D3D v20.04 Calculations
Bed Weight and Lifting Capacity
- Motors advertised at 84 oz in or 5.25 in lb
- with 1/2 diameter pulley, that is about 20 lb driver force - about right.
- Total lift is 40 lb from both sides
- Weight of bed - 7.5 lb for top and bottom, 3.5 lb for sides. Rods - .26 lb per foot, we have 3 feet - 1 lb more. Insulation - maybe 1.4 lb / cu ft . We have 1/6 cubic foot, so only a quarter pounder of fluff.
- Total bed weight: about 12 lb
- Bed volume of 1440 cu in, is 25 lb of max plastic mass that can be printed (assuming 50% full build plate, the maximum foreseeable print weight based on 100% infill.
- Density of plastics is about 1 g/cc. . So 1 liter is about 1 kg.
- Thus, if steppers can hold 25 additional lb, that would suffice for any print whatsoever. Let's test. See D3D v20.04 Data Collection.
- turns out that at most about 7-10 lb can be lifted in addition to bed weight using 2 stepper motors in parallel with RAMPS 1.4
- Steel block, 2x4x3 inches (24 cubic inches) - weighs 6.7 lb. Need 2 of these as counterweights - these could counterweight the bed fully.e
- 4x4 block, 1" thick - weighs 4.5 lb
- Concept of slab counterweight on 2 rods - 4x4" with 12" bed printer (18" axes) - File:Counterweight model.fcstd