So, a while back, we ended up with a CNC router that was donated to us by the neighboring metal shop.
The router itself is in pretty decent condition, and the control system runs Mach3, via an Ethernet Smooth Stepper on Windows 7.
One of the things we’d like to do with it, is come up with applications for scrap aluminum-composite. Unfortunately, this requires both profiling and v-grooving operations. While manual tool-changes may work for some processes, in this particular case, the impact on repeatability with regards to tool-height is a bit of a problem. While not absolutely critical for profiling operations (as you always end up going through the material and into your waste-board to some degree), the grooving operations require some amount of precision: Too deep, and you cut through the material where you intended to fold it. Not deep enough, and you end up with material that is difficult or impossible to fold.
The solution to this is to replace the spindle motor (which currently uses an ER-25 collet), with a spindle that uses a taper for toolholding. Switching out tools now becomes very simple, and you only have to modify tool heights if you replace an old or damaged bit. A spindle that has a taper also lends itself to fully automating tool changes. Here’s a good video of an ATC on a Shopbot. So, after a fair bit of research, a good candidate for the replacement spindle seems to be the HSD915.
This spindle is used on the Shopbot, as well as numerous other CNC machines, is ~5HP in power, and can still be run on 220V. This means we can keep the existing Variable Frequency Drive (VFD), we don’t have to worry about having a step-up transformer (everything is currently set up for 220V), it has an equivalent amount of power to what we currently have, and has the benefit of being popular enough where we can find an existing dust-foot (like the one made for the shop bot), and not have to worry about fabricating our own.
In addition, another useful feature to have would be the ability to cut vinyl (or the protective film on ACM). For this, the TCM-3, a Tangential Knife made by ECOCAM seems the most appropriate. The knife is spring-loaded, and the pressure is adjustable via a knob on the front of the unit.
The idea would be that these two tools would be mounted side-by-size, sacrificing a certain amount of usable Y-Axis travel on the machine to do so. The neat thing about this is that this is all fairly feasible without too much trouble.
On the software end of things, Mach3 supports tool-change operations, and can be configured to do various things upon parsing a tool-change operation in the gcode. Mach3 also supports a 4th axis for a tangential knife. Unlike a drag-knife, which is simply allowed to rotate freely, the TCM-3 actually has a stepper motor built into it for rotation of the blade. This ensures that the blade always follows the direction of the cut. The 4th axis is a rotational axis, representing 0-360 degrees.
On the hardware side of things, the Ethernet Smooth Stepper has plenty of spare I/O, and there happens to be a spare multi-conductor cable run all the way from the control cabinet, through the drag-chain, and up to the gantry. The extra conductors would serve to pass the stepper signals to the knife, as well as pass back interlock/safety sensor status from the spindle.
Having assessed the feasibility of the project, we are now trying to determine how to fund the project.