Got the 3off E3dTitan extruders mounted in a sort of flying arrangement so now the printer has grown by another half metre in height. I've also added a means of mounting filament spools (2 lengths of 32mm waste pipe). Tip to toe, it's now 1.7 metes tall.

I'm really chuffed that I've ended up with with 300mm long Bowden tubes for a print area a shade under 400mm square on a frame which is 600mm square and over a metre tall.

I don't know how to add pictures to posts - perhaps someone can enlighten me. Meanwhile, I've added folders named "Extruders" and "Wiring" to the shared google drive folder - link here. https://drive.google.com/folderview?id=0B_MwtHtQR_ZvSkZlRWphTnJ3X0k&usp=sharing

Big thanks to AussiePhill for the idea but also apologies for not using his STL. I needed to tweak the design and it was just easier for me to start from scratch with OpenScad which is all I know how to use.

The extruders are mounted together on a custom mount which is suspended above the centre of the bed on a pulley arrangement with a counter balance weight (printed container with lead shot). This allows the whole thing to fall when the print head is at the extreme corners but the rise again to "lose" the Bowden tubes when it is directly above the centre of the bed. The combined weight of the three extruders with their stepper motors and mount is 905 gms, the counter weight is a little more than this to overcoming and friction and "sticksion" and ensure that they rise up when needed to and prevent the Bowden tubes from buckling. So, there is a slight upward pull and I've fitted cords between the extruder mount and the X carriage so that this pull is not transmitted to the Bowden tubes which are slightly under compression, keeping them firmly attached at both ends.

Inevitably, there is some drag on the X carriage due to the wires and tubes but it is tiny compared to having to lug 900 gms of extruders and steppers around.

A more elegant solution might be to mount the counter weight on a vertical linear rail using a bit more V slot, but I'll wait until I've tested the printer to make sure it's viable.

The wiring is about as far as I can get - just needs the Duet (batch4) but my daughter's wedding is only a couple of weeks away so further work will have to be put on hold. I've braided most of the visible wires and fitted printed labels covered with clear heat shrink. Where possible, I've run the wires inside the Vslot and fitted cable covers which makes quite a neat job. I've used flexible conduit for all the wires from the hot and and x carriage. This still looks untidy to me but there are a lot of wires (heater, pt100, xmin, xmax, hot end fan, print cooling fans, z probe and of course 3 extruder motors) and they have to be long enough to reach all 4 corners of the print area.

I've added separate micro switches to the extremes (max) of all the axes and connected them in series to try and prevent crashes during commissioning or in the event of a probe failure. I've added a separate emergency stop button too. The mains to the heated bed is in a flexible cable chain. The bed plate is earthed, and also connected to the frame which is also earthed in two places and I've fitted an RCD plug to the mains inlet. All the mains wiring is inside a printed enclosure so all in all, it should be safe.

@T3P3Tony:

Hi Phil

If you want to print delta frames then you should check out @RichRap's #3dr project if you have not already seen that:
http://richrap.blogspot.co.uk/2013/07/3dr-reprap-delta-printer-part-1-release.html

Its currently divided into parts but you could reduce the part counts by printing the top and bottom in single pieces

Thanks Tony,

I have followed Richards blog/site for quite a while, he's mega delta is the inspiration for my large design.

I'll likely put any real design work on hold now till next year as I gear up for christmas lights display time

I do have a few issues and tweaks that I am trying to resolve but I do not have enough hours in the day at the moment.

The print size is X300, Y200, Z240 with a heated bed with glass print surface.
The power supply is 12.9 volts which seem to be sufficient, seeing I only print pla at the moment.
The motors are nema 17, 1.8 hybrid 425TH47-168AAC
At the moment I am running at 4200 mm/min and am gradually increasing as I make improvement to the basic design, which is adapted from the D-Bot corexy by D Spaulding which was based on cfeniak's C-Bot printer
link http://www.thingiverse.com/thing:1001065

This is still a work in progress and some of the design will change.

@T3P3Tony:

Nice!

(off topic) how are you finding the split bottom corners for frame assembly? Is the advantage just that they are easier to print?

Cheers

Tony

Thanks.

I was simply wanting to double up on the bottom structure for what little extra rigidity it would provide and to give me plenty of space in there for power supply and other components - so you guessed correctly about being somewhat easier - I only need to print a single part design for all 9 corner pieces. As you can see in the photos, I downsized the lower section of my new 200mm delta to use 20x20 and designed the 20mm corner piece for it. As far as assembly goes, it is just enough of a challenge to get the two lower sections to be perfectly parallel to each other that I am going to design an all-in-one corner which will make the bottom of the printer easier to assemble.

What a star you are! Thanks.