[First Printer] circular profiles are not circular!

Hey there,
This is my first printer. I finally went through the adjustments and calibration.
Here is the problem for now, I tried to print this [www.thingiverse.com] So I started with the simple Spacer part.
The profile from the side looks horribly unround!



I'm also having trouble with warping. I'm printing PLA at 185 and bed at 60 at beginning, later i turned it off cuz the fist couple of layers were drooling down and not sticky.

One thing also I that my extruder fan is not working for now. I will replace it soon. Hopefully today. Yet, I think that not-roundness has another cause.

Any help?

EDIT: I'm using a Prusa i3 with Plexiglass frame two threaded rods for z axis
EDIT2: I just noticed somthing. I think my prints are bulged/skewed in the Y-direction! like the Y-Axis is moving more than it should... Does that mean anything? I already calibrated the Y&X axis with Prusa Calculator


Edited 2 time(s). Last edit at 04/06/2015 05:31AM by ishe7ata.

First layer to far from built plate, do not turn of your bed heater, calibrate your Z axis and fix your hotend fan.

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ggherbaz
First layer to far from built plate, do not turn of your bed heater, calibrate your Z axis and fix your hotend fan.

So I keep the bed at 60? or do i need to lower it ?

Edited 1 time(s). Last edit at 04/06/2015 09:10AM by ishe7ata.

Ok I just noticed that my z axis motors are not on the same height! the thing is I already calibrated them before!!!

Any idea why they are not running exactly at the same length?? I have the potentiometer almost turned up to max and both motors on parallel in the two z-axis sockets on Ramps.

Yes keep the bed at 50-60 degrees.

Each motor is unique, just turning the pods isn't enough, you need to measure the voltage at the pods and both needs to be identical.

[reprap.org]

It shows how to properly calibrate the stepper drivers.

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ggherbaz
[reprap.org]

It shows how to properly calibrate the stepper drivers.

Hey there,
Thanks for your reply. I'm confused though.... my motors are rated at 1.7A so if I'm powering both Z axis with one driver I should aim at what Amps rating?

I amp is usually enough, and will reduce the load on the driver. If not enough you can go up to 1.7 without problems since the A4988 can handle up to 2 amps, but definitely put a heatsink in the driver and be sure to cool it with a fan all the time.

The best thing to do is to measure each motor coil resistance and use for Z the 2 motors that have the closest value possible.

Edited 1 time(s). Last edit at 04/08/2015 01:34AM by ggherbaz.

Quote
ggherbaz
I amp is usually enough, and will reduce the load on the driver. If not enough you can go up to 1.7 without problems since the A4988 can handle up to 2 amps, but definitely put a heatsink in the driver and be sure to cool it with a fan all the time.

The best thing to do is to measure each motor coil resistance and use for Z the 2 motors that have the closest value possible.

Thanks for the guidence so far. I got the print going smooth for now. Fixed my fan. Calibrated Z. Now I get round profiles correctly.

Hoewever,
I get gaps between layers on one side of the print! See pictures below





any clue?

If only on one side of the print I would assume to be a bed leveling problem, but the part is small and should not be affected by that. I think it's a combination of 2 things: too big of a layer combined with low temperature.

It looks like a 0.3mm layer? And assume you still printing at 185? Change it to 0.2 and go to 195 or even 200 degrees and either keep bed at 60 or raise it to 70.

If that doesn't do it, then try with slower speeds. I cant see in the picture how the first layer looks, if thin in one side and thicker in the other side( where the gaps occurred) then its a leveling problem.

Edited 1 time(s). Last edit at 04/11/2015 03:44AM by ggherbaz.

Quote
ggherbaz
If only on one side of the print I would assume to be a bed leveling problem, but the part is small and should not be affected by that. I think it's a combination of 2 things: too big of a layer combined with low temperature.

It looks like a 0.3mm layer? And assume you still printing at 185? Change it to 0.2 and go to 195 or even 200 degrees and either keep bed at 60 or raise it to 70.

If that doesn't do it, then try with slower speeds. I cant see in the picture how the first layer looks, if thin in one side and thicker in the other side( where the gaps occurred) then its a leveling problem.

For now I print at 185 I'll increase that later on my next print. For that part bed was turned off.. I now usually keep it at 50.
Now it works fine I mean for everything else, yet the bed leveling issue is giving me pain in the ass! THIS IS HARD!
I really want to install auto bed tramming, yet I'm using a glass bed.
Any suggestion how to get it work with a glass bed?
Will a conductive sensor with an aluminum foil work?

I use a capacitive sensor which is heavier and more expensive but work with glass. But either an inductive or better yet an IR sensor will do the job nicely.

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ggherbaz
I use a capacitive sensor which is heavier and more expensive but work with glass. But either an inductive or better yet an IR sensor will do the job nicely.

Thanks for the help so far...
I'm looking for a capacitive sensor to buy now.. I found this... [www.ebay.com.my]

Do you have any guide regarding the setup and so on?? I couldn't find a good one...

