Small Footprint CoreXY Y Carriage (derrivative of Smartrapcore) :: X rods are end-supported and clamped, linear bearings are clamped

See the 3D Model in a better viewer than thingiverse's at Sketchfab:

https://sketchfab.com/models/b88a3147d5fb47189e2bd58f871331e8/embed

This is a design of an Y Carriage for a CoreXY I am building.
It uses 8mm rods for the X axis and 10mm rod for Y axis. The bearings are 608s.
Note: the diameter of the rods has been calculated based on their unsupported length and the weight of the parts they'll be supporting. More details you can find on reprap forums.
The X rods' back-rest bolts are M4 and the lower bolt is intended to clamp both the LM10UU bearings while also providing support for the lower X rod. The X rods are clamped using M3 bolts/nuts. Extra rigidity comes from the side wall, which is the side you will print this thing on

Update 10/06/2016: Uploaded an 8mm (LM8UU) version by just filling the gap between the LM10UU hole for the bearings and the LM8UU diameter. Also attached the RSDOC file with both designs. NOTE: PLEASE check the RSDOC and do the measurements so it fits your design!!!

I must say that this is my slickest design to date for "CoreXY" Y Carriage with Vertical Stacked X rods.

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[Older updates]

Update 12/04/2016: I did an overhaul of this design, changing some of its core features: I have managed to get both rods back-supported. The solution is easy to see in the attached images.

Update 11/04/2016: It has been brought to my attention that any plastic carriage for Y axis that is not offering a solid back-rest for the X rods will be suffering of Y rods flexing due to the tension in the belts. The X rods in the current design don't stop flush with any wall, instead they are clamped with plastic features via M3 bolts/nuts. This might be sufficient as the Smartrapcore proves (is it?) but I will be migrating to designs that can sport back-screws for the X rods's ends.

I have updated the STL as well as attached the RSDOC (DesignSpark Mechanical) source file for the "SmoothRod-Backrest" version, where only the upper rod is back-supported by an M3 bolt. The lower rod should be flush with the plastic wall, as shown in the attached pictures.

You can read a bit more about this at: http://forums.reprap.org/read.php?397,650342,650430#msg-650430

Update 24/03/2106: New version: got rid of M8 bolt (too massive, heavy) and replaced it with M5 bolt + M5 Round Coupler (OD 8mm), the washers and 608 bearings remain for this version. Both STL & .RSDOC uploaded.

Update 04/03/2106: New tweaked file uploaded together with the RSDOC for easy CAD (true geometry) editing.

Update 23/02/2015: If you are printing in PLA, the previous design might have been too easily to break for the rod clamping lips. I think I might have forced it too much though, as I tried to touch the two lips without the rod so the flex was too much for PLA to take. As a result, I have reinforced a bit the thin side at the rod hole level, as you can observe from the attached update.

Update 18/02/2015: I have uploaded a corrected design for the Y carriage, one that has a bit larger gap for the two 608 bearings and the washers that will prevent the outer race of the bearings to make contact with the plastic or with each other.

I have also added a second hole for the mirrored carriage, a hole that was missing from the previous design.

Another modification is the curved cut that makes easier the opening or closing of the smooth rods receiving hole as it was pretty difficult to clamp in the previous version.

Update 24/01/2015: For the less precise printers, which can't ensure very accurate hole sizes (which are an absolute requirement to clamp at the same time the 8mm X rod and the linear bearing), I have uploaded Ver2, which has one screw per hole. The M8 bolt still performs two functions, clamping the linear bearings as well as being the shaft for the 608 bearings, while the 8mm rods are clamped by M3 bolts/nuts.

With this design the Y carriage can be pushed very close to the frame. The orientation of the print is the same with the first version, on the flat side.

The 8mm holes are exact while the linear bearings hole is a tad larger than the LM10UU OD. It doesn't matter much with the slots that allow for diameter variations accommodation as well as easy insertion. The Nut insert holes are also exact and I recommend hot insertion of the nuts.