Another success story!

I have been researching, building and waiting for parts for my Prusa build for the last 8 months. Finally just the other night I managed to get it to print after all this time. A lot of time was spent gathering money to put into the project, waiting for overseas parts to arrive or trying to find time to build it.
Over the last two months I have had it almost to the point of printing but just not quite. I had issues with faulty Pololus, then accidentally shorting out the board and some firmware issues which were caused by being inexperienced.

The other night I put the new Pololus together, inserted them and tested the stepping. After a change on the Z axis it was pretty close to spot on with all motors. Within 0.5% accuracy. When I went to print all I got were loads of large (8mm dia) lumps of extruded filament. After an hours research online I found it was the Teacup firmware's E_ABSOLUTE. I defined this tag and it printed!

Here is the first ever print with default Slic3r settings.


I printed the thin walled square from the wiki. Layers seems good but there was a bit of warping out of one wall. I don't think this was a over or under voltage stepping issue as all the walls are upright but one..?



With some layer height adjustment, temp adjustment and speed adjustment I managed this custom piece for calibration. Just like on the first print though, the small piece on top (5x5mm) tends to get dragged around while it prints. It stays too hot. I tried running much cooler temps and the small pieces print better but the large pieces don't get the adhesion I want.


I haven't had to change much. But honestly I'm not sure what I can change or which way to change it to get the prints working better...

The major issue I am having is with sharp corners on squares. They tend to lift up/build up too much..?

Edited 1 time(s). Last edit at 12/11/2012 09:21PM by Phizinza.

Have you got the "cool" function enabled in slic3r. Try setting it to 10-15 second minimum layer time and perhaps 3mm/s minimum speed. If this works gradually speed it up until small features are ok.

After much experimentation, this is what works for me.

Melting / warping / bridging - you need a small fan with the air directed to the area around the nozzle (see nophead's latest blog on the mendel 90) start it running after the first layer or just where you have bridges or the layer time is too short for the previous layer to cool adequately.

Adhesion to bed - either get it very clean (bathroom cleaner followed by acetone) - this generally works for me but it's marginal and often fails with large objects. Alternatively apply a thin layer of dilute PVA glue to the bed (I use EVO Stick wood adhesive at 1:4 glue:water but any PVA should do). Parts can be tricky to remove (allow to cool and slide something solid along the bed into them) but they won't curl up and it doesn't need reapplying every time. I have seen recommended a bit of ABS in some acetone but haven't tried it.

For the thin walled square, its definitly a cooling issue, I have been redoing my calibration lately and forgot to turn on my fan, it did the exact same thing.

Are you printing in ABS or PLA?

PLA definitly needs a fan, there is no way around it.

I skipped the cooling settings as I just assumed they were only for fans!
I'll play around with those using your suggested settings.

I fixed my board adhesion issue with isopropyl alcohol cleaning and more heat bed temp. My thermistor is out by about 8 degrees so I used my IR temp gun and tuned the board to 110 degrees (reads 118 in pronterface)

I'm printing with ABS.

I will look into setting up a fan if I can't get it good enough with the cooling settings.

Cheers for the help!

PS, here is a model off of Thingiverse I printed. It is about 90mm tall and hollow. I'm quite pleased with the overhang it managed to do!


Edited 2 time(s). Last edit at 12/12/2012 07:00PM by Phizinza.

That looks like a very nice print!

Now you have installed a fan you probably don't need to limit minimum layer time as much as I originally said. You will need to experiment, 15 seconds is slower than needed without a fan in my experience, but it's a good starting point that should work.

It's still useful to have a layer time limit even with a fan since it really helps parts that finish at a point come out nicely and shouldn't really affect build times significantly for anything but the smallest objects.