Summary

This is an extruder/X-carriage set designed for the ORDbot. It is based off of WildBill's extruder body.

It has low weight and keeps the mass close to the extrusion to reduce vibration and enable faster movement.

Instructions

WARNING: THE FREE END OF THE MOTOR OUTPUT SHAFT MUST BE SUPPORTED BY A BEARING. IF THIS IS NOT DONE THE GEARBOX MAY FAIL. My fix was to drill a 1/2" hole in the far side of the extruder body and hot-glue a bearing in. This seems to work well enough to prevent any issues.

Attached are the following files:

ORDbot_PG35LExtruder.STEP :: STEP file of entire assembly as seen in the picture.
ORDbot_PG35LExtruder.zip :: Packed SolidWorks assembly, version 2009.
WheelPlate.STL :: STL file of X carriage.
WB_Extruder_IdlerArm.STL :: Extruder idler arm
WB_Extruder_Mainbody_R1.STL :: Extruder body.
Assembled_Frontview.JPG :: Picture of physical assembly showing zip tie routing and general details.
Assembled_Rearview.JPG :: Picture of physical assembly showing zip tie head location and extruder body mount bolts.

I strongly recommend printing the carriage in PLA. I tried ABS and it is not stiff enough.

I designed a belt clamp piece but it didn't work out. I resorted to a M3 screw with an M4 washer and just clamped the belt between the washer and clamp block. This works fine and doesn't rub on the extrusion.

The belt clamp block may rub on the extrusion, file it down if it does. It's a little too tall and I didn't redesign it.

The extruder body should be printed in ABS, both pieces can be printed at once. Since Slic3r can make its own plates now I didn't bother.

NOTE: The extruder is set up to take a J-head hot-end, mounted with metal squash plate with 2 M4 bolts set 15mm from the CL of the extruder.

The extruder is mounted with 4 M4 bolts, one of which uses a blind nut trap. This bolt needs to be cut to length so it doesn't bottom out in the hole.

The belt should be run through the slots in the side ribs.

The eccentric space should go on the bottom wheel. This way most of the load is carried on the top 2 wheels, which are much more stiffly mounted since the standoffs are integrated into the plate.

The motor should be zip-tied to the plate using the slots above and below (see picture). This helps reduce oscillations of the motor.

I got lazy and just hot glued the fans to the carriage instead of making fancy brackets.

The motor runs hot and requires a 40mm cooling fan. The motor can be found here: http://store.trinitylabs.com/trinitylabs-micro-extruder-gearhead-motor-and-options/

ORDbot PG35L Extruder & X Carriage