I need help identifying the problems of my printer

Hi guys.

I'm a noob, and I need some help getting my first printer to "work".

I've built a Prusa i2, with RAMPS 1.4 and a E3D 3mm direct Hot-end.
I'm printing PLA.

First: I'm having some serious issues getting the extruded PLA to stick to my hot bed.
I have tried the following:

Printing on glass: Even though I've cleaned the glass thoroughly and leveled my bed a million times, I still can't get the PLA to stick to the glass. It just curls up behind the nozzle as it moves around, and creates a blob around the nozzle.

Printing on glass with hair spray: A tad better adhesion with the hairspray, but not even close to "acceptable".

Printing on blue tape (with no heat on the bed): Somewhat OK adhesion, but the blue tape leaves "residue" on the printed part, and makes it look "ugly".

Printing on kapton tape (with heat): Almost no adhesion at all. Extruded PLA doesn't stick to the surface.

Printing on Kapton with hairspray (and heated bed): Not to bad adhesion, but far from perfect.

I would really love to be able to print directly on the glass, without having to apply tapes and/or any form of spray?

Also, when I get the print to stick, it doesn't look good.
Something is wrong, and I can't figure out what..

I started printing a fan holder/nozzle yesterday, and after a few layers, I had to stop the print.
The infill leaves plastic sticking up, so when the nozzle passes over on the next layer, the "collision" with these "mountains" causes the steppers to skip steps (x and y)?!?.

I've included a picture of the part i tried to print yesterday (on heated kapton with hairspray).
Can anyone help me with these issues?

Thanks.



\Martin

This issue has ben covered many times in the forum, it would be easiest to do a little looking around here.
There are many causes of not sticking - I think the list is almost endless..
the 2 I would look at is bed temp and layer height. make sure your first later is "pressed" down on to the platform.
I too had this issue when I started, now I rarely have problems, seems like once you get it, you got it.

Quote
cat.farmer
This issue has ben covered many times in the forum, it would be easiest to do a little looking around here.
There are many causes of not sticking - I think the list is almost endless..
the 2 I would look at is bed temp and layer height. make sure your first later is "pressed" down on to the platform.
I too had this issue when I started, now I rarely have problems, seems like once you get it, you got it.

That's what I have been doing for the last few days.. Searching and searching.. I've found many threads about this, but no matter what I try, I still can't get the PLA to stick to the glass..
I'm beginning to think that my thermistor in the hot end is showing the wrong temperature, and perhaps that can explain the issue?
I've tried printing the PLA from 190C to 220C (if the thermistor is showing the correct temp), but it doesn't make any difference..
I've also been trying different bed temps.. 50C, 55C, 60C 65C and 70C.. Not much difference there either..
Whats better, a low temp or a high temp, when printing the first layer, and getting it to stick?

I've tried 0.2 and 0.3 layer heights, with 0.25 and 0.35 first layer heights respectivly.

I have to set a Z offset of - (negative) 0.25mm to get the noxxle close enough to the bed, or else the PLA just curls up and gets dragged around by the nozzle..

Thanks.


\Martin

frist adjust your z height so it is resting on the bed, and do the sheet of paper adjustment. there should be no need for a negitive offset.
hotter is better, too hot - bad..
I think if you get your z height correct, and a .15 to .2 firist layer height, you should have good results.

I use PVA glue (white glue and water 50/50 mix) and 65C on my bed for PLA, PVA and 100C for ABS

Edited 1 time(s). Last edit at 05/20/2014 02:16PM by cat.farmer.

I use blue painters tape heated to 60C. At layer 5 or so, I reduce the heat to 45C. If the PLA is not sticking to my bed, the I raise the bed 1/8 turn on all screws until it sticks.

You adjust your Z-height according to the nozzle [classic paper trick or otherwise] while both are heated, right? In my mind, it would have the opposite effect, too close, if you didn't, but you never know.

---

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

I've had the same problem and struggled for weeks on end.
I see from your picture you're using black PLA. It tends to get long fine strands like very fine hair that stick to the nozzle and pull your print up.
You will most likely have a lot less trouble with other colours.
I found the best way to print with black PLA is on blue tape with the bed heated to around 60 degrees, too hot and it is hard to remove your print after it's finished, and the hot end at around 190 degrees or a little less.
You have to balance hot end temperature with speed of print, if you print too slowly you may find the filament melts higher up the hot end and jams. So you need the filament to keep taking the heat away.

