Hi speckledpear/Stefan,
While it is always difficult to do a remote assessment, I'll give you my first two cents worth of tips and comments.
speckledpear hat geschrieben:I believe the nozzle is held too close against the filament because I can see some marks of the nozzle grinding against the filament in the top layer.
This 'bug' is quite normal in many cases - it can be minimized after you have gathered more experience and succeeded in 'dialing in' your printer better. Don't worry about it too much for now.
speckledpear hat geschrieben:However, a little bit tighter and my driving gear clicks and a bit looser and the gear will turn without gripping against the filament (grinding?)
This sounds interesting ... Normally, increasing the spring preload should not cause 'clicking' in itself. The clicking you hear is presumably the extruder stepper losing steps. If the extruder starts losing steps once you've tightened the springs more, then you are probably grinding filament with the springs not tightened as much. This is an indication that your extruding forces could be on the high side. Now there are several possible causes for high forces. Before we get to those, you should check just what your 'F-Digits' read as you print. The F-digits are shown on the display of the printer, right below the 'Z' value, i.e. on the third line. Two values for the F-Digits are important here: the idle value and the higher (highest) values seen when printing.
The idle value is the number shown when you turn on the printer (preferably without any filament loaded), or when the printer has been at printing temperature for a minute or two, but is not printing. The idle value is a result of build variation and internal stresses within the system. Ideally, this should be close to zero, but don't worry, I've printed for more than 4 years with an idle value of around 1600.
The actual F-Digits encountered during printing can be much higher. On my RF1000, I start hearing the extruder lose steps when the F-Digits start exceeding "
idle value + 6500", in other words, when the F-Digits start going above 7000 or 8000, depending on my idle value (and spring pre-load).
Let us know what kind of values you see (idle & printing).
What can cause high extruder forces?
- Printing speeds too high
- Temperature too low
- Clogged nozzle
- Mis-aligned filament lead-in
- Sharp edge at filament lead-in
- Friction in the original filament feed tube (does not apply to you!)
Some of these are easy to check and remedy.
Re: Printing speeds: anything below 60mm/s shouldn't be an issue (provided the temperature is OK).
Re: Temperature: I don't think this is an issue in your case, but it is easy to check - run the same print with a temperature 20° higher and see what you get.
Re: Clogged nozzle: this also doesn't appear to be the main issue for you, as it looks like there is enough filament being extruded. But play it safe and use a filament cleaner (the simplest is just a half-inch cube of sponge that you poke the filament through.
Re: Mis-aligned fliament lead-in: This was an issue on some early RF1000s. If you remove the filament (and your printed filament guide) and look through the hole in the aluminum piece from the top, check to see if the brass filament lead-in lines up nicely with the hole. The slop in the assembly holes allows for a good amount of play - which can result in mis-alignment.
Re: Sharp edge on filament lead-in: This was also an issue, early on. The brass filament lead-in had a fairly sharp edge on some units. With an otherwise acceptable degree of mis-alignment, this sharp edge would cause the filament to continuously get shaved off on one side, increasing friction, with the shavings getting caught in the lead-in, also increasing friction. Check the bore and use a needle file, or other suited tool to remove the sharp edge, should there be one. Be sure to REMOVE any file residue or chips when doing this!
Check these and report back.
Now to a different topic altogether - The MK8 drive gear:
You need to re-calibrate the extruder in the firmware if you use a different drive gear (the
STEPS/MM value). There is a good thread on the topic,
here, plus a revised one,
here.
Bed adhesion:
This is always a topic. This forum probably has a hundred posts on the issue. Aside from the obvious, it is also important to have the correct distance between nozzle and bed for the first layer. This can be a challenge for a beginner. Your Heat Bed Matrix states "
offset = -334 [steps] (= -0.26 [mm])", which tells you where your bed is with respect to your nozzle. Normally you can compensate for this distance in your start gcode. I'm just not sure how the Community Firmware handles this at the moment, it may be automatic. Nibbles or AtlonXP could help out with that. The non-Community version of firmware would benefit from a slight Z offset in the start gcode, since it does not automatically compensate.
Once you have the nozzle-to-bed distance down pat, we can discuss other adhesion enhancing options.
speckledpear hat geschrieben:There is a cooling modification that's made for cooling the nozzle. I don't think this works effectively since I barely feel any air coming out of it
The fan, provided you are using the stock hot end, is used to cool the printed part and should not cool the nozzle, if possible. The stock fan was not the greatest engineering solution, many in the forum have come up with alternatives. You photo seems to show an alternative solution, also. There is little air flow on many of these alternative designs - increasing the cooling power can lead to other issues.
... Enough for now, I'm hitting the sack...
Good night and Health to All!
mjh11
