Share:
Share
Notifications
Clear all

Thickening of bottom layers like Elephants foot but over more layers

peterb8f15b29
(@peterb8f15b29)
Famed Member

I have attached the photos of the print which seems to have slumped down towards the first layer. It seems that the about 1mm+ has thickened towards the first layer. There was no indication of elephants foot as the printing progressed.

I have a Geeetech A10T and was printing white eSun filament with a nozzle temperature at 195C and

with the bed at 60C.

What could be causing this.

Regards

Peter

 

20211003 071844
20211003 071617

 

Quote
Topic starter Posted : 03/10/2021 3:29 am
peterb8f15b29
(@peterb8f15b29)
Famed Member

I have run the print again at 180C and 50C

with a minimal elephants foot but I am also losing height on both of the prints - they should be 7mm high but they are only 6mm. The width is ok at 5mm. The printer is indicating that it is printing to 7mm as it finishes.

I have attached the gcode file for the white print.

Kind regards

Peter

ReplyQuote
Topic starter Posted : 03/10/2021 6:45 am
peterb8f15b29
(@peterb8f15b29)
Famed Member

I have run the print again at 180C and 50C

with a minimal elephants foot but I am also losing height on both of the prints - they should be 7mm high but they are only 6mm. The width is ok at 5mm. The printer is indicating that it is printing to 7mm as it finishes.

I have attached the gcode file for the white print.

Kind regards

Peter

ReplyQuote
Topic starter Posted : 03/10/2021 6:45 am
peterb8f15b29
(@peterb8f15b29)
Famed Member

I think I have found the cause of the incorrect height. I have stopped the print at 1.4mm and measured the thickness with a vernier. It was 0.8mm! I started the print again and it screen starts at 0.2mm as the 1st layer and I measured it and it was 0.2mm. Surely if the print screen shows it has reached 7mm then the print should be 7mm, shouldn't it?

Regards

Peter

ReplyQuote
Topic starter Posted : 03/10/2021 8:32 am
Pablo
(@placherre)
Member Moderator

Hi Peter! 

I apologize for the very late response… 

According to your description, I believe there is a specific miss calibration of the Z-Axis. Between the real height and the final printed height, there is quite a difference. That means that the stepper motor is not raising the correct distance in Z, affecting the final measurement in this direction. Luckily you were able to see it with this model, which is not very high. If you were printing a much taller model, you will notice a much higher difference between the real measure and the one from the original model.

Posted by: @peterb8f15b29

Surely if the print screen shows it has reached 7mm then the print should be 7mm, shouldn't it?

In this case, this is not really what happens. Because the printer doesn’t have a sensor measuring the Z height of the nozzle (or gantry assembly). The software will take into account the rotation of the stepper motor according to the electrical signal received by the mainboard (E-Steps/mm), which will be shown on the display.

Since you are printing with a 0.2 layer height and the total height of the model is 7 mm, the slicer should create 35 layers (7 mm divided by 0.2 mm). So, if the printed model is 6 mm high, for every layer there is a 0.028 mm difference between the real and the expected heights (1 mm divided by 35 layers). This distance is imperceptible; but only by measuring it with a micrometer; because a Vernier´s caliper precision is only 0.1 mm. Therefore, you will be able to measure the layer height without noticing the real difference. In that case, I recommend you print a calibration cube (20x20x20 mm). The idea of printing this cube is that you can see the correct XYZ steps calibration, which can be modified in your printer. Since your printer is showing a difference in the Z-Axis and that difference is too small, you can verify the correct value by printing several layers (by accumulating that error). Does it make sense? 😎 

For every increment in Z (or X and Y as well), the stepper motor will rotate a certain angle. If the electrical signal is not properly calibrated, there will be a difference between the real value and the one established in the Gcode.

The procedure is very simple. First, configure the model (I attached it at the end of this replay) with your slicer and send it to the printer. I would recommend you to print it with a 0.2 layer height. Since it is a regular layer height for a 0.4 mm diameter nozzle. In addition, since the cube is 20 mm high, the number of layers will be an exact number (100 layers). Once the print is finished, measure every side in the XYZ directions. In the X and Y directions, the measure should be 20 mm exact. But, the Z axis should be around 17.2 mm, which corresponds to 100 layers times the difference of 0.2 mm and 0.0028 mm (according to the 0.0028 mm difference in each layer).

