These were supposed to be the first cylindrical studs of thing 28240 on thingiverse. I think I have a serious issue with under extraction on this Prusa Mendel r2. Is there something else I could try than tightening the spring loaded bolts on the wade extruder?
Do you mean under extrusion? Try extruding into open air first. It could be a combination of many things. Like you said, check the extruder gear for tension and make sure it’s not clogged with plastic bits. Make sure your nozzle is hot enough and is not clogged. And make sure your nozzle is not too close to the bed on your first layer as this could cause your extruder to strip the filament.
All that @Eric_Moy said, and make sure your extruder is calibrated.
Ah thanks. Turns out I have to clean the hobbed bolt better from earlier cases of stripping filament. Much progress with every try 
Classic reason for this, you didn’t see the settings for slic3r in repetier to tell is what size plastic and nozzle you have. Hope it’s that easy for you.
On the hardware side of things, I’ve sharpened my hobbed bolt and it made extrusion and retraction much more reliable.
Just a thorough clean of the other half of the bolt made a huge difference. From more or less an oozing nozzle to a clean start-stop. I’ll switch to a better test object too, slic3r seems to have sliced that brick upside down.
Thanks for your help everyone, I now get recognizeable objects!
I keep a can of computer duster with a long nozzle tube. It seems to blow the filament bits out of the hobbed bolt fairly well.
Totally forgot about setting the filament size correctly. I usually don’t and just tweak on the first layer. I’m lazy like that
@Cameron_O_Neill
pray tell - how do you sharpen a hobbed bolt? Dremel disk to every groove?
I used a tap in a drill and put the bolt in a set of bearings. It’s actually really easy. There’s a video of the process on my YouTube channel, just make sure you read the comments