Printing problems, Help?

I've done building my self designed printer and thus far the mechanical aspect looks very good, but now, offcourse, I'm searching for the optimal print settings, wich are clearly different than for my other pinter.

My hotend is an cheap E3D and I'm running marlin on a Ramps 1.4 board.

1. When a print starts, it looks like he can't extrude enough material at the beginning, there is a little bit coming out and curling up on the nozzle, but after about 1 skirt line it suddenly sticks to the bed and everything is fine, but then, when the first layer is layed down itself, it looks like he only extrudes enough when the hotend is closest to the extruder (bowden), when the bowden tube is extended further, it looks like it lays down less filament and perimeters are not touching and lines become taller. I checked the bed and it's perfect level! So I guess it has something to do with the bowden cable. One thing I noticed, and what I personally think is the problem, is that my bowden tube (that came with the cheap E3D) is 3mm ID and 4mm OD, but I use 1.75mm filament. Normallt this has to be 2mm inner. Can it be that because of this play inside the bowden tube, the pressure on the filament is more when the hotend comes closer to the extruder motor? My extruder motor is near the X min, so when the X axis goes to fully max, the bowden is extended more, and because the filament has play, it gives less pressure, meaning less extrusion? But I'm not sure of that. I've attached a picture of what a first layer looks like. On the lefst it's still ok, but on the right it's not even getting on the bed anymore


2. I personally think I'm overextruding, but when the top layers are printed, the infill lines are not touching each other.

3. When printing small objects, after a few layers (10 maybe) the corners and sides start curling upwards, I personally think it's because of no fan on the print, but I see allot of prusa's that don't have a fan on their print not having this problem? Picture of the cube

Hope you guys can help!

It is bad to have 3mm inner diameter (I think). I also got clone and genuine e3d v6, bowden tube supplied are totally different. I think genuine e3d's inner diameter around 2mm or something (I didn't measure them)

1. I would recommend to buy a machined 2mm inner diameter e3d heat break, I'm pretty sure you can find it easily in online stores from china. But the way the thermistor sleevings supplied, you can't go beyond 250'c with teflon sleeves for it (correct me for this) also with the bowden tube going all the way inside the heater blocks. Did you do bed leveling of bed and nozzle with piece of paper? You need to feel some friction during these procedure, do it 2 pass and most likely you're good to go.

2. It is clearly visible that it's under extrusion, try to ramp up the flow rate a little bit. But I would suggest you to calibrate your nozzle and bed distance first

3. You didn't specify what plastic you've printed, I'm assuming you printed pla judging by the looks of the cube. The curls often affected by temperature being too high as they are too hot and being cooled by the ambient temp, it shrinks. You also didn't specify the temperature to print as well, my rule of thumbs are, low temp for small object, high for large. But still won't get you off from curling though

Thanks for your response.

I levelled the bed with a feeler gauge of 0.15mm, first layer seems to look good now, don't know what it fixed, but I'm happy already

2. I tried ramping it up by 10% but it is still a problem. I can pull the outer perimeters off and can see that the top layers are not fully solid, maybe higher tempereature can fix this?

3. I'm printing PLA, at the moment at 195°C so I think I can't go allot lower, would a fan fix this issue maybe?

is you hotend completely solid on the x carriage? if the hotend moves at all or has any play in it, you will have all sort of strange happening and you just can't seem to find them