Monday, 31 January 2011

HobbyCNC stepper kit

The HobbyCNC Pro driver package I had on order arrived last Friday, so I have spent the week on and off assembling the driver board into the old UPS case that I had. It's a nice fit. I had planned on falling back on using a PC case, but with a bit of magic and luck, it all went into the smaller UPS case. I'm glad I persevered, as it's a really neat little unit when the cover is on.

The package includes everything needed, except the case and transformer. Luckily, the transformer from the UPS was suitable (not ideal, as the final DC supply to the driver board is ~ 22V. Ideally, it would have been about 35V or so, but the board will work down to 12V ). I don't know the exact specs of the transformer, but from the UPS spec (600VA output) and judging by the thickness of the low-voltage leads, I think it should be good for at least 10A of current. I'll be monitoring the DC voltage for droop once the CNC is up and running.

I got the largest steppers that HobbyCNC sell in the package - they are a lot heavier than I expected. I think there will be more than enough torque for most applications. Here's the first run, driven by Mach3 (took a while to get it configured to use the right parallel port address. Laptop was confusing it apparently)...

Having got the steppers running, I had to work out how to connect them to the threaded rod. I had expected to turn down (in a lathe) the end of the threaded rod to 1/4 inch ( the same size as the stepper shaft ) and then use a 1/4 inch shaft coupler. My mate Gordon (who has the lathe) came up with these instead...
Stepper - lead screw couplers. Thanks, Gordon!
8mm tapped on one end, 1/4 inch hole with grub-screw on the other. Perfect! Great work, Gordon.

Next post...should be the CNC machine assembled. I hope.

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