# D3D v20.04.27 Calculations

From Open Source Ecology

# Extruder Driver Calculations

- 5 mm drive radius on drive means - about 20 lb drive
- Measurements: about 10 lb before filament slips; motor does not skip before slipping, so tensioner is the limiting factor
- Note push is very easy with full melt (from standing extruder upon startup). This implies, that under the limit of good heating, it is kinking of filament in 'mystery zone' that requires much of the push force.
- Say teeth grab at 1 cubic mm of volume. 1/25^2 = 8 lb of 5000 psi filament. Thus, max push before stripping is about 10 lb. We have 2x that in the drive motor already.
- Thus, geardown is calculated to not be needed, as we run into filament stripping limit.

# Bed Lift Capacity - Weight and Counterweight

- 18x18x17" (D3D v20.04.27) of plastic weighs 90 kg!
- For practical purposes, only half of that would be a useful print assuming you have some geometry at 100% infill beyond a simple cube. 45 kg. But - if you are printing 2x4s or many verticals at 100%, you can indeed get close to 100% of the 90kg. Thus, leave 90 kg as the max. That would be a 10 day print with Supervolcano.
- That is 200 lb.
- 13 lb is current lift capacity. A counterweight would do well, so that together with bed, we have 24 + 13 lb = 37 lb total lift.
- Counterweight should be 24 lb.
- The print bed is limited to 37 lb prints - so it does not display the full capacity of what can fit on the bed.
- Interestingly - making the bed heavier - and the counterweight heavier - produces a ready solution. This can go up to the limit of friction loss and holding capacity of the GT2 Belts.

# Counterweight

- 1"x10"x4" counterweight is 10.3 lb from [1]