Vintage Craftsman 150 Drill Press - Restore/refurb

hman

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About a week ago I bought myself a new project. It's an old Craftsman 150 drill press I saw at a Habitat for Humanity thrift store. Sold "as is," with a sign indicating the motor didn't work. Bought it for $25.

I posted a gloat on the Tool Junkies forum - http://www.hobby-machinist.com/threads/vintage-drill-press-score.49601/ - and it was suggested that I put my restoration/refurb posts on this forum. So here I am!

First off, photos of the DP as bought:
kHPIM4427.jpg kHPIM4428.jpg kHPIM4431.jpg
Vital statistics: The model number is 103.24530. Comparing features to catalog descriptions, I'm pretty sure it's catalog number is 99M2453N (floor model, sold without motor), from the 1960/61 catalog. The DP includes the optional "Vari-Slo" variable speed pulley system (Sears Cat #9-2340).

Initial disassembly showed that this DP is actually in very good mechanical condition. There's some light surface rust on the table and column, and just two small divot holes on the table. Other than that, no broken parts, nothing jammed or stuck, only the chuck key missing. I cleaned up all the internal parts and found two pairs of ball bearings (spindle and motor) that I thought were due for replacement. Ordered those from eBay. After removing everything from the castings, I gave them a pressure wash and rinse at a local car wash. Stubborn gunk was taken care of with Zep citrus cleaner.

New clamp ring: When first trying to remove the head from the column, I'd almost had a "woopsie" that could seriously damaged some parts. When I loosened the clamp bolt, I didn't have a good enough grasp on the head and it slipped downward. Part of the Vari-Slo mechanism extends over the column, and when the head moved downward, it ran the column into the mechanism. Luckily it didn't hit hard or cause any damage. But I decided I needed some kind of safety collar under the head to limit its downward travel ... just in case I or some future owner had occasion to again remove the head.

I started with a 5 lb cast iron dumbbell weight.
kHPIM4441.jpg
After covering the lathe ways I faced the outer section of both sides. Luckily, I could ignore the nasty scallops near the center, because that part would be cut away. The column of the DP is 2 ¾" diameter. I used a 2 ½" hole saw to make a rough hole, then finished it to the final size. I then offset the remaining ring by ¾", using three of the jaws of my 4-jaw chuck. There wasn't room for the fourth jaw, but I was able to hold the part securely with what I had. I used a 4" hole saw to cut out an eccentric ring.
kHPIM4442.jpg
After cleaning up the OD, I went to the mill to drill, tap and counterbore for a ¼" screw. Finally, I saw cut across the widest part of the ring.
kHPIM4446.jpg
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The result is an easily adjustable ring that fits well on the DP column and can be clamped tightly in place.

-- to be continued --
 
Motor testing: Because the notice on the DP said the motor did not work, checking it out was one of my higher priority items. As bought, the power cable and on/off switch cables on the DP had been snipped off. You can see some of that in the photos attached to my first post. Once I had the motor disassembled, I started checking each of the elements.

First off was the centrifugal switch. The mechanism looked OK. Couldn't spin up the rotor, but the springs and weights looked OK, and their motions were unimpeded. The switch itself had good continuity when closed, and infinite resistance when open. Just for fun I gave the contacts a good cleaning with some 600 grit sandpaper.

Second was the motor windings. Hmmm - the stator has 5 leads. I assumed that meant split run windings, plus a start winding (because it connected to the centrifugal switch and capacitor). The meters I had - an HF freebie with at least 1.5 ohms resistance in the leads, plus an analog meter whose lowest resistance scale was in k ohms - were of little or no help deciphering the three run winding leads. It did appear that two of them were shorted together, but I couldn't be sure. So I cobbled together a 110v AC test rig - basically, a pair of alligators in series with a 150 watt lamp. When connected across a good motor winding and you touch a screwdriver lightly to the motor poles, you can feel a slight buzz from the AC magnetic field. If the two leads are shorted, there will be no buzz.
HPIM4485.JPG
PS - If you want to build such a rig yourself, be sure to use an incandescent bulb (remember those?) of at least 100 watts. Energy efficient bulbs just won't do it!

