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