Prusa Mendel build update #4: build platform assembly

Posted on July 15, 2013 in 3D printing

After getting the frame assembled and tightened for my Prusa Mendel i2 3D printer, I tried to assemble the build platform my the printer. This turned out to be more frustrating than I was expecting, and I actually built the bed in a way that was nearly impossible to level at first. However, after buying a few extra parts I was able to assemble the bed in a way that I’m happy with, even though it is considered to be “outdated” by the RepRap community.

Bad print bed top installation

When I first tried to install my top print bed (the larger 8×8″ heated build platform and wood back), I realized that I didn’t have M3 bolts long enough to reach the Y carriage board. This was because I used some thick belt clamps to attach the Y axis belt to the Y carriage, which were just way larger than they needed to be.

A RepRapper from the RepRap IRC room told me that I could use aluminum standoffs to couple two M3 bolts together to make up for the super large belt clamps. However, once I did this I realized that I couldn’t adjust the level of the bed at all! The top bolts were inaccessible because they were covered up by the heated build platform, and the bolts on the bottom required a screwdriver to turn – not an easy thing to do when the printer is sitting on the table!

Better print bed assembly

Once I realized that the real root of the problem was these absurdly large belt clamps, I opted to instead use much thinner clamps to hold the Y belt in place. While this does cause the belts to come down at a slight angle, it allows me to use a single bolt and nut at each corner of the bed to hold things in place.

Using these sweet knurled leveling knobs, I am able to adjust the compression of each of the springs and maintain the level of the bed. The bolts spin a little too much in their countersunk holes, so I will want to rebuild the print bed top assembly, but it is good enough to use for now!