volcano" which, when you use a 0.5 to 0.8mm nozzle can easily do flow rates of something mad like.... 200c^3/min - particularly when combined with the huge 40:1 gearing of the flex3drive which can *accurately* deliver the kinds of torque needed. the volcano basically turns the heat chamber round, so that the heat area is 20mm long instead of the usual 10mm.
Torque for what? Again, maybe a link would help us stay on the same page.
google them, please. i have a lot else to take care of.
<snip>
I thought you were waiting for the PCBs to get done (which was going to take another week I think),
yehyeh.... still waiting: mike has family issues as well as pressing production to deal with, he's got one side of the PCBs done, the other side is next.
and had nothing better to do than play with that oh-so-giggly-and-fun little girl in the youtube vids?
:) my daughter's currently in the US, her grandmother's 80th birthday was this month.
ok so i re-read what i wrote a bit, one of the reasons why you can't push extruders beyond a certain point is because the heat chamber can't keep up with melting the filament fast enough, but also it takes quite a lot of pressure to do that. if you can get higher torque out of the motors by having a 40:1 gear ratio instead of the usual "direct drive" or maybe 3:1 or 4:1 as is usual even with the mendel90, lulzbots and so on, you have enough torque to be able to do it.
that's what i meant.
l.
arm-netbook@lists.phcomp.co.uk
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David Niklas -
doarkļ¼ mail.com
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Luke Kenneth Casson Leighton