I recently purchased a Zen ToolworksTM CNC 7×12 3D Printer/Milling Kit
so I could etch better and smaller PCB boards. While it hasn’t been too complicated to setup, I’m documenting my setup for the good of the CNC community and mankind in general.
The CNC machine was purchased in January of 2012. I did not purchase the driver that Zen Toolworks sells, mainly due to cost. I was trying to stay under $500 for the whole project; and I did.
The assembly of the machine was slightly confusing at first, as they only had instructions for the 7×7 and the 12×12 machine. To its credit, Zen now has a manual for the 7×12 at its wiki site.
Overall, I’m extremely happy with the machine, but it’s not without its faults. The first hurdle I ran into when assembling the CNC machine was a simple washer not fitting on a bolt due to the backlash nut.
As you can see in the image above, I had to grind the washer down. Zen Toolworks said to leave it off altogether. If you have the F8 leadscrew, then you’ll be running into this problem. Additionally, the falan that screws onto the leadscrew is nylon, whereas the regular leadscrews are made of a metal (I think brass). I was slightly disappointed about this, but it’s no big deal.
The largest letdown of the entire machine was that I didn’t have 2 inches of clearance between the Z axis and the table. Zen sells this unit as a 12x7x2 inch machine, yet, there’s no way in a stock configuration to achieve a 2″ deep cut, as the material simply won’t fit.
There’s just over an inch and a half clearance (1-9/16ths). Unfortunately, I had to modify the unit. I ended up drilling holes in the back of the Z axis where it attaches to the X as shown in the image below.
You can see the lines marking out the new holes.
And the axis mounted in the new holes gives a clearance of the advertised 2 inches. I guess what do you expect for such a cheap CNC solution? I’m still happy with my overall experience.
After this, I mounted a 1x (3/4″) piece of lumber on the table so I wouldn’t be afraid to screw PCBs down or gouge the table with a drill.
My driver board, the ebay bought China 3-axis TB6560, has had many critical reviews. Some of which never got the board to work, or had blown it up shortly after hooking it up. I can only speak from my personal experiences when I say that I have had little to no trouble with this driver. If I had one complaint, it would be that the motors are noisy at Idle. I don’t know what affects this, but I’ve still to mess around with the decay settings. It’s currently set to fast decay (100%).
I mounted the board using a couple nuts, bolts, and some nylon spacers. If you’d like more information on the driver and how it’s setup, read TB6560 ebay 3-axis driver settings.
I bought the wire harness to minimize the clutter on the machine and reduce the chance that the gantry would catch a wire and rip it off the board.
The completed back of the machine. Notice the Y-axis limit switch mounted to the motor mount.
Above you can see the limit switches mounted for the X and Z axis, along with my custom pen mount. I hacked a spring pen so it will keep a consistent pressure on a piece of paper (for testing purposes). Router mount soon to follow.
In the background you’ll notice a Pyramid regulated power supply. This unit is 13.8 volts and can supply 5 amp constant, 7 amp surge. I should be using a larger supply, but I have the driver running at 25% current so the power supply stays very cool to the touch. I haven’t had the need to increase the current to the motors as of yet. But it’s coming.