This is my second model of a Sarrus linkage type linear axis. A Sarrus linkage uses hinged joints to create linear motion. The point is to get a linear bearing acceptable for making a portion of an x-y cartesian assembly without having long polished metal sticks, thus obtaining a 3D printer that can create more of its own pieces.

Notice that there is a set of 4 holes on the top armature that fit 4 hole patterns on the end pieces. It follows that one axis could mount on two others at right angles.

Drive system: DC motor from a inexpensive garage sale inkjet printer, using the timing belt in the printer. The pulley at the other end of the belt is a screw/washer/spacer combination with a skate bearing. The skate bearing is mounted in a flexure plate design mount to provide tension the belt.

Optical feedback: I took a optical quadrature encoder and encoder strip from the same printer as the motor. The encoder is mounted on the moving armature, and the strip is anchored at both ends in the end blocks.

Hinges: The hinges on the Sarrus linkage are made with 1/16" diam brass pole as the hinge pins. The holes for the hinge pins were reamed out with a 1/16" drill bit.

Frank Davies


all_parts. Stl is for looking at the completed assembly, and how all the parts go together, it's not for printing.

The individual stl files for printing are in the . zip file.

Total printing time about 30 hours.
Printed pieces:
quan 1 pulley_plate
quan 1 belt_plate
quan 1 motor_plate
quan 2 end_piece
quan 2 armature
quan 4 spine
quan 6 hinge_plate_type_a
quan 6 hinge_plate_type_b

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