Building my Repstrap Smartrap 3D Printer... and the setbacks (Part 1)

I finally did it!  I've decided to stop waiting for a 3D printer that I can afford and just build one myself. Of course prices of 3D printers will eventually go down but I wanted one NOW! And I wanted it to be as cheap as possible.  And if you want cheap, you'd have to build it yourself - Pinoy style ;-).

So I started searching for a good base model and came across Smartrap - an open-source 3D printer designed by Smartfriendz.  I fell in love with the simplicity of the design and I thought it's a great way to get my feet wet with 3D printers.  Their price isn't actually bad but the long line of orders put me off so I thought I will just order some parts here and there so I can start building one.

This is to document how I built my Franken-SmartRap, with parts sourced from different places and share the problems I came across during the build, hoping that it will help other people avoid the mistakes I've made and inspire my fellow Filipinos to start building their own 3D printers. I will split the post in different sections like so:

Part 1 - Sourcing parts and building the base/frame
Part 2 - Electronics 
Part 3 - Power supply
Part 4 - First prints and modifications 

Ready?  Let's do it!

I was about to make this a step by step build guide but I noticed that Serge from smartfriendz.com updated their build documentation so I will stick to the parts where I had issues and how I dealt with them.

Looking at the parts, it seemed like I can source some of them locally but after visiting a few big hardware stores and home depots, I then realized how difficult it will be to find them around so I gave up the hunt. It was just sooooooo frustrating that even the biggest hardware stores like ACE do not carry bolts that are in metric system.  I eventually found a supplier that sells the bolts that I need for my build but it was far more difficult to find.  If I was having that much trouble finding bolts, I can just imagine what else will come my way.

I do not know anyone who has a 3D printer so even the printed parts were ordered online. Ordering online will cost me extra money and time but I really didn't have a choice. I ordered the printed parts from a seller in the U.S. which came with the fishing line, drive gear, and servo motor. Then, I ordered the electronics from China, along with the motors, hot end, smooth rods, bearings, LCD and some filament.

After a couple of weeks, the first to arrive were the printed parts:

After a long wait, the other parts came in...

As soon as I open the package, I immediately noticed some parts were missing.  First, there were only 4 smooth rods instead of 6.  Second, the linear bearings were missing. I immediately emailed the seller and told me to check the box if it's been opened by some 3rd party.  There was a tape on one corner of the box that says "repacked".  I took a picture of it and sent it to the seller.  They insisted that it was opened by someone. I contacted DHL's customer service and they said they just applied tape over it because they saw some damage. After a few emails with the seller, he agreed to refund the amount for the missing parts but the situation will delay my build.  Without those bearings, I wouldn't be able to build the 3D printer. I searched for some local bearing stores and spent an entire day going from store to store but linear bearings proved to be a very rare part.  I finally found a store that carries LM8UU bearings.  They are were not cheap but at least I can continue with the build.  Whew!  Knowing how hard it was to get the bearings, I ended up paying the seller to ship the missing parts to me along with some other parts I ordered as backup.

Onto the build - I am still lacking 2 smooth rods but the rods were long enough such that if I cut two of them in half, it would be enough to give me about 130mm x 150mm build area. I could live with it so I went ahead and cut them. I've got the parts that I needed, but they were not exactly the same parts used in the original design so I definitely had to make some modifications or even make some parts myself.  One of them is the X axis hot end mount.  I failed to notice that the printed parts I ordered was for a different kind of extruder and what I had was a J-head hot end.  Another setback!  The fix? I made the part out of wood! Using some scrap wood, I carved a similar shape leaving some space for the servo.  This would not have been a problem for someone who already has a 3D printer but if you're like me who is building his first 3D printer, wood is a good alternative for the printed parts in case you'd need to make one.

 I intended to use another piece of wood to hold the hot end in place but in the end, I just used cable ties. I wasn't sure if it could handle the heat but it worked surprisingly well. The head will not be carrying to much load so it didn't take much to keep it in place.

 I also didn't need the tongue so I just used it to hold the tube in place.  Now you understand why I called it the Franken-Smartrap :-) I didn't care about how it looked.  I just wanted it to work.

Now, I really must have ran out of luck because I was having one issue after the other. After the j-head mount problem, I found a few more issues because of the incompatibilities of the parts I ordered.  The BOM of the original design asks for a 5M threaded rod for the Z axis. I am hoping the world will realize how inconvenient the english unit of measurement is and scrap it altogether.  I just could not find 5mm threaded rod anywhere! I learned that I could change the steps per mm of the motor so I settled for 1/4 in threaded rod. This means that the Z axis coupler will not be even since the threaded rod is thicker but it's not a show stopper.

However, the associated issue with a thicker threaded rod is that the bolt will not fit the slot in the printed part.

 I held the nut over a flame and tried forcing it in the slot.  It softened the plastic a little and opened up a bit enough to push the nut inside.  It slides out sometimes so I just applied blue tack over it to hold it in place. I planned to print the part with the right dimensions once I get the printer running. 

One other thing is that the shaft of the stepper motors I bought were a little short. It's a little blurry but you will see in this picture that the winding of the fishing line is okay if the Y carriage is in the middle but whenever it is on the far end, there is a chance that it will slip right of the top. For now, I will limit the build area to be as small as 50mmx50mm to keep the carriage at center to prevent the fishing line from slipping off the shaft. At least until I am able to print an adapter.

One last piece to install is the servo before we wire things up. There was no way to drive a crew on the other end so I just used a cable tie again to hold it in place.

Not bad, right?  The next part will be all about the electronics. Stay tuned!