RepRap Prusa Mendel i2 first print! - layers squashed

My printer arrived 2 days ago and I was unable to print as I had to wait for my order of kapton tape to arrive ( this was quite essential as the filament that came with the printer was ABS ).

Once the tape arrived I designed a simple 20x20x10mm box and tried to print it, link to the file on thingiverse: http://www.thingiverse.com/thing:415902.

I stupidly thought it was a good idea to try a print before I had done any calibration at all! any way it turned out as I had expected, not very good but not to bad. Here are the pictures:




As you can see there is no clear definition of the layers and the edges are very rough. Also the print has lost its shape as the corners are very rounded. This has happened because the hot end was too close to the print bed and so the extruded filament got squashed down on top of each other. This caused some of the filament to be squashed out of the supposed size of the object. In other words an extra .2 mm of filament on each side due to not enough room for layer to be laid down. Therefore for my second print I need to make sure that I have the hot end a little bit further away from the bed.

This picture shows that I had Slicer configured wrong because it printed out a hollow box but then for 3 of the top layers it tried to do a solid layer. This result in the filament sagging into the hollow box bellow. So for my second print I will set the infill to 100% or 1 if using Repetier host.

Z axis jarring problems on RepRap Prusa Mendel i2.

After a few days of using my 3D printer, I found a problem, the Z axis would jar on the right hand side causing one side to be higher than the other and then both sides would jar as a result of the X axis not being level.


When this happened I notice that I could move the right hand side of the X carriage up and down and sometimes the nuts on the X carriage would be "left behind". this meant the X carriage would no longer be raised up and you could also move the X carriage up and down on the side that jarred because the nuts ( one on the top and one on the bottom of the plastic part that joins to the threaded rod ) would no longer be pressed tight against the plastic part.

I thought that this problem was because the X carriage wasn't level in the first place as I hadn't checked it. So I levelled the bed making sure the distance D on the diagram was the same on both sides ( see image below ). However when I checked it was level and put the nut back into place I kept on getting the same problem.

I then looked online to see if any one else had this problem, I found one post on the RepRap forums about the Z axis stepper motors vibrating and not turning and the solution was to reduce the speed of the two Z axis stepper motors. I tried this and it worked! I slowed mine down to about 50 mm/min in pronterface and the axis stopped jarring.

I also found other causes of jarring, jamming and vibrating Z axis, these are:

- over heated stepper motors
- damaged threaded rods
- something has got caught in the nut
- X carriage not straight

and my solution, slowing down of the stepper motors!

This problem was all to do with the force that the stepper motor needed to exert to turn the Z axis was to great and so it was missing steps, stopped rotating the axis. therefore anything to stop forces building up would help. things like cleaning and lubricating the smooth and threaded rods would help reduce friction etc...

Here is the video of the Z axis jarring:

Please correct me if anything I have said is wrong!, and please message me if you found this useful or have any other suggestions :)

Slic3r, pronterface and Repetier host

So now you have uploaded Malin to your Arduino mega, you are now ready to control your printer and make slight adjustments to you printer through Marlin.

There are two options that I would suggest,

Pronterface or Repetier host, these programmes are used to control your printer from your computer, you upload G code files to your printer through these programmes. Both are simple to use and there is well documented help on line as to how to set them up correctly, basically setting com port and baud rate and you good to go.

Before you print you need a design or file to print, you can download quite a few things on Thingiverse or you design your own products on free CAD software called Google sketch up and install the STL plugin which converts your design to a .STL file.

Once you have downloaded your STL file or created it you need to slice it into G-code. This creates your file as layers of X and Y movements to print the layers. To do this I would recommend Slic3r. Once you have slicer you need to go through all the settings and make sure these settings are correct for you printer. There is a great video below, this video goes through all the settings in Slic3r.

How to setup an arduino Mega and upload Marlin

So I have been using Arduino's for quite a while before I got my 3D printer, when I saw the listing for this printer (as I got it on Ebay) I was thrilled to find out that it used an Arduino Mega. I thought great I might be able to add things into Marlin, I was wrong, the Marlin "sketch" was a lot more complicated than I thought (I didn't even know you could create tabs at the top of the page!).

Before my printer had arrived I had a look at the code and started to configure it for my printer that I had just bought. Setting up Marlin without any additional features is fairly straight forward as the sketch is very well commented so I managed to do it in about 10 minutes or so.

However if you aren't familiar with the Arduino language or how to set it up in the first place it can be quite frustrating.

The first thing you want to do is install the Arduino IDE, you can download it here: http://arduino.cc/en/Main/Software

Next you will need to install the driver for the Arduino Mega, the guide below is for an Arduino Uno but the process is very similar if not the same. 

Here is the guide: http://arduino.cc/en/guide/windows

Once you have installed both of these you can go ahead and download Marlin here: https://github.com/ErikZalm/Marlin

The Marlin firmware is down loaded as a .ZIP file so you will need to extract it, to do this, open the .ZIP file and at the top you will see a tab saying "Extract". Then click "extract all" and choose or create a folder for the files to be extracted to.

Once extracted you can now open the Arduino sketch, to do this, open up the Arduino IDE, go to File -> Open -> Marlin folder then select the Marlin.pde file.

This will then open the marlin sketch in the Arduino IDE so you can upload this to the Arduino mega board. To upload click the arrow button, right of the tick button.

However make sure you settings are correct in the configuration.h file before you try to print as it is very important to make sure the correct thermistor is being used to prevent overheating and stop a possible fire hazard. To open configuration.h file, open marlin in the Arduino IDE and you should see tabs across the top of the page. One of these will be the configuration.h file.

Also before you upload make sure the correct board is selected by going to tools => board and select the Arduino mega 2560. Also make sure the correct port is being used by going to tools => serial port and select one of the com ports.

Once this is done you can go ahead and open up and software that you prefer to use to control your 3D printer. I will be going over one of the most common programme used to control 3D printers in my next post.