Thanks FTW. The KMG grinder, as you probably know, is a respected brand that started as a Knife Makers Group, no weld project. There are plans all over the net on this baby. As you can weld, it is even easier for you to build. KMG sells parts for those who do not want to buy the commercial version they have now come to offer. Ebay also has all kinds of cheap deals on motors and controllers. A key to these machines is a big variable speed motor. I like to run mine out of doors, so I am limited to 110, and 1.5 hp. Otherwise I would have a 3hp motor. Of course I am talking general use, tubing does not have much heft to it.
I want to make a 1x42 machine to the same standard, as I use that belt size a lot, and it is much cheaper for me to source the belts, and it is wide enough to do a lot of, admittedly mostly non-tubing, things. The serious abrasives are available in 1x42. Though the selection of 2x72 is uneatable, and in the US you would not have any problems getting the stuff.
What about this guy, note the double shaft design:
http://www.polarbearforge.com/grinder_kit.html
This is the wheel I am going to use on the 1"
http://usaknifemaker.com/grinders-sa...el-70duro.html