Multi-tool CNC platform in progress atop the optical table to enable ultra-precise fabrication on a massive scale. Derived from FlexReplicator. Tool compatible with FlexReplicator, TazMega, TazStiff, MightyTool, and related projects.

This is the kind of machine one might use to laser cut giant tractor parts, 3D print large herringbone power transmissions for lost PLA casting, or carry out a VLSI production run. Or of course, typical laser paper cutting.

Status

Assembled and operational.

Features

• Approximately 7'x2'x1.5' build area.
• Built on 100W Laser Cutter (tube down ATM).
• Rock-solid, supported by optical table and 40 series extrusions.
• Supports multiple tools and capabilities, starting with 3D printing and Laser Cutting.
• Simultaneous multi-tool use will enhance utility, such as milling down 3D printed layers.

Documentation

• Part of design hosted on github.
• Rest of design hosted at The FossCar Project.

Tools

IR Laser

Tested. Mirrors are in place, but laser tube has died.

Extruders

In progress. Works just like any other 3D printer. Plan on at least two nozzles, one for high-precision (<0.35mm), one for high-speed (>1mm).

Mill

In progress. Standard 120V AC drill, connected to control circuitry by SSR.

Pick And Place

In Progress. camera system, part feeders, and vacuum based pick up and rotate tool will need to be added.

VLSI Projection Lithography

In progress. Modified (ultraviolet) DLP projector and camera mounted to microscope, used for high-resolution patterning. Absolute accuracy (inter-frame) is expected to be ~2um, while relative accuracy (intra-frame) is expected to be <0.5um, scalable down to diffraction-limited performance.

Casting

Direct metal printing thus far is either highly expensive, low-strength, or both. Compromise is to 3D print a plastic (PLA) part, then cast it to metal. Besides low cost, this process can be used to achieve parts traditionally infeasible, like pre-assembled herringbone-gear power transmissions.

Pricing

As with other HacDC tools, operators are asked to pay for consumables used only for heavy usage. However, this machine can easily consume a few hundred dollars of filament in one job...

Safety

Usual safety precautions apply.

ClassIV lasers can typically cause catastrophic retina damage will instantly upon viewing the projected spot. Ideally, a 'defense-in-depth' approach should be taken combining safety glasses and guards at all times.

Somewhat less true of CO2 lasers, as the far-infrared wavelength cannot be focused by the lens in human eyes. Nonetheless, polycarbonate safety glasses should be used, and walls should be in place to keep the collimated beam on the table.

Assembly

1. Fix the policy around the basement so volunteers can work with less politics.
2. Replace the tube. Maybe try a cheap, expendable tube for the first few hundred hours.
3. Stiffen the joints between axes. Not essential, but nice.
4. Add OctoPi or similar web interface, for usability.
5. Add walls for safety, to keep the collimated beam on the table.
6. Add an acrylic lid, again for safety.

If the FullSpectrum's appearance and software stack really is crucially important, then we could literally adapt its control electronics to drive the OpticalTableRobot's systems. Bottom line, we can achive much better performance, usability, an especially durability.

With regard to budget decisions, it is important to consider that we have not only lost a $1k laser tube, but also about the same value in linear motion equipment. Both the long-life tube and extra linear motion equipment are technically non-essential, but would contribute greatly to durability. Keep in perspective that the laser tube is not the only casualty or near-casualty related to either of our laser cutting systems. Moreover, irreplaceable volunteer hours have gone into both. On that note, our custom exhaust system for the FullSpectrum machine was nearly trashed.

Upgrades

For absolute maximum performance, consider the following upgrades.

• Interferometric linear optical encoders.
• Vectran rope timing belt replacements.
• Angle iron brackets reinforced by welded plate.

Troubleshooting

When troubleshooting precision errors and planning upgrades, it is helpful to review the most likely causes.

1. Inadequate or excessive wheel pressure (check eccentric spacers).
2. Poor alignment along axes with multiple drivers.
3. Twisting at or near linear motion carriages.
4. Backlash at boots joining X and Z axes.
5. Separation between highly stiff (table, 40 series extrusions) and less stiff (20 series extrusions) materials.
6. Warping of stiff materials (should not ever occur, would imply gross overloading and abuse exceeding several hundred pounds force).