Sunday 17 August 2014

New electronics: RAMPS-FD and DRV8825 drivers

I got some new electronics a couple of months ago! I was hoping it would help me solve some issues I was having with the RAMPS 1.4 board which runs on an 8bit Arduino Mega.

The biggest issue I was facing was momentary stalling/ pausing when printing curves and circles, this was causing quality issue because whenever the print head would stall plastic would still ooze out.

I never had this problem when I was using the Megatronics board which uses the same ATMega 2560 chip, My bad for blowing up the ftdi chip I guess. :(

Anyway! Something that has interested me for a while is 32bit 3D printer controllers, there are a few options out there, the Duet http://reprap.org/wiki/Duet which at first seems a bit pricey however after a little bit of research is actually quite good value, it has all the stepper drivers built in with the capability of 1/32 microstepping  and the possibility to expand, it's a tidy all in one board with ethernet and SD card reader built in too and the firmware is in constant development. The downside for me was if anything happened to the drivers I'd be a bit stuck and would have to either solder new components on or get a whole new Duet board if it couldn't be repaired (highly likely with my lack of soldering skills). That's when it would start getting quite expensive.

So then I started looking at the RAMPS-FD board (RAMPS For Due)
http://reprap.org/wiki/RAMPS-FD
This board really appealed to me as my ultimate goal is to create an all in one system using a Udoo.
http://www.udoo.org/

If the name doesn't give it away, it's been designed to work on the Arduino Due, a 32bit Arduino that uses the AT91SAM3X8E micro controller. I think it's still under development, it's currently on V2.A but I bought V1.A from Geeetech a couple of months back, sooooo I'm not sure what changes have been made since. So far there haven't been any fires though. It's compatible with most 3D printer stepper drivers on the market today and they can easily be replaced.
From looking through the forums and various other posts people had made regarding the quality of the board from Geeetech I wasn't expecting much for my £18 but I have to say the soldering quality was actually quite good and there weren't any bent pins either. The only things I did change were the fuses for my own peace of mind really.

The first big challenge I had was finding firmware that would work with the Due, the first one I tried was the one on the Geeetech wiki.
http://www.geeetech.com/wiki/index.php/Ramps-FD#FILES
It's a modified version of RepRapfirmware for the Duet and is uploaded via the Arduino IDE.
I didn't change anything with this just uploaded and made a note of the baudrate but once uploaded I couldn't connect to the board through Repetier-host, Cura or Simplify3d...very weird!
The same happened with the Repetier for due firmware, I spent a while searching online but couldn't find the reason so scrapped those two (If anyone can shed any light on this then please do).


I then decided to try aprinter, this has been rewritten from the ground up in C++ and is compiled and uploaded in linux using the supplied script. All configurations are made in one main config file, it's very easy to use and once your build environment is setup It's very easy to modify and upload to the Arduino Due. I had a few minor noob issues but Ambroz was really helpful and responsive.


Useful info
A few things I have noticed with this firmware are:
  • It doesn't like the default start gcode in Cura, anywhere in the code where it says {travel_speed} it needs to be changed to an actual value otherwise the printer returns an error and won't print.
  • When you start a print and the printer prepares the hotend and heat bed, the temperature read outs in the communication console stop until the print actually starts so you never really know when the print is going to start.
Both minor issues really but worth mentioning.
Check out the Git for more info, (link below) Ambrop has done a really good job with this, I can't wait to see more features to be added.
https://github.com/ambrop72/aprinter


Once the firmware was all setup and my laptop was talking to it and I could control the stepper motors using my current blueice stepstick drivers, I installed my shiny new DRV8825 stepper drivers, They are capable of 1/32 microstepping, are a direct replacement for A4988 or A4982 drivers, support up to 2.5amps and along with my new control board make the printer run very smoothly and a little more quietly.

Check out this video on youtube to get an idea of the noise difference.

https://www.youtube.com/watch?v=tGd2ulVkDTM


I will be putting some on Ebay soon so stay tuned.


Here's a link to the printer in action, It's a corkscrew glass printed in T-glase.

https://www.youtube.com/watch?v=CXgFLbCsfT8


I've added some pictures of prints since the upgrade.



The cup from the video


Open RC truggy tyre printed in flex filament. you can check it out here:


 This was a test with ABS, historically I've been unable to overcome warping but this went well.
I put the heat bed up to 130 degrees and extruder was at 240.
  
Printed with old electronics


Same print with RAMPS-FD
(Check out the difference in the curved corners)






Dual extrusion test...very tricky print.

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