Recently, I’ve been working on making dual extrusion very easy and cheap, but I can’t figure out if most people have a Bowden or DD system. This changes the design significantly, so I want to find out which is more impactful. Which do you have?
Whatever system you build, good advice has always been to; “Build-a-little, test-a-little”. That means get it working first, then tailor it to what works best later. If its a good idea, you will want to build it both ways to demonstrate which system has the better advantages, not which system is more popular but has performance drawbacks in your application.
Well… The systems I had in mind for each version are fundamentally different. Both would perform just about the same, so I wanted to make the one that would help the most people. I have to say though, the direct drive system would have been easier to make for me.
@Sahil_Jain Then start with that, make it work, then try the other method. You will learn along the way, and might find solutions to make the other work better. But unless you try, you may never know. Good luck.
Direct drive dualstrusion rigs end up being too heavy for most people’s printers (eg CR-10s) to perform well. Motor mass…
I’d agree with @Ryan_Carlyle , if you’re going to make a multi extrusion system, bowden is probably the way to go. You can get away with two (my FF Pro works just fine with two mounted motors), but three or four and you’ve got a print head the size of a shoebox.
Only drawback of Bowden that might be a problem would be flexible materials.
The direct system I was thinking of is like the mmu v2 from prusa, it only has one motor on the carriage.
@Sahil_Jain If it’s one nozzle, that’s not dualstrusion, that’s filament switching. I personally don’t even like calling one-nozzle systems “multi-material” since you can’t do stuff like combine PVA with PC due to nozzle temp incompatibilities.
Well that’s kind of the conundrum. If you go with multiple nozzles, there are a lot of complexities added for the user, but you gain functionality. The goal of this is to make a system that is as easy to use as possible, however I was considering a separate, scaled down hotend and extruder for PVA only to sidestep the temp issue in most prints.
For me, a “multi” system that can’t handle different temperatures is really not much use. It’s really rare for me to have jobs that require different colours of the same material, much, much more common to need different materials, e.g. support & primary.
I am another one who can sign the rule: One material print head → direct drive. Dual (or more) materials print head → bowdens. (Tested on many existing printers around me, from kits to production machines.)
There is another way… perhaps ERRF will turn up something… (wink)
I thought long and hard about this topic. And I compromised where I can so I ended up with as close to direct as can be but still a multi material printer. ZideX link to Onshape for reference
https://cad.onshape.com/documents/0a614a4674c34d17fad6ca34/w/c56dc46b54dffcec5b4223f7/e/2df415dc5961ccc9e1978c58
I think the best approach for this is a mix of the two, a remote-direct-drive… Offload the motor but keep the extruder gears just near the hotend. Like the https://flex3drive.com/flex3drive/. The zesty was trying to do just as well or better, but reliability suffered iirc. Friend of mine made his own DIY version and sent me one to use - I’m now a convert.
https://flex3drive.com/flex3drive/
Brook sits quietly with tape over his mouth mumbling something… guess he will wait a little bit to rip the tape off 
@Brook_Drumm you have me interested:-) one of these years I’ll make it.