Friday, 14 August 2015

Scara 3d printer cost calculations for V1

Approximate cost calculation for V1:
  • 51$ — 5 Nema17 (you need only 4, so you get 1 for spare parts)
  • 32$ — Ramps 1.4+5 Dvr8825+LCD (you need 4 drv8825, so you get 1 for spare parts)
  • 7$ — E3DV5 (china made) with 1m PTFE tube (0.5m for spare parts)
  • 2$ — extruder gear
  • 6$ — gt2 pulleys and gt2 belt
  • 5$ — 6mm smooth rods (2x20cm)
  • 4$ - 4 LM6UU linear bearings
  • ~10$ — ball bearings+bolts+screws+other stuff
  • 10$ - external power supply 8.5A 12V

Total: 127$ (with power supply, but without ABS filament — approx 200g)
NOTE: All prices from my aliexpress orders, free shipping to my country, no taxes (in my country taxes begins only from 200+$).

NOTE2: V2 seems to be in the same price level, but not cheaper.

Ways to save costs:
  • ~8-10$ - get rid of of LCD module 
  • ~5-7$ - Replace one Nema17(for gearbox) to small 2.5$(28BYJ-48 12V) stepper + printed high ratio spur gears.
Not a lot.

More global idea:
Replace 2x10$  Nema17 steppers to cheap DC MOTOR + Hall Sensor + L293N + gearbox. The main problem is a backlash free gearbox. I think gearbox should have approx 1:100 gear ratio.

Backlash free gearbox ideas.
  1. Looks like it is possible to combine 2 stage of 1:10 belt driven gears. Belt driven gear theoretically backlash free. 1:10 belt driven gear is a 16 teeth gt2 pulley and 160 teeth pulley (~101mm diameter), or use more stages with less teeth pulleys (seems like better due to the less belts length).
  2. Planetary gears - at least 2 stages required - i tried to print - seems like printed does not work well.
  3. Hypocycloid Gear - looks better but seems like it does not work due to printing precision, plus vibration may affect print results.
  4. Harmonic drive - not tested
  5. Classic gears - seems like not backlash free, there are a few ways to decrease backlash, but i not sure.
NOTE: It is just an idea

Wednesday, 5 August 2015

Printrun is forked

My first ideas:
  • Add mark to show center of ccordinated - DONE
  • Fix or rewrite ugly 3d viewport rotation (is Repetier like viewport rotation) - DONE