I’ll poke my head in here and try and answer some of these.
I have a TAZ 4 that I have been upgrading and mad science-ing on for about a year now. From what I can tell, the TAZ 2-5 are relatively similar to each other - essentially evolutionary changes, not revolutionary. Upgrading a TAZ3 to a TAZ5 spec isn’t that difficult. Elsewhere on the forum, there’s a thread about Kauri, which is the next generation TAZ - it seems to be quite different in terms of structure, but I’m also quite happy with my TAZ 4, I don’t think you would be upset with a TAZ5.
This one is a bit weird for me to answer - I previously had a Lulz-style Dually mounted on my printer, and recently switched it out for a thing-of-my-own-design. The Lulz Dually, to me at least, caused me a lot more headaches than it should have. Leveling the nozzles is annoying, but more importantly it’s just REALLY heavy. There’s a good deal of flex in it - and paired with the stock smooth rods that hold it, there’s a good deal of wobble. I replaced all my smooth rods with hardened ones, and all the pillow bushings/bearings with ball bearings – MUCH more rigid now. My new extruder works with the E3D Chimera (a dual-nozzle single-heatsink jobby) and a DGlass 3D HPX2-MAX extruder. The HPX2Max is nice because it uses only a single, small stepper motor - along with a servo - to drive two filaments. It’s rigid, the nozzles are ALWAYS levelled because they fit in the same heatsink, etc.
All that said, get a dual extruder. Maybe not IMMEDIATELY - get used to printing with a single extruder first - but dissolvable support is heavenly.
PLA tends to be easier - except for one major thing, which is heat creep. In all-metal hotends, for some reason, PLA tends to jam. There’s a couple fixes I’ve heard, namely ‘seasoning’ the hotend by coating a small amount of filament in oil. The other is to use thermal paste on the heatbreak and nozzle threads when assembling, but I haven’t tried this.
ABS is great, but does require a bit more effort at first - I personally use a very thick ABS/Acetone slurry, atop PET tape. PLA can be printed on the bare glass bed, or use a gluestick to put a thin coating on the glass. I actually usually use a mixture of wood glue (PVA) and water to coat my bed for PLA.
The TAZ 5 has a PEI build surface, which I haven’t used but is apparently great for a lot of materials.
Yes. It won’t be EASY, but I don’t see why you couldn’t. You’d need wider aluminum extrusions, wide smooth rods, different belts, lots of stuff.
I’ve printed at .06mm layer height on my TAZ4, using an E3D all-metal hotend. Takes forever but man does it look good.
I don’t think nylon is particularly harsh on the nozzle - something like the Carbon Fiber infused PLA filament will destroy a brass nozzle VERY quickly, however. The biggest problem i’ve had with nylon is adhesion - to both itself and the bed.
Assuming they’re for sale, I would suggest getting another PEI surface. I actually have two print beds now - one I use for ABS, one for PLA/soft filaments. For the glass and the heater I think it’s about $90 total.
You’ll also want some acetone, and a few acetone safe bottles. I now have a supply of zip ties, a lot of various M bolts, springs, connectors, etc - because I am apparently addicted to modding my printer.
Firs thing I would do after getting used to printing, is print some more extruder gears (they should be on the SD card that came with the printer) - I’ve had a few of these fail, or nearly fail on me, and it’s a pain to be out of commision while you try and source more. I’d also suggest, if you’re going to be modding the printer, to buy a bunch of the Littelfuse fuses (I don’t have the model number off-hand, sorry). I’ve ‘killed’ my printer by accidentally shorting a fan connection briefly - I just blew the fuse, but with no extras on hand the printer was dead until I got more.
Other than that, nothing has ever broken on my printer.
Where I live, Matterhackers is about an hour and a half car ride away from me - so I get most of my filament from them, because it’s free shipping and it gets here the next day. I would say get a roll of PLA, and a roll of ABS, to start. Once you’re more accustomed to printing you can get more colors or find more interesting materials.
Digital calipers. I have two and I need more - I want one in every corner of my apartment. Needle nose pliers, wire cutters.
The TAZ’s come with a ‘direct drive’ (ish) extruder - essentially the filament leaves the gears/motor section and goes directly into the hotend, and that’s it. A Bowden system has the extruder (the gears and motors) mounted on the frame of the printer, with a PTFE tube leading from there to the hotend/nozzle. The benefit of a bowden is that the X-carriage is much lighter - it doesn’t have to pull a heavy motor around. The downside is that soft filaments (like Ninjaflex) essentially can’t work in them, they’ll kink up. You get a lot more oozing of filament with a bowden, so you need a much higher retraction to prevent it. I ran my Chimera extruder as a bowden briefly while I waited for the HPX extruder to arrive - I did actually manage to get it printing Soft PLA, which was surprising, but overall bowden felt like more trouble than it was worth. I also found myself wasting a lot more filament, because the stuff left between the extruder and the hotend was a bit chewed up from the extruder.