How to Fix a Slipping F-style Bar Clamp – It’s Easier Than You Think

Many of us have experienced the phenomenon of F-Style bar clamp slippage. It can happen to quality clamps that had been put through extensive use, but it is more common with inexpensive clamps, where the manufacturers tried to cut on production or material costs. The problem is that the moving jaw can’t anchor itself to the bar because the bar is too smooth.

The first thing you need to do is to clean the bar from any oil residue using denatured alcohol etc. If this doesn’t solve the problem, you should corrugate the edges of the bar.  The way I chose to do this was with a cold chisel and an anvil. Your biggest challenge here is to stabilize the clamp on the anvil. You can use an auxiliary clamp, magnets, or both.

Pacing the indentation is up to you. You can mark them with a rule and a sharpie pen, or you can trust your senses and let the muscle memory kick in after some practice (which I promise you it will).

With a little effort, you will be able to rehabilitate many of your challenging clamps. So the next time you see a crippled clamp in a garage sale, which in the past, you would have probably dismissed, you would now consider giving it a new home and a productive future.

– Yoav Liberman

PWM Shop Blog, Woodworking Blogs
Yoav Liberman

About Yoav Liberman

Yoav S. Liberman is a woodworker and a teacher. His pieces have been featured in several woodworking books, most recently in Robin Wood’s CORES Recycled. Yoav teaches woodworking at the Rudolf Steiner School in Manhattan, and also frequently guest teaches in craft schools across the country.  Between 2003 and 2011 Yoav  headed the woodworking program at Harvard University's Eliot House. Yoav’s articles have appeared in American Woodworker and Woodwork Magazine. He frequently contributes woodworking web content to a number of digital publications   Yoav has a degree in architecture and later held two competitive residency programs: at The Worcester Center for Crafts in Massachusetts, and the Windgate Foundation Fellowship at Purchase College, New York. He lives in Chestnut Ridge NY.