It's best to remove glue before it hardens, but sometimes that's not possible. When I face cement-hard glue, I pull out this robust scraper to bull my way through it. The blade is 1/8-in.-thick tempered steel, as tough as a chisel. There's no chatter, because the tool's long body is made from heavy iron pipe. Extra weight and leverage really count!
I ordered the blade through a catalog for about $8 and bought the rest of the parts from the hardware store for about $10. The pipe is a prethreaded nipple. The blade comes with a predrilled 1/4-in. hole, but I had to drill holes through a dowel and the end cap for the threaded rod. The rubber washers dampen vibration. To remove old, dried glue from the blade, I scrape it with a chisel or soak it in hot water.
Source Woodworker's Supply, (800) 645-9292, www.woodworker.com
Blade for glue scraper, #511-004, $8.