Prusa i3 calibration issue

I recently finished building my Prusa i3 and am now trying to calibrate it.
I'm having trouble getting sharp corners print nicely, especially on the first layer. It seems like too much plastic is extruded on. I've tried tweaking first layer height, extrusion width, extruder steps and pretty much anything else I can think of.
What am I missing?

Congrats on the new I3. Enjoy it and have some fun.

Your issue is common to everyone. Many issues are at play. Mechanically, for a square corner, you need infinite decel/accel rates (just not possible) and an extruder that respond instantaneously to extrude/stop commands (not possible either). There are also issues about volume packing as well.

Since that is not possible, you have to cheat and it will take some experimentation to find out how square your corners can get. I made a cube and then rounded the corners. Several prints were made with increasing radii on the corners to find the point where I ended up with the cleanest corner without excessive rounding. To be honest, building the printer is the easy part. Calibrating it to find out what it is truly capable of is the hardest part. Perseverance here will pay off in the future with some fantastic prints.

Also, the forums have tons of info on print quality, issues, and corrections. The search bar is going to be your best friend here.

Good luck!

-Could be:
- temperature of hotend try lower temperatures
- try lowering print speed, tweak xy jerk, this will help with the corners
- see if your slicer prints wider on the first layer, often like 200%. It depends on your nozzle if it prints well. I'd try setting it at 100% and see if that improves it.
- recheck the z offset, try increasing it if the extrusion overlaps too much. Try to aim for a good balance of extrusion multiplier and z offset. When done correctly it will print a good solid first layer and all consecutive layers will have a constant extrusion width. If it is squashed on the first layer but too thin on the other layers extrusion multiplier is too low or filament diameter is too high while the z offset is too close to the print bed.
- It can also happen that the layers get thinner going up, buildup over extrusion, especially in the corners will give your prints an uneven look. A z offset too close to the bed causes this. Calibrating using a single width cube and measure the extruded width and compare it to the expected width. Look in the gcode produced by slic3r, it will say what the width should be. Use a digital caliper for accurate measurements. After calibration adjust the z offset until it is as desired. It can happen that a sheet of paper between bed and nozzle isn't accurate enough and it also depends on the filament. Using auto bed levelling allows you to set a variable in firmware in hundreds of a mm to zero in on a good and repeatable setting. If you're using an lcd it's even more convenient, you can set it in marlin under control/motion.

See reprap wiki for calibration procedures, youtube also have a few good tutorials, like those from zennmasterm

Edited 1 time(s). Last edit at 08/25/2015 12:26PM by imqqmi.

I had a similar issue. I got much better prints after I put the belt enstioners in. THe biggest factor I found in my case were 3 big things. I was dealing with ABS.
1) Exteruder was too hot. it stopped popping at about 198c thats woring well for me.
2) Heat bed wast as hot as i thought it was. I used a surface thermometor to check the temperature of the glass on the heat bed. The glass wasnt as hot as the bed. So i raised the repiter temp to aboout 110, got my glass around 102ish. I Before I start i let Repiter preheat the bed and let it sit at temp for a couple minutes before I start the job.
3)I found a video from Toms Guide. I highly suggest watching his stuff if you havent already. His Calibrating Extruder guide was a big help. I found that mine wasn't right. [www.youtube.com]

A good tip I found too (cant rember if i was one of toms or not) was to put a thin layer of plastic down before heating the bed. Simply put a tiny bit of acitone on the glass and then use an old junk print and just rub it in the acitone all over the area your print will be on. Let it dry then start. It makes great adhesion to preent the print from sliding around.

[www.youtube.com]

Tom's videos have been a HUGE help. I am printing ABS with 235 at the nozzle and 110 on the bed. Belt tension is a HUGE issue. I printed my way up so to speak. I printed my first set of upgrades (belt tension adjusters) that looked like crap installed them printed a new set which looked great and so on. I use hair spray on my bed tried glues stick and the acetone trick but hair spray works great for me.

As someone said building is the easy part everyone has brought up good points and advice but sometimes what works for one does not for others for example some people hate hairspray and have no luck with it while others think it's the only way. Trial and error is the best way i bought a roll of ABS just to learn with and print my upgrades.