ShopBot on OSX

Where is zero again?

While cutting parts for an LED Grid prototype yesterday, about a third of the way through the cut file the ShopBot stuttered to a very slow movement. Thinking I’d hit something with the tool, I stopped the process. I inspected the machine, checked the bit, examined the material, and couldn’t find anything unusual. I resumed the cutting file and the ShopBot continued on normally. After another ten minutes the same thing happened only this time the cutting was off position and had dropped about 0.25” off the x-position. Since the machine was cutting 0.75” plywood it was doing multiple passes per part the later tool paths didn’t line up so that part was ruined. On a PRS Standard ShopBot the motors do not send feedback to the controller so the machine doesn’t know it is off course. The only way to remedy this is to re-zero the machine.

I re-zero all time, but have never done it mid-file. I’d heard you can restart a file from a line number so I looked at the screen and jotted down Line #102971. After a quick 3D re-zero with the SuperZero, I was ready to resume cutting. Since this is a prototype and I’d already wrecked one part, I must have read the screen to fast to restart from a line. Everything was fine until…

That would be the cutter ramping into the material on the way to line #102971…across what were still good parts. Clearly some more practice is needed starting midway in a file.OK, I’m busted – RTFM.

A to B to C

Random problems are the worst. If you can’t reproduce it, you can’t fix it. One way to test the ShopBot is by doing “air cuts”. Simply zero the machine but set the Z-axis Zero a few inches above the work table, turn off the router, and run a cutting file. The ShopBot will carry out the instructions but the blade doesn’t touch anything but air. Hanging up in an air cut of the previous parts would tell me if there is a problem with the material or the ShopBot movement in a certain spot.

This time the machine did stutter to a slow speed in the air, but in a different area. Recognizing that the problem was being experienced, I stopped the cut. Out of habit or reflex I looked at the tool and clicked “Resume” and the ShopBot returned to air cutting at normal speed. That felt to me like a computer communication problem, not a machine issue.

XP can you hear me?

The ShopBot is running on an old ThinkPad laptop with Windows XP, one of the few remaining Windows boxes in our ecosystem. It is the ONLY reason I still use Windows, having converted to Apple in 2006. After attending Austin ShopBot Camp 2014, I remembered that some ShopBotters are using OSX/Parallels Desktop to run the ShopBot Control Software. I use Parallels for design in V-Carve Pro/Aspire but didn’t trust virtualization to run the machine.

To isolate the XP laptop, testing a Mac laptop seemed worth trying since we have all the parts, MacBook Pro, Windows 7, and ShopBot Control.

Install success! After loading a part file, the MacBook Pro with Mavericks OSX ran the ShopBot without issue for 33 minutes. Repeating the same air cut again on the ThinkPad hit an issue around 9 minutes. So… that’s enough proof for me to say the ThinkPad XP is the weak link.

The only option on the ThinkPad is to bail XP which is being “end of life”-ed in a few weeks anyways. Two hours later a fresh copy of Windows 7 Home Premium was up with ShopBot Controller. Repeating the air cut test, the ThinkPad Win7 failed at 13 minutes. It made it longer than WinXP, but a fail is a fail. Time for a new computer to run the ShopBot!