Thank you. I just saw this log. Is there enough room for the gear inside the base? Just to be sure before I start the very long print next weekend.  Just a small remark. Wouldn't it be easier to use vertical holes instead of horizontal ones? This way it can be printed without support. 

And is it possible to insert a fan mount on the other side to? In one of Olafs logs he is using 2 fans to blow air inside the base and that air then goes up trough Axis 1 to cool the motors in ART2. (He doesn't use a slipping). It would also be possible to use 1 fan to blow air into the base and one to suck the air out of it.

Also another question.  According to Angels Freecad drwawings a 5mm shaft has to be inserted into the Art 3 Pulley. The axle of the Axis 3 Stepper Motor with gearbox is 6 mm. So I also ordered a Pulley with a 6mm bore. How do I put a 5mm shaft inside a 6 mm hole. Do I have to use a spacer for it? Or did you order another bearing ring with a 6mm hole.

I could also use a 5mm Pulley and drill a 6mm hole for the motor shaft.

I only need one fan in the base. I was using a 30x30 mm fan instead of a 40x40 mm and was concerned that it would not be enough. I do not have a slip ring so my cool air also gets pushed upwards cooling the 3 stepper-motors above it. It was 26 degrees in my room when I tested this.

A 40x40 mm fan makes less noise. This is important because I tend to have free time after midnight. 

There is enough room for the maingear, a second fan wasn't possible because of the end sensor but I changed the direction of the holes to vertical for you, you can download at my page. :-)

I drilled out the pulley to 6mm.

Thank you very much!

I think it depends what brand and price you take, some while ago I ordered some very cheap 40x40 fans and they make a lot of noise, ordered some other twice so expensive and these you don't hear anymore! Sometimes the cheapest isn't the best solution ;-(

The 40x40 mm fan is making less noise than the 30x30.