Building your very own 3d printer !

The first step.

Building your own 3d printer seems to be an amazing project but could also be a bit confusing in the beginning. The aim of this guide is to give you a basic idea about the procedure and for those of you who live in Chennai procurement details are also provided. 

So getting back to the first step which is construction of the frame. The frame is the part that acts as the support and carries the loads of the motors,rods, bearings etc. It needs to be rigid and you have to make sure it doesn't bend at any point during loading. I have worked with two different materials, one was Acrylic and the other was sheet metal you can choose what material to go for based on cost and availability. Make sure you design it properly to avoid any sort of bending that may take place due to the loads. Those of you who know how to use  advanced CAD software's can design the frames using the help of these software's  and for those of you don't you guys can just download google sketchup and design it there. Sketch up is a relatively easy software and is free to download and has many tutorials on youtube. While designing your frame you will have to keep in mind that accommodations for joints, motors and bearings must be given. In the beginning its better to use pre-existing designs of the more famous desktop printers with maybe a few modifications of your own. The following is a list of basic materials you will need. Some of the frame design will depend on the specifications of the parts you are purchasing.

A picture of my design on the Catia software

1. Linear bearings : Linear bearings help for smooth movement along the given axis. Since we have three axis's we will require three sets of these. There are various types of linear bearings like smooth rods with bush bearings ( ex : LM8UU ) or rail with block bearings these are the two I have worked with. Stability of the rail with block is much higher but comes out a bit more expensive as well.  
   
   
   
   
                          
2. Stepper motors :  Steppers are used to create the X Y Z movement. Their positioning is very important and there are also various ways to transfer the motion. You can use a rack and pinon set up, Screw rods or Timing belt and pulleys. I have used the timing belt and pulleys cause of their relative ease and also since I have never worked with rack and pinon before. For the Z axis alone we use screw rods cause it can carry the load on its threads. Positioning plays a major role in the design so make sure you have decide this before you start the frame design. Most 3d printers use the nema 17 stepper motor, so in case you are new to this you can stick to buying the nema 17.                                                                                             
   
3. Joints for the frame : Since the frame is made of acrylic you might have to make the frame by joining the various sides of  the acrylic. The acrylic can be laser cut to any shape you want, but remember that the machining can only be done from the top. You will need to keep in mind the exact location of the joints on each piece so that they are aligned at the time of fixing. This is done only for acrylic.
   

A piece of my frame drawn in 2d on Sketch up.

So these are the basics for you to start of on you CAD model. While working with the CAD software the most important thing is the shape of the frame and placement of steppers. I generally make sure the placement of the motors and bearings are perfect and don't add the joints. After am happy with the 3d visualization I then start drawing each piece of the acrylic on 2d using sketch up which is an open source software. On sketch up I add the details of the joints along with the other details from my CAD drawing. Once that is done it can exported to .svg format and this file can be used for laser cutting. To convert your 2d diagram to .svg, requires a pluggin that can be downladed for free as well.                                                                                      

A close up of the joint ( this gives you an idea of how to design the joints )

 If you are new to CAD then I suggest you make your printer with acrylic frames as its a lot easier for you to design and you are likely to make lesser mistakes. Also try using this software called tinkercad.

Below is list of parts that needs to be bought. Incase you don't understand the need for a part you can leave a comment below

List of parts and specs

1)      Acrylic frames  :  12 sq feet area , 6mm thickness for improved stability, laser cutting process for close tolerances in dimensions

2)      A2 stainless steel rods : for support.

3)      Acme screw rod + nut : length of the rod 255mm , 10 mm dia 3 mm pitch , 

4)      Stepper motors : Nema 17 stepper motors , No. of motors 5., Procurement based on calculation and price

5)      Bearings : Ball bearings arranged in a cylinder : LM8UU this has two types cylinder type and flange type : Ball bearings arranged in a block : MGN12C

6)      Extrusion Mechanism: Mk8 nextruder mechanism ,

7)      Motor to shaft coupler : 5mm to 8 mm dia coupler , Procurement based on shaft dia’s

8)      GT2 pulley + GT2 timing belt : pitch of 2mm , belt width of 6mm, Procurement based on research done by other 3d printing projects

9)      Fastners : dimension yet to be decided

10)   Electronics : Arduino mega board + RAMPS 1.4 shield + 5 stepper stick

11)   Power source: 12V, 20 A , Procurement based on Arduino board requirements

12)   Limit switches

Most of the electronic parts were purchased from http://diy-india.com/store/ the advantage of using diy india is that they are located here in Chennai, they still charge for shipping though.

The hardware parts such as the bearings smooth rods and screw rods were purchased at Parrys. The street names are Thambu chetty, lingi chetty etc. They have tons of shops that sell bearings. make sure you visit at least five shops before you purchase anything.