Up Mini Adjustable Bed Mod for Raftless Printing

thingiverse

To achieve perfect raftless printing, the print bed must be nearly perfectly level. This is exactly why this mod was performed. Fortunately, it's completely reversible and doesn't require any alterations to the printer itself. Since completing the modification, I've been able to level the bed within 0.1mm across its entire printing area. I'm currently using a print bed consisting of 0.03" PEI laminated onto 3mm borosilicate glass with a 3M 468MP adhesive sheet. You'll need to print: 4 x Spacers 3 x Locks (for securing the wing nuts in place after adjustment) 4 Clips (two of each type) - printed at 0.2 with no support An adjustable heat bed support: http://www.thingiverse.com/thing:1689233 4 x Shims (if you want to use the original perf board) Bolted Linear Rail Clips (Optional, but the clips are quite fragile and tend to break): http://www.thingiverse.com/thing:1688852 First, remove the heat bed and frame from the printer. Take out the two screws at the top of the heat bed and slide it forward or backward to expose the ribbon cable connection underneath. Gently pull down on the retaining clip and carefully remove the ribbon cable. Next, remove the two screws that attach the belt clamp to the underside of the frame. Loosen and remove the two linear rail clips at the front and slide the entire frame out. Remove the "L" support block from the center of the frame. Remove the four suspension clips and springs from the frame. Cut two lengths of 12x3mm Aluminium Flat Bar at 140mm long. Drill 4 holes in each, centrally aligned with the (spring) holes in the frame and the holes in the corners of the heat bed. I used 25mm long bolts throughout and just cut them down to size as required. Fit the flat bar to the frame using the printed spacers. The bolts should not protrude much past the nuts on the inside of the frame. The left-hand rear corner bolt head (when viewed from the front) needs to be countersunk to avoid clashing with the printer's frame at that location. The (spring) holes in the frame may need to be enlarged slightly to fit the M3 bolts through easily - I used a 3.2mm drill bit for all the holes. Fit the new heat bed support parts to the frame and heat bed. Place a bolt in each clip, using the springs removed from the frame and positioned between the underside of the clip and the top of the flat bar. Place a wing nut to the underside of the flat bar. The bolts should not protrude below the underside of the wing nuts. Do this for 3 of the clips. For the left-hand rear corner, countersink the flat bar from underneath and place a nut in the top of the clip - again to avoid a clash with the frame in that corner. The thread should not protrude above the nut on the top of this clip so as to not touch the underside of the heat bed. Adjust it so that it's at an appropriate height relative to the frame. Slide the frame back onto the rails and reattach the belt clamp. Secure the rails back into place with the linear clips. Replace the heater bed ribbon cable back into the bottom of the heat bed. Slide it up and back into place from the front through the clips until the heat bed support part slots down into its counterpart on the frame. The holes in the corners of the heat bed fit the dowels on the clips. Press them into place. Slide the print bed into the clips (it's easiest at the outside corners as they taper inwards), and push it all the way back into position. I've found no need for any additional clips to hold the bed in place, but YMMV. You can use the original perf board by printing four of the shims to fit into the clips. The board then just slides over the top of them inside the clips. Use the wing nuts to adjust the level of the bed on the 3 corners to match the height of the (fixed) back left-hand corner. Once aligned, push the locks over the flat bar with the wing nuts running parallel to lock them into place. Adjust the nozzle height and enjoy raftless printing! :) If you wish to return the printer to stock at any stage, simply remove the flat bar and refit the original suspension clips, springs, and heat bed support. You can see from the cross sections that using the glass+PEI bed (4mm) means there's very little room for vertical adjustment. However, in practice, I had no issue with leveling the bed. The clips have been designed for my Glass+PEI print plate, but I've included a step file so they can be modified if required.