multiple hotend electronics for large printers?

Hi guys. I'm building a 600mm x 600mm x 400mm 3d printer with 3+ e3d hotends. (as the kraken doesn't support 3mm plastic)

But there seems to be a lack of forum topics posted this year about the state of tri and quad systems. If it all goes well I plan to go up to 4 hotends in the long term. Probably dual for the first few months.

I know people keep talking about architecture of the systems, that the earlier ones wouldn't be able to handle such big prints. I see a duet board.. and I remember the diamond hotend posting about a second option (they are down at the moment, oops!)

As i've had no less than 6 arduino boards randomly fry at the USB (different computers, and only 2 were my fault) so I hope to stay far away from them..

What do you all think? Is there a good resource comparing these boards? I more or less just want on that will work and not have any issues (don't we all?)

Thanks!

Oh I'll be doing 24v and the bed is a silicon bed with a SSR.

Edited 1 time(s). Last edit at 07/05/2015 09:35PM by L4nce0.

I don't know anything about arduino other than it seems to be aging... though I've also read Duet is based on it and some say the firmware is a wreck because of it. Though I don't program, it doesn't seem to affect operation. Other than that I haven't seen much comparison between the two that I can remember atm.

I'm running build envelope about half your size with a12v Duet+x4 & PanelDUE using 3-1.75 mm extruders and either a 115v 400w chamber heater or a 115v 300w bed-using the SSR method.(firmware doesn't currently support both, though there have been G codes reserved for it). Longest print to date has been ~7hrs without issue. I've been using it once or twice a week in this almost finished state for a couple weeks is all. on a single extruder maybe a month or two.

The adjustment for 3 heads was rougher for reprap hotends because none of them seem to be designed for multiple setups(adjusting height mainly) so a slip-fit design like the cyclops or kraken would probably be easier than the other options I've seen.

File transfer could also be an issue for you @600mm, Ethernet on the duet... while I prefer it to messing around with WiFi. is slower... a 20mb file takes a min to upload... but you also have the option of just using the SD card.

Quote
DC42
...
The sustained speed for uploading a file to the SD card via the web interface seems to be a little over 170kbytes/sec. The card interface is SDHC, so it doesn't have the speed limitation that Smoothie seems to have when uploading to SD card from the web interface.

RepRap Wiki comparison of electronics just in case you haven't come across it.

Yeah.. fun how these projects snowball. But hey I figure all this will lead to some great topics for the blog I'm going to start this month. All I know is some people had problems with the size of the printer in relation to the architecture of the chip. Lets see.. using my comp sci degree.. 8 bits 255 addresses, 16 bit 65,536 addresses.. gcode is a 3 decimal point float in gcode.. I know its been 4 years since I took advanced operating systems, but it doesn't really seem to matter to my brain the chips architecture. That said they didn't offer the class on ARM programming my senior year. I guess my gap is understanding how these boards process gcode. To me its a simple long list of movement commands. Those commands are , or two maybe three if its xyz every command .. which in this case is a pair of floating point in the form of xxx.xxx. Which isn't that big. There is no sense in putting the whole list in memory, and thats the only reason I can think you would need to worry about the architecture. Hmm

[en.wikipedia.org]
as its almost 3 am I cant quite add up a 3 precision float and see if its max value is over 600. Maybe the issue is having the arm trying to process 3 of these (not that big) numbers? Surely not! I think I'll have to hunt these guys down and have them explain it a bit better. . . but I can see how 3 hotends would start to be an issue with addressing.. moreso than the size.. depending on how all this works under the hood.
Trying to store 3 sets of 3 precision 0 to 600+ floats, for 3 sets of hotends on an arm.. That must the the issue

Well, I was thinking 3 because I might want to put a diamond hotend on at some point. As it stands today it will be 2 and the mendelmax will get the third.

Edited 1 time(s). Last edit at 07/19/2015 04:47AM by L4nce0.

Quote
Epop
I don't know anything about arduino other than it seems to be aging... though I've also read Duet is based on it and some say the firmware is a wreck because of it. Though I don't program, it doesn't seem to affect operation. Other than that I haven't seen much comparison between the two that I can remember atm.

I'm running build envelope about half your size with a12v Duet+x4 & PanelDUE using 3-1.75 mm extruders and either a 115v 400w chamber heater or a 115v 300w bed-using the SSR method.(firmware doesn't currently support both, though there have been G codes reserved for it). Longest print to date has been ~7hrs without issue. I've been using it once or twice a week in this almost finished state for a couple weeks is all. on a single extruder maybe a month or two.

The adjustment for 3 heads was rougher for reprap hotends because none of them seem to be designed for multiple setups(adjusting height mainly) so a slip-fit design like the cyclops or kraken would probably be easier than the other options I've seen.

File transfer could also be an issue for you @600mm, Ethernet on the duet... while I prefer it to messing around with WiFi. is slower... a 20mb file takes a min to upload... but you also have the option of just using the SD card.

Quote
DC42
...
The sustained speed for uploading a file to the SD card via the web interface seems to be a little over 170kbytes/sec. The card interface is SDHC, so it doesn't have the speed limitation that Smoothie seems to have when uploading to SD card from the web interface.

RepRap Wiki comparison of electronics just in case you haven't come across it.

I was aware of the different ones. That page no. That helps!

I think I see the issue ..

RUMBA GPL 1.0 3 2 3 6 4 ? 1 0 USB & ISP Headers for both microcontroller 8 bits Atmega2560, Atmega16u2
8 bits.. thats super tiny...

I can't see any reason why the Duet + DueX4 + RepRapFirmware won't handle that system. The restriction on print size for older electronics/firmware combinations that was mentioned might be because the firmware in question was using 16-bit integers to represent certain quantities, and those integers overflowed when the distances got too large.

btw if your Arduino boards literally fried at the USB connection, that suggests to me that the ground wire from your PSU output to your electronics may be been intermittent, so that the power supply ground current was routing via the USB port and cable to the PC, through mains ground, and thence to the power supply. The Duet is typically controlled via Ethernet, which avoids creating a ground loop.

---

Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].