How to make a compass for milling any holes with a screwdriver

It is impossible to make a large, perfectly even hole in sheet material with a jigsaw or grinder. To do this you need a special tool, which is easy to make with your own hands. In combination with a drill, it is capable of cutting round holes in plywood, chipboard, MDF, and sheet metal.

Materials:

• steel strip;
  
• pipes 10 mm, 25 mm;
  
• furniture bolts M5 – 2 pcs.;
  
• wing nut and washer M5;
  
• broken crowns – 2 pcs.

Compass manufacturing process

A steel strip is selected to make the compass rod. Its length should be slightly larger than the radius of the maximum hole that is planned to be milled. A 6 mm wide cutout is made along it in the center. A concave rounding is machined from one end of the pipe for joining with a 25 mm tube.


A piece of 25 mm pipe, 50 mm long, is welded to the ground edge of the strip.


Before cutting, a piece of thin tube 35-40 mm long is welded onto the workpiece itself. Then a crossbar is welded between the resulting posts to create a handle.
Next, you need to weld a drill-centering sleeve into the upper part of the wide tube.To do this, you can use a cut shank from a broken crown.



It is also necessary to cut a ring with a clamp from another shank to make a limiter.


Then you need to weld 2 bolts with their heads facing each other. After this, notches are made on the compass as on a ruler.

To complete the assembly of the compass, you need to insert the welded bolts into its slot and tighten them with a wing nut through the washer.

Then a regular drill with a stop from part of the crown shank is installed in the sleeve so that it does not fall through.


To use a compass, a 5 mm hole is drilled in the center of the sheet material. A protruding welded bolt is inserted into it. The drill shank is then clamped into the drill and milling is performed in a circle. By adjusting its reach, you can even avoid damaging the tabletop on which the work is being done.

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