Unanswered Trying to calibrate printer and print correctly

OK, then as I said a sheet of float glass cut to roughly what the bed size is will work like a champ. Plus -- if it ever does crack or break, it is a few bucks to replace it In all honestly though, I never had an issue with it breaking on any printer. Most hardware stores will cut it to your size so just measure the bed and size it accordingly. These will keep it clamped down:

 

Great -- that means you are printing it at the correct offset from the bed and is an excellent start.

OK, so now you are into what I like to call ... "SlicerLand" since all of those features are more effects of how the model was sliced and less about how it was printed. All of them. Experiment with your slicer settings. Infill type, infill percentage (those can make the infill stronger or weaker) add more top layers (with a layer height at the default 0.2mm three top layers is woefully too little).

The only symptom you mention that can be printer/filament specific is the stringing and even then adding more retraction in your slicer settings is the normal fix for that.


Overall though -- Yay! You have it started printing.

 

There are a number of free slicers out there, I would suggest you try all of them to see which works best for you.
Personally I don't use the free ones, but I did until I started getting models complex enough that there were problems.
For FDM I only use Simplify3D (bit not free so try all the free ones first)

The parts fan is controlled by the slicer so you need to find the settings for it in whichever one you are using. For some filaments (like ABS) you probably want it off since cooling can increase warp. However for PLA you certainly want the parts cooling fan to be on after the first layer or two,

Which infill works best depends on the model and the slicer. Experiment with your slicer to see which works best for you. Some infill patterns are inherently stronger than others, but you need to see what the slicer offers before you can make a decision:

Here is a starting reference: https://all3dp.com/2/infill-3d-printing-what-it-means-and-how-to-use-it/

 

An excellent idea
You will get some experience now that it is mechanically working better on how to tell what is a printer problem and what is a slicer problem.

When in doubt -- try another slicer.

 

You probably want to add autoleveling as a first step. While it is not a perfect solution it is a big help. The parts are listed here:

https://www.thingiverse.com/thing:349935

Note that the only part that needs printing is the mount that holds the Z switches in place. There are some other parts needed (like the second Z switch and the nuts that go into the X carriage and are used for the Z switches mounting) but they are standard hardware and available many places.

Many parts are available generically (even the heater pads) although they may not be exactly what Robo used. Also
PartsBuilt.com has what remains of Robo spares in stock so check there when you need parts too.

All of the electrical and electronic parts are generic (Arduino Mega 2560, RAMPS 1.4, all of the stepper motors, the switches, the GT2 timing belts, etc).

 

With the autoleveling done you will effectively have an R1 and if you eventually replace the bed with linear rails and perhaps a replacement bed plate from PartsBuilt you will pretty much have an R1+.

Rails:
2x of https://www.partsbuilt.com/linear-rod-y-chrome-r1-robo/

and 4 additional LM8UU bearings plus you print the mounts that the rods and bearings use:
https://smile.amazon.com/Printer-Bearings-JGAurora-Bearing-LM8UU/dp/B083BQKMYY

mounts to print and rail end-pieces (as well as a description of how the mod is done):
https://www.thingiverse.com/thing:681894

Bed:
https://www.partsbuilt.com/heated-build-plate-r1-robo/

If you do not want to print them get the bed rail end brackets too:
https://www.partsbuilt.com/y-bracket-r1-robo/

 

There are a lot of similar switches out there so pick any you like that are similar like these:

https://smile.amazon.com/MXRS-Hinge-Momentary-Button-Switch/dp/B07MW2RPJY/

 

or really, any switch that you want if you can mount it... it can work.

 

Yes, those are fine. The metal just presses the little trigger and allows for some slop, it is fine with or without for the new style you need -- the original single Z switch really needed the lever unless you were careful lining it up. If you are moving to autoleveling the new z switches do NOT need the lever.

 

Autoleveling is a nice feature, but it is not magic or even very precise in the version of Marlin Robo used on this printer (version 1.x)
If you have the bed manually leveled and then run autoleveling it is decent and will help even out any dips/bumps, but if your bed is not mostly level to begin with, it will not sort it out for you.

Later versions of Marlin had better autoleveling features, but there is no free lunch Those require some work to implement as well (like MESH leveling)

 

Honestly I suspect you will get more use out of the improved bed if you go that route than the autoleveling. Still it is easy enough to add and is worth the effort.