Is there any reason that anyone can see that I can feed the filament from the rear for both the hot ends? I was thinking that if I moved the other motor also to the back and created a little holder mount on the top it would lighten up the carriage a lot. That would in theory allow you to print faster with the same level of quality and also give you better quality at the same speeds. Is there a down side I am missing?
The advantage is a lower mass on the carriage (less ringing, quicker movement) and the disadvantage is not as good retraction, poor handling of flexible materials. Retraction is a particular issue even if you don't print flexible stuff as all plastic is somewhat elastic and flexible and so retraction many cm away from the nozzle doesn't produce a necessarily consistent retract as it does when the extruder is right there.
someone designed a plate for the Hybrid carriage for a dual bowden setup http://www.thingiverse.com/thing:1576749
Now I need to figure out how to print that so I can duel bowden setup instead of building my printer and then having to take it all apart to put that on.
I don't see how you would be losing precision unless you are printing flexable materials. Am I missing something?
The retraction must not be a major issue or they wouldn't have went with a 1 and 1 set up with the duel. So it just at least be able to be dealt with. I am going to guess the flexibility is by material. So is there a was to set the retraction by material?
This depends on your slicer, I think that you could do it with S3D profiles. They went with a 1x1 because they primarily use the direct for the main material, because it is accurate and high quality and then the bowden for support, that, whilst you want to be good, you don't really care if it isn't so good because you throw it away.
This is my understanding to if you want to print traffic cones or two colour frogs then stick with the direct dual. If you want to to engineering work (one colour and one support) then precise operation is more important.... (Not exactly the correct words but quite close to the answer I got when asking why not two direct Titan's )
It's a compromise as @PsyVision and @GrodanB mentioned, between lower mass (i.e. more precision/less ringing) and retraction/precision extrusion. There is of course variation in extrusion on the bowdens as well as the stiffness of the material changes (since each time you start extruding you first need to compress the entire length of material). While this is technically true of a direct, you are talking mm vs. major fractions of a meter. The idea (if you read Sanjay's post) was that you would use the second extruder (bowden) to extrude support material (such as scaffold) and while a bowden is pretty good, you don't need perfect surface etc on support material.
