I started on the CNC path because my Legacy Ornamental Mill would not do the size I wanted and it is boring standing there watching the machine run and having to manually reset the machine after each cutting pass, http://www.legacywoodworking.com/ . This is my indexer based primarily on the Mechmate design (www.mechmate.com) . I wish I had found this site before I started as I would have saved me a lot of work, time and money. For an industrial DIY machine this is the best on the web and designed to run 40+ hours week in a industrial environment. For a hobbyist or small shop then go to www.joescnc.com where you can purchase the plans and bill of material for a 4' by 4' router. Because the Hybrid is designed with lead screws it is limited to about 4' of travel. Though designed using MDF it should be good for at least five years in a small shop and 10+ for a hobbyist. At $100 it is a bargain for the printed materials and access to the forum. More details on the Joe CNC will be posted on my site as I get mine built. Personally I would recommend for the first time DIYer to first build the Joe CNC Hybrid and then build the Mechmate. There is so much to learn and it is a lot easier and cheaper to correct your mistakes with the Hybrid than with the Mechmate. You can always sell the Hybrid or Mechmate for more than you have invested. The 4by4 Hybrid will cost you around $3000 and the 4by8 Mechmate will be about $7000 and add $500 for the rotating axis. Both machines can be expected to run with a tolerance of at least .02".
Both machines run Mach 3, http://www.machsupport.com/ , as the controlling software. At $178 for the hobby version it is a steal. A commercial version is available though I don't know the price. The only difference between the two versions is that the commercial version includes phone support for those that can't wait several days for an answer. Mach has gone through many revisions over the years and several commercial manufactures have gone to it because of its qualities. For the commercial users it's biggest drawback is that there was no telephone support. In a commercial environment you can't wait several days to get your questions answered via a tech support forum. This is an important step for Mach as they now have a professional staff available to support those who need immediate help and are willing to pay for it. I expect to see more commercial manufacturers move to Mach as they can have great software and eliminate their software support centers. It is also great for the rest of us as we hang on to their coattails. Presently updates are free for registered users and the forum has some 3500 active users who along with the Mach people will usually step you through a solution to your problem within 3 days. You can download the latest version from their site and the only difference is that it will only run the first 1000 lines of the file you load.
My machine is runs in three modes; router, indexer or lathe. A router works with three axis X, Y and Z. It is the same as a mill except not as strong and not intended to work metal though a router can do limited work with non ferrous metal such as aluminum, copper and brass. A indexer has X, Y and Z plus a rotating axis, usually A . The rotating axis is not a constantly turning axis but is moved by degrees as desired. A lathe has the same four axis but the rotating axis turns constantly.
This is the controller that I used. I got it from http://campbelldesigns.net/ . Fortunately for me Bob is only about 20miles away. It would have been cheaper for me to have built my own but I had enough to learn without building a box that I didn't understand all that it had to do. It turned out to one of the best decisions I made. I have had a lot of problems but none of them were the controller though sometimes it took a lot of digging to discover it. Like Mach, Bob has strived to constantly improve his products and when I get ready for the controller for the Hybrid I will again get it pre built from Bob. Here is the basic flow of the process. Mach 3, running on the PC, reads the G code one line at a time and sends commands to the controller which then sends pulses to the stepper motors which control all movement of the machine.
This is the A axis. There is a 920 oz/in stepper motor mounted to a 10:1 gearbox. At 25 RPM a 3" diameter piece is cutting at 225 IPM. The fastest I have run it was 100 RPM. Originally I was running a large gear on the shaft that gave me a 5:1 ratio which was fine except that when the router bit grabbed on the stock it could overpower the stepper motor holding power. I got lucky and got this gearbox instead of adding a jackshaft. The main consideration is that you want enough mechanical advantage so that kickback won't move the stock. I have run the A with a 640 stepper and turned a 8 foot by 10 inch column with no problems. That is 6400 oz/in output. If I was to do it again I would look at Oriental Motors for a 10:1 geared motor with 6000 to 10000 oz/in output. If you look in front of the back bearing block you will see the index zero sensor. A proximity sensor that protrudes from base and senses the bolt head in the shaft. In the picture on the right you can see the 5 staggered holes that align to holes at different heights to raise and lower the bed. Because of the mechanical advantage I recommend that you limit the Z to 6 inches of travel and raise/lower the A as needed.
I mounted the key board tray on a swing arm so that when I want to sit and edit files it is at the right height to sit and work and when I am at the gantry I swing the keyboard 180 degrees. The keyboard is a VersaPiont which is a wireless game keyboard with a mouse button and comfortable to carry. The mouse button is not as nice as a regular mouse but saves chasing down a mouse. The keyboard comes with a pointer that will do all mouse functions. It is to the left of the keyboard. Above the keyboard is a Texas MicroCircuits CNC MiniPendant - MP1, www.randyray.com/bcd/.
This is the MachBlue touch off. The software and full instructions can be found at, http://www.cnczone.com/forums/showthread.php?t=56079 . This is great as it makes it easy to set Z zero, material edge in X and Y plus zero X and Y any where you want on the cutting surface. When used without an automatic tool changer, ATC, the machine stops when a tool change is read. The tool is replaced and a Z zero is done . Then start is pressed and the job continues with the Z set to the proper height. As far as I am concerned this is an absolute necessity.
This shows the Z touch off for center of the spindle. Eventually I will have a permanently mounted touch off plate and write a macro so that machine will go to the plate and do a touch off. Also you can see the 2" face plate that I normally use to mount stock. On larger stock I drill a 2" hole about .5" deep and mount the face plate inside. This allows me to remove the face plate and use a chuck to mount the stock on the manual lathe for sanding
Here is the dust foot in which I cut a slot so that the collet wrench can get to the router shaft. Makes it a lot easier when you only have to worry wit one wrench. Also shown is the brush I use. Comes as one flexible molded piece 36" long. Works great and most of the time I don't use it in the front and still very little dust escapes my 650 FPM dust collector. Part # is FPVC143036 from McMaster Carr.
This is Hall effect limit switch found at http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=US5881LUA-ND . At $2.18 it is a good deal. The hall effect switches current when a magnet is sensed. The yellow dot on the rail is a rare earth magnet that activates the switch.
If you are running an indexer or one of the Legacy CNC Ornamental Mills this software is absolutely essential. At $100 USD these wizards by Rich do about 75% of the columns I do, They can be purchased at http://www.wizardsbyrich.embarqspace.com/. The upgrades are included in the price. Above are 3 different columns done with Rich's new wizards. All started with square stock which was rounded to 4" to start and the then the fluting or rope was done. Total machine time was less than 30 minutes. Starting at the left is a 9 sided with a 1" taper and 1 twist in 36", next is a 29 sided piece with 1 twist in 36" then five 4" rope columns with 2.75" rope, one twist every 7.5" and 3 starts and finally two 17 flute columns. Version 2 has been released and it is even better. I heard that even Legacy told one of their customers to buy it.