Craftsman 15-inch Drill Press
This is another excellent article by Mikey, a frequent contributor to MachinistBlog.com and winner of our “Machining Metal as a Hobby” contest.
The Craftsman 15″ Drill Press, Model 137.229150, is a floor model commonly found in many home shops. Made by Rexon of Taiwan for Sears, Grizzly and others it is a typical consumer grade drill press. When new this machine is quite functional and if you use it to drill holes in wood and the occasional piece of metal then this drill press will give you years of service. However, if you are a metal worker and need more accuracy in your machine it’s a whole other ball game.
The accuracy of these machines when new is not too bad but in a few short years mine developed significant run out, with 0.003″ total indicator run out (TIR) at the spindle and double that at the chuck. That may not seem too bad but let me tell you, 0.006″ of run out at the chuck is enough to visibly see the bit wobbling! My spindle bearings had developed play that I could hear and feel and I knew it was time to do something about it.
While it may appear to be daunting it turns out that restoring it is not difficult. However, it does require access to a hydraulic press and a puller for the spindle pulley so take that into consideration. Other than these tools no special tooling is required beyond that found in the typical home shop. If you or your friends don’t own a hydraulic press all machine shops and most auto repair shops do; the cost to press the bearings off and on should be minimal.
If we consider where run out could come from it will likely be the spindle assembly, the arbor or the chuck. The spindle assembly is basically the drive sleeve that drives, supports and guides the spindle at the top, the solid spindle itself, and the four bearings that support these components. I suppose the quill could contribute but unfortunately there is no provision for improving the accuracy of the quill so it’s a moot point.
The manual does not list part numbers for the above components but you can order them from the Sears Parts Direct website at reasonable cost using their illustrated parts breakdown. I suggest replacing the spindle, the drive sleeve and all four bearings at this time.
I also suggest you obtain precision after market bearings instead of using the OEM bearings. You will need 3 each 6204ZZ and 1 each 6203ZZ. I chose to replace one of the 6204ZZ bearings with a 6204-2RS; this bearing is sealed and resides at the bottom of the quill where it is exposed to chips and cutting fluid. All of these bearings are available from your local supplier but are cheaper on eBay. I prefer to use Nachi bearings for their quality but this is a personal choice.
If/when I need to rebuild my drill press again I will use an angular contact bearing to replace the lower quill bearing; the near equivalent for the 6204-2RS is the slightly longer 5204-2RS. Note that I have NOT done this yet so I’m not sure if the bearing would protrude a few millimeters. If it did you could chuck the quill in the lathe and bore the bearing recess deeper, or live with a little protrusion. Only the lower bearing needs to be an angular contact bearing; radial bearings are fine for the upper spindle bearing and drive sleeve. Why an angular contact bearing?
Angular contact bearings are designed to take both axial and radial loads, unlike radial bearings which are made for radial loads only. Consider that when using a drill press to push a drill into a work piece both axial and radial forces are at work. Sort of makes you wonder what the designer was thinking, doesn’t it? Take a look at a good American drill press, like a Clausing, and you’ll find an angular contact bearing at the end of the spindle.
The chuck arbor is another potential source of run out and I typically change it to a new Albrecht or Jacobs arbor when installing a new chuck. The OEM spindle requires a #2 Morse Taper.
Two precision drill chucks, an Albrecht keyless chuck and a Jacobs Super-Chuck 14N
If you are using the OEM chuck for woodworking or general use then it may suffice. However, I would consider replacing it if you need to drill a precision hole. You can use a keyed chuck, like the Jacobs Super-Chuck 14N on the right, or a keyless chuck like the very accurate Albrecht on the left. Both are far more accurate than your drill press will ever be and can be had on eBay at reasonable cost. If I could only have one chuck I would choose the Albrecht for the obvious convenience and accuracy it provides.
In summary, we are going to replace the parts in the drive train that could be causing run out and consider replacing the arbor and chuck, which are additional sources of potential run out.
Okay, let’s get this thing apart! As always, please work carefully and proceed at your own risk.
Teardown
- Use your arbor wedge to knock out the arbor and chuck. If you don’t have one you can make one from 1/8″ thick mild steel.
- Remove the light bulb from its socket.
- Loosen the two set screws that hold the head to the column and move the head to your work bench. It is heavy so try to have another person assist you if possible.
- Open the belt cover and remove the belts. Now remove the nut at the top of the spindle – this is a LH thread. You can insert the arbor wedge into the slot in the quill to hold the spindle still.
- Remove the spindle pulley. You will need a pulley puller for this.
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Remove the quill.
- Loosen the quill adjusting set screw just to the right of the spring.
- On the left side of the head find the quill return spring assembly. It has two nuts; the outer one is a jam nut. Remove the jam nut.
- The manual recommends that you place a screwdriver into one of the slots to control the spring as you release tension but I just used a gloved hand to grab hold of the spring housing and, while controlling the spring tension (turn the housing slightly CCW), remove the nut. The tension is not that strong and is released in about a single turn. It will look like this when removed [photo 4].
- Turn the feed handle and catch the quill as it drops out. Continue reading Restoring a Craftsman 15″ Drill Press
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