Trouble with PLA inter-layer adhesion

Hi guys,
I've been lurking on the forum for a while and finally decided to build a Prusa i2. I'm printing glowing blue PLA onto glass heated be and I've managed to get some ok prints out of it but I'm struggling to get consistently successful prints and I was hoping you guys could point me in the right direction. There seem to be a couple of major issues. One is that my Y bars are bowed enough that my bed can't be made flat, I've rotated them to find the best orientation but still can only get 2 corners level. I have some new bars on the way, but at the moment i'm a little restricted to printing small things in the centre of the bed.
The other problem I'm consistently having is that when I manage to get a well adhered first layer, which isn't always, about 4 or 5 layers in my infill will stop sticking to the layers underneath it. I've bumped the extrusion temp up to 205 deg C at some points to try to improve adhesion but that hasn't helped significantly. Also on the first layer of solid infill the tip of the hot end seems to drag across the other layers and pull them up as it passes them. I have my bed at ~85 deg C and can't get good adhesion below that.
I've attached some images of some failed prints to show what I'm talking about with the lack of adhesion between the layers.
I can print single layer width objects like the calibration piece in the other image without problems, but when I try to print something solid I get this problem.
I'm using Slic3r 0.9.9, Pronterface and Marlin firmware.
Anyone got any tips? I'm going to order some normal PLA soon to see if the filament is the problem, but It'd be good to get some consistency from the PLA I have.

It might be you need to set to extrude more filament. I saw something similar when i had wrong filament diameter sete. I also had serious problems with layer adhesion, until i fixed Z axis/hight endstop on my Huxley.

How's your Z-Steps/mm?

If the first couple layers are ok, and they the layer adhesion gets worse and worse, it sounds like a Z-Step problem.

I probably should have listed some of the things I've already tried but I have done quite a bit of messing around with the e steps, filament diameter and e multiplier in slic3r. Initially I had set the e steps wrong , but ive recalibrated and am pretty confident its correct now; when I do single wall prints I get pretty much exactly correct widths and don't seem to have adhesion issues.
Also i'm fairly sure my z steps are good, im using standard 8mm threaded rod with 1.8 degree steppers and 1/16 microstepping and when prints work I do get correct z dimensions. Ill recheck this in my firmware when im home though.
The probem seems to be mainly present when I do largish prints with lots of flat infill like the extruder, which you can seegot maybe 7 layers in then came to pieces.
How much of a proproblem is room temperature? Its been about 10 to 15 deg C ambient while ive been trying to print, should I put a room heater on it?

When you say "glowing blue PLA", is this glow in the dark? or just clear with a blue tint?

What is your print like with plain white PLA?

Try printing a single layer hollow cube (no infill, 0 solid layers, 1 perimeter, uncheck generate extra perimeters when needed) and cancel the print after about 10 layers. After printing, measure the width of the walls and make sure it is pretty close to what Slic3r set for the trace width. Slic3r sets that automatically by default based on your nozzle diameter and you can find the value it's using by looking at the gcode (it's in the comments at the top). If the walls are too wide or too thin then too much or too little plastic is being used and you'll need to check your E steps, filament diameter, or extrusion multiplier.

Yeah it is glow in the dark PLA from an austalian supplied called bilbyCNC. at the moment thats the only filament I have, I'm planning on picking up some more standard black or white PLA and ABS next week because I thought the filament might have been adding to the problems I'm having.

And yeah sheck I have done that and after adjusting the e multi I get single layer wall thicknesses pretty close to exactly what they are listed as in the g code, within .01mm with a caliper.

If room temperature were a problem, would printing a single line thick wall around the piece help ? Outskirt all the way up ?

I think the idea of that is that it shields the build from drafts, which I'm pretty sure isn't the issue. Someone else posted something similar with the glow in the dark blue PLA recently on this forum so maybe that's the issue, I'll pick up some other filament tomorrow and see how I go.

So I got some natural PLA from Lybina here in Australia and its pretty much immediately solved the problems. I guess the glow in the dark filament just isnt much good

BilbyCNC's green glow PLA was very weak.
There blue standard was also easy to break layers.
There white is super strong,but I've just posted about an issue I'm having that may be related to this fillament.

Still they're local and quick to deliver.

If it's moving up too high on the z, and plastic isn't landing properly on the previous layers, sounds like z steps in firmware might not be correct.
Also, you said your waiting on the new rods, did you get them in?

I just looked at your cube, and looks like it starts moving higher in the z, the higher it goes basically? really check your z settings, measure with a ruler how high it moves when you hit 1cm or 10cm on slic3r, then adjust the Z steps in the firmware
you can use this formula to help get closer and closer to the perfect value
[ (previous steps)/(distance measured) = (new steps)/(distance it should be) ]

IMO, printing on anything that's not level is like, way harder if not bascially impossible to print anything big.
Try to get a glass bed and get the nozzle as level as you can to the bed itself.

If you spend the time to get it all neat and tidy with good leveling, you will see a dramatic increase in quality,

If you have everything calibrated, and have a level bed, try to make sure your printing close enough to the bed so that it sticks consistently, but not too close or it can damage your nozzle.

You can adjust the amount of plastic coming out with the extrusion ratio in slicer

Edited 1 time(s). Last edit at 07/02/2013 01:46PM by dustynus.