MakerFarm 8" i3v Prusa build by Printbus

[printbus]

HEAT BED INSTALLATION
The MK1 heat bed has circuit pads for an LED and current limit resistor(s), and I opted to take advantage of that. The LED will face the rear of the printer, but I like the idea of having a visual indicator that there is in fact power being applied to the heat bed. I didn't have surface mount components on hand, so I tacked on a leaded-type T1 LED and 1K resistor. I also replaced the power wires on the MK1 with 18 gauge flexible silicone wiring. In addition to being very flexible, the high strand count of the wire will hold up better. Another trick from my RC helicopter hobby.



As an insulator between the Y bed and the heat bed, I picked up an 8-inch (200mm) square silicone pot holder/trivet from eBay to try. It's a perfect fit for the heat bed. This has a mesh pattern on both sides, and I trimmed away some of the mesh ribbing on one side to clear the bolt heads on the top of the Y bed. The silicone pad is thicker than what the typical piece of cardboard or cork sheet would be, so I had to increase the nylon spacer in the rear right corner to 3/8-inch. 3/8 of an inch might still be a bit short. I'll convert over to cardboard or cork if I end up needing that printable height loss back at some point.



FOLLOWUP COMMENT #1: In the later post on BED LEVELING, I describe how I revamped the approach to mount the heat bed to the Y bed. All four corners are now equipped with a spring. Longer and fully threaded M3 x 30mm bolts were used and a locknut is used to fix the bolt to the heat bed. Thumbwheels used on the bolts extending through the Y bed to provide a fast, tool-free means of adjustment.

FOLLOWUP COMMENT #2: For a printing surface, I had the local Ace Hardware cut some 1/8-inch glass to 8-3/8 inches square, roughly the same size as the heat bed. They wouldn't cut the angled corners needed to clear the mounting bolts, so I used a wet tile saw with a diamond blade to carefully cut them. I figured if the tile saw can cut glass embedded in mosaic tile, it would likely cut the glass better than I could do with a scribe. A bit of effort with a sanding block softened up the edges around the entire glass plate.

FOLLOWUP COMMENT #3: After using the printer a while, I realized the binder clips used to clamp the glass print surface to the heat bed rub on the heater traces on the bottom side of the heat bed. While I've never heard of anyone reporting wearing through the protection on the heat bed and shorting trace loops with metal binder clips, next time I have the heat bed assembly apart I'm going to add some kapton tape along the bottom sides of the heat bed as an extra precaution.