Drill press runout

Re: Drill press runout

Larry Marker in Alabama

>If you have a machine shop supply outfit anywhere near, you can buy a 36 inch piece of 1/2" drill rod for a few bucks. If not, a 1/2 " or so drill bit that is good and straight will work if you can chuck it in well and have part of the shaft without any flutes sticking out.

A dial indicator with a magnetic base will measure the runout easily. Measure close to the chuck. Run the quill down about 1/2 or 2/3 of the max for yur measurement. If you see a lot of runout, try also measuring with the quill all the way up. If the chuck and/or the arbor is the culprit, the runout won't change with quill extension.

I had a lot of runout in my Jet. A new chuck and quill fixed it.

Larry

Re: Drill press runout

Gene Gauss

>I think you can measure the runout of your drill press using any old piece of round stock that will fit into the chuck as follows: Clamp the piece of round stock into your chuck and using a marking pen, match mark the chuck and round stock. Then rotate the chuck slowly by hand and record the difference between the high and low readings on the dial indicator. Then, remove and rotate the stock some with respect to the match marks, to try to locate the relationship between stock and chuck that gives the maximum runout, i.e., the runout of the drill press and any bend in the stock add. Next, remove and replace the round stock in the chuck with the stock rotated 180 degrees from the relative position where the runout was greatest and repeat the runout measurement. The difference between these two readings should be the runout of the chuck/quill set. I struggled with excessive runout on an old Craftsman drill press that I bought used several years ago. I replaced the bearings (which were noisy) with no improvement. Next, a neighbor who has a machine shop in his basement, tried to straighten the quill, but that didn't help much either. Then I replaced the chuck with a new one purchased from Sears (for $70 - it's not an ordinary off-the-shelf chuck), and that didn't help either. I finally solved the runout problem by buying a used old Delta drill press on which I measured the runout before purchasing. Of course, it was three-phase, but that gave me the opportunity to make a single-phase to three-phase inverter using a three horsepower, three-phase motor that I was able to get for free. (Scrounging is much more satisfying than buying the solution to problem.) Good luck. Gene Gauss

Re: Drill press runout

Ink Man

>Gene & Larry-appreciate the feedback. I am in the process of removing the chuck and inspecting/cleaning the arbor. When that is complete, my next step will be to numerically check runout. I do have a 1/2" bit which is 12" long that I will use as a straight rod for measuring purposes. If this shows excessive runout, I guess I will need to take some additional steps. Thanks again.

I suggest a 1/2 x 3" dowel pin

Forrest Addy

>I suggest a 1/2 x 3" dowel pin purchased from your nearest fastener shop. These are centerless ground to close tolerances. Conduct your test but do not be surprised if your chuck runs out 0.005" near the jaws and 0.008" three inches away. A home duty drill press is not really a precision tool.

A 3/8" drill sticking out 4" is pretty flexible. You can deflect it 1/16" by pushing on it with your thumb. Any problems you may have drilling a round accurate hole will probably be associated with tecchnique. Thus a drill press is more of a source of rotation and consistant thrust for twist drills than a precision boring machine.

Regular twist drills tent to follow grain and hardness of wood and tend to generate a three lobed hole in metal. If you need to drill precise holes in wood I suggest you resort to brad point bits and forstner bits. These have a central spur around which the cutting edges orbit. Brad points used with care work particularly well in sheet metal that's backed up with wood.

For general drilling technique I refer you to any trade school text but in particular to the Henry Ford "Shop Theory" trades apprentice text. There's a lot to drilling (there's a lot to any basic skill set for that matter) and the prudent home shop worker will build skills deliberately rather than fling himself at a project unprepared.

Runout Minimized

Ink Man

>To all: I believe I have minimized my problem. In my TS Aligner Jr. set, I found an aluminum rod which I used to check runout. I was seeing as much as .007-.008! NOTE: my measurement was taken about 1/2" below the mouth of the chuck. I removed the chuck and arbor assembly and checked runout on the arbor spindle. This measured < .001. Cleaned the arbor and inside of the arbor spindle, put everything back together and checked again. About .003-.004 runout now. Cleaned the inside of the chuck and reseated the aluminum rod. Checked again and runout was only .001. Checked about 4" down the rod and got a reading of about .002+. Completely acceptable for my purposes. What did I learn? Keep the inside of the chuck clean, and make sure the bit is seated properly. Thanks for your input on this.

Forrest-I really appreciate your insight on drill presses and their limitations. Very informative and helpful.

Tim