Clamping Glued Joints
By Craig Brougher
Hi, Dee. Craig here. Neener neener to the single clamp on glued joints, but ok on the balanced 4 clamps of Ampico blocks. Nothing at all wrong with that!
For the other readers: Clamps tend to slide parts when used without restraints, and to imagine the detailed work required to restrain a hundred small parts while clamping them is beyond my imagination.
I suggest weighting small parts, such as pneumatics, with 1-2# blocks of lead weight. If you are suggesting that rubber bands should never be used to clamp very small stuff like valve blocks, then perhaps you will also tell us why. Don't worry. I will be appropriately ashamed of myself.
The reason I suggest weights for most things is because the force applied by a weight is vertical and cannot slide the parts insiduously. You don't have to watch to see which way it is going to take off and skid on you. Not so with single spring clamps (if that is what someone may assume). A single spring clamp has gravity pulling down on its handles for one thing, so it tends to have a component of force tangential to the surface you are trying to glue. Sorry, but it's a fact of life. Just using a little trig will show you that you have vectors in two directions, one of which will slide the joint, whereas with weight (or a rubber band circle), you have a single vector normal to the gluing surface.
Now, suppose you make it a point to keep the clamp handles vertical... No more gravity, but instead, you have the almost impossible requirement (with a single clamp) to keep the contact points of the jaws perfectly aligned on a plane normal (perpendicular) to the gluing surface. Otherwise, they will still have a sliding component. Some people are very adept at positioning spring clamps and never have any trouble. On the other hand, some of us on occassion discover too late that they are not as experienced, and end up breaking the joint and redoing it.
I can't fault anyone who successfully uses clamps, but I sure can warn anybody who imagines themselves to be as good as you are, to learn the trick first.
Craig B.
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(Message sent Sat 3 Aug 1996, 23:52:52 GMT, from time zone GMT.) |
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