Projects/uberbot
From 757Labs
Contents |
[edit] Uber Bot
The purpose of this project is to come up with an enhanced print head system to replace the current one used on the MakerBot.
The follow on work will detail creating a totally new 3D Printing system that will allow for a wide range of thermoplastic materials with a resin feed system vice the current extruded rod style systems.
[edit] Design Notes
This is a high level design picture of how the power supply for the heater core would be.
This is an input voltage curve versus adjustable regulator output ranging from 0 to 5 volts. The LM138K has an output range of 1.2 to 32 volts. The ideal voltage input range to the adjust pin would be ... approximately 0-3.0 volts for a full range swing.
[edit] Power Control
The LM138K can output from 1.2 to 32 VDC with a current capability of up to 5 ampere. The projected power requirements of the heater core should not exceed this range. The high level power supply design is further detailed as follows:
- The 36 VDC supply will be the single rail voltage for the entire project
- The 5 VDC supply represents the maximum output from a 12 bit ADC
- The ADC will be under control of a micro-controller with a feedback loop generated by the K Thermocouple sensing system. In addition, the output voltage from the LM138K will be controlled with a N-Channel MOSFET into the 6.6 Ohm load that is the current nichrome wire core value.
- The virtual Op Amp is used to boast the output of the ADC in order to properly supply the required voltage values into the adjust pin on the regulator.
[edit] Material Injection
So far the MakerBot and RepRap use a feed line of ABS which is pushed into the melt area of the print head itself. There is no true "melt pot" where there is waiting pool of molten plastic to be printed ... only a melt zone for the incoming rod stock. The following type of alternate feed systems are being considered:
- Archimedes Screw style injection head
- Linear pump system
- Hybrid Rotary / Linear pump system
It should be noted that all of the material that is being pumped is in a solid granular state of various grain sizes.
[edit] Status Updates
In this section I will put the ongoing status updates of materials ordered / received and various testing results of portions of the prototype system.
[edit] November 4th 2011
- .25mm nozzles
- Metric to NPT Couplings
- Bare Nichrome wire (28, 30 and 32 gauge)
- Digital Scale for measuring chemicals
- 2500 Deg F+ Ceramic Paper and Heat Conducting Adhesive
[edit] Materials to Obtain (11/4/11)
- K Style micro bead thermocouple
- Omega Temperature Controller
- Nylon 6 Resin - Budget price $2 per pound
[edit] November 26th 2011
Have both a K Style thermocouple and a digital multimeter setup for reading temperature. Prototype heating core is producing end of pipe temperature readings as follows:
|
|
|
| 12.8 | 2.0 | 375 (20 minute ramp from 70 degrees) |
| 16.5 | 2.5 | 471.5 (5 minute ramp from 375 degrees) |
| 20.6 | 3.0 | 620.1 (20 minute ramp from room temperature starting with 2.5A and advancing to 3.0 at 470 degrees) |
The brass tubing is running a lot cooler than the stainless steel coupling between the 1/8" nipple and the .25mm Brass print tip. The case temperature of the 6mm to 1/8 coupler while the tube is 471.5 is 510.0 degrees
