Raise3D N2/N2+ bed mod for leveling, stronger springs

I started with TobyCWood's excellent Raise3D N2 leveling mod, and made some changes.

Our Raise3D printer is probably newer, and has a fully insulated plate under the bed, so we could use metal washers instead of printed washers.

I couldn't source the same springs used in the original, so I used some much stiffer springs from McMaster Carr, and resized the stabilizer to match.

I also regenerated the wing nut as a slightly larger part, easier on the fingers to turn. I used 40mm flathead screws instead of 35mm, since the nut is deeper.

I printed the wing nut and the stabilizer using Colorfabb HT filament, it's designed to be stable at high temperatures. On our printer, there are no printed parts in contact with the heated bed (we're using metal washers against the insulated plate under the bed) but it feels safer to use a tough high temperature plastic.

Aside from that instructions are exactly the same. I do find that when leveling, it makes sense to completely loosen the center screw, adjust the four corners, and then tighten down the center as needed to prevent bulging upwards. If you tighten the center screw first, then you are in effect doing a three point leveling with the center and two corners, and it is difficult to get right.

Here are the parts from McMaster Carr

92125A150 18-8 Stainless Steel Hex Drive Flat Head Screw M3 x 0.5 mm Thread, 40 mm Long
90377A116 Black-Oxide 18-8 Stainless Steel Washer Oversized, Number 5 Screw Size, 0.141" ID, 0.625" OD, Packs of 25
9657K308 Steel Compression Spring Zinc-Plated Music Wire, 1.00" Long,.420" OD,.047" Wire, Packs of 12
90576A102 Medium-Strength Steel Nylon-Insert Locknut Class 8, Zinc-Plated, M3 x 0.5 mm Thread, Packs of 100