PCB Milling Part 1

I tested my PCB milling capability the other day by pulling apart one of the kids felt tip pens and putting just the felt nib into the chuck of the drill on the Darwin.

Ran up the “old” Darwin software and setup the Z axis so that the bed was fully up (normally fully down for plastic printing) even then I had to put an extra block of wood on the deck to get the felt nib to touch the A4 sheet of paper that I had taped to the block of wood.

Loaded an example PCB layout and printed it using Pronterface after a little fiddling with the profile setup for Milling.

It worked surprisingly well other than my Z axis did not appear to move at all in fact I could hear the stepper stalling when it was supposed to be lifting the drill up and moving to the next mill point.

I remember that I had these sorts of problems with the Z-axis before when I was trying to print plastic and I solved it by setting the “Limit” to 1mm I tried this on the new milling profile but alas it did not work, this got me to thinking that there is no reason not to upgrade the firmware on my old G3 set now as if I am not printing plastic then I won’t need the extruder at all and this was the key reason I could not upgrade to marlin firmware before, because it does not support RS485 driven Darwin style extruders at all, if I want to print plastic using this G3 set I will have to bodge a G3+ adapter together so that I can drive the additional extruder stepper directly from the motherboard.

As yet I have not tried this I will attempt to change the firmware to Marlin and see if this cures the Z axis stalling problem without the need to use limit  function in SFACT.

If all goes well I may be milling PCB’s sooner rather than later, although I have read online that Darwins are not stable enough to do any sort of milling, I am still going to try and set it up for just PCB milling, if it does not work at all it may well sound the death-knell for the Darwin.

Multiple extruders required!

I have been investigating the best electronics/firmware combo for multiple extruders, I really need 3 extruders minimum to do the experiments that I am interested in, on closer examination of the electronics comparison table

http://reprap.org/wiki/Comparison_of_Electronics

it looks like we have a new contender that is for the first time quoting that it supports 3 extruders! Phoenix

Great, so off I went to join the TVRRUG (Thames Valley Rep Rap User Group) so that I could post on their forum and investigate how true these claims are.

I have the feeling that although the cool looking electronics set they have developed may well support 3 extruders in principle, unless they have already recoded the Marlin firmware then it is unlikely to directly support the additional (3^rd) extruder (I think Marlin supports 2 natively although I am not sure on this)

Anyway I had a very nice response from one of their moderators asking why I was interested in their group considering my (relatively distant) location, after explaining my reasons for interest in their electronics set I am now awaiting final confirmation of my account so that I can get posting on their forum.

A fair few electronics sets can support 2 extruders but not since the old days of using the RepRap Host (remember that!) did the host program natively support multiple (more than 2) extruder configurations, I really also need to experiment with some different software configurations rather than just staying safely where everything just works (i.e. with Pronterface and SFACT)

Maybe I could use RepRap Host now I have the firmware issues sorted (i.e. I am using Sanguinololu with Marlin FW) although I think development of this software set stopped some time ago.

There are several other configurations of electronics and software that I need to investigate, I noticed recently that there is a new PRO electronics set available (not cheaply though) R2C2 electronics this set although not cheap can print at extremely high speeds.

And I need to play with a Ramps set as this seems to be extremely popular and is quoted as being feature rich, I also think I could mill the boards for this set.

I have been asked to build a couple of 3D printers for a friend so I may get a chance to investigate more on this front depending on which electronics sets they choose.

The Pheonix Set has some great build instructions on their website also which should aid the construction process significantly.

Darwin Upgrades Part 2

OK, seeing as most of my cash is being eaten up by the new EV project and I can’t stretch to get a stepper motor for the Darwin so that it could print plastic once again, and seeing as I already have the Prusa printing plastic, I thought I would use this as an opportunity to try my hand at designing a part from scratch (1^st time ever).
I used Open SCAD to design a part that fits the Quick fit X carriage that will secure a mini chuck drill to the Darwin so that I can mill PCB’s.
Picture of part
My first Open SCAD designed from scratch part comes of the printer!
I am seriously impressed with this, not the part that's just a very basic part to fit the quick fit x carriage and dock a basic chuck mini drill (dremel style) to my Darwin printer.
But I am seriously impressed by just how quickly you can go from a need to an idea to a CAD design to a physical part in your hand, a matter of a few hours (this will get shorter as I get better at CAD).
The part I designed and printed mates a basic mini drill to the Darwin, I have been investigating the tool chain for taking a PCB layout say in Eagle and using PCB-GCode plugin to produce a G-Code file for sending to the printer (using yet more 3^rd party software) this should allow the direct milling of PCB’s on the now unused Darwin.
I hope to be milling a Gen7 electronics set and a Hot Bed (both on thingiverse) I even found a gen7 set that uses discrete alternatives to pololu stepper drivers. http://cnc.maket-city.ru/index.php/cnc/gen7tm

Rostock build

I have begun printing the parts for a Rostock printer, I tried printing the rods in both PLA and ABS to see if either were suitable, ABS warped horribly and the rod turned out more like a banana, the PLA one did come out straight once cooled but was far too flexible in my opinion to be useful, so I will probably take the alternative option for the rods and use a stiff rod of some sort and just print the ends and glue them on, I have a long length of glass fiber rod (in the days before carbon fiber this was the best stiffest rod you could get)  if I can find it I will use this for the rods.