Trouble with my new Mendel90

Hi there,

i just bought a Mendel90 kit from Nophead. Building the kit and calibration worked like a charm. Then i started my first testprint with the Androidsample provided on the SD-Card. But the androidsample didn´t print correctly. I tried printing it about 20 times. From these 20 tries only one android was printed completed but also had tangled fillament at the hole on the backside.

Between the tries i did the calibration another 4 times (got alwas the same parameters +/- 0,1 on the Z axis homepoint). When the first layer is printed, the molten plastic sticks at the nozle. Sometimes more layers were printed but then again it stuck at the nozzle and pulled the printed part from the printbed. It looks like the filament doesn´t come out of the nozzle in a straigth line. It come out in an angle of ca. 60° and then sticks at the nozle instead on the printbed/layers (thats how it looks to me at least). I have attached some of the failed prints and one of the nozle. I realy hope someone can help me.

regards

Xerius

Is the thickness of the skirt equal to the layer height, i.e. 0.3mm?

Try cleaning the glass with acetone or vinegar.

---

[www.hydraraptor.blogspot.com]

As well as getting the bed level across its surface and at the JHead at the right distance which you can confirm by measuring the skirt, the glass needs to be "squeaky clean" all over - if there is the slightest hint of oil or grease the print is liable to fail as the first layer will not adhere as it needs to do. Also make sure that the hot end nozzle is free of any debris before you start.

Alan

about debris on the nozzle....
how can i prevent the filament from dripping out during heating up the hot end while waiting for the print?

The settings and the sample I provide park the nozzle on the bed before heating so that does not happen.

---

[www.hydraraptor.blogspot.com]

muelli Wrote:
-------------------------------------------------------
> about debris on the nozzle....
> how can i prevent the filament from dripping out
> during heating up the hot end while waiting for
> the print?

If the nozzle has space beneath it, you can't! The term for this is'ooze' but there is a solution.
Take a look at Nophead's blog here: [hydraraptor.blogspot.co.uk] and then investigate the settings he has published for the start GCode file in Skeinforge.

Alan

After a couple of failed attempts i edited the android G-file and set the bedtemperature to 75°C and the Hotendtemperature to 190°C. Next try was a particular success. The android was printed out although the first layer didn`t stick completely to the bed. But the result looks way better than before as you can see on the attached picture (latest print on the left side).

The thickness of the outline is between 0,27mm and 0,33mm. The glass was cleaned after every failed print with isopropanol.

Do you think i should increase the bed temperature further?

Edited 1 time(s). Last edit at 10/13/2013 08:25AM by Xerius.

You could try a higher temperature but I think 70C works for everybody else.

Isopropyl is probably your problem. It seems to leave a white residue which stops PLA sticking. Use Meths, acetone, vinegar or glass cleaner.

---

[www.hydraraptor.blogspot.com]

I tried it again and again the last days. Changed the temperatures back to the standard settings again. I used glass cleaner. Doesn`t make any difference. I got me some Acetone too, Same with the glass cleaner. The PLA always sticks on the nozzle when the details or the rings in the inside are printed. Best try was 6 layers and then all stuck on the nozzle.

Is the room where you print very cold or in a draft?

---

[www.hydraraptor.blogspot.com]

About 22°C Room temperature.

Have you tried printing at 220C or something close?

Try a bit of hairspray on the print bed. I always use it with my PLA prints and it helps it stick well.
Make sure to cover the rods when applying it though.

It shouldn't need hair spray or different temperatures. Same kit, same PLA, same gcode, same glass sticks for everybody else.

The android should stick until the bed cools down at the end. When you say the PLA comes out at an angle that implies to me that the Z height is far too high. It should be 0.3mm above the bed during the first layer. The filament should come out at more than 0.4mm diameter so it it squashed between the nozzle and the glass so there is no opportunity for it to come out at an angle.

Have you measured the skirt to check its is 0.3mm high?

---

[www.hydraraptor.blogspot.com]

That the PLA is coming out in an angle did i notice when i was calibrating the Extruder when the Z-Axis was at the top because it sticks directly to the hotend.

Ofcourse i can`t see in what angle the PLA comes out of the nozle when the android is printing. The height of the skirt is between 0,29 and 0,32 mm. i already played around with the Z-Homepointvalue to get the height of the outline so close to 0,3 as possible.

I attached one of the latest testprints. On this one the first layer was printed completed, but on the tight turns and on the startingpoints of new Lines the PLA didn`t stick to the bed.

Edited 1 time(s). Last edit at 10/16/2013 09:08AM by Xerius.

The first layer is too sparse, which will be why it is not sticking. Either it is too high or the flow rate is far too low. The flow rate should be correct if you calibrated the E steps per mm to and the filament diameter is close to 2.85mm.

Are you sure you are measuring the skirt accurately? Are your callipers accurate? Have you tried measuring the thickness of that first layer of android?

---

[www.hydraraptor.blogspot.com]

After many prints I find the best surface for adhesion is blue tape. It is rather hard to remove the print afterwards sometimes. Second best for me is lemon juice on glass. Cold drafts are a major factor. Winter is coming - I think I will need an enclosure soon.

Finally it is working!

I started to use Acetone for every try (used it befor for only two tries, because my wife hates the smell) the first layer sticks to the bed like hell. Looks like the "super shine protection formula" in the glasscleaner kept the PLA from sticking to the bed.

Thanks for the help guys.