Not fuming, just venting!

When I first started using the hood I thought everything was fine, but after using it two or three times I did notice a downward draught, that was cooling the bed slightly.
My first thought was to seal all the gaps but this did not help. I then tried adding a sort of extension skirt around the bottom of the fans. This seemed to do the trick.
I might be wrong, but I think there are all sorts of turbulent air currents and this helps still the air. I can still feel a slight draught but before I added the skirt,  it actually felt like the fan was blowing down!
I am beginning to feel more confident about 3d printing in general now. Usually once they have started printing I walk away, with only a periodic check.
Some prints have been >5 hours after the bed had come to full temperature.
To test out my new hood I printed this catapult http://www.thingiverse.com/thing:391508 The amazing thing about this catapult design, is that it prints in one piece.
This was my second attempt to print it. The first came out okay except the bucket of the catapult, being printed on it’s own, started to move. I saved it by holding a screwdriver and it sort of fused together.

A one piece 3d print of a catapult
Printed in one piece

I could see all it needed was some supports so I modified the file look like this

Catapult with supports
The coloured areas are the areas I added

Added support pieces are coloured

A hood for all seasons

Extractor fan with hood
Ready for sucking

I measured and cut foam board to go around the fan, then I got the glue gun out and glued it together.
I added weather stripping to the edge so turbulent air inside the hood would not blow down.
I got some drier hose and connected it into the hood.
Looking like a giant slinky, it sits on top of the hood with the window end propped against the wall.

When it is time to extract fumes I put the window end into the sliding window. The idea is that it is put in the window and the window slides shut jamming it in the window.
I made the window end by cutting some hardboard a little smaller than the open window space. For some extra insulation I glued some foam board to it. I also added some more  weather stripping so that there are no cracks when the window is slid closed.
So far when placed in the window there does not seem to be much of a drop in temperature in the room or at the 3d printer though it’s hard to tell because it is not winter and not minus 30 degrees C outside. Noise level is good.

Will have to wait and see. Now I can get back to some printing.

Extractor fan in use
Ready for action