Air Vise Modification

This was a reverse engineering project to see if we could safely add jaw position sensors to it without compromising the mechanism. I drew up a detailed model to verify that our desired hole placement would work.

This vise is a pretty simple design that follows the design of a lot of other pneumatic vises. Because the vise is made of aluminum, the tapers that draw the jaw together are not machined into the vise jaws themselves. This taper was transferred to steel yoke that is attached to the piston. This yoke rides on a pin in each jaw to draw them together.

In our experience, there are a couple limitations to this vise. Obviously, being made of aluminum, the clamping force and rigidity are lower than the standard vise. It does exhibit good repeatability due to the machined steel yoke. Another limitation is in handling high pressures with parts not set deeply into the jaws. This is largely due to the flanges holding the jaws being a little too loose. This allows the entire jaw to pitch. Adding to the pitch, the cross-section of the jaw below the pin is quite thin. Fracture occurs around the pin, blowing out the bottom of the jaw. This is not an issue in normal use because the force of the yoke is sufficient to compress the vise jaw against the base of the vise.

I believe this flaw could be easily remedied by slightly lengthening the yoke or moving the bearing surfaces closer to the top. This would allow moving the pin higher into the jaw and remove that weak spot.

That said, these are great value for the money and I wouldn't expect failure under normal use.

• Reference Vise - this is the vise that I re-modeled
• Vise Model - this model is not the full version, I removed the internal mechanism in this version so that is is suitable to use as a fixture in cam software