Introduction: Angle Divider for Perfect Miters No 2

About: I miss the days when magazines like Popular Mechanics had all sorts of DIY projects for making and repairing just about everything. I am enjoying posting things I have learned and done since I got my first to…

In January 2016 I did an Instructable on my copy of a Stanley No 30 Angle Divider. This is another version of the Stanley No 30 Angle Divider that looks a little more like the original from 1903. (Search your favorite browser for Stanley No 30 Angle Divider to see images of the original version with a wooden handle.)

This version offers a better way to ensure the center for the arm axis and the center line for the adjustment slot are on the same line. It is a revision of the method that was used in this Instructable. I think it will be more reliable, yet.

The photo shows this version of the Angle Divider in use to set a power miter saw. The other member of the miter would be set and cut by turning the Angle Divider 180 degrees and adjusting the saw to the other half of the fence. The fence on this saw had a wavy profile. I needed to catch more of the blade because I was cutting some tall baseboard molding, so I added 3/4 inch plywood to the face of the fence. That brought the work out toward the operator and caught more blade. It also gave a flat top surface for the Angle Divider, which resulted in easier and more accurate setting of the saw.

Materials

  • Hardwood fully cured
  • 16 gauge sheet steel
  • 1/4 inch steel rod
  • 3/16 inch steel rod
  • 3/8 inch steel rod
  • 3/16 inch nylon locking nut
  • 1/4 inch flat washer
  • 1/4 inch wing nut
  • Wood glue

Tools

  • Table saw
  • Router and router table
  • C clamps
  • Spring clamps
  • 4 1/2 inch angle head grinder with cutting wheel
  • Straight piece of 3/4 inch angle iron for a cutting guide
  • Vise
  • Drill press and drills
  • Electric hand drill
  • Hacksaw
  • MIG welder (GMAW)
  • Bench grinder

Step 1: Cut Steel for the Arms or Wings

I have some rusty scrap 16 gauge steel that works well for making an Angle Divider. It is about 2 inches wide, but has nice straight edges.

See the first photo. I cut a piece 7 inches long.

See the second photo. I marked a diagonal line across the 7 inch piece of steel. The diagonal is laid out so that one end of each 7 inch piece will be 1 1/4 inches wide and the other end will be about 3/4 inch wide (minus the width of the cutting wheel). I used a piece of angle iron as a guide to get a straight cut. The angle iron is clamped to the 16 gauge steel sheet.

Step 2: Drill Holes Simultaneously

Place the two pieces for the arms on top of one another so the straight edges align with each other. I could have clamped them together with a Vise-Grip pliers. I chose to tack weld the two pieces together in an area where each weld would later be ground away in the process of shaping the arms. See the text boxes in the photo. The holes in each piece are 3/16 inch in diameter and are 2 1/4 inches apart on center.

Step 3: The Connecting Arms

I had another piece of 16 gauge steel, also scrap and rusty, but about 9 1/2 inches wide. I used the angle iron as a guide and marked a strip 11/16 inch wide for cutting so the final piece was about 5/8 inch wide. I cut two pieces 4 1/4 inches long from the 5/8 inch strip and tack welded them one on top of the other for simultaneous drilling. See the text boxes for the size of the holes and their spacing. One set is 3/16 inch in diameter, but the other is 1/4 inch in diameter. Grind away the tack welds, round the corners, and grind away any sharp edges.

Once all four metal pieces have been made and drilled, grind away rough edges that interfere with smooth action of the parts or could cut skin. Use a power wire brush to remove rust deposits.

Step 4: Lay Out the Pieces and Weld Pivot Pins in Place

It is important to lay out the pieces properly so they slide over one another as they ought. Then one must be careful to preserve that order when welding pivot pins in place. But, it is also very easy to become confused and make a mistake.

See the second graphic. Click on it so you can see all of it. It is a cross sectional view. The gray piece is the arm or wing. The olive drab piece is the connecting arm. The 3/16 inch pivot pin is in blue. The lower red rounding is a weld to the connecting arm. The collar (blue) is a piece of 3/8 inch rod center drilled 3/16 inch in diameter. The 3/16 inch pivot pin is sized and cut to length. The collar was put onto the end of the rod and welded in place.

When assembling and welding the mirror image of the opposite half the olive drab piece and the gray piece exchange positions, as you can see from the first photo.

Shortcut--Rather than welding, #10 machine screws could be used. Use a nylon stop nut to keep joints snug.

Step 5: The Wooden Body

The wooden body is fully cured hardwood. I am using some beech that is over 75 years old. It is about 3/4 inch thick and 1 1/2 inches wide. It is about 10 inches long. I cut both corners on one end at 45 degrees.

See the first photo. I fitted the metal assembly made from the hinged arms to the wooden body to mark the approximate limits of the slot so the arms have a full range of motion at 90 degrees to the body to folded over the body and I marked the ends of the slot. I set the fence on the router table so the 1/4 inch bit will cut on a line centered between the sides of the body.

See the second photo. I set end stops to limit the sliding of the body when routing. I raised the router only a little after each cut for better control.

See the third photo. After several cuts the router bit poked through. Keep your fingers near the ends of the body so you will not be injured by the router. I lightly made a few strokes on each side of the slot with a wood rasp to make the fit with the adjustment bolt smoother.

Step 6: The Adjustment Bolt and Its "head"

The first photo shows what I wanted to make, except the smaller rod has not yet been cut and welded.. (If you want to reduce your work, just buy a 1/4 inch carriage bolt and file or grind two opposite flats under the rounded head so it fits the slot smoothly.)

See the second photo. Use a thread cutting die to make about 5/16 inches of threads on the end of a 1/4 inch rod. The threads should be 1/4 x 20.

See the third photo. Drill a 1/4 inch hole in a piece of steel bar 1/8 x 3/4 inch and cut it to about 1 1/4 inches in length. Drill a 3/16 inch hole to fit a rod as you see in the first photo.

See the fourth photo. Put a wing nut onto the threads on the 1/4 inch rod, but leave it at least one turn loose. Add a washer. Add the connecting arms. Put the rod through the body slot. Add the 1/8 inch "head." Saw to length with a hacksaw.

See the fifth photo. I drilled a 1/4 inch hole into a piece of sacrificial wood so the 1/4 inch rod would be perpendicular to the flat steel that is the adjustment bolt's head. See the sixth photo. Place the 3/6 inch rod into its hole and cut to length. The 3/16 inch rod keeps the head from turning when the wing nut is tightened. Weld both rods.

Step 7: Placing the Axis Hole

See the first photo. Place a 1/4 inch drill in the chuck of a drill press. Let the bit be in the slot of the angle divider body. Bring a piece of wood with a straight edge against the edge of the divider body. Clamp the straight edge to the drill press table. Remove the 1/4 inch bit.

See the second photo. Slide the divider body down and place a 3/16 inch bit into the drill chuck.

See the third photo. Drill the hole.

See the fourth photo. This Angle Divider will help you get miters like this on any corner with ease. (The test pieces are from an old park bench. Edges were not planed or particularly smooth, but are fairly straight. The test pieces are 2 1/8 inches wide, which is more than enough for any inaccuracies to show clearly, but the miter is tight and neat. The corner is more than 90 degrees.)

(For outside corners, record the angle of the corner with a T bevel square. Fit the Angle Divider to the T bevel square and proceed as if you were working with an inside corner.)