Don't know why they can't put it in the books...
Your explanation was about what I was figuring as to the answer to my question, but wanted to be sure I wasn't missing anything...
Of course now I've found another cute issue with my POS Smithy machine - it appears the table flexes a little bit! In order to get the work up close to the millhead, I am using a couple of spacer blocks so that the workpeice is about 6-8" off the table, but still solidly mounted. Doing this, I only have to come down with the bit about an inch to make contact with the workpeice.
I was using two clamps on it, and found that even making shallow cuts and slow feeds, the setup would slip. So I added two more clamps on an angle from the other T-slot, and tightened everything up as much as I dared. My clamps are strap clamps, with the workpeice on one end, the securing bolt in the middle, and the other end held up by two 1-2-3 blocks stacked on end and a step block.
Once I had everything torqued as much as I dared, I found that the workpeice didn't slip any more, but it was also difficult to move the table. I had to really turn hard on the table handle! Once I had made my cut, and taken the peice back out, the table moved easily again. Only theory I could think of to account for it is that the cast iron table is flexing just enough to bind up the gibs. I didn't think I was THAT strong...
Gooserider