Sinds few weeks my printer is in operation. I have to say that the clear description makes it rather easy to finish the job. The couple of small problems which are met could be solved by visiting this forum. In the mean time I have made a few improvements/additions. As many users I have covered the flat bed by a glass plate. The distance between nozzle and flat bed is now the same over the whole area. By the way; I found that transparent sheets for copy machines show a very good adhesion with PLA filament.
However, the adjustment and sensing of the height was still rather primitive and not realy reproducible. I have solved this by canibalizing a cheap micrometer. This device is mounted with some printed aids at a good accessible place. The adjustmen is very convenient now.
Since the electronics become rather warm a fan from an old computer was mounted in front of the control board. The fan is directly connected to the 15V power supply via a micro switch. When the X- wagon is in home position the fan is switched off.
The printer is more or less located in a case. It was easy to make a hole in the wall of soft concrete, so that a suction system could be made with plastic tubes. The outlet in the roof for the loundry dryer is used to blow off the air. An additional temperature sensor is located near the print head so that the fan starts if a temperature of about 180 degress is reached.
Although I think some new ideas will coming up, I am satisfied at the moment.
Love your micrometer idea! I think I’ll might copy that one 
Thanks for the tip!
And btw: Great pictures!
@ merallas : do you have the stl files for the micrometer support? Did you remove the clamp of the micrometer? I’ve got one and it has a c-clamp atteched to it. Is it possible to use that one also?
You can find the stl files here: hgballersma.net/print3d It are very simple structures, made in SketchUp. When loaded in repetier you have to multiply the dimension by 10. I modified the support somewhat after printing. Perhaps your micrometer has other dimensions. I sawed away the largest part of the c-clamp. A hole was drilled in the small segment which was left, so that it could be attached to the printed support.
For better flatness I had covered the heated platform with a glass plate. However, the adhesion with the filament ( in spite of cleaning the surface) was not very well, so that several prints failed at some stage. Therefore a new solution has been made. In this case the glass plate is use to support the original flat bed. They are glued together with dubbel sided tape. Four holes (8mm) are drilles for the bolds, where a hole of 20mm was drilled to make space for the temperatue sensor. The flatness is now sufficiently accurate and the adhesion of the filament with the original flat bed is very good. A glass plate of 4mm has been used (a thinner plate damaged during drilling). It appeared that the additional weight (0.4kg) did not influenced the printing process in a negative way. Moreover, it is believed that the flat bed is more stable after this modification.
Because my printer is situated in the living room it is not allowed that flavour is generated. Furthermore it is not desired that the accessibility is deteriorated. A suction system has been designed which meets these requirements. An commercial available adapter (used for systems draining away rain-water) has been modified so that it could be attached to the printer. The suction opening is in oppsite of the fan. The adapter is connected to the previous described suction system by means of a flexible tube.
To get a better idea about the flatness of the print bed I have mounted a dial gauge close to the nozzle. The distance to the flat bed can be measured with an accuracy of 0.01 mm. The bed is started at the zero position. The manual control function in Repetier has been used to displace the bed over distances of 50 mm in the x- and y direction, respectively. An exampel of the measuring grid is shown below. It has to be taken into account that the properties of the transportation system can also influence the distance.
I think it is not a bad result. As could be expected the deviation is somewhat larger in the corners, due to the bolts.
The nozzel height can now be adjusted at a location which is close to the averaged height. This will result in an optimal ajustment.
I am curious if more users have perform such a measurement and what their findings are.
Thanks for the tip!
