The CNC_Torch_Table consists of a stepper-motor-driven CNC XYZ table intended to carry a plasma torch or oxyfuel torch for metal cutting. However, additional functions could be supported by the same table by substituting or adding to the torch head.
secondary tool actuator
If a secondary tool is mounted adjacent to the torch head, to be used in conjuction with cutting operations, it will need to extend and retract independently. A small air cylinder could advance the secondary tool to a fixed-location "extended" position (hard stop) well below the torch tip, and retract it to a clearance position well above the torch. Finer adjustment is the role of the Z axis. The secondary tool retraction does not require any precision slide as long as the final extended position is firm and repeatable.
Auto retraction (on collision)
A common issue with torch tables is that once a part (or a waste slug) is cut loose, it can tilt up. The tilted-up part can be high enough to interfere with the tool while it is moving around. Some commercial torch mounts even have a "breakaway" feature for protection. If the secondary tool actuator is on an air cylinder drive, it could retract very quickly if a collision is detected.
Light-duty (limited cutting force) cutting of wood, plastic, foam materials.
(From email ChuckH 17:15, 3 December 2012 (CET))
"Plan C": use the CNC table as a marking machine for layout, and do our cuts by hand.
I suggest using round soapstone, like http://www.atlweldingsupply.com/Round-Soapstone-Gross_p_254-1393.html, in some sort of spring-loaded holder. Alternatively, silver sharpies http://www.amazon.com/Sharpie-Metallic-Permanent-Markers-39108PP/dp/B00009RAX4
Although this is clearly not a final solution, it actually has certain advantages:
- Does not require completion of torch height control and plasma supply interface on torch table for Dec 18 CEB build
- We can mark much faster than we can cut
- Marked parts can be hand-cut in parallel, shortening overall production time
- Glitches in CNC table operation are unlikely to cause ruined parts (i.e. we can catch them before we cut)
- We can place layout marks for other operations besides cutting (e.g. center marks for drilling or punching)
- We can mark index number and orientation on each part
- Allows us to prove out most of the torch table toolchain on this build.
Either the soapstone or sharpie will wear down and start making broader, possibly off-center lines. The soapstone can be pointed much like a pencil, while the sharpie you'll just throw out. Probably get a bunch of both and see how they perform.
pneumatic impact engraver
A probe using two (or maybe more) force sensors processed with A-to-D conversion and Arduino might be more reliable long term than contacts (which are subject to oxidation, dirt etc.) Although force sensors often drift there is always the opportunity to re-zero in free space just before making a probe measurement.
Artifacts made from cloth include clothing, canopy/tenting, furniture upholstery, and reinforcing-fabric plys in composites (fiberglas, carbon fiber, etc.).
Swivel knifes, much like a vinyl sign cutter, are often used on CNC textile cutters, working against a perforated hard plastic backboard with vacuum hold-down.
On the XY table, textiles can also be notched, hole-punched, and pen-marked with guidelines for stitching.