INDUSTRIES

Drill Press Test #2
Checking Chuck Runout and Spindle Play

A few years ago, I decided to make some "rosettes" for a remodeling project that I was doing at home. I bought a really nice cutter (that was to be used in a drill press) for this purpose. The first time I tried the large bit, (on the oldest drill press in my shop) I was astonished at the problems I was having. The machine "rattled" every time the cutter made contact with the material. The cuts were tearing out like mad, and I could barely hold the pieces solid as I made them, even with a clamp holding them against the fence that was mounted on my drill press table. I couldn’t believe how poorly the pieces were turning out! My first thoughts were that the cutter I bought was "junk". I thought about calling the company I got it from, but decided to try it on another machine first. I put it into the old Bridgeport (milling machine) that I had in my shop, and put a piece of wood in the machinists vise that was mounted on it. When I turned on the machine, and lowered the cutter into the face of the material, it produced a satin smooth cut with no problems whatsoever. This immediately proved there was no problem with the cutter; the problems were in the drill press that I had tried the cutter on. By checking the table squaring, as shown in Drill Press Test 1, I confirmed that the table was perfectly square to the spindle. This left only two other possible problem areas in the drill press; runout on the chuck, or excessive spindle play. Either of these problems would cause the cutter to "wobble" as it rotated, which would explain why I was having such a hard time making the pieces that I needed for my project.

The following procedure will allow you to check runout.

1. Install the dial indicator onto the mounting bar, as shown in the photo to the left.

2. Install (and tighten) the 1û2" pin into the drill chuck.

3. With the spindle of the drill press all the way up, set the drill press table height so that about 1û2" of the pin extends into the hole in the table. Lock the table.

4. Clamp the A-LINE-IT™ in position so that the tip of the dial indicator is centered on the 1û2" pin.

5. Open the cover of the drill press, and then lower the spindle to a position that places the tip of the dial indicator about 1û4" clear of the teeth in the chuck.

6. Zero the dial indicator.

7. Observe the pointer on the dial indicator as you slowly rotate the spindle. (Turn one of the pulleys by hand.) The pointer should move no more than three thousandths of  an inch.

If it does, I would recommend that you do a couple more tests to help identify the problem:

A. Loosen the 1û2" pin in the chuck. Rotate the pin about 1û4 turn as you retighten the chuck, and test again as described earlier to make sure the pin is being held properly in the chuck.

B. If the test above doesn’t solve the problem, I would recommend that you remove the chuck from the spindle, and clean the spindle shaft and interior mating surface of the chuck. With the chuck off, take a reading directly off the spindle in the same manner as you did using the 1û2" pin. If this test shows that the spindle is straight, any significant runout that you saw earlier has to be caused by the chuck. Reinstall the chuck, and re-test using the 1û2" pin. If the spindle shows good, and the chuck is producing runout, you have two choices; replace the chuck (with a high quality chuck) or learn to "live with it".

The procedure will allow you to check spindle play.

1. Configure the A-LINE-IT™ as described in steps 1- 6 above.

2. With the spindle lowered, grasp the chuck with one hand (as you hold the spindle’s vertical position with the other hand), and try to move the spindle back and forth. This will show you the amount of play on the spindle.NOTE: This reading does not necessarily mean you have bad bearings in your drill press. On most drill presses, there is some play between the main housing of the drill press and the housing in which the spindle is mounted. On the drill presses in my shop, there is a screw (and locking nut) on the side of the main housing that fits into a slot in the side of the spindle housing. It is used to keep the spindle housing in proper alignment. I have found that by carefully adjusting this screw, you can help minimize play in the drill press. Just remember not to tighten this screw enough to cause any sort of drag that makes it hard to raise and lower the spindle as you drill.