If you use them for woodworking it shouldn't be too many, I have about 2 dozen of these and I could use them 3 times more. My wife has actually started using them too, which could mean I need four times as much. The clamping force is strong enough to hold heavy work in place. I've used them recently to hold curved wood in place and never had a problem. I've used them to hold a variety of pieces together for gluing and even used them to create "stops" for repeat cuts. Once you have them, you'll find a million uses for them. A note: you should have pretty strong hands with these (and smaller ones). This should of course make sense from the outset, but it is worth mentioning. My wife often has to use two hands to use them, not for lack of strength, but her hands aren't big enough to hold handles and have enough leverage to use them with ease. However, she loves them and uses them in many projects. Six gets you to a dozen, so just start with two packs, you won't regret it.