Infill Calibration Help

Hi all! I've built my first RepRap and I'm printing! Woohoo!

So I think my first calibration object, the 5mm wall came out pretty well. However, infill calibration is not going so well.
I printed out the 20mm-box. The infill actually looked good as it was printing the honeycomb pattern. However, the last couple of top layers did not create a consistent top layer. I'll let the picture speak for itself.

I am using Pronterface with slicr.
Marlin firmware on a rambo board.
Prusa i3.
0.5 mm hotend.
3 mil PLA.

Any help, guidance or requests for more info are much appreciated!
Ben

Have you got a fan facing your hotend? Sometimes it makes a cleaner finish.

Also did you calibrate marlin, calculate and check the flow of your filament?

Thanks. It looks like my extrusion rate was about twice what it should be. Printing box now. Wish me luck!
Ben

It came out beautiful!
Thanks!

Sorry to hijack your post screamn, but I have similar sort of problems with my Prusa i3. I currently don't have a fan facing my hot end and I've calibrated my extruder steps without the hotend attached. I've had several good prints but then other days things start well only for the filament to stop being laid down evenly. I've attached an image of a sample print, this print is supposed to have a 100% solid infill but you'll note halfway through the print the plastic stopped being printed evenly, this happens for other prints with 25% infills etc. Any ideas? I've had a few good prints when I slow down the print speed by 50% this doesn't always work either.

Hey Niel. My prints started to degrade and I noticed short periods where no filament was extruding. This looks to have been caused by hobbed bolt slippage on the filament. First, I brushed all fine debris out of the hobbed bolt teeth. Now I also tighten the filament guide a bit more than before.
Along these lines, it is also possible that the small gear is slipping on the extruder motor shaft.

Hope that helps!
Ben

Thanks Ben, I have noticed that I do get a lot of build up of plastic on the hobbed bolt (which I do clean regularly) and I actually loosened the 2 screws slightly to try and prevent it. I've just cleaned the hobbed bolt again (using some methylated spirits) as well as tweaked the small gear on the extruder so for my next print I'll try and tighten the feeder a bit more. Does anyone know if you get the same plastic build up using PLA?

I've only printed with PLA so I'm afraid the answer is yes.

You want the screws on the clamp to be *very* tight. The shaving of the plastic comes from it being to loose or from trying to extrude to fast for your layer height.

If anything is loose or slipping on your extruder, that needs to be fixed. They don't work at all well with loose parts.

Thanks for all the help guys, I've made some head way. Firstly I rebuilt my Wades Extruder as originally I didn't know how to mount the hot end but a few days ago I spotted a couple of holes which I've now drilled which allowed me to securely attach my J-Head hot end. I've also swapped out my .5 hot end for a cleaner .35 hot end and the early signs showed good promise but this morning I had feed problems, I either have too much tension or too little (struggling to find the sweet spot) so my final thing I'm going to try is to buy a replacement hobbed bolt as the one I'm currently using seems very shallow allowing the filament to drift off the hobbed part of the bolt onto the smooth part.