DIY 3D Printer, cheap

Your next project could be DIY 3D Printer.

Creating things out of thin air has always been man’s dream. Unfortunately 3D printers are not molecular synthesizers. No doubt in near future every household will be using 3D printing device, just like microwave. We’re talking here about really close future.

Why Smartrap?

I’ve done some research and found out 3D printers’ prices can be ridiculously high (e.g. 20x cost of materials and labour). Price was an important factor. Even though I wanted to tinker a bit, I didn’t want to bother with collecting all the parts by myself.

Smartrap 3D Printer is open sourced design and part of RepRap project, which means you are free to modify it and/or source your own components (more about it in my next post). Its simple design and compact size makes it great entry level 3D printer.

You can order your Smartrap at: I chose the RAW version.
Please note! With this printer you can use only PLA filament! PLA doesn’t need heated bed. It’s much harder than ABS, which makes post production (smoothing, removing supports) more difficult. PLA is generally non-toxic, food-save (buy certified) and biodegradable.

Unfortunately Smartrap distributor had some problems with parts being imported and I had to wait over 2 months for the kit. Still communication with Smartrap Crew was fast and they were answering all my questions and concerns quite quickly.

Tools you will need

  • Multimeter
  • Pliers
  • Electrical Tape
  • Two sided tape
  • Soldering Iron/Gun (make sure you know how to use it)
  • Drill
  • Cardboard knife
  • Blowtorch (to soften plastic parts or bend them, also great for Crème brûlée)
  • Hex/Allen keys of various sizes (M2.5,M3,M4 mostly)
  • Screwdriver (buy whole kit, you will need every size eventually)
  • Hammer – when some parts just don’t fit, you make them fit
  • Time – achieving good quality printing may take few days, after you get some experience you can build it again in less than 4 hours.
  • Cat – probably the most interested with your work, not judgmental, ball of fur. Steals cables, though…


Everything came neatly packed, nothing was broken. Yet… 100k thermistor was missing, had to buy it at local electronics store (fortunately these are really cheap).


Some photos were made with my phone camera – those are not the best quality ones.

As a picture speaks a thousand words I tried to make best possible shots of the building process. I’ll comment only on steps which I found difficult or mistakes that could be costly. Assembly of mechanical parts is quite self explanatory. Just remember that if you want to attach something to plywood, drilled holes need to be slightly smaller than screw diameter. For M3 screw use 2.5mm drill. Very often holes in plastic elements are too tight, you can use drill to make them wider. Keep in mind that whole construction needs to be as rigid as possible, so having loose screws may influence greatly on your future prints’ quality.





I don’t like the original design of the Z bearing as it failed me after few prints – it gets loose and eventually breaks. You can easily upgrade this part later on.

End Stops

End stops let your printer know where your printing bed ends. You have 3 end stops, X-Axis, Y-Axis and Z-Axis. They form really simple mechanism which just closes circuit (logical 1) when the lever is pressed and signals the electronics. With Raw Kit you need to do soldering on your own to get them wired. Connect them to RAMPS.


Huxley hot end used in my version of Smartrap is easy to assemble and quite ingenious. Unfortunately it can be used only with PLA filament prints. There are different hot end designs available for both ABS and PLA (e.g. J Head Nozzle).

I found it really difficult to screw both ends (metallic tubes) of bowden tube. One end holds bowden tube attached to the extruder motor while the other one attaches it to the hotend. Important step you shouldn’t forget is to put thin teflon tube into the nozzle and trim it just at the edge.

Merlin firmware (on configuration later) used by Smartrap introduces mechanism to compensate for not perfectly levelled printing bed. Printer probes 3 (or more) points and triangulates real printing plane. Z Axis endstop is used to detect surface level at each point.

Whole thing

Finally your printer should look similar to the one below:


Smartrap comes with Arduino Due, RAMPS 1.4 and four step motor controllers (step sticks). Raw Smartrap comes with raw, uncut ribbon and cables (stepper motors, thermistors, extruder heater). You have to install all the female or male pin headers yourself.

Clamping header on ribbon cable is really easy and you shouldn’t be afraid of messing things up. I used bare hands to clamp and all works well so far. Just remember to pressure evenly otherwise you will probably short circuit neighboring cables, which is never a good idea. These posts helped me a lot:

To install PIN headers you don’t need solder iron. Pliers are more than enough. Always use multimeter before you attach cables to electronics to check if everything holds tight and is connected correctly.

RAMPS should be installed on top of Arduino Due. RAMPS is designed as an Arduino Shield (an extension) so all the pins should fit perfectly. With RAMPS 1.4 you will find few jumpers which need to be installed under step sticks. Putting 3 of them under the step stick makes 1 step equal 16 microsteppes. It’s my configuration. Step sticks should be installed at E0, X, Y and Z positions (should be labelled on RAMPS board). Make sure your stepstick pins order matches the one on the board (e.g. GND, VDD Enable – should be labelled both on RAMPS and stepsticks). You don’t want to attach it upside down. Take a look at yellow dot on photo below.

What’s next?

After your build is done you will spend some time configuring software and calibrating the printer. About it in my next posts.

For those wondering how fast can this printer print (with acceptable quality) here is a short video:


Extruder upgrade

After my new DIY 3D printer was ready and printing it has became clear some parts’ design wasn’t best, this especially applies to the extruder. Thanks to the I was able to easly repalce it, even though I had to push filament with my bare hands for 2 hours so I could print it in satisfactory quality…

If your extruder motor kicks back and you are sure your printing surface is perfectly flat and printer is calibrated correctly, you can slightly increase current it gets by adjusting little screw on top of the stepstick controlling it. As it’s easy to short circuit use plastic screwdriver or use electrical tape on the tip of screwdriver as an isolator (still dangerous). You will find more information on this topic here:

Plate upgrade

Other arguments against my version of printer are Linear bearing holders, which get loose due to vibration, and regular need of glass plate removal. Thingiverse offers upgraded designs. I used blowtorch to tighten the holders. I will model upgrade in Google SketchUp in near future.

Clone it!

As I have my very own DIY 3D printer now I’m able to clone it and upgrade it. Just recently my step father asked me to build a 3D printer to use in his architectural studio, so he will be able to offer models of future buildings to his customers. How cool is that?

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