Hi guys:
I was wondering if you can give me some ideas on why my Simple is bridging very poorly. I get severe drooping on even very short bridges.
I have tried two types of filament, Zen Tool works and Radio Shack. A friend’s Kossell bridges fine with the RS stuff. I have tried temps from 185 to 205. Speed is running at 30 for perimeters and 40 to 60 for bridging in Slic3r.
When I first built the printer the step cubes printed great. Any idea what I can do to improve it?
Thanks!
Rotate it 90 degrees so you don’t have so much to bridge when printing with support. Or use support.
I’ve always set the bridge flow rate in Slic3r down to 0.95 or 0.97; this will help yank the filament across and suspend it better. Don’t go much further than that, otherwise you’ll simply yank it off the edge.
Also, layer height is a huge factor. The smaller layer height you have (I’ve found) the worse chances you have of completing longer bridges.
Performance bridging gaps can vary pretty wildly.
I have had to bridge at 80 mm/s before to get them smooth. Too hot will droop, compensate with speed. Too cold will break, compensate by slowing down.
@Det_Ansinn , not in this case, really. This is a tiny bridge, there’s no reason it should be failing this badly. I’ve done 60mm bridges with no gap just fine, without having to rotate a part or enable support material. And this is a calibration piece, telling the guy to just rotate the part when he’s clearly calibrating is useless.
Think about the physics involved. Hot plastic needs to stretch a specified distance to provide support. If your print-head goes too fast, the hot molten plastic will break. If it goes too slow, the plastic will droop. Based on your image, the plastic seems to “droop”. Your print-head may be moving too slow and the gap is too big. Try increasing the print-head speed. In my opinion, it’s not worth it. Just print with supports and cut the supports out. On a small print like this, there won’t be that many supports to cut away.
What version of slic3r are you using. I found that I was having the same issue with the built in version of slic3r that comes packed with Repetier but it does much better with the latest release. Also, stick with cooler temps and make sure you have a fan shroud pointing at the tip to help with cooling the bridge before it droops.
What in the world is with all the people suggesting you enable support material on a calibration piece… /sigh
Whoah! This is a calibration piece? How are we supposed to know that? A little more information would have been helpful. Answer: Don’t use supports and speedup the print-head. /sigh
@berry_jordaan it was probably assumed that it was since it’s the standard step/bridge/cube calibration piece that is in all the printrbot starting guides for the first print. It has quite a number of features on it that help with specific calibration issues. I personally use a variety of objects to calibrate with ranging from solid and hollow cubes and long bridge calibration files but this is a good one to start with. If you never followed the starter guide for a printrbot then I can see why you wouldn’t know it’s a calibration piece 
40 to 60 is plenty fast enough for a bridge this small. I would try adjusting your temperature even lower, checking your extruder calibration, and definitely making sure you have a fan to cool it down.
This is a Slic3r issue not a bridging issue. Looking at the gcode for this particular calibration object, you will see that Slic3r is creating a perimeter bridge of 1 threadwidth then attempting to infill. Slic3r is not recognizing that the entire area needs to be bridged.
Update: Looking at the photo closely on my laptop. The failure mode looks different than what I’ve experienced. Still worth checking bridging layer to see if Slic3r is dealing with STL correctly.
@Josh_Ajima 100% correct. I did find that the latest release of slicer fixes this somewhat. A gap this small sometimes wouldn’t register as a bridge but it seems to do it now for me just like on longer more obvious bridges. My suggestion would be to download a bridge calibration object from thingiverse and not use this piece for bridge calibration.
Even if you didn’t know its a calibration piece if you read the posters information you’d see he’d had it bridging correctly.
And as a simple owner I’d say get a fan nozzle printed if you don’t have one. And speed up your printing speed a touch. And increase your retract it looks like your over extruding slightly…
In my own personal experience, my printer bridges best when it goes very fast, or very slow to bridge, but not when its moving at a medium speed.
@Michael_Spano_Jr_Ama
I didn’t know that. I have a MBot and are stuck with the silly ReplicatorG slicer. But my advice stand. I thing he should experiment with the print-head speed and then with the extrusion speed. It’s quite a process.
@berry_jordaan which mbot do you have? I have a couple rep2s and find that the makerware slicer works pretty well for most things. Is there something in repG that makerware can’t do?
Try using a fan close to e nozzle, you can configure Sli3r to use it for bridges. This has worked for me.
That was the first piece I printed on my Simple 2014. With all default settings and Slic3r 1.0.1 it was fine. I was running lower temps though.
Have you got cooling on? It should blast the fan on the bridges.
