INDUSTRIES

Drill Press Test #1
Checking Table Squaring

Most drill presses have adjustable tables. They can be moved up and down, from side to side, and can be pivoted to allow you to drill holes at angles. Normally, the vertical position of the table is pretty much considered a "rough" adjustment. To compensate for this, there is usually a mechanical stop on the drill press that allows us to control the amount of quill movement that can take place, controlling the depth of the hole we are drilling. We normally try to "center" the table from side to side by aligning the drill bit so that it will clear the hole through the center of the table. For the most critical setting on a drill press, (squaring of the table to the spindle) most of the woodworkers that I know use a small square against a drill bit. To say the least, this may get you close, but not necessarily perfect. The following technique will allow you to adjust your drill press table using the same technique that most machinists use to check head-to-bed squaring on a milling machine. When done properly, this will set the drill press table perfectly square to the spindle of the drill press.

The following procedure will allow you to check drill press table to spindle squaring.

1. Measure from one side of the drill press table to the middle of the hole in center of the table.

2. Measure from the rounded end of the mounting bar (with 12 holes in it) provided with the A-LINE-IT™ , and determine which of the 12 holes is about 1 1û2" less than the measurement you got on the table.

3. Insert the 3û4" socket head screw from the A-LINE-IT™ into the countersunk area of this hole, and screw the 1û2" pin provided with the A-LINE-IT™ onto the screw. Hold the pin by hand, and tighten the socket screw.

4. Mount the dial indicator as shown in the photo above, and lock it in position square to the mounting bar.

5. With the drill table lowered, place the 1û2" pin into the chuck of the drill press, and tighten the chuck.

6. Rotate the chuck to position the dial indicator toward one side of the table.

7. Raise the drill press table to height that causes the dial indicator pointer to rotate 1 to 2 times. Center the table from side to side, and lock the table into position. If you are using the correct hole in the mounting bar, the tip if the indicator should be approximately 1û2" or so from the edge of the table. If it isn’t, move to another hole on the mounting bar or rotate the dial indicator to position the tip of the indicator close to the table edge.

8. Make sure the indicator tip is on a smooth, flat surface, and not in a groove on the table.

9. Zero the dial indicator, and note the reading on the small revolution counter on the dial.

10. Rotate the dial indicator 180 degrees to the opposite side of the table. (You may need to lift the tip of the indicator as you do this to prevent it from plunging into slots in the table top.

11. Check the reading on the dial indicator. (Make sure the revolution counter is on the same reading that it was on the other side of the table. If your table is out a tenth of an inch (.100") from side to side, the pointer on the indicator would still be at zero, but the revolution counter would have moved 1 division on the scale.)

WHAT ARE THE READINGS ON THE DIAL INDICATOR TELLING YOU?

1. If the reading on the indicator went positive when you rotated and checked the second side, this side of the table is higher than the side where you set zero.

2. If the reading on the indicator went negative when you rotated and checked the second side, this side of the table is lower than the side where you set zero.

HOW CAN YOU MAKE ACCURATE ADJUSTMENTS TO THE TABLE?

Drill press tables have a center pivot. When you raise one side of the table, you are automatically lowering the other side. Let’s say that you set your zero on the right side, and when you rotated to the left side your reading was fifty thousandths of an inch (.050") above zero. This side of the table is high. By lowering this side of the table by twenty five thousandths, (.025") you are raising the other side the same distance. Re-check your readings after locking the table into position. If you take your time, you should be able to get your drill press table within .002" from side to side. This is much more accurate than you will ever get using any other method of squaring the table.