Two of the leads were definitely shorted together. But it looked like they both went to the same place. Assuming I had nothing to lose, I carefully cut away some of the ancient, crusted tape over what looked like the right joint and discovered that both leads were soldered to the same motor wire. I guess it was done to make the many connections easier(?) Anyway, I re-insulated the joint with "liquid electrical tape" and declared the windings OK. I did add heat shrink tubing to all the motor leads, both to identify them and as insurance - the wires are rubber insulated and cloth covered. Though the original insulation seemed OK, such ancient rubber is not too flexible any more, so it's very easy to crack.

Next was the capacitor. The form factor and construction of the original capacitor is fascinating - a solder sealed rectangular metal box, about 3/4" x 3 1/4" x 5", slipped inside a cardboard sleeve. This shape allows the capacitor to nestle inside the motor base. No bulky cylindrical "warts" on the outside of the motor case for Craftsman! So I sincerely hoped that it would be good. A replacement of the same size and shape would probably be impossible to find nowadays!

An initial test with an analog ohm meter indicated that it was indeed acting like a capacitor.
[For those interested, make sure the capacitor is discharged by shorting the leads together. Connect across an analog ohm meter. The needle should immediately swing to somewhere in mid scale, then decay to infinite ohms as the capacitor charges. Wait a second or two and reverse the test leads. The needle should immediately peg at zero ohms, then decay back to infinite. If the needle does not go to infinite ohms on either test, or the second test does not peg the meter, there is probably a high resistance short in the cap. If the needle goes to low ohms and stays there, there's a low resistance short. If the needle doesn't move at all, there's an open.]

The question was, what value was the capacitance? I'd read that old capacitors slowly lose it, so I was concerned. Went to Radio Shack and found a very nice meter (SKU #2200075) for $45. It not only has capacitance, but also several other useful scales not normally found on meters. Plus the range of the capacitance scale (999.9 uF) was wider than that of a $70 meter they had. The nominal value of my capacitor would have been out of range on the other one. Tested the capacitor when I got home. It read 190.6 uF - smack dab in the middle of the value range (167-210 MFD) printed on the case. Golden!
kHPIM4468.jpg

Bottom line - I have every reason to believe that the original motor will run just fine, once I get the new bearings and reassemble it. Not having to replce the motor or add a clunky new capacitor will definitely help preserve the "vintage" look of this old veteran! I don't know why the DP was originally marked as having a non-working motor.

PS - Use caution when ordering bearings (especially Chinese) from eBay!!! I'd originally ordered the same bearing number as that originally on the motor (with a different suffix for shielded). The bearings I got did not fit (though they were somewhat close)! I went back to the motor and measured the shaft diameter and housing bore. They were different (metric) from the nominal sizes (inch) of the description on eBay, even though the numbers were the same. Did a new search, just for the metric ID, OD, etc. Found some matches and ordered a pair of these. Then, just for fun, I did another eBay search, based on the bearing number listed for one of the correct ones. Bleah! The hits I got for that number were for a different ID!!!
 
Usually if I'm buying bearings I get them MCM or another trusted source. You gotta watch some of the sellers on Ebay, sometimes they are cheap for a reason.

 
Got the correct bearings in the mail today, so I completed the rewiring and reassembly of the motor. Gave it the blue smoke test ... IT WORKS!!! Durn, it feels good to know that the original motor will stay on this old classic!
 
hman,

Before you reassemble the motor, you need to run one more electrical test, a short-to-ground test. This would preferably be done with a megohmmeter (AKA Megger) but if you are careful and don't have any knob-twiddlers or other children around, you can use the AC line and an incandescent lamp (but I would use a lower wattage one than that floodlamp). Put the stator assembly into a large plastic bowl. Identify which contact in your wall outlet plug is the Neutral and which the Line. With the line cord NOT plugged into the outlet, connect the line cord wire that will be Neutral to the stator frame. Connect the Line wire to one side of the lamp socket. The other side of the lamp socket will be the test lead. Connect the test lead to either Run winding wire. Plug in the line plug. The lamp should not glow, even dimly. Unplug the line plug. Connect the test lead to either side of the start winding (assuming that the capacitor is still disconnected). Plug in the line plug. The lamp should not glow. Unplug the line plug. Disconnect the Neutral wire from the stator frame, and replace the stator in the bowl with the capacitor. Connect the Neutral wire to the metal case of the capacitor. Connect the test lead to both capacitor terminals. Plug in the line plug. The lamp should not glow. Unplug the line plug.

