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Jan 8, 2021
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How to make a compass for milling any holes with a screwdriver

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

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

Materials:

  • steel strip;
  • pipes 10 mm, 25 mm;
  • furniture bolts М5 – 2 pcs .;
  • wing nut and washer M5;
  • broken crowns – 2 pcs.

Compass making process

For the manufacture of the rod of the compass, a steel strip is selected. Its length should be slightly larger than the radius of the maximum hole that you plan to mill. A 6 mm wide cutout is made along the center. A concave rounding is machined from one end of the pipe for joining with a 25 mm pipe.

Marking the steel strip

Making a cut in the steel strip

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

Steel strip with pipe sections

A piece of pipe is welded to the cut edge of the strip

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

Broken drill

Cut off the drill shank

weld the centering drill sleeve into the upper part of the wide tube

It is also required to cut a ring with a clip from another shank to make a stop.

It is also required to cut a ring with a clip from another shank to make a stop

cut a ring

Then it is necessary to weld 2 bolts with caps to each other. After that, notches are made on the compass as on a ruler.

it is necessary to weld 2 bolts with caps to each other

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

Compass assembly kit

Then a conventional drill is installed into the sleeve with a stop from the part of the bit shank so that it does not fall through.

a conventional drill is installed in the sleeve

Milling compass

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. Then the drill shank is clamped into the drill and milling is performed in a circle. By adjusting its overhang, you can even not damage the tabletop on which the work is done.

We mill a hole in plywood

We mill a hole in thin metal

Watch the video

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