Home built CNC Router (part 2)

One of the many great things about building your own CNC router, is that you can design it to suit your needs. A few of the things I had in mind when I started down this path were:

1. It had to be small enough that I could fit it on a rolling cart that could fit through the shop doors here at the school.


2. I'd like to be able to cut useful templates and jigs with it.


3. I'd like to be able to make a Banjo head on it (8-11 inches in diameter).

With those few things in mind, I poured over various websites looking at possible designs for making a CNC that was about 3-4 feet long by 12-18 inches wide with a Z axis travel of at least 3 inches. I found the blueChick design on buildYourCNC.com and it seemed to have everything I needed and not much beyond so I decided to go with it.

They have two purchase options:

• $1739 for the complete kit which includes: Structure, hardware, mechanical components, and electronics, you supply computer, cable/wires, and router.


• $1360 for the structure kit which includes: Structure, hardware, and mechanical components, you supply electronics, computer, cable/wires, and router .

I went for the structure only kit as I had some stepper motors and was going to try to use them when building my CNC.

The kit arrived within a week of ordering it and using the online videos it took about 8 hours to put the structure and mechanical bits of it together. The kit I received had several missing nuts and bolts and I spent another 2-3 hours chasing them down locally rather than have them shipped by the Mfg. There were also 3 missing V bearings and I did end up calling the Mfg to have those shipped out as it wasn't possible to get them locally and they were going to be expensive so it was worth it to get them sent from the kit maker. They were very responisve and sent them the next day.

Electronics

After doing a bit of research, I did end up ordering the stepper controllers and parallel breakout board from buildYourCNC.com and then went looking for the cheapest PC I could find with a parallel port. Turns out there aren't many options when it comes to buying a modern PC with a parallel port. In fact there are none that I coule find other than "roll your own" brands. I opted for a cheap HP desktop into which I planned to  install a PCIe parallel port card. And that's when I started running into all kinds of headaches.

The PC I bought came with Windows 7--The first parallel port I bought didn't have drivers for W7. I ordered a different port that claimed to have said drivers--it didn't. I order a third port and was able to install it, but never got the CNC driver software (Mach 3) working with that port.

After somewhere north of 10 hours of trying different things to get it to work and combing through the various online resources, I gave up and decided to look for a USB based solution. I found one at http://www.planet-cnc.com/ and ordered their 3 axis controller along with their CNC driving software. It arrived within days (no small feat as it shipped from Slovakia) and I began wiring it that evening. After several hours spent trying to get the PC to talk to a single motor, a search on the obscure planet-cnc user forum turned up the information that the silk screen on the screw terminals switch the step and direction pins for all the motors. Swapping those connections solved my problem and my first stepper motor was turning under the control of the PC.

<continued in part 3>