IKBot is intended to be a robotic arm reprap that can print its entire plastic parts list in a single print. Additionally, it should be able to print parts larger than any of its individual parts. In essence, this means you could incrementally build a larger arm to increase the build area.
So far I've nailed down all the firmware and IK concerns, I do think there may be some resolution concerns at the max extent of the build area, though those should be minor. Another concern is speed, though the use of variable stepping division should make it a little faster when needed.
Base will have attachment points to secure it to the surface that will be printed on.
Main Rotation Gear Train
The main rotation gear train will have a reduction of 14.4:1, which will change the step distance to 0.125 degrees (2880 per 360 degree revolution). Speed will be maintained due to the fact that it only ever has to make a 180 rotation while building (worst case travel). This is so that the resolution at 230mm from the base (edge of the build area for generation 1) is an acceptable 0.5mm. This can be improved by either using partial stepping, or adding an additional reduction gear to the train.
Arm Gear Trains
The arm gear trains will have a reduction of 10:1 to maintain a small enough step to get good resolution on the line heading away from the base (this is constant WRT distance from base, unlike the rotational gear). For 150mm length arms this is sufficient to maintain good resolution, for each doubling, partial stepping will enable good resolution.
- Motor Torque/Arm Torque vs. Plastic strength/Arm Weight
- Need for reinforcement on the arm segments?
- Use bowden extruder to reduce arm weight
- Resolution difference as a function of distance from base
- Make worst case resolution acceptable and all other area should have >= acceptable resolution.
- Arm could technically add parts to its own base while the base was still attached. Self-decoration for the holidays perhaps?
Bill of Materials/Assembly
The following is auto-generated by ThingDoc. It is also incomplete and wrong in a lot of places. It will continue to be so until I finalize the documentation. But as sections of the design get finished, so will the assembly instructions, thanks to ThingDoc :).
Bill of Materials
|2||2 to 1 Reduction Gear||RP|
|1||4 to 1 Reduction Gear||RP|
|1||Base Rotation Gear||RP|
Fasteners & Rods
|18||5/16 Inch Nut||Fastener|
|18||1/4 Inch Washer||Fastener|
|3||Nema 17 Stepper Motor||Motor|
Assemble 1x Base
- Attach all Base Gear Train parts to a Base Bracket.
Assemble 1x IKBot
- Attach the Upper Arm to the Lower Arm by inserting a 50mm Long 5/16 Inch Threaded Rod through the attachment holes.
- TODO: Do stuff with nuts/washers
- Attach the Upper Arm to the Base by inserting a 50mm Long 5/16 Inch Threaded Rod through the attachment holes.