Last night I completed a strip-down & rebuild of my 1st Child Prusa printer, and to be quite honest I was stunned by the resultant improvement in print quality to the point where I am not quite sure exactly which of the improvements made the difference but the difference is enormous.
Here is a list of the improvements I made over the course of a couple of days (evening’s).
1)
Stripped out partially
melted PLA X carriage and replaced it with my new (not great print quality) ABS
X carriage, (which I broke slightly whilst fitting it due to delamination
issues mentioned above, but this should not affect its performance)
2)
Stripped off the hot bed
and remounted with a center fixing bolt to prevent the hot bed from warping down
in the center, this was causing issues with getting the first layer right
without constant tweaking of the Z end stop position.
3)
During the X carriage
replacement I broke the thermistor (again) and decided to switch to a much
simpler thermistor sourced from Maplin’s UK (ref part number) it is much larger
than the micro sized glass bead thermistors that are recommended for Reprap’s,
this required me to drill out the brass heater blocks thermistor location point
hole to 3.5 mm, The Maplin thermistors are quite large in comparison to the
glass bead type but they are a third of the price (£0.99 each) and a hell of a
lot easier to deal with as they have decent thick leads rather than hair like
leads for connection and are therefore much less prone to breaking.
4)
Whilst I had the whole
thing apart I thought I would add a couple of electrical connectors one for the
thermistor leads and one for the heater leads, this way when I need to strip
down the hot end for any reason I can simply unplug the leads, snip the filament,
unscrew the 2 mounting screws for the hot end and run the extruder motor (with
the heater off of course) until the hot
end drops out.
5)
Also whilst I was
rebuilding the heater block with the new thermistor I wrapped the whole block
in Kapston tape, I have seen other people do this before on various RepRap
blogs and presumed it was just to stop the melted plastic from sticking to the
heater block, but I now remember back to the days of the Darwin how insulating
the hot end was important in maintaining a constant temperature without putting
undue strain on the heater electronics, this may be part of the reason for the
sudden quality improvement.
6)
I also reduced the layer
height to 3.4/6 mm and increased the temperature to 250 Degrees C (these were
going to be my next software tweaks anyway before I decided it was time for a
complete strip down.
7)
Adjusted Y end stop switch
position to give me full access to the whole print bed size, needed to do this
as the last thing I was trying to print before I decide on the strip down was the Savonius & Gorlov VAWT http://www.thingiverse.com/thing:16504 this also demonstrated the need to fix the warping hot bed issue.
Considering the
massive improvement in print quality I am not going to tweak anything more
until I have taken measurements of anything that may affect the print quality.
E.g.
Measure the exact
temperature of the hot end and hot bed as I am fairly sure they don't exactly
match the Pronterface settings and this should give me an indication of exactly
what this Premium Black ABS likes to be printed at.
Measure the exact
length of the idler screws, this should give me an indication of how tight I
need to clamp the filament so that it does not slip or strip.
Save the default
configuration (yes I have just been tweaking the default config rather than
creating new ones, I have already done this last thing after the extremely
successful print, I immediately saved the config as a new separate one and named
it sensibly (Premium ABS Black) this way I can begin to build up a set of
config’s for each type of filament I have at my disposal.
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