Lost in extruder calibration

[VerticalSpeed]

Hi dears,

I'm a little lost in my Rostock MAX extruder settings. First thing, I hav made a firmware calibration by mesuring the length of the extruded filament. The initial value was too high because for 30 mm extrution I got 45mm. So I reduced the number of steps to:

#define DEFAULT_AXIS_STEPS_PER_UNIT {106.666, 106.666, 106.666, 380.0} // default steps per unit for rostockmax

instead of

//#define DEFAULT_AXIS_STEPS_PER_UNIT {106.666, 106.666, 106.666, 578.0} // default steps per unit for rostockmax

I thing its a pretty big difference and I'm wondering if I'm not missing something with the 8 or 16 steps..
The fact is that the lines of platic doesn't stick together, there is holes between them.

So I'm wondering also if my nozzle is 0.5 or 0.4, cause I don't see anything else.
I tried with 0.40, I have finer results, but the problem is still there, and I get som little blobs here and there.

Somebody can help?

Thx

[MorbidSlowBurn]

Are you measuring the distance before or after the extruder. If after you may have the step value too low as you could be distorting the filament if the pressure is too high in the extruder drive. A good way to check is to measure the diameter of the filament after it passes through the extruder to verify if you have too much pressure (have to remove the Bowden tube). You want just enough pressure to prevent slippage but not so much to crush the filament.

The 30mm distance is really the amount of filament entering the extruder.

[VerticalSpeed]

Yes you are right, my value is too low.
But about the nozzle diameter, because I don't get a part list, I'm not sure it's a 0.5 or a 0.4. Which one comes with the rostock max now?

[MorbidSlowBurn]

The included nozzle is normally 0.5.

You could verify by extruding into air. I know mhackney in his build discusses measuring the diameter when extruded into air. If I remember correctly you should wind up with about 0.55 diameter extrusion for a 0.5 nozzle. I haven't verified it myself yet as I haven't had time to work with my printer in a couple of days.

[Polygonhell]

The included nozzle is normally 0.5.

You could verify by extruding into air. I know mhackney in his build discusses measuring the diameter when extruded into air. If I remember correctly you should wind up with about 0.55 diameter extrusion for a 0.5 nozzle. I haven't verified it myself yet as I haven't had time to work with my printer in a couple of days.

Depending on the plastic it could be as high as 0.8mm extrusion into free air for a 0.5mm nozzle, it's wider than the nozzle as a result of die swell. I believe kits still ship with a 0.5mm nozzle by default.
If you pick something like 0.2mm layers and 0.5mm extrusion width it doesn't much matter anyway, in most slicers it's only used to compute the optimal extrusion width, in everything except CURA you can set that value explicitly, and I don't think very much of Slic3r's definition of optimal in this case.

[MorbidSlowBurn]

Thanks for the clarification. I forgot about the different materials having different extruder characteristics.

[VerticalSpeed]

The output of the extruded plastic in the air is between 0.4 and 0.5 mm.. You think it can be 0.3?

[Polygonhell]

The output of the extruded plastic in the air is between 0.4 and 0.5 mm.. You think it can be 0.3?

They only sell 3 sizes of nozzle that I'm aware of 0.7, 0.5 and 0.35 if your measurement is accurate it would imply the latter, but support should be able to tell you.
The best way to verify is to buy some 0.5mm or 0.35mm drill bits and use them as a pin gauge.
Even if it's a 0.35mm hot end you should get away with 0.2mm layer height and 0.4mm extrusion width.

[mhackney]

That's a pretty big variation.

Do this: get the hotend to temperature. Extrude a little (say 1-2mm) and when it has completed. break it off at the tip of the nozzle. Now, extrude 10mm into the air - let it dangle down - and let it cool. Now measure the diameter in the middle of this length. It should be a lot less variation than .4 to .5mm. I get exactly .55mm on most of my ABS filaments very consistently.

I would doubt that SeeMeCNC would send you a smaller nozzle unless you requested it. Check your invoice email, it should say on there.

[Eaglezsoar]

I would recommend that every one get an inexpensive #61-#80 drill bit set to clean and verify the size of the nozzle holes.
They are inexpensive and with a drill bit chart they can be mighty handy to have around. The chart will show you both the
decimal and metric diameters of these small bits. The bits are at Amazon at this link:
http://www.amazon.com/Anytime-Tools-pie ... drill+bits

The chart (one of many) can be found at http://www.csgnetwork.com/drillsizeconvert.html

Looking at the chart, the bit closest to .5mm is #77 Just be careful and not use the wrong size bit and end up enlarging the hole in the nozzle.
I suppose you could find a set of metric bits but in the small sizes we would need they would be hard to find and more expensive. They are on
Ebay but from overseas sellers. If someone knows of a USA seller of small (.1mm-1mm) please let us know the source.

[mhackney]

I have a set of these 15 micro metric drills purchased from this vendor on Amazon. Good price, good product, good service!

[Eaglezsoar]

Good find! I don't know how I missed those but I just bought 2. Thanks!

[theverant]

I have a set of these 15 micro metric drills purchased from this vendor on Amazon. Good price, good product, good service!

Seriously Amazon, why must you toy with my emotions - <$3 on Amazon.com, ~ $15 on Amazon.ca. Gah!

[mhackney]

Wow, that's a big difference.