m0n5t3r
1
Hi anyone who’s still left on this thing, newbie question: I am getting beautiful results with Colorfabb XT when there are no overhangs / bridges; however, things turn ugly when trying to print something that includes bridges and / or overhangs (say, Marvin’s underside, or an Urchin extruder body).
I am using Cura on Ubuntu - Slic3r is more flexible, but stuff doesn’t even stick to the table at exactly the same speeds / flow rates as Cura, no matter the material: PLA, PLA-PHA, XT, (conductive) ABS - I think maybe its flow rates .
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What printer/hot end are you running and what temperatures and speeds? How does the infill look? Are you running any cooling? What build plate temp?
My guess is that you’re running a bit hot, need a bit more cooling, and might need to tweak the speed on the the bridges, but the answers to the above will help confirm.
Meh, I should have included more info, but I was too sleepy… Also attaching a few nice photos of my last failure (it failed due to other reasons, most likely Y driver overheat - it was supposed to look like this: https://github.com/zbysniew/Urchin/blob/master/stls/64\_01\_01\_b01\_urchin\_chassis.stl).
Printer
Electron3d (Prusa i3-based) with the stock hotend slightly modified (it looks like this: https://3dhubs.s3-eu-west-1.amazonaws.com/s3fs-public/fan\_duct\_0.jpg - I made a brass heater block because the stock aluminium one couldn’t keep the temperature stable, and I had to make a nozzle as well because the original had an accident while I was learning how to use the thing - let’s say it left a deep scratch into the aluminium bed; however, the original nozzle / heater block had the same issue, and PLA prints just fine). The filament path is not all-metal, for some reason there is a bit of PTFE tube in the heated part of the stainless steel screw thing. I’m planning to upgrade to a lighter extruder and an E3D-like hotend sometime soon - I just have to devise a way to mount them to the X carriage.
Parameters
250 deg. C hotend, 70 deg. C bed covered with Kapton, the last one was 0.1mm layers and 40mm/s shells, 60mm/s infill; the infill looks bad, so I guess 60mm/s is too much.
Cooling
The fan duct is the one in the picture I linked above, the blower was in theory full on after the first 3mm (… but Cura is steeped in the “user is stupid, I’ll do what I want” way of doing things, so grep M106 thing.gcode shows that fan speeds alternate between 127.5 and 255 for some reason). When testing the duct I actually put some incense sticks in front of the blower and looked where the smoke goes: it hits the workpiece where it’s supposed to - close to the nozzle, so I’m pretty sure my duct design is at least ok-ish.
As I said in the original message, I can’t get prints to stick to the bed with Slic3r at exactly the same parameters (temperature, speed, bottom layer height, filament flow, bottom layer extrusion ratio) as Cura. It does … something that messes things up and I have no idea what, so I’m stuck with Cura for now, and Cura won’t allow me to customize the bridging speeds…