Thanks guys.

I've leveled my bed so that the gap between my bed and nozzle is almost nothing.
Still, when the print starts, the Z axis is lifts (I reckon it's the first layer height, i.e. 0.25mm, it is going up), and without the negative Z axis offset, that is to high for the PLA to be "squished" into the glass.
I've experimented with different speeds for the first layer as well, but it doesn't help much..

I think that if the Z axis wasn't lifted at the start of the print, I could get it to "squish" the PLA down onto the bed better.
But I guess the Z axis allways will lift to get to the first layer height?
Maybe I should try a 0.1 - 0.2 mm first layer height, as cat.farmer suggests?
Do I need to set the layer height for the rest of the layers lower than the first, or doesn't that matter?
I think I read somewhere that the first layer height should be higher than the rest?

Thanks again.



\Martin

I've printed .4mm layer height a lot easier than .1mm [my bed isn't perfectly flat, thanks Obama]. That shouldn't affect squishing. In my firmware I have it set to move away from the endstop 1mm, so when I put my bed at the right z-height I'm not moving it until it's at the nozzle, I'm adjusting my z-height screw and hoping it's right. Maybe your firmware has that same feature turned on and it's moving away. Home your z-axis and see if it's where you set it [unless that's what you've already been doing].

---

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

Quote
MrDoctorDIV
I've printed .4mm layer height a lot easier than .1mm [my bed isn't perfectly flat, thanks Obama]. That shouldn't affect squishing. In my firmware I have it set to move away from the endstop 1mm, so when I put my bed at the right z-height I'm not moving it until it's at the nozzle, I'm adjusting my z-height screw and hoping it's right. Maybe your firmware has that same feature turned on and it's moving away. Home your z-axis and see if it's where you set it [unless that's what you've already been doing].

I'm not sure I understand what you mean by this..?

I'm using Marlin firmware btw..


\Martin

When I home my Z-Axis, it homes as normal, but once it's homed it moves away from the endstop by 1mm and resets zero. So it is 1mm lower [my bed moves on Z] than where it would otherwise home. This is to prevent accidental triggering of the endstop, which I chose because I have to adjust mine often, I don't have the best printer. Are you adjusting according to where it is after it homes? Are you confirming by homing, and afterwards checking?

---

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus

I think by having your layer height set in slicer and then forcing the print head down with a negative offset you are causing the problem. The software wants to push out a certain amount of plastic based on the layer height and width it needs to fill. When you change the height down to basically nothing using the offset the printer still tries to put out enough plastic to fill the 0.25 gap. In your pic you can see the bottom layer is pressed out much wider than the object should be. This will also cause you too get lumps of uneven plastic as it tries to escape around the edge of the nozzle. It's easier to print a 0.2 first layer than 0.1 as someone else already said and 0.25 might be too high for your nozzle diameter. Also have you calibrated your extruder, and then done it again to verify your e-steps. Also have you tried lightly sanding Kapton with 1200 grit and wiping with acetone (not nail varnish remover it has other things in it, acetone has to be pure acetone) then heating to 50°. Mine sticks like shit after I did this.

For me, I have the nozzle almost right on the glass, you can just get printing paper through the gap. I don't you Kapton tape ,ABS slurry or hair spray. 235 for the extruder and 110 for the bed. First layer hight is .15mm and each layer is .1mm. Takes a bit longer but the prints are nice. Are your belts loose at all, looks like the holes are misaligned?

Edited 1 time(s). Last edit at 06/07/2014 12:01AM by Dreadnaught426.

I'm going to suggest these steps. If you have done a step, move on to the next one.
Have you done:
-Motor movement calibrations.
-Extruder calibration.
-PID for temperatures
-Tighten belts.
-Used Blue tape with hair spray (No Heated bed, My favorite PLA set up)
-Bed leveling so that all four corners are the same level every time you "Home Z". Then you can adjust your Z endstop so that it when you start printing, it shouldn't print out swiggly lines. If it does that, cancel print and lower the Z endstop a little. If it looks like it's squishing too much or that the nozzle has contact with the bed, then raise the end stop. Don't mess with offset and just adjust Z home manually with the Endstop.
Lastly, switch to a different color PLA and try to replicate the fault.