Building Prusa I3 3D Printer With Direct Extruder

Here, you can find a lot of information about building a 3D printer, also you can find free drawings on Thingiverse. Today, i'd like share my experience of building such a 3D printer. Maybe not good enough, but for me, it's working great, especially the auto bed leveling. You don't have make any change after you move the printer from one place to another. Videos can be found here.

Here is a brief idea about the printer, as i started this project from scratch, and i have no idea about it before, i read a lot but found it confusing that there are so many choices. I really don't know where to start at that time, it looks so hard at that time, but as said by others, "neven underestimate your own ability of solving problems"

Prusa i3's structure looks like CNC router, table moving type, and you can see some combine them tegother.
Before i stared this project, i saw buch of information that i can hardly understand. It looks like a impossible mission. But, actually, it's not so hard. At least, you can build your own machine.

Now, let get started. A brief understanding about I3

1, Frame: First, you need to get a standard or redesigned drawing of its main frame. I used acrylic 6mm (actual thickness is around 5.8mm). Strong enough. On thingiverse you get a bunch

2, Hardware: Prepare the hardwares needed for the construction of i3. Including hardened round rods, screw rod, printed parts, 5x nema17 stepping motors, bearing blocks (4xSUS8uu), linear bearing (4xLM8UU and 2xLM8LUU), heatbed (MK3, alu based, or the like), switching power supply, 2 cooling fans, 1 control board (the one i used is a all-in-one board, rather than two boards installed together), and screws and nuts). For different designs, the amount of screw and nuts might be different. Never underestimate these small stuffs. If set wrong, the whole machine won't work.

3, Firmware: when i read articles about firmwares, i saw a lot of information, and don't know where to start. Too much choice sometimes is not a good thing to get started. At last, i just tried Marlin. It proves to be great and easy for configuration. The lastest Marlin can be found here.

4, 3D printing control software: I was introduced to use Slic3r. But, I really like Cura (free, too). Firmware and control software used to be my headache before i started this project. You can choose the one you feel comfortable. The one that make you comfortable is the best for you.

5, Get machine installed and test it. One thing that takes me a some time to solve is the auto bed leveling. Marlin has supported this function. You just need a little time to read before working on it. Better prepared than sorry.

After going trough all these steps, the "hard work" becomes much easier now. So,never underestimate your ability.

Next, i will show you pictures on different stages.

Get the hardened round rods and 304 SS screw rod. As the hardened ros are under constant wearing, i chose good quality staffs. As for screw rods, i use 304 SS. 201 would also be ok.

This is a aluminum based MK3 heatbed, it can be used as support directly. 2mm in thickness. I prefer 3mm. However, this 2mm heatbed is working good. Since i use 12V for heating,i welded wires on position 1 and 6. This bed support also 24V. (heatbed supplier sometimes will have marks on the heatbed for wiring, don't worry about that. I was before).

Instead of plugging two boards (mega2560 and ramps1.4) together, i chose a stable all-in-one control board which use the same CPU atmega2560. Its heat dissipation is good, i purchase only one fan for it. One good point is that the board use only one cable instead of two cables and it has anti-reverse connector, so i won't make wrong connection which is safe. You can get this board here,

This part is important. The prints shown in the pictures above are from the machine made. However, before that you can ask someone who has a printer to make thse prints . Of course,you can ask me to make these stuffs for you.

One important thing i need to remind you is that you need to check the drawings you are using, to see if they fit your purpose. For example, some print wall thickness might be wider. Some hole position might be not correct with other drawings. To prevent this happening, you can use Google sketchup, Namocad, FreeCAD to check the 3D/2D drawing.

And, for 3D printing, you'd better have the model solidified before printing. Otherwise, sometimes you will find it a mess under your hotend. Even solidifed model may face silmilar problems. But, the chances will be decreased. This check work won't cost you much time. But, if you only find this problem hours after printing, you will fee sorry.

Have acrylic frame installed. Not too much to say about it. It's easy .

i made a mistake previously. The heatbed should be upside down. Now.it's ok.

For wire connection, make sure + and - are all connected correctly. Wrong connection would ruin your board.

For motors, wrong connection may lead to reverse rotation. You can set it in Marlin or rewire it.

For limit switch, normally, you need to connect COM and NO with your control board.

As LCD comes with the board, connection with one cable is easy. I have wires protected in fire resistant nylon tube. It looks better than plastic one. The position was on top of the printer, later i put it in the beam.

The tightener for both y axis and x (on the right) is important. The new design use a print to control the tightening. Very easy. You can also find the drawing for both x/y on thingiverse. Find the one you like. The original design requires spring, which is difficult to use and takes long time to put on. Further more, if loose, you have to put one extra (totally 2 springs) for it. But, the new design just use one screw and in few seconds, you will have it done. Perfect.

I used two software, Cura and Repetier Host.

1, Cura is very easy to use and slicing is very quick. For greenhand, it's pretty easy to use.

However, it also has a lot to improve. Currently, it's 14.12.1, not suggested. Many control buttons are lost. If you want to add more, you need to know codes. 13.12 would be better. This is only my experience, just for your reference.

2, Repetier Host. Version 1.06 has made a great change to include curaengine. So, you can use it to slice. And, many useful buttons can be found there. And, furthermore, you can see the slicing result after setting different parameters before printing. If you set wrong, sometimes, the printing result would be a little dfferent from your model. Use this function, you will find where the problem is. So, for both greenhand and advanced users. This software is greatly suggested.

check if the model is solid and whether the faces are correct in Sketchup. This is very important.