EDIT: I was writing this while you were writing the above. Apparently you got lucky. But I wouldn't have bet on it, given that the motor had been reported as bad.
 
Robert -

You're absolutely right about the importance of short-to-ground testing!

Once I had the motor disassembled, I did an initial test with my HF DVM. I did it again, using the new meter I'd bought, after I had the motor reassembled and the wiring completed. As mentioned in my previous, I was concerned that flexing the old insulation might break it and expose a wire. I was also concerned that I might have unknowingly pinched a wire (old or new) between parts of the motor housing. The new meter auto-ranges up to megohms. Checked each end of both windings, plus both sides of the line cord, to ground before closing the connection area cover. Everything was open to ground. I also did a quick-and-dirty instrument check, holding a test lead in each hand with relatively dry fingers - about 6 megohms.

I do like your test method and thought of a simple variation, using a volt meter - Connect a winding in series with the bulb, as in my test above. Then connect one side of the volt meter (set to the most sensitive AC scale available) to the motor case and probe both ends of the winding. Should read zero! Test the other winding the same way ... likewise the capacitor.
 
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No, that won't work the same. Mentally simulate a short at one end of the winding by connecting the lead wire coming out from that end to the frame. You would have a hard short to case but no reading on the meter with the meter lead connected to the frame and that end of the winding. You would get a small reading with the meter leads connected to the wire for the other end and the frame (where the cold end of the lamp would be connected due to IR losses in the winding since the flood light would be drawing around 1.25 A and there would be a small drop in the motor winding.
 
Hmmmm ... gotta think about this some more. You're definitely right about a hard short ... though it should find high resistance shorts quite efficiently. And of course, a hard short to the motor case is very easy to find with even a junky ohm meter and no additional hardware.

One reason I went off on this tangent to begin with is your saying to look for the lamp to glow. I don't think a few volts or a few milliamps will cause the filament to glow at all. I forget the actual value, but I think something like 5 milliamps is where GFCI devices pop.
 
Painting: There are several blogs having to do with restoring these drill presses. Whenever they mention paint, it's Rustoleum Hammered Bronze. Unfortunately, I don't think it's available any more - tried several stores, couldn't find that color. So I bought the three rattle cans that seemed to be closest to the right color. Painted up some aluminum coupons and set them on the DP head to compare:
kHPIM4452.jpg
The uppermost (Rustoleum Universal Metallic "Champagne Mist") looked to be the best match. It's a bit more golden than the original, but it's pretty close - and without the original on hand for comparison, it'll surely get by.

Masked off the holes and hit all the castings with at least one coat. The head got one coat inside and two outside.
kHPIM4489.jpgkHPIM4478.jpg
I left all the parts out in a sunny spot to dry for a couple days.

Spindle reassembly and test
: I started reassembling the drill press today. I was most concerned with possible runout in the spindle and chuck, so I did that assembly first (using the new bearings I'd ordered from eBay). I mounted the spindle sleeve in the lathe chuck - not to spin it (the lathe was not under power), but simply because the lathe chuck and carriage were handy to hold things. Mounted a ½" Thompson rod in the drill chuck. Used an Interapid .0005" DTI and checked the runout at 1", 5" and 10" from the DP chuck (rotating it by hand.)
kHPIM4492.jpg
ALMOST UNBELIEVABLE! Runout was 0.0010" at 1" and 10", 0.0025" at 5"! I think I mentioned earlier that all the parts I'd taken from the drill press looked to be in very good mechanical condition ... but WOW!
 
Hmmmm ... gotta think about this some more. You're definitely right about a hard short ... though it should find high resistance shorts quite efficiently. And of course, a hard short to the motor case is very easy to find with even a junky ohm meter and no additional hardware.

One reason I went off on this tangent to begin with is your saying to look for the lamp to glow. I don't think a few volts or a few milliamps will cause the filament to glow at all. I forget the actual value, but I think something like 5 milliamps is where GFCI devices pop.

With that frosted face 150W flood lamp, I'm sure that you are correct. I should have been more specific and said to use an unfrosted (clear) bulb 12.5 or 15 Watt lamp.

However, assuming that you are using a three-wire plug in a properly grounded outlet, as it hasn't tripped the breaker yet, it is most likely alright.
 
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