CNC Torch Table 2/Research Development

Status

This is my (Dan Benamy's) understanding as of Oct 2013:

There's a torch table base in the shop at FeF which needs just a little more work to be usable.

There were various Stepper Motor Drivers being considered. We have an (inactive) project to develop an OSE driver called CoolRAMPS. The fallback was to use the Steppernug open source stepper motor driver. The folks behind it are amazing and we love open source. It's not clear to me (Dan), if the Steppernug is quite ready. For the short term I'd like to try to get the version 2 table up and running with the RAMPS system so we can get something working and build momentum. Then we can quickly iterate to version 3 where we switch to the Steppernug which will allow us to cut faster.

Lots of info on the control systems at CNC Torch Table 2/Control Overview.

Next Steps

My (Dan Benamy's) plan/suggestion as of Oct 2013 would be to try getting the torch table 2 up and running with the minimal possible features and work (eg no sensors, no custom electronics...).

I'd do it something like this:

• Order and add a few missing springs and screws to the FeF torch table and mount all the motors.
• Put some wd-40 or other oil in the moving parts so it slides easily.
• Wire up the motors to the arduino/RAMPS board we have and run the test ramps code to ensure it's all wired up right.
• Attach a sharpie to the tool head and put poster board or similar on the bed for initial testing.
• Load the Marlin firmware onto the arduino and do any needed configuration. Grbl looks sweet but doesn't support RAMPS out of the box and we're going for simple here for the moment.
• Draw a rectangle in librecad, run it through dxf2gcode and use [Printrun] to stream it to the arduino. Get the table to draw the rectangle.

Then I'd do incremental improvements, keeping the table working after each step so if I had to leave or something didn't work, it'd be easy to revert to the most recent working stuff:

• Add a circle to the dxf that's not touching the rectangle. Re-run and make sure the head lifts up between the shapes.
• Add gcode postprocessing if still needed for piercing and torch width. The "torch" should move back and forth while making an initial "pierce". For the circle, I think it should make the pieces inside the circle. I'm not sure if it should pierce the rectangle inside or on one edge. We want it to make the pierce in a part of the metal we won't use. I wonder how the piercing code knows what that is... There's a conversation here about integrating this functionality into dxf2gcode which would be great for ease of use and gives us a gui where maybe we could click where we want the pierce to be.
• Try it with the real torch!!! For future steps, I'd switch back to the sharpie for testing and only use the torch once things look good.
• Computer control of the torch since the ratio of fuel to oxygen should change for piercing vs cutting.
• Endstops.
• More powerful stepper drivers to allow faster movement (and use more open hardware).
• Height sensing to automatically deal with different thickness material and maybe uneven material.
• Rebuild the table using as many Warehouse parts as possible.
• There was a comment that said "Height Controller for oxyacetylene and plasma torches". I don't know what that means.

Developement Board

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Design

Lots of information about the control system in CNC Torch Table 2/Control Overview.

Additional discussion at TorchTableModularTooling

Files

Github, mostly solidworks - [1]. - DXFs of motor mounts. - Sketchup files

Additional Notes

• As a large x-y-z coordinate table, the Torch Table has potential applications with other tooling besides a cutting torch. One limitation is that the drive system is not powerful enough or stiff enough to support heavy cutting-tool forces.
• A modular tool mounting (possibly dual mounting, so two tools could be available simultanously) would facilitate tool changeover.