Wool winder / spool

A major disadvantage of buying knitting wool from dope-headed hippies is the fact that it doesn't come in ready to use form. It has to be pre-washed, color-fixated and -last but not least- wound up onto spools or into the familiar playthings of the common household cat.
In order to save my son from being used as a living wool-holder by his knitting-crazy mother, I designed this thing.
Design was by myself, although I frankensteined parts from other things into it:

http://www.thingiverse.com/thing:1832235
From this one I used the rollers as a mount for the skateboard bearings.

https://www.thingiverse.com/thing:1959208
Here I used screw and screw hole of the back plate for the table mount.

Design principle is a scissor-extender on two movable mounting plates. Two, because I was too lazy to design a fix for one of them. Some fixation for the mounting plates is provided by the friction between the bearings and the aluminium rod. Important ! The aluminium rod has to be of the