how to replace hexagon nozzle?

It's pretty much exactly the same as for E3D, but you'll need to do something about that black boot to get at everything.
FWIW, you don't need it. New Robos don't have it. You'll just need to tape the thermistor down with some high temperature tape. I'm surprised yours is still intact!

 

Either one is fine. Whichever you feel easier dealing with.

 

if all you changed is the nozzle i'd double check a paper leveling then go with @Mike Kelly suggestion of the auto level. is your nozzle the same as before (.4) or did you buy a different size, if you did get a different size did you input that into your slicer?

 

Please note that the auto-level is not really funked, it is just the way the probe/endstops are designed on the Robo. Because of the design the z Axis must travel below the level of the nozzle hitting the bed. It must do this in order to disengage one or both endstop switches. So your Robo believes that 0 in the Z axis (where the endstop is triggered) is lower than where the actual bed is. There is also some flex in the bed but we can ignore for our discussion. Hence the need to tell Robo that the endstop is offset from where the actual bed is. In the 1.0.0 version of Marlin that Robo has provided this is accomplished by using the M565 command. Since the triggering occurs below the level of the bed the offset is negative. More negative the bigger the offset. No offset and the nozzle scraps the bed.

Please note that M565 is not supported in all newer versions of Marlin. Every single pseudo-version of Robo firmware is based on Marlin 1.0.0. If Robo ever decides to move away from this buggy version and do a proper tweaking specific to the actual Robo hardware we will need to learn this all over again using a different command.

 

I wouldn't say flawed. I do a paper leveling all over the bed. In my instance I noticed the back of my bed was lower than the front so I shimmed my bed accordingly so the auto level has less work to do. Is this the correct way? I have no idea lol but it worked for me

 

Exactly the correct way to do it.

 

Awesome ! I work in a print shop so I cut some steel shim stock that's adhesive on one side comes in a long roll for super cheap. Can I ask what you use?

 

Kitchen shelf contact paper and a hole punch, easy, cheap, what more do you need!

 

I used standard shim steel. I had an assortment box (multiple sheets) in various thicknesses and just combined those as needed to make it level. Mine was not adhesive on one side Still, works like a charm.

 

@mark tomlinson great minds lol!!!!

@WheresWaldo i would have never thought about using contact paper! That's a good idea!

 

I have outlined my procedure several times before, briefly, I punch out a bunch of holes, saving the discs. working only on one side of the bed at a time, I level from front to back only and place those little adhesive discs where appropriate on the magnets. Once one side is level I move to the other side of the bed and repeat the same process, then and only then do I level from left to right. Results are that if you watch my printer printing there is almost zero movement on the Z axis while printing to tram the bed level. It is as close to perfectly aligned bed and extruder nozzle as humanly possible.

 

That's pretty awesome ! I mounted an indicator and used the difference in the bed as the measurement for my shim stock thickness under each corners

 

I use a dial indicator, but it can be done with paper too.

 

I think I'm going to try that as well and see how far off my measurements are