Open Hybrid Mendel

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Open Hybrid Mendel (OHM)

Release status: Working

Description	A hybrid between Prusa and Mendel models using several improved pieces from the community
License	GPL
Author	User:Community
Contributors
Based-on	Sells Mendel, Prusa Mendel, Community improvements
Categories
CAD Models
External Link

Overview

The Open Hybrid Mendel (or OHM) is a project of the Penn State Reprap User Group. It is a Mendel design, which uses both standard Sells Mendel parts, a Prusa Z drive, various redesigns from the community at large, and a number of small design improvements developed in our PSU Reprap class. It is so named due to this hybridization of designs, and obtains the 'Open' designation from the OpenX and OpenY axes it uses. The prototype for the OHM design was Etherdais_Unit_One

Any Mendel can be broken down into 6 sub-systems, which are somewhat interchangable between designs:

Frame - The OHM uses Camiel's thin shelled Vertex design, maintaining vertices similar to the Sells design, but using less filament

Y-axis - The OHM uses a modified OpenY, with an optoless belt harness (add thing), and a second 90/180 arm in place of the 90/270 arm. This demands two additional bearings, but we find the result is more stable, while retaining the benefits of the OpenY. A modified Sells y-motor bracket is used, which avoids printing an unused endstop holder from the original Sells design.

Z-drive system - The OHM uses a Prusa, double motor design for driving the Z axis, avoiding the large prints and continuous belt of the Sells Z-drive design. We still use Sells bar clamps to clamp the smoothe rod to the Z-motor mounts, as they are compatable, and look sharp together.

X-Z assembly - Currently, the OHM build uses a standard Sells X-Z assembly, as described here in Mendel_X-axis.

Carriage - The OpenX carriage is the design of choice currently. This, and the OpenY

Extruder - We are in the process of finding a design which is more compatable with the TechZone steel hot tips we've been using recently, though the current design is a hack of herringbone extruder gears, and GregFrost's hinged wades extruder.

Parts

Quantity	File-Name	Comments	Diagram
4	bed-spring_4off
6	Camiel_frame_vertex_7off	Alternative part by Camiel
2	z-prusa-motor-mount
2	prusa_bar-clamp_2off
2	Pla_coupling_nophead	Alternative part by Nophead
2	X-180-z-bearing-plate_2off
2	X-360-z-bearing-plate_2off
2	X-360-z-bearing-plate-mirror_2off
1	Xaxis-motor-bracket_1off	Alternative part by Rhys-jones
6	X-bar-clamp-m3_6off
4	X-bar-clamp-m4_4off
1	X-end-bracket_1off
4	X-vert-drive-nut-trap_4off
2	X-vert-drive-side-plate-180-end_2off
2	X-vert-drive-side-plate-360-end_2off_rebuild
4	Y-bar-clamp_4off
1	Y-idler-bracket_1off
1	Y-motor-bracket_1off_mod3-15	Modified by PSU Reprap Collective
2	Z-bar-top-clamp_2off
2	Z_leadscrew_base_with_apron_mod_3-19	Modified by PSU Reprap Collective
1	HerringboneDrivenGear	Alternative part by Rhys-jones
1	HerringboneDriveGear	Alternative part by Rhys-jones
1	Gregs_accessible_wades_v6	Alternative extruder by Greg-Frost
1	Gregs_accessible_wades_idler
1	OpenX_Carriage	Open X by Buback
1	OpenX_Undercarriage_Bracket	Open X by Buback
1	OpenX_Arm	Open X by Buback
1	8mm_Belt_Harness_1off	Open Y by Buback, modified by PSU Reprap Collective
2	8mm_Crossbar_Mount_2off	Open Y by Buback
2	Arm_90_-_180	Open Y by Buback
1	Arm_210	Open Y by Buback
1	OpenY_Undercarriage_Bracket	Open Y by Buback
3	Electronics_board_mount	Created by RUG member SethG
2	X-axis-side-plate-nut-jig_2off
2	Z-leadscrew-base-bar-clamp_2off
4	modified endstop holder	Prusa opto holder modified to have a thicker end	No picture yet