How to Install Flush Bolts on Doors
Like the familiar, surface-mounted barrel bolt, flush bolts consist of a metal rod that slides from a door frame into a door jamb. Unlike barrel bolts, flush bolts mount into recessed channels, called mortises, which are usually located at the inner face of the door's top and bottom rails or the bottom edge of the lock stile. Carpenters cut the flush bolts' channels and recesses with routers or chisels and bore the flush bolts' rod holes, called bolt keeps, with power drills. Special guide assemblies, called jigs, quickly create precise mortises for flush bolts.
Align the mortised end of the flush bolt router jig with the door's bottom edge. Twist the jig's clamps clockwise to secure the jig to the door. Select a router bit according to the flush bolt manufacturer's specifications; the bit must route to the precise depth and width of the flush bolt.
Mount the bit to the router and adjust the bit's depth to the deep mortise dimensions specified by the flush bolt's manufacturer. Rest the router's plate on the jig's edge and align the bit with the channel that cuts through the door's stile. Move the bit away from the door.
Activate the router and slide the spinning bit through the jig's channel until the router halts against the jig's stop plate. Remove the router from the jig and allow the bit to stop spinning. Rotate the router and align the bit with the channel that cuts through the door's bottom rail.
Activate the router and slide the bit through the channel until the router halts at the jig's stop. Remove the router from the jig and allow the bit to stop spinning. Remove the stile-side stop plate from the jig. Reduce the router bit's depth of cut to the shallow mortise dimensions specified by the flush bolt's manufacturer
Align the bit with the stile channel. Activate the router and push the router until it halts against the end of the channel. Remove the router from the jig. Turn the jig's clamps counterclockwise to loosen.
Remove the jig from the door. Fit the flush bolt into the mortises, long side on the stile and short side on the bottom rail. Use a screwdriver to drive screws through the flush bolt's screw holes and into the door.
- Route mortises and drill holes for flush bolt keep plates after hanging the door. With the door attached to jambs, you can swing the door into a closed position to check for proper keep plate layout.
- Check with your flush bolt manufacturer or retailer before purchasing a jig. Some jigs might not be compatible with specially designed flush bolts.
Based in Hawaii, Shane Grey began writing professionally in 2004. He draws on his construction experience to write instructional home and garden articles. In addition to freelance work, Grey has held a position as an in-house copywriter for an online retailer. He holds a Bachelor of Arts in theater arts from Humboldt State University.
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