It's pretty much a simple and straight forward procedure:

Sensor comes with three cables black, brown and blue where brown is positive, blue the negative and black is the signal. I prefer to power the sensor from power supply but you can power it from the ramps (you will loose sensing distance) but it's the simplest one, just connect to a three pin jumper connector and plug it to the ramps endstop pins. Or get an LM7805 and then power brown to 12 volts power supply, blue to ground of power supply and black to pin 1 of the LM7805, pin 2 of LM7805 to ground of endstop pins and pin 3 to signal of the endstop pins ( you can add diode, capacitors, etc to the lm7805 or just the regulator) it works both ways.

The sensor you posted it's a NO type and mine it's a NC as the ramps Wiky recommend, but it works just as fine as long as you switch it's logic in the firmware.

They look like neat devices. Do they have an adjuster for setting the trigger distance, or do you just move the entire sensor up and down? Not sure I follow your suggestion for connecting via a LM7805 - that's a 5V voltage regulator isn't it? Connecting it across the endstop pins seems a little odd.

On top of the sensor is a trimpot that you can use to increase or decrease sensing distance.

The one you posted is for up to 5mm distance, mine is up to 10mm buth it is much thicker and heavier so keep it close to nozzle height, if you can design the housing make the insert for the nut on top and the hole for the sensor and then thigh from bottom.

I use the LM7805 because I powered the sensor with 12 volts to guarantee reliability and full sensing distance, if I plug the signal to Ramps without a voltage reduction I will fry the board, I don't trust a simple resistor for voltage reduction as many people use, so I use the regulator to secure a true 5 volt signal at the ramps pin. The LM7805 is a simple 3 pin regulator in, ground and out, so I apply the 12 volt signal to in and then ground and out to Ramps, when sensor send a 12 volts signal the regulator convert it to 5 volts which is the maximum voltage that the ramps can take on those pins.

Ah, I see. Thank you.

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ggherbaz
On top of the sensor is a trimpot that you can use to increase or decrease sensing distance.

The one you posted is for up to 5mm distance, mine is up to 10mm buth it is much thicker and heavier so keep it close to nozzle height, if you can design the housing make the insert for the nut on top and the hole for the sensor and then thigh from bottom.

I use the LM7805 because I powered the sensor with 12 volts to guarantee reliability and full sensing distance, if I plug the signal to Ramps without a voltage reduction I will fry the board, I don't trust a simple resistor for voltage reduction as many people use, so I use the regulator to secure a true 5 volt signal at the ramps pin. The LM7805 is a simple 3 pin regulator in, ground and out, so I apply the 12 volt signal to in and then ground and out to Ramps, when sensor send a 12 volts signal the regulator convert it to 5 volts which is the maximum voltage that the ramps can take on those pins.

GREAT detailed explanation man.... Thanks a lot....
I've contacted someone to fabricate the metal bed for me.. Once I have that I'll purchase the sensor and find someone to print me the housing and get it done...

NOW...
I'm getting very nice small prints so far... HOWEVER, there is one issue I can't diagnose.. I get this weird spiting between layers at high layers sometime and sometime at lower layers too... I sometime get drooling to the outside of the permiter as well... I have some issue with my Z axis but I solved those so it's running smooth now...


Any idea what may be causing that??? Maybe temp? I print at 180C and 50 for bed PLA 1.75

I use 50 on the bed if part is small, and increase it as the size of the part increases, so that part it's ok.

Now 180 it's kind of cold for PLA, and you can suffer delamination if printing fast. The least I print at is 195 and go up to 220 on certain colors and filament quality.

On the photo you posted, it looks like extrusion failure more than delamination because the rest of the print is perfect and you can see on the right side the blob the extruder created when started extruding again, so most likely your temperature was too low.

I have printed several pokemons for my kid and since they are small I print on the low side of temperature and slow speed for better details, try to raise temperature to 195 and keep speed under 40mm per second.

If your infill to perimeter overlap is too big you will have the drooling you mention so just reduce it when printing small parts or when using small walls.

Just as a note, you don't need a metal bed with a capacitive sensor. My bed is a pcb board with glass or bakelite on top.

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ggherbaz
I use 50 on the bed if part is small, and increase it as the size of the part increases, so that part it's ok.

Now 180 it's kind of cold for PLA, and you can suffer delamination if printing fast. The least I print at is 195 and go up to 220 on certain colors and filament quality.

On the photo you posted, it looks like extrusion failure more than delamination because the rest of the print is perfect and you can see on the right side the blob the extruder created when started extruding again, so most likely your temperature was too low.

I have printed several pokemons for my kid and since they are small I print on the low side of temperature and slow speed for better details, try to raise temperature to 195 and keep speed under 40mm per second.

If your infill to perimeter overlap is too big you will have the drooling you mention so just reduce it when printing small parts or when using small walls.

The thing is, i tried this part with same settings later and it worked just perfectly. Also other pokemons work well and sometimes this thing will show up...
I will try again tonight with 195C and i keep the speed at 25mm so I think it should be more than fine...

now there is something else, I put the filament roll like above the printer but behind it so It's like the motor has to exert some force to pull the filament out of the roll. Now i know -correct me if I'm wrong- that steppers are always using full current hence full torque. I was thinking maybe the motor was having trouble pulling out the filament so amps pile up inside and pull out too much filament hence the drooling after the failure, yet if what i just mentioned about the full torque capacity then it doesnt make sense..

I'm gonna use inductive sensor for now. I can't find a capactive one nearby....