So, this is the 3rd time since the beginning of the year that I've stripped threading or destroyed something through over tightening.

The first was tightening the clamp on a cheap, no-name stem. Both the stem and the bars were 26.0 clamp diameter, according to the shop that sold them to me. I could never get the clamp tight enough to keep the bars from eventually rotating. It eventually gave. Looked like it was forged aluminum.

The second was tightening the cable clamp on some old (old!) Weinmann brakes, shearing the bolt in two.

The third was last night while I was tightening a no name seat post collar, trying to eliminate creaking from the area (removed post, cleaned up as much dirt as I could from tube and post, light grease before reinserting). The pivot on the collar looks to be brass. It's been loosened and tightened a number of times and I've had a lot of trouble keeping it tight enough to keep my seat post from migrating down the tube. Started tightening and felt the tell-tale give.

Anyone else go through this problem? Is it time I buy a torque wrench? I don't want to keep destroying parts as I slowly upgrade.