American Woodworker
Contact Us | Help | Report a Bug
Sign in | Join
 

Strong, Perfect Lock Miter Joints Bennington VT

When correctly cut, the parts go together at a perfect 90-degree angle and the interlocking tongues and grooves make for lots of mechanical strength and glue surface area. Lock miters are also great at keeping parts aligned during assembly.

The Home Depot
(802)447-9997
121 N Bennington Rd
Bennington, VT
Hours
Mon-Sat: 6:00am-9:00pm
Sun: 8:00am-7:00pm

H. Greenberg and Son
802-442-3131
321 Main St. Bennington, VT, 05201
Bennington, VT
 
H. Greenberg & Son Inc
(413) 664-4576
1366 Curran Highway
North Adams, MA
 
Carr Hardware True Value
(413) 663-6600
192 State Street
North Adams, MA
 
Miles True Value Lbr.
(802) 375-2525
178 Chittenden Dr
Arlington, VT
 
H. Greenberg & Son Inc.
(802) 442-3131
321 Main Street
Bennington, VT
 
Hoosick True Value Hardware
(518) 686-7238
21953 Ny 22
Hoosick Falls, NY
 
W W Building Supply
(802) 464-3022
Route 100
Wilmington, VT
 
Deerfield Valley Supply
(802) 464-3364
211 Route 9 W
Wilmington, VT
 
Stanleys Lumber & Building Supplies
(413) 743-0831
20 N Summer St
Adams, MA
 

Strong, Perfect Lock Miter Joints

Strong, Perfect Lock Miter Joints

 

Lock miters are strong, attractive joints that make assembly easy. So why the heck don't we use lock miters more? I think it's because they can be a pain to set up. Well, no more excuses. Here's a clever technique, sent to us by Jim Rodgers of Martinez, California. Give it a try and you may become a lock miter enthusiast.

What's Lock Miter?
A lock miter router bit cuts a 45-degree miter with a tongue and groove. When correctly cut, the parts go together at a perfect 90-degree angle and the interlocking tongues and grooves make for lots of mechanical strength and glue surface area. Lock miters are also great at keeping parts aligned during assembly. Use this joint on drawers, boxes or even hollow columns like newel posts.You can cut a lock miter on end grain, as shown in our photos, or on the long grain. Almost anyplace you'd use a miter, you can successfully use a lock miter.

The Tooling Up
Lock miter bits come in a range of sizes. The size you use depends on the thicknesses of your wood. Even the smallest lock miter bit makes a substantial cut, so I prefer bits with a 1/2-in. shank. They're more stable and result in smoother cuts. Expect to pay $50 to $100 for a bit, depending on the size. Note: The maximum size lock miter bit you can run in a 1-1/2-hp router is the 2-in. diameter. Larger bits must be run in a 2-hp or higher machine. It is essential that you run these massive cutters at the right speed—about 10,000 rpm. Your router must have variable speeds so you can slow down for these big cutters.

The Perfect Set-Up
Follow the sequence shown in Photos 1 through 7 to produce perfect lock miters on your router table. Remember to have on hand the material required for your project plus six test pieces. It's critical that the test pieces be the same thickness as the project pieces because the bit set up is specific to the thickness of your material. As you get more familiar with the set up procedure you'll need fewer test pieces.

Fig. A layout
First, center the bit on the material

PHOTO 1:
Center the bit on your workpiece by eye. Be sure your router is unplugged.

 PHOTO 2:
Adjust the router table fence by eye to its approximate position. Three points must be aligned. The top of the workpiece, the face of the fence and the 45-degree angle of the cutter ( Fig. B ). This is just a preliminary set up. You'll perfect the fence position later.

PHOTO 3:
Test the height of the router bit by cutting two test pieces. Hold each piece flat on the router table.

 PHOTO 4:
Assemble the test pieces. When the cutter is perfectly centered, the faces of the two pieces will be aligned. Adjust the bit as needed. You must have the bit centered on the material before you start working on the fence position.

Now, set the fence position.

PHOTO 5:

Click here to read the rest of the article from American Woodworker