Extruder Trouble

After more than 100 hours successful printing on my new 3D printer, it suddenly failed heavily.
An overnight print stopped halfway, leaving a mess of scattered plastics on my print bed. The problem was obvious: the thermistor got loose from the hot end, and the printer stopped after detecting a 'thermal runaway'. Prior to this however the temperature of the head did exceed the maximum for PLA and so the nozzle seemed jammed with burnt plastic and it looked like the inner tube of the hot end was filled with plastic.  

After spending two days trying to solve the jamming without any success I decided to give up and order a new hot-end. And not go for the lowest price this time, so I chose the E3D Lite6. Still not very expensive at about €35,- 

The kit is really complete. Everything from the smallest grub-screw to the required Allen-keys is included.

And there is a really good assembly guide.Which, near the end, mentions that after assembly you should tension the nozzle again when the extruder is hot. Of course I assumed that would not be necessary if I just tightened it properly in the first place. WRONG!
At one of the following prints I suddenly found black spots and blobs. At first I assumed that the it was just over-extrusion and that the excess of plastic was slowly building up at the tip. So I decreased the extruder flow by a few percent, but that did not help. Then I searched for 'black blobs in 3d print' and many suggested that probably the extruder was leaking. Which was exactly what happened. And after tightening the nozzle again, now with the extruder at 230 degrees, the problem was solved. 

Despite the very promising first two prints using the new extruder, the third failed again due to a clogged nozzle. And so did the fifth, so I decided to give up on the 0.2 mm nozzle and go to 0.3. At first I was reluctant to do that, since somehow it always stuck in my head that a smaller nozzle would give cleaner results. Which is basically true, but not as much as you'd expect as explained in the 'Everything about nozzle diameters' post on the site of Prusa Printers. And it's just so much easier to get a good flow rate. With the 0.2 nozzle I often experienced that the filament feeding would 'skip' due to the fact that the filament just wasn't feeding through the nozzle fast enough. Something I tried to solve by increasing the temperature to 230 degrees. The disadvantage here is that any excess filament on the nozzle tip seems to burn and finally this burnt plastic will clog the nozzle.
 

The 'Makr-B-Bot' Part 2: Building the mechanics

After collecting the parts and studying the drawings and instructions of the Printrbot it's time to  start building. Before I got started I realized two things are very important for a 3D-Printer: It must be rigid, and all angles must be exactly 90 degrees. For lengths up to 30 cm the makerbeam seems rigid enough, although in the end I found that if you lift the bottom frame at one end it still deforms slightly. By using only the pre-cut length pieces I made sure all angles 90 degrees and all guides are exactly parallel .

This is the basic frame. Although over time many things have adde and modified, this part has remained basically unchanged.

Fixing the vertical rods,both at the bottom and at the top.

Mounted the Y-Axis stepper motor on a piece of Aluminium L-profile. A frame made from 4 pieces of 100 mm  is used as the carrier. Four ball bearings on the side, four on the front to carry the Y-Axis sliders.

The Y-Axis slider is assembled from two rods and some 100, 50 and 40 mm makerbeams. Note that on the photo's most parts are still assembled using Ty-Raps. Later on I replaced most of these with hose clamps, but during the build and test phase this is more flexible.

The print bed will be placed on a frame made from two rods and some 100mm makerbeam pieces. I mounted a piece of 40mm beam to the front of the steppermotor and two 10mm ball bearings to that. 

 The Z-Axis motor is placed in the corner, and fixed using one long hose-clamp.

Basic setup, with some electronics to test if all motors run and if it all moves as expected...

The 'Makr-B-Bot' Part 1: Getting started

When the 3D-Printing hype started a few years ago with the RepRap and it's followers, I immediately considered building one. By that time however it was not really easy to collect the parts. People were building their own electronics, frames and extruders from scratch which included a lot of experimenting and tinkering to get it right. Round the same time I ran into a product called 'MakerBeam', an aluminium T-Slot profile for small constructions. This seemed like the right framework for a 3-D printer so I bought the starter kit. Bolted a few parts together and decided it would still be a lot of work to build a printer from this. So the kit ended up in a closet, and I have not used it since..

MakerBeam

In the following years the 3D printer market exploded, and at some point even got mainstream with little €1000,- plug and play printers you could buy at the supermarket. So I lost interest.  The idea of building one did stick at the back of my mind however. And over time I did collect some parts like a set of stepper motors, some extra Makerbeams and  some electronics.

Until recently I got inspired by pictures of the Printrbot Simple Maker kit . This amazingly simple design is probably the most minimalistic printer possible, yet it performs remarkably well for it's price, which is as low as US$350 for a complete kit. Now US$350,- is absolutely a good price for the full kit, but unfortunately that only works if you live in the USA. Once you get it to Europe the total price has become a whopping €550,- (= US$ 590,- !) which more or less defies the idea of a 'cheap DIY printer'. 

Since this is an 'open source' printer so it is possible to download the drawings and make the plywood parts yourself, but that would still be quite expensive for a single unit.

While looking for additional pictures of the PrintrBot design I also found the R360 Printer by Replicator warehouse :

This looks almost identical, but they chose a rotating bed to print on. That seemed a bit too experimental to me, although I understand it works pretty well. I do think it's a little bit too much plastic...

So I wondered if it would be possible to build this specific design using standard Makerbeam parts.

   

And I did not want to spend too much money on it so I spend quite some time to find the cheapest parts....

Parts.

• Makerbeam starter kit.+ extra set of right angle brackets. ( €100 )
• Acme rod (trapezoidal thread) with nut . ( €20 ). This one used to be hard to get, but nowadays most 3D printer shops sell the standard 30 cm version that is used in the RepRap Mendel  (MakeMendel,VanAllesEnMeer (Dutch) )
• Flexible coupling 5 mm to 8 mm.n (€6,50) Any 3D printer shop has these in stock
• 2 pcs Aluminium pully, T2.5 (€ 6,50)
• 1 m. of T2.5 5mm Timing belt (€4,50)
• 12 pcs.  LM8UU linear ball Bearings (€12,-) (€1,- / each is really good deal ! Kromhout Electronixs (Dutch))
• 3 pcs. NEMA 17 stepper motors (€30,- (special package deal, might be hard to get them that cheap now..))
• Funduino Mega 2560 R3 Module (Arduino Mega compatible board) (€15)
• RAMPS 1.4 interface board (€18, including the Motor Drivers)
• 4 pcs. 4988 Motor Driver (Polulu or compatible) 
• Geeetech MK8 All Metal 3D Printer Extruder (DealExtreme) (€45)
• AT Power supply (second hand, from an old PC)
• Lots of Ty-Raps
• 16 Hose clamps, 12-22 mm (€10)
• 2 pcs. 1m. 8mm.  Steel Rod (€15)
• Heated bed (€15)
• 16x24 Photo frame (€1,50)
• 12V/ 20 A Power Supply (€24,-)

Total: € 322,50
 (Actually a little less since not the whole MakerBeam kit is used)

Again, the US$350,- for the the PrintrBot Simple kit seems like a bargain. You probably have to buy all parts in really large quantities to get that low. Not to mention the US$179,- TIKO 3D , or the US$199 Genesis UNO  ..
And with the colourful DaVinci minimaker entering the local toy-shop, 3D printing definitely entered the realm of consumer goods.