Printer Bed Upgrade

3d Printing / Slicers / Setup / Problems
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My SainSmart Coreception 300 printer had a 310 x 310 x 3mm build plate with a 4mm borosilicate build surface. While it seems the glass should make a warped bed flat, it seemed glass is fluid enough to follow build plate. Warpage also varied with temperature. I could straighten bed by using a steel ruler to identify low and high spots, and carefully applying hand pressure to correct flatness. This worked short term, but warping returned.

I did research and found there was a company called Precise Printer Parts. They sell a 1/4" (6.35mm) thick cast aluminum build plate that is great! They actually have Corception, it started them on developing build plates.

I like working on printers, so the install process involved additional work.

  1. Bed heat was upgrade to 120V line power, using solid-state relay and 750W silicone heater. I added secondary IEC line receptacle just for bed heater. I did not use 4 pin circular connector, since it was not rated for bed current, or voltage.

  2. Printer configuration reversed, so home at 0,0 not Xmax, Ymax. Build plate installed 180. Backside of printer became front. This was done using Robin_nano35_cfg.txt configuration changes. Using MKS Robin nano firmware V2.03.6. This firmware enables many user settings and configurations. Nozzle is now easy to view from front of gantry! Belts not in the way.

  3. Additional weight caused bed to drop without motors active. Leadscrews lead was changed from original 8mm to 4mm, and motor steps from 400 to 800. This fixed bed drop. At same time optical endstops were installed with optical flags mounted on top of leadscrews, with optical sensors mounted on horizontal extrusions.

End result, printer is working great, without need for auto bed leveling. Manual bed adjustments are very stable.

I will add pictures of printed parts for Installed bed, cable strain relief, magnetic build plate aligners, endstop mounts and flag.

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20240507_144552
20240507_144552800×963 315 KB

BedCabSptBot.pdf (34.4 KB)
BedCabSptTop.pdf (34.3 KB)
EndStpMnt.pdf (31.7 KB)
OptoFlg.pdf (27.5 KB)

Bed cable support is two parts clamshell design. Top section is for top of bed thermistor wires, bottom is for heater power with entry for over temperature fuse wiring. Bed has extra 15mm length and pre-tapped M3 threads for mounting fuse, build plate stops, aligners, and ground.

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Build plate locator.
BldPltLoc.pdf (46.4 KB)

I printed locator in polycarbonate carbon fiber, used slicer mirror function to print other side. It mounts in bed accessory holes. The half circle cutout is for build plate end stop using M3 cheese head screws that came with build plate.

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Many people have found the same issue with a glass bed on the Ender 3 V2. I’m not sure whether the glass is ‘following’ the under-bed or whether the glass is just distorted in places.
One solution which I used is to place a layer (or two) of tinfoil under the low spots. Fortunately mine was in the middle only, so one application cured it.

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Yes, I learned similar, using a scrap of paper from Irv, founder of this site. It works well, but converting to PEI magnetic build plates helps too on 235 x 235mm plates.

I found a 310 x 310mm magnetic build sheet issue of raising up at center above 75C. The thin 0.4mm metal warps at high temperature, and magnetic surface not strong enough to hold it flat. I purchased an in expensive Geetech sheet 0.5mm thick, it stays flat.

I think die stamp cutting of defective work hardened plate edges, resulted in dome switch behavior; and crazy warping at high temperatures. I don’t want to name company of defective sheet, but i see them selling at discounted prices. It still works at lower temperatures and has smooth and textured, so not total loss.