Blake, here is a thread about my home-made (sort of) HUGE mount.
Home-made but made in the workshops of the CSIRO by Bert (avandonk) and his CSIRO buddies.
I didn't make it but I restored it, replaced the bearings with new ones, etc etc.
It may not suit what you want to make, but you might be able to pinch some ideas of it, like the Holden Torana wheels and bearings.
If a car can carry a ton of weight, then this mount will carry lots too.
It was originally designed to carry a heavy tubed 16" Newtonian, but I use my 12" on it and it isn't even breaking a sweat.
Have a look and see if you like any of the ideas built into it. You may be able to adopt them into your project:
http://www.iceinspace.com.au/forum/s...ead.php?t=5657
This one is a briefer account but has better pics of the finished product in Black:
http://www.cloudynights.com/ubbarchi.../o/all/fpart/1
Also, here is a Stepper module and a link to the stepper program to run steppers by your computer:
http://www.jaycar.com.au/productView...r&form=KEYWORD