Quote:
Originally Posted by cbale2000
Anyone have any thoughts on something like a Shapeoko or an X-Carve?
These seem to be a much lower cost alternative to a lot of CNC routers I've seen and it looks like a reasonable project for a team to assemble. |
Both are using stepper motors.
With open-loop steppers you have to move slowly to stay in the band where the stepper motor torque is high.
Move too quickly and you'll miss steps which could ruin the work piece.
Used with O-Flute cutters you can often cut aluminum with some basic mist coolant but be aware that if your spindle is open-loop as well you might have some interesting moments getting the speeds and feeds right to insure the longevity of the tool and the quality of the cuts.
The Shapeoko uses a small router which may or may not have a standard collet tool holding system while the x-Carve has a ER11 collet equipped spindle. Extending the tool out from the spindle always risks some run out either way. To put this in perspective the little Sherlines, Taigs and MaxNC mills often can be gotten with head stocks and spindles that can run ER16 collets (larger diameter tools and more powerful spindle motors at lower RPMs more suitable for the low speed feeds you may be limited to).
I suspect you can upgrade the Shapeoko to a closed-loop spindle with a SuperPID. Turns out there's a YouTube video for that. This would allow the router to run at a lower speed and to maintain it's speed even under cutting load.
Due to rigidity a Tormach or cheap retrofitted vertical mill is better for general aluminum cutting (on smaller plates) than this would be. Still plenty of people use bridge mills to: drill, route and cut aluminum plate even if it takes light passes to do it especially if the plates in question are large (I've worked plates as large as 4'x8' in a ShopBot).
I have some Velox pieces on some of my CNC rigs. Take a good look at the length of the steppers Velox is using versus these. Notice those steppers are double as long? That's because those are higher power steppers. The higher the power the steppers the more likely as they loss torque with increased RPM they will still have enough torque to finish the job without missing steps.
There's not much stopping someone from getting a Taig spindle cartridge some cog belts and a 1/3HP motor or servo motor and control and making a Taig style head assembly for a bridge mill - just make sure the bridge can handle the side loading.