ReliaBuild 3D - 20 tooth Pulley Option

These brackets are the official ReliaBuild 3D printer brackets for using 20 tooth pulleys. They will work with the RB3 and RBB3. They will also work with the Rigidbot Standard and Big printers if they are using the upgraded bed carriage. In general these will work on a 0.75" or 19 mm square rail with rounded edges.

Assembly hardware needed for a pair of brackets:

• 4 x MF115ZZ flanged bearings
• 4 x 9.5mm x 5mm x 3mm Nylon spacers
• 2 x GT2 5mm bore 14mm tall 16 tooth pulley for a 6mm belt (3 or 4 mm set screws)
• 2 x 5x25 mm 4mm socket head bolts and nuts
  Use the same M4x8 bolts (qty 8) used to mount the original brackets

These are designed for using two MF115ZZ flanged bearings in each X and Y bracket set with a 5x11x4mm size and opposite of a GT2 5mm bore 16mm tall 20 tooth pulley for a 7mm belt. Since the idler bearing with the belt wrapped around it has the same diameter as the 20 tooth pulley with a belt around it the brackets can be centered in relation to the pulleys. The same bracket set will work for the X and Y directions. There is however a top and a bottom bracket piece with the slot for the nut intended to be facing down for easy tightening.

A 9.5mm x 5mm x 3mm spacer goes on either side of the bearing set between the brackets. A printable version is included here.

Two 5x25 mm 4mm socket head bolts with M5 nuts are needed for assembly of the two bracket sets. The assembled brackets mount to the rails with M4x8 bolts.

The belt clips on the bed carriage and the extruder carriage need to be moved over towards the new belt location. A drill guide to mark the holes is included. The small pegs go in the original holes and the through holes mark the new location to align the belt clip. Use a 1/8" drill to make teh through holes in the bed and extruder carriages.

DXFs of a modified carriage for a Single and a Dual extruder are included for those that want to have one cut from 1/8" thick flat aluminum plate.

Adjust the height of the pulleys such that the belt clip barely clears under the carriage.

If you have an RB2 or ReliaBuild 3D board in your machine change the number of steps in the firmware for the X and Y directions to 80.3309814
If you are using an original Rigidbot board the Y value will be half of this.

There is a belt tightening key to help push the bearings in and tighten the belts.

Use thermally calibrated filament for best fit results. I use this clip method.
https://www.thingiverse.com/thing:1037301