Better Bed Mounting - Folger Tech Kossel revB

thingiverse

Edit 2016/08/07 - My new layer cooling has taught me a valuable lesson. I've uploaded revised versions of the mount - one is 4.5mm and one is 6.5mm. This height is measured from below the heated bed, making the 4.5 perfect for a thin cover like a PEI sheet and the 6.5 suitable for glass. I'm not creating a version specifically for the bed alone because first, you should get some PEI as it's incredibly easy to work with; and second, that extra 1 or 1.5mm is probably small enough to fit under whatever you have dangling off the side of your hotend. I encountered an issue where the heated bed would wiggle due to the holes in the acrylic being cut too large for the M3 screws. Since I couldn't use larger screws to better fit the mounting plates because the heated bed has only M3 holes, I had to find an alternative solution. Additionally, I disliked trying to hold nuts under the bed while making adjustments, as they kept falling off. My initial versions featured spacing for inset M3 nylock nuts but then I discovered M3 brass knurled insert nuts and stopped improving that design. The mounts I've uploaded work perfectly with nuts from Amazon (https://www.amazon.com/M3x5mm-Metric-Threaded-Insert-100pcs/dp/B00Y20YLKY/) and completely fixed my problem of bed wobble. One of the printed mounts seems to have cracked at the top, so I created a new version with an integral spacer that should help improve structural integrity. Even with the crack (on one side of the screw hole), it still holds the bed entirely still as two points and the upright arm are enough to keep it aligned - the top piece is just there for extra alignment when screwing it on. The part with the integral spacer doesn't need acrylic disks to act as a standoff. Simply melt an M3 insert into the bottom (should be flush with the bottom), then the mount slides over the acrylic mounting plates. The notch is slightly deeper for the acrylic than the bed because the acrylic sticks out a little farther. There's also an upright piece that forces alignment with the other points. This part is taller than necessary to facilitate different bed surfaces like glass or un-taped PEI. If you print these solid, you can cut them down or leave them sticking up. Do not try making these from PLA - this part is in contact with the heated bed and may have to deal with temperatures of 110 degrees or more. ABS or better only are recommended; PETG would work as well if you've replaced your hotend. The acrylic pieces slide between the two printed slats, with the flat side down. The bed (or bed and spacers) sit on top of the upper slat, with the upright section pressing against the edge of the bed. Depending on your printer, you may need to do some filing to get the holes to line up perfectly. Tighter is better than loose as loose is the problem in the first place. Fine Tuning: These are a tight fit for me. My printer isn't super dimensionally accurate (50mm comes out as 52ish). I needed to smooth the top inside of the part after inserting the knurled nut because it melt-squished the plastic up a little. I also had to remove a bit from the back in the acrylic space to get the holes to line up perfectly. I designed the part to center, but it seems like the bed aligns more toward the inside of the supports rather than the center. Nothing a minute with a file can't fix. And better to remove a little plastic than need to add a little, right?