Ultimaker blue PLA, not great?

[gr5 2,170]

but I can check on it every few hours just to make sure there is still plenty of loose filament

 

So this is like a newborn? You have to wake up every 2 hours to check on your print?

 

[gr5 2,170]

Is that a problem on the UM1 as well?

 

YES! It's much worse with the UM1. If you have a clog or if you print too fast or too cold you get grinding ALL THE TIME. It's a very serious problem on the UM1 and you learn not to print too fast or too cold.

The reason it's not much of a problem on the UM2 is because the current that goes to the stepper motor is much lower on the UM2. The motor has much less power and doesn't have a huge mechanical advantage like it does on the UM1. This is done on purpose - the idea is that as the force gets very strong pushing on the filament, the stepper slips before the filament slips. That's the goal. So the UM2 is a huge improvement in grinding and I was surprised that anyone at all had the problem. This is a problem on other printers also. This is one of those really nice things about the UM2 over most competitors.

 

[illuminarti 18]

So this is like a newborn? You have to wake up every 2 hours to check on your print?

 

More like every 8 hours.

 

[yellowshark 153]

"Also all you guys who talk about temperature and speed keep leaving out layer height. There's a huge difference between 50mm/sec at 220C with .2mm layer height versus .1mm layer height. In fact it's a 2X difference."

Good point Gr5.

My figures were based on running at 300 microns(210 at 80ms).

In context the difference is not huge though; with 100 microns at 60 or40 m/s I run at 205.

I could possibly take that down to 200 but have not tried. Unlike most people (I suspect) I always run the first layer temp at the same as the rest of the build (with PLA) to avoid any transients as the temp. changes and stabilises

 

[das_enginer 2]

My figures were based on running at 300 microns(210 at 80ms).

In context the difference is not huge though; with 100 microns at 60 or40 m/s I run at 205.

 

Hi yellowshark,

Are these on a UM1 or a UM2? These wouldn't surprise me at all for a UM1, but my own UM2 and number of others I've been reading on the forums with UM2s can't extrude anywhere near this fast at these temps. I'm curious, namely because if you are using a UM2 with your listed temps/speeds, then there is some discrepancy in parts/build/setup I'd like to find.

To get .2mm layers at 50mm/s, I'm running 230-240C (filament dependent), with.1mm layers at 50mm/s taking 210-220C. I would probably have to drop down to 20mm/s in order to run .1mm layers at 210C reliably (eg no underextrusion and no stepper skipping).

Danke!

 

[illuminarti 18]

Yes, what Das said/asked!

 

[braddock 1]

Hi guys, I've been doing a bit more testing, it seems, for reasons unknown to me, that slowing the retraction speed seems to encourage under extrusion.

Also, running a print now at .06 50mm/s and it was exhibiting slight under extrusion, not a lot, but enough to make the surface quality slightly porous. I slowed the print to 30mm/s and it seems to have cured it.

Does it make sense that higher resolutions require slower print speeds?

 

[illuminarti 18]

Well, it's always going to be easier to extrude at slower print speeds that faster ones, but 50mm/s should be quite sustainable at 0.06mm layers i would have thought - unless you were doing something odd like spiralize with a thick wall setting.

Regarding retraction speeds - one thought is that slower speeds mean that hot plastic spends longer in the cooler part of the head, and so promotes thermal creep, which might increase friction between the filament and the walls, slowing extrusion.

 

[braddock 1]

shell thickness is 1.2mm. Overall the print looks fine, it's not the kind of under extrusion that causes a print to fail, it's very slight, making for a slightly imperfect finish.