Hank's 3-point bed leveling for Printrbot

thingiverse

This printrbot print bed platform and base starts with Beardface's printrbot bed ( http://www.thingiverse.com/thing:17717 ) and incorporates a three point leveling system using the leveling knob idea from http://www.thingiverse.com/thing:9094 (reimplemented as an OpenSCAD file), but using a 3-point leveling approach. The bed platform and base are designed to be cut out of 1/4" MDF using a laser CNC printer. The spinner knobs can be 3D printed from ABS or PLA. Caveats: Since the leveling system uses two layers of MDF with at least 1/4" spacing in between (for the two nuts and a little space for leveling) this system will reduce your printable Z-height by about 1/2" or a little more. The holes for attaching the print bed to the bed platform are spaced for clipping an 8"X8" bed to the base from the outside. If your heated bed attaches via holes in the corner, the 4 holes for attaching it may need to be adjusted. The SVG file included can be edited using InkScape ( http://www.inkscape.org ). Instructions Bill of Materials: Original parts from PrintrBot 3 #6 panhead machine screws 1 1/4" to 1 3/4" in length. 9 (optionally 12) nuts to fit the screws. Standard or 1/2 height jam nuts are fine the bed platform, cut from 1/4" MDF or plywood the base, cut from 1/4" MDF or plywood 6 copies of the spinner knobs The holes and knobs are scaled to use 3 #6 panhead machine screws and nuts to attach the bed platform to the base. It attaches to the existing printrbot Y axis connectors and belt holders. Print out 6 copies of the spinner knobs: three fit above the base and three underneath. Nine nuts are used: 1 on each screw immediately below the top platform and one each above and below the base. The first nut holds the screw firmly to the bed platform, and nut and spinner knob above the base is used to adjust the height, and the lower spinner locks the platform firmly to the base. If desired, the top nut can be locked with threadlock, a 4th nut added to use as a jamnut, or it can be left alone (perhaps with an occasional retightening, if needed). For my bed, the layers are as follows (from top to bottom): glass plate heated bed cork sheet 6 pan head screws (heads up) MDF bed platform (all the above held on to the MDF bed platform with clips in the corner) uppermost nut, locking panhead screw to bed platform upper spinner knob (with nut inside) MDF Y-axis base Y-axis mounts from original Printrbot, attached with original machine screws. Install the base and the bed platform such that the 2 leveling screws are to the front, and the single leveling screw is to the rear. To level: Once installed, no tools are needed to adjust the level of the bed, the upper spinner knobs adjust the bed height and the paired lower spinner knobs allows one to lock the bed firmly to the base one leveled. Start by loosening the three lower spinner knobs. Then, using the upper spinner knobs, lower the bed on all three screws until the bed has 1/4" free space between the uppermost nut and the upper spinner knob. With the printhead to the front of the platform, use the upper front two knobs to level the bed left-to-right. move the print head over (or even with) the first leveling screw, and adjust the Z stop. Move the head even with the othe front leveling screw and adjust til the height matches. If needed, readjust the 1st screw and repeat until both are level. Lock them in place by tightening the lower spinner knobs. Once the front is zeroed in, move the printhead to the middle, then level the bed front-to-back using the third leveling screw and spinner knobs. Lock the rear knob once the bed is completely true.