After a couple of months experience using UM2, and Octoprint, I thought I would share some of the info.
I have my UM2 outside in a garage, connected to a Raspberry Pi running Octoprint (octopi). I try to reduce the number of trips in and out using Octoprint to do some of the work. Primarily Octoprint is used for the Camera, which is a logitech WebCam which hangs from the top front of the UM2 from a little bracket I printed.
The camera works pretty well, although I can't see the while bed from that position and it can't focus on the front part of the bed. However, it gives me a pretty good picture of roughly what is happening, including failure and completion.
I have previously posted about my challenges with cold startup - sometimes the UM2 refuses to start because the temperature of the print head is 5 degrees or less. In this case I have to warm the head a bit with a hair dryer - only takes a few seconds, then UM2 starts OK.
The major thing I try to optimise is how much time I have to spend stood in front of the UM2 waiting for the bed to warm up. This can take quite some time to go from 5 degrees to 75 degrees. One technique is based on starting the UM2 (optional hairdryer sequence), and using the Advanced menu to manually warm the bed to 75 degrees. (this is trip 1 outside). Then I go in and wait for a while, perhaps prepare an SD card. Then on trip 2, I can often insert the card, and hit print - because the bed is already hot, I can generally wait a little while and babysit the startup of the print. I try to do this due to fairly common issues with startup such as nothing coming out (too much PLA dripped out during head warmup) or avoiding mess contaminating the print when the pre-extrusion PLA gets involved in the print.
Another option is to simply start the print, and let the UM2 sort out heating up the bed from cold, and the new firmware now delays the head heat up. This can often work, although a number of times I have found that the print simply doesn't start (not sure why) and I go out to find the head front left, bed up, but no printing started. Hence, my babysitting.
Now, to the Octoprint : This is a great tool, and running on a Raspberry PI it is very convenient.
I use the Octoprint for 3 jobs.
2) Manual Warm up, before a UM2 front panel print
3) Complete Print jobs.
1) I have already talked about above
2) If the UM2 is already turned on, from a previous print, I will often connect with the Octoprint and set the bed to warm up to 75 degrees. This allows me to monitor the warm up from inside, then only go out and start a front panel print (babysitting startup) when the UM2 is almost ready to go
3) Sometimes I will do the entire print from Octoprint. Note that this requires you to make a machine setting in Cura which outputs RepRap instead of UM2 code, since it requires some extra steps which the UM2 front panel normally inserts. In this case I manually warm up the bed, then manually warm the head, export RepRap GCode from Cura, drop into the Octoprint web page, then start the print. Quite often this will work nicely. I have observed that the retraction in RepRep mode is not as good as the native UM2 language retraction, so I usually only use method 3) when I don't need any retraction. Also, by default, the RepRap code doesn't lower the bed, although no big deal.
Overall, the Octoprint adds a lot of extra flexibility and limits the number of trips I make out to the garage. Once you get used to all the variables its pretty easy to juggle these different methods.
One thing which I can't really get around is the need to wait for the bed to cool before removing a print, then warming it up again. This adds quite a bit of time between prints. Trying to remove a print with a hot bed is tricky and usually results in you damaging the print. Pops off nicely when cool tho (especially in a cold environment). I clean the glass in warm water once in a while, then apply a full coating of gluestick, then carry on with that for a few days - I don't bother re-applying it, since it seems to leave a residue even after a print which serves the next one.
I have tried PLA from a few companies so far. The UM2 blue was nice, good prints, I then got 100M of Black and White PLA from Faberdashery and was astonished to find it didn't come on a spool. So I ended up unspooling all the blue and manually winding on the Black (that was a chore I can tell you). So, a tip - make sure your PLA comes on a spool !!!
I also got 100m of white PLA/PHA from ColorFabb (which did come on a spool) but that led to some blockage, and I have abandoned that reel.
I have also got some 10m samples of PLA and ABS from 3D Filaprint, but not tested those yet.
The Faberdashery 3mm PLA material has printed *great*, but I still need to find a good UK supplier with quality filament *on a reel*.
Outside of the UM2 ecosystem, (I am mostly making engineering parts) I am using Sketchup Pro on Mac, with a couple of plug ins : susolid and a STL import / exporter. SuSolid is a great tool and let's you easily visualise model glitches, which can be essential if you want to make 'solids' which can be combined by Sketchup. I had been using Blender to convert .stl to .dae to import stuff into Sketchup, but I have now found a good STL Import plug in which is working great.
The very best thing I have bought (apart from the UM2) is a 3DConnexion Space Navigator 3D mouse. This works really well with Sketchup and *transforms* the experience of 3D Modelling.
Hope all this info helps people new to Ultimaker.