Once you have that value, you should adjust the E-Steps in your printer. These steps are the relationship between the electrical signal and the angle of rotation of the stepper motor for every layer (or Z increment). This concept also applies for X and Y movements. In order to calibrate your E-Steps, you should make a simple calculation in order to determine the new E-Steps value. But, don’t worry, I am attaching an Excel file which makes the calculation, you just have to input the corresponding cube measurement and the actual E-Steps values loaded in your printer. 

E Steps Procedure

The calculation sheets is used by the following the next procedure (according to the previous picture):

1- First, write in the D6 cell the present E-Steps value. In your case, from the display: Control > Motion > Steps/mm > Zsteps/mm

2- In D9, write the Z side that you measured in your printed model. The cube has a letter stamped in each direction for better reading.

3- The new E-Steps value will be shown in D12.

4- Next, load the new E-Step value on your printer (obtained in step 3). In the display scroll look for Control > Motion > Steps/mm > Zsteps/mm and adjust this value with the control wheel. In order to save this change, go back to Control > Store settings. Normally, when you save a new value, the printer makes a beeping noise. If this is not the case, verify that the value was stored properly by turning off and then on your printer.

5- Then, print a new cube in order to confirm that the E-Steps are properly calibrated. In this case, the second table will be useful for fine adjustment if necessary. You will notice that the I6 cell will load the D12 value. Therefore, all you have to do is to input the measure of the second cube.

The procedure described above applies for X,Y and Extruder E-Steps. Since you are performing this calibration test. I would recommend you to verify the X and Y also. 

In order to avoid interference for the elephant's foot, I recommend you to check the build plate to nozzle distance. If you notice a flared out on the first layers, slightly raise the nozzle. However, make sure the first layer pattern (so you won’t sacrifice the layer adhesion to the bed). Also, use the same settings you normally configure for your models.

Bearing in mind the previous explanation, I considered that the hardware doesn’t have any loose bolts or belts and the gantry can move freely without resistance. Also, make sure the gantry assembly is firmly attached to the vertical frame.

I am looking forward to your response.

Kind regards,

Pablo

ReplyQuote
Posted : 06/10/2021 4:56 pm
peterb8f15b29
(@peterb8f15b29)
Famed Member

@placherre

Hi Pablo,

Thanks for the reply. It makes eminent sense especially in that the z axis is only calculated from the stepper motor not the actual height of the z axis carriage.

The attachments were missing from the reply. Can you post them again please.

Regards

Peter

ReplyQuote
Topic starter Posted : 09/10/2021 12:32 pm
Pablo
(@placherre)
Member Moderator

Hi Peter!

Sorry, I forgot to add the files... 🤪 

Now, you should be able to download the calibration cube and the Excel file.

Kind regards,

Pablo

 

ReplyQuote
Posted : 09/10/2021 1:42 pm
peterb8f15b29
(@peterb8f15b29)
Famed Member

Thanks for the files Pablo. You were right it was a miss calibration of the z axis. For different reasons I had to replace the motherboard. The e-step settings were different so I printed the test cube and lo and behold it was exactly 20mm on all axis'.

Thanks so much for your help and I am learning so much so fast. It is great.

Regards

Peter

ReplyQuote
Topic starter Posted : 10/10/2021 9:44 am
Pablo
(@placherre)
Member Moderator

Excellent Peter! I am glad you we able to solve it... 😀 

So, after replacing the mainboard you had to change the E-Steps?

Kind regards,

Pablo

ReplyQuote
Posted : 11/10/2021 4:22 pm
peterb8f15b29
(@peterb8f15b29)
Famed Member

No Pablo, The factory settings were exactly right.

 

ReplyQuote
Topic starter Posted : 12/10/2021 5:47 am
Pablo liked
Share:
Share

About us

We’re a bunch of 3D printing and design nuts. We just want to make great 3D design available to everyone. 

Our mission

Good design takes time, great design takes a process. You can learn this with us, to build your skill set in this rapidly expanding market. 

Learn with us:

© Copyright: 2019 io3dp.com
Close Menu