Tomhe

In this smaller model, the printing speeds are generally lower than in a bigger model. I suggest going down in temperature (5-10C) in your next try, that could make a big difference in a model like this. I also see that you scaled down the print speed, which makes it print the outer walls really slowly. I'm scared that the outer walls get printed at ~10mm/s (this scales with the print speed), which will lead to even more degradation of material. If you really want to print it at those speeds, I suggest going down another 10C in temperature.

My new favorite new features are the initial and final print temperature . But in total I think it's a huge update and I think people will enjoy playing with this during the holidays, even if their printer is at the office and they can't reach it. I know that I'm going to enjoy saving my prints as projects so I can iterate easier with the same model, orientation and profile.

I think for Nylon you had raft activated, which is the standard bed adhesion method for Nylon. The first layer of the raft has a big spacing between the lines, to allow for more uniform print cooling.

I wouldn't go higher in temperature, 225-235C should work fine. But after an atomic pull, I would try with 110% flow instead of 145%. This will reduce the pressure on the material a bit. Is your feeder set to the 'middle' setting?

This is very material dependant, and probably also model dependant. You could use the horizontal expansion feature in Cura, a value of 0.08-0.1mm should do the trick.

For the UM2 there are no separate material profiles; the temperatures and fan settings are handled in the machine. For the UM2+ the profiles are material dependent so here you do see the material profiles.

26.7mm/s is slower than 30mm/s, that is true. But it was made in such a way that it scaled nicely for all materials and qualities, the 10% decrease in speed for just the top and bottom layers isn't 'way slower' in my opinion.

I see that the printing speed was set down manually to 40mm/s (in the first picture), that setting should be 60mm/s. It's visible because it has a 'restore' symbol next to it. This means that you are not working with the standard profiles. Unchanged, the profiles are about as fast as the profiles in 15.04.x.

If you are in expert/full settings view in Cura and you only change the nozzle diameter manually, your print will fail. But if you use the quickprint settings for 0.25mm for the UM2+ (lower speeds) everything should be fine.

When all the speeds in the advanced tabs are set to a real speed (not 0), the 'print speed' option in the first tab only controls the support printing speed. A good number for line support would be around 25-30 mm/s, 50mm/s is too high.

When you use Cura 15.04.4 (which has the latest UM2+ profiles and firmware) you can chose Nozzle, Material and Quality in the quickprint screen. And for bed adhesion; normal gluesticks seem to work fine.

The resolution of the 0.25mm nozzle is no longer limited by the nozzle design, but by the amount of steps of the feeder. When you go below 0.06mm layer height, it can happen that the amount of material that should be extruded is less than the amount extruded by one step of the feeder motor. This means no material will be extruded when trying to print really small features. From what I've seen, the difference between 0.06mm layer height and even lower layer heights is hardly noticeable.

You could try the uPET/CPE option in Cura and the printer, that should print hotter and with less fan.

Polyethylene can have very good mechanical properties and chemical resistance, but it has very bad printing properties. It prints with a lot of die swell, it warps, it oozes all over the place... I don't think it will be a printing material in short term. Although normal polyethylene is easy to find and low in cost.

I think it would be a good idea to print it in CPE once, it is PET based. PET is mostly solvent resistant. But before actually using a part, first let it soak in every one of those chemicals to see how it behaves.

The polymer linked to by you is chlorinated polyethylene. This is (fortunately) not what CPE stands for, it stands for CoPolyEster. Most copolyesters are pretty solvent resistant though, especially if they are PET based. It would be nice if Chloroform works, and I would like to see an example. Unfortunately Chloroform is something you really don't want to inhale. It is toxic in both short (headache) and long term (liver damage, possible carcinogen).

I think 0.1mm layer height on a 0.15mm nozzle is a bit high, maybe try 0.05mm layer height? Print will take twice as long but it look better anyway. Too bad you can only see it at the end of your print (although you could print the head only to see whether there is improvement)...