GUS looked great and simple but lacked the dimensional accuracy to print itself rep-rap style.
Then I found Morgan, the single arm SCARA bot that looked so alien while being so friendly... but it used linear rails and a lot of metal inside its center pole.
I needed something else. I could have waited for the next versions of the mentioned printers or some forks but why not try to learn something until such a time and design one that suits my needs. Understanding 3d printers will be important for engineers in the future.
This is how after many posts in the "Ideas for the next Wally" section I ended up creating a new thread for this project.
I introduce you Lander, the bot that can land on your desk, on the floor or on the wall or can print in a continuous fashion on even ground. It's a Lander, it must cope with on-grid, off-grid and other adverse conditions and must have everything on board.
This is the nomad offspring of Wally and Morgan.
The goals for this project are:1) rep-rap to the bones
2) no specialized or hard to find parts (linear rails, linear bearings, aluminum extrusions, etc)
3) low vitamin count, preferably more of the same kind than different ones (for emergency replacements/etc)
4) no timing belts, until we can print them, fishing line or other type of strong thread will be used instead
5) large printing area
6) multiple configurations and enhanced mobility: on the wall / off the wall, folded for transportation
7) as little metal as possible because of its energy intensive extraction and processing
8) precision over speed (complicated printed parts are allowed if precision permits; this is to ensure self replicability)
9) can be easily scaled up by modifying a small number of components (grow the double parallelogram arms and lengthen the SCARA arms )
This is an initial sketch that I will use as a reference while refining it:
As the solution I have chosen:
1) a single arm SCARA that functions just like Morgan, being constrained on the left or on the right of the possible printing area, so that I can reuse Morgan's firmware,
2) and a Z movement via a winch and a double parallelogram system.
- The double parallelogram is built with a Double Lamina Compliant Joint to force a controlled symmetrical movement
- The winch will be designed in such a way as to prevent the triangulation errors associated with the way the cable is spooled. In commercial winches this is not a priority while for a 3d printer this is a must. As a consequence, there will be a limited length of wire that will be possible to spool but this works well within the scope of a 3d printer (20-30cm Z).
3) there is no solution chosen yet for the other functional elements of the bot like extruders, electronics, power source, etc. These will come as I go but the intention is that this bot can eventually print with different materials in the same print, possibly through the same nozzle.
Note: bear in mind that i am learning as I go, I am not an everyday maker, my engineering skills are limited and I have to learn pretty much everything as I go. Moreover English is not my first language and a lot of this engineering lingo is making knots in my brain. I will try to learn as much as I can from the people that give me constructive feedback. Many thanks to Nic for his professional approach.