print head slows down for detail

[ppope357 0]

hi

I've been having problems printing smaller details - when the print gets to the detailed sections, the printhead speed slows down a lot. This leads to too much PLA being extruded, and the surrounding plastic melts, leading to a bit of a melted mess (but fairly localised). I've tried slowing down (and speeding up) the print head speed, but this has failed to noticably change the printhead speed. I've also tried reducing the extruder feedrate, again without any impact on the problem. I've tried to attach an image showing the gear cube I have printed, showing the problem - which only occurs on the corners of the gear cube for some reason (the rest of each part prints fine).

I've been using replicatorG, with a layer thickness of 0.15mm, temp 220, 230 also.

Really not sure of the cause - it's like the whole build goes fine, then I get to the area with the small cross section, and the printer just slows down massively, maybe a movement of 1mm per second, for a movement along one side of the cross section. Then once the slow section has been done, it will speed up again - but the extrusion is then sitting on a melted blob of plastic, and the fresh extrusion melts a bit more and kind of sinks into the mess.

Anyway, any help or suggestions would be much appreciated.

many thanks

[Daid 306]

Most likely the result of the "cool" settings. What happens is that because the layers are smaller, the printing speed is reduced to make sure the previous layer is cooled down. However, because of this is can go so slow that you get the melted problems. Reducing the temperature also helps.

Cura 1.0 will have a setting to ensure a minimal extrusion speed, which solves this issue. (but isn't released yet)

[ppope357 0]

ok thanks, I'll try reducing the temperature as far as possible. I'll also try getting cura up and running when it is released.

[ppope357 0]

I have tried reducing the extruder temperature, and this helped a little, but did not resolve the problem. To be clear, the problem was that the print head would slow down dramatically, to maybe 1mm per second, for travel along one side of the triangle. This would result in too much plastic being extruded, and also localised melting of previously extruded material.

I then got round to installing netfabb on my machine, and started testing it - and so far it does not seem to have the same problem. I've tried using the standard ultimaker profile, and also the same profile but with the temperature range increased by 10C which gave me better results. (Note I'm using netfabb to generate gcode then sending that to replicatorG to do the actual print, and i'm using a linux machine with Wine, if that makes any difference).

As a result I'm not sure of the source of the problem - temperature obviously plays a role, but is not the main factor. I think it must be something with the way replicatorG generates the Gcode.