Finally, after over 2 moths I post something. (I am aware it proves I am a poor blogger, but what meh...). In fact the main reason there were no post was that there was nothing to report. I am having one of the most tense periods in my file, and the printer simply went into the second range of interest.
Anyway, playing with my RepRap still proves to be a great way of "getting away from wicked reality", so throughout these moths I found like 3 evenings to look into it, and here are the results.
In the last post I mentioned that I needed to add a heated bed, and get a better hobbed bolt.
These things were acquired. The bolt was a tiny thing, costed like 7eu with shippimg, and I got it from a very nice guy from UK. The heated bed was a bigger deal, still did not kill me with its price. I got it from eBay page of Reprap.me, and paid 40$ (30.5eu).
Of course after I got the parts, they lied a lot of time. Finally they caught my eye and got mounted.
Here are some pics:
Looks quite nice, doesn't it ;) The addition of heated bed made it necessary to move the printing layer up, as seen on third picture. The heated bed requires to have a thermocouple to measure its temperature. The bed has a tiny hole in the middle, where you are supposed to put it. There was some fun with that (especially to make it stable) but as seen in the fourth picture, I managed to to that :) Regarding the hobbed bolt- it went into the extruder.
Now, we have the printer ready. There was some calibrating to be done. First- level the whole thing. After that, there was the fight with matching proper extruder engine speed. It was going too fast, thus insted of pushing the filament, the bolt was also "drilling" it. In the end the drilled hole was so big that the filament could not move down. I re-calculated the parameters like 10 times, and still there was something wrong. All the problem revolves around converting rotation distance of the engine, through the gears onto the bolt. Finally I found out that there are two ways that the G-code (language of the printer) interprets the distance of extrusion: absolute and relative. Of course I had the wrong one selected. After selecting "relative" the extruder slowed down and it seemed that I can start the work!
As the first print, I decided to try a "test" geometry. Here is how it looks like:
Well, its not hard to tell that something went wrong ;) In fact most of the parameters were off. The extruder and bed temperatures, the layer thickness, the speed of all motors, well, almost all. After giving even more thought into selecting them (and after reading all of them carefully :P ), and after several unsuccessful initialization, I made the second print:
You have to admit it looks much, much better! There was some trouble with initial layers, and the 3rd to last one did not stick properly, resulting in crippled arch in the top-left part. but overall I have to say that am very proud of it :)
After that success I thought- why stop now? I twitched a bit the parameters again, and started a print of a pulley:
This was a nice experience. I learned that I can not be cheap, and save on electricity too much. After printing the first layer I instructed the printer to lower the bed temperature from 110 centigrade (for ABS plastic to stick) to 60 centigrade. That was s bad call, since after few layers, during printing, the nozzle touched some irregularity on the part and disconnected it from the bed. Of course this destroys the print immediately. Here are some pics of what was done before the print broke:
As the last thing in this long post I want to address a health and safety issue. When your printer is idle, and just a moment ago you extruded some plastic, the pressure will push some of it out. It is a common practice to take it away using some pliers. You will often do that during heating of the nozzle. REMEMBER! The current going through the heating resistor is high! Always use insulated pliers. Also, be very careful not to connect the resistor wires to anything grounded with your pliers. I learned the hard way. During "plastic removal" I touched the resistor wire and the thermistor one. There was some light, sparks, heat and a melted wire. Here is a picture of the nozzle with modified wire positioning and "repaired" thermistor. Fortunately it did not burn and works, but still I will replace it as soon as I get some cash for it.
As a note- the white goo is a thermal paste used in computers for better conductivity. The brown spots are the burned plastic. I still work on getting proper nozzle temperature.
Well, that is it for today. I am finishing my PhD shortly, so expect that just after that there will be a lot more printing, and more content on this blog! :)
See you later!
