Separate names with a comma.
Some features disabled for guests. Register Today.
Discussion in 'CNC Mills/Routers' started by AWoodbridge, Apr 21, 2021.
Replacing the Pro Light control box with a Open Builds BlackBox.
AWoodbridge published a new build:
Read more about this build...
Hi, I'm actually doing the exact same build.
I was able to put all of the components into the original Light Machines enclosure which worked out well. I just had to add a USB connector to the back. I repurposed the TTL IO DB9 connector on the box to handle the 0-10v spindle speed control.
A few notes:
There's a solid-state relay in the box that switched 120v power to the spindle output. The spindle has its own 120v mains power --- the output from the control box just turns the DC power supply on/off. It would have been perfect to control the solid-state relay with the "Relay" output from the Blackbox, and the Blackbox relay can be configured to turn on/off with the spindle, but both the 0-10v output and the input to the relay are controlled by the PWM output. When the spindle speed is low (less than 50%), the PWM output doesn't supply enough power to trip the Blackbox relay input and the spindle doesn't turn on. Kind of a goofy setup, but for the price I guess we can tolerate a few shortcuts. I wound up wiring the spindle relay to the coolant output from the Blackbox. My postprocessor in Fusion 360 automatically adds the M8/M9 codes to turn on and off the coolant so it works OK.
The mill I bought is in perfect condition and has seen very little use, however, the slo-syn stepper motors don't seem to work well ... or at least they don't work well with the Blackbox. I was only able to get speeds of ~350mm/min before the servos skipped even when I cranked up the amperage output on the BlackBox. I picked up 3 STEPPERONLINE Nema 23 269oz steppers from Amazon for $80 and they work perfectly.
There seems to be a lot of backlash in the table movements and I tracked it back to end-block used on the ballscrew and the XL belts. The end-block uses two cheap 6201 radial bearings with a shim in between to create a preload. There's about a full 0.001" play in mine. I got a good price on some 7201 ABEC 5 angular contact bearings as replacements (I bought a lot and I have extras if you're interested). They should arrive next week and I hope that solves one of the issues. The XL belts also have a half-thou backlash. I'm replacing them with GT3 pulleys and belts. I found no perceptible backlash in the ballscrews.
In general, it's a great little mill and I expect that after these few upgrades it'll produce high-quality work. Happy to share more info if there's anything specific you'd like to discuss.
Use the Spindle Enable option: See docs:blackbox:jumper-relay [OpenBuilds Documentation] along with gnea/grbl - for PWM independant control...
Hi Peter, thanks for the quick reply and for the helpful feedback. I totally missed that section of the documentation, and since my mill currently has only one spindle direction the workaround is perfect for me. I'll give it a try, as I'd like to use the coolant output to control coolant (when I get around to that). I have to spend more time exploring the options on the blackbox ... it worked almost perfectly out of the box so I haven't had a reason to dig too deep.