I came across the Yet another dispenser for filament spools
by Think_3D and the SIMPLE SPOOL HOLDER FOR MENDEL which I liked very well but it had some problems. The main problem was due to the fact that the spool is so low and far back that the filament would rub against the threaded bar which was not good. There are quite a number of different solutions to this problem, mine was the Mendel Filament Guide which is the ancestor of this thing. It snapped onto the top of the Mendel and allowed using left over round bar as a guide so the filament didn't rub against the threaded bar. This served its purpose but as one Thingiverse user pointed out required round bar that he didn't have on hand. It also proved something else; my snapin design worked very well. Then a couple of weeks ago I saw the Over The Top Spool Holder V2 by BackyardWorkshop and thought that this was very similar to my snap-on filament guide. I especially liked the idea that the spool was mounted above and not as far behind such that the filament went straight down. That thing had to be held by M8 nuts and I thought I could improve upon that so I started with my Mendel Filament Guide thing and then decided where I wanted the center of the filament spool to be relative to the guide holder and put it there. Then I added to circular support struts such that the snap-in capability wasn't lost and then added a support circle with the RepRap LOGO.
Print out one left spool holder and one right spool holder and snap into the inside of the top frame vertices by sliding the long hook to the front threaded bar and pressing on the rod holder to snap onto the back threaded bar. To remove grab entire spool holder with one hand down low and pull up and back.
Print out two wheels, pop one 608 bearing into each of the wheels.
Cut a piece of threaded bar to a length of 24cm.
Put one wheel into each side of a standard filament spool.
Put the threaded rod through the bearing with the same amount sticking out of both sides.
On each side add an 8mm washer, 8mm nut, 8mm nut, 8mm washer, 8mm washer and an 8mm nut. The inside nuts should be make tight enough to hold the two wheels in. The second set of nuts should be 1 cm from the nuts just tightened with the following washer right next to it. The last set of nuts should be as close to the end of the threaded bar as possible with its matching washer right next to it.
Now center the threaded bar onto the Mendel snap-in filament spool holders and by hand tighten the second set of nuts to the inside of the filament spool holders. Now tighten the outside nuts to the outside of the filament spool holders. Tighten with a wrench.