Might have an opportunity to buy a taz 3. What are the differences between the taz 3 and the new 6? Can it be upgraded? Software and hardware? If so what would you update?
The taz 3 lacks leadscrews ( it uses threaded rod) pei surface, the higher temperature hotend and bed auto leveling. There are numerous frame differences. Internally its the same Rambo, lower wattage power supply, same heated bed, same-ish wiring except for the z axis, and the taz 6 specifically has a slightly wider frame than the previous ones. You can convert a taz 3 to 5 or 6 spec ( mine started out as a taz 3 and it looks very nice these days) expect to pay $300 to $400 depending how close to 6 spec you want to get. It works is going to be your main source of upgrade parts https://itworks3d.com/product-category/parts/taz-6-parts/
Step by step assembly instructions are here for most taz versions. https://ohai.lulzbot.com/ , downloadable Stl files for printing are in download.lulzbot.com.
If the price is right, upgrading a taz 3 is very feasible and can be done in stages. The motion segment to 5 or 6 spec is priority 1, then the pei sheet and hotend. You will need to know how to install heat set inserts, crimp wires, change arduino firmware, and print parts in the first place ( or source them)
Also consider the openbuilds x and y axis upgrades.
You can find the full change log going back to TAZ 1 here: http://devel.lulzbot.com/TAZ/TAZ_changelog.odt
Link is not working on mobile. I’ll try later on my laptop