CNC update + rotary table start

I received our first CNC package of THK linear rails, they are about 30" long were used, but in great condition. My only gripe is the wipers on some of the carriages have a tendency to "catch" on the rail a little bit. I simply hand bent it up a marginal bit and it rides smooth as butter. You can see the ground sheen off them. I put electrical tape on the ends of the rails to ensure the carriages don't slide off. Pictures of these rails will come later.

I had done some research on the spindle, and found several examples of folks using treadmill motors to power their mini-cnc's typically in the 2-3 HP range, (DC motor) with an operational range of 0-6750 RPM. I didn't know much about the controller, and Troy instantly thought that was a great idea, because the VFD we were looking at for the 3 Phase 3HP motor he has would cost 300$. Where we found a treadmill on craigslist for 20$. Hopefully we can pick it up tommorow for that price. In any event he found a DC controller for the motor for less than 100$ on ebay on a 'buy it now' auction which puts at a much more cost effective solution for the motor control system.

There was also a discussion about frame materials, cost, rigidity, ease of manufacturing, and ease of transportation. So things like extruded high grade aluminum (6061), welding steel vs. warpage, and granite composite were discussed. No conclusions were drawn up with that except that we want our solution to incorporate all the attributes listed above.

When I met Troy and Bryan at the techshop. They showed me how to do assembly's in SW. This made me tremendously happy because it's like doors are being opened up for my imagination. Since we finished the fly cutter, we are now going to move onto other bigger and better projects, (which involve the use of our previously made fly cutter tehehe.) This time it is a rotary table. So I started working on modeling the rotary table on solidworks. Here is what i've got so far:



One of the problems i'm encountering is I don't know the dimensions for a standard t-slot so i went with an arbitrary depth of 1 inch and 0.25" slots. The beauty of parametric modeling, is I can go back and fix the dimensions later, Yay! I've also been playing with screw placement, clearance issues with mounting bolts and the bolts that hold the rotary table together.

The problem is I'm trying to make use of material that I already have (0.38" thick steel stock.) Which I have plenty of so I'm going to have to carefully play with the dimensions and design internal blocks to bolt everything together since 0.38" steel is not thick enough for me to comfortably drill and tap strong bolts into it. While I could calculate the yield load and fatigue life of bolts that would fit into the stock, I simply am going to use the KISS principle and oversize the bolts, and use internal mounting blocks.

References:
http://www.technologystudent.com/gears1/worm1.htm
http://www.helicron.net/workshop/gearcutting/cutting_gears/
http://www.astronomiainumbria.org/advanced_internet_files/meccanica/easyweb.easynet.co.uk/_chrish/worms.htm
http://www.cnczone.com/forums/showthread.php?t=63992