Restore a Vintage Power Drill

This is a Black & Decker No. 100 1/4" power drill with a Jacobs Model 6141 Rubber-Flex Hex-Key Chuck.

From what I've found, this drill was manufactured sometime in the early 1950s.

It's not a terribly complicated process to clean up an old tool like this, but perhaps some of the things I show will be beneficial to someone who wants to do something similar.

Alrighty. Let's dig in.

Step 1: Before

Here's the state of the drill when I got it.

The original power cord had broken off. (I still had it but it was cracked, crumbly and in very bad shape.)

The chuck was locked in place and I couldn't turn the motor over without a decent amount of effort.

The exterior was oxidized and pretty gunky - an indication of things to come once I opened it up!

Step 2: After

Here are some after shots.

It's not perfect, but it cleaned up pretty well and the motor spins, although much slower than it likely did when it was new.

If I hold the trigger for more than about 10 seconds at a time, the whole drill gets extremely hot. At 30 seconds on, the motor started to sizzle and let out some of it's smoke! And there's only so much left in there . . .

So . . the motor is nearly shot, but it works well enough for occasional "proof" of functionality.

The following steps outline everything I did to get from the before condition, to the after. Enjoy.

Step 3: Handle, Switch and Internal Wiring

I started by removing the handle and examining the condition of the switch and wiring.

The internal wires coming from the motor were in decent condition (not cracked, still flexible), so that was a good sign.

Side note: This is not a complicated tool compared with others I've worked on. All the parts and pieces go together pretty logically. However, it's always smart to snap lots of photos along the way with a project like this, to help you out when reassembling.

Step 4: Brush Assemblies

The brush assembles are take apart next.

Some notes in the photo, so check those out. Here's the order:

• remove the Bakelite brush caps and pull out brushes. Be sure to note orientation of the grooves worn into the ends. Reinstalling these differently than they came out will result in lots of sparking till they wear down evenly again.
• the brush housings have a wire attached to each that is held in place by a spring in a ring shape. These just pop off. There is a washer underneath each one that can be pulled off.
• Loosen/remove set screws holding brush housings in place. Pull out brush housings.

Step 5: Remove Chuck - Jacobs Model 6141

This type of chuck is removed by locking a hex key into it, and then striking the key with a mallet in the direction the drill spins (clockwise).

This old drill only had one direction and one speed. The chuck is threaded on in reverse to that direction, so it stays tightened in place by simply using the tool.

A few firm whacks and the chuck is loosened and can be unthreaded and removed. I used a shot of WD-40 to penetrate the threads before trying to knock it loose.

Step 6: Remove Front End

The front end of the drill is held together with three screws. These were removed and the various pieces were pulled from the drill case.

A later step shows all the cleaned parts laid out in order.

Step 7: Remove Motor Components

With the brushes removed the shaft/armature assembly can be pulled out. The armature assembly is shown in the next step.

The stator magnet assembly is held in place with two screws. These are removed and the this can be pulled out of the case.

Step 8: Clean Armature and Commutator

All the gunk on the armature and stator assembly was gently brushed away with a toothbrush. Q-tips dampened with goof off were used to do a deeper cleaning as needed.

The copper commutator was black with burn marks from the brushes. This was burnished clean by gently going over it with a carbon steel wire wheel in my rotary tool.

Step 9: Clean More

All the remaining parts got a thorough cleaning.

For the internal parts with thick coatings of grease, as much as possible was wiped away with a paper towel.

Anything with hard-stuck-on gunk I soaked in a plastic bag with goof off. This loosened up stuff and dissolved a lot of the crud.

Then everything (aside from the motor components) was washed and scrubbed in hot soapy water with dish soap.

Step 10: Clean and Polish Case

The drill case parts were all cleaned with goof-off to remove whatever was on there - various dribbles of paint and what appeared to be lacquer, as well as a layer of greasy gunk.

The parts were then washed with hot water and dish soap inside and out.

I made a simple buffing station a while ago with a cheap grinder.

Brown tripoli compound was used to machine-polish all of the pieces.

That was followed with a hand-polish using Mother's Mag & Aluminum Polish.

I didn't feel inclined to over-do this, as it will just get oxidized again over time. The goal was a just quick cleaning and a light polish. I also did not want to give the case a clear-coat or anything like that.

Step 11: Parts Layout

Here are all the parts cleaned and laid out.

Step 12: Reassemble

The stator magnet assembly was reinstalled, and the brush housings were put in place and the wires reconnected.

Step 13: Motor Shaft

The motor shaft was put in place next. The brushes don't get installed till later.

Step 14: Front End Reassembly

The front end is reassembled with some fresh grease. I think this is axle grease - it's just what I had on hand.

Step 15: Front Cap

The front cap was reinstalled.

Step 16: Rewire

The brushes were installed, and their caps screwed in place.

The trigger switch got a couple of drops of lubricant, as did the sleeves that hold the ends of the motor shafts (the front sleeve got a drop or two before reassembling the front end).

A new power cord (I used this) was threaded in through the handle and the retainer clip was installed as it was on the original cord. I put on two layers of heat shrink underneath before pinching the clip in place.

The wires were fastened exactly as they had been originally (I even used the same bullet connector).

SAFETY NOTE: As mentioned by several commenters, it's best to replace the original ungrounded two-prong cord with a three-prong cord. The green/ground line can be attached to the inside of the case with a small bolt or screw. This makes the tool much safer to use, and I may upgrade to a three-prong grounded cord at some point.

Step 17: Close It Up

The handle was wiggled into place and the screws were replaced.

The chuck was screwed in place, and after a final wipe-down with a rag and it was done.

I don't claim to be an expert on any of this - specifically related to electric motors. If you've got related experience that will benefit future readers who may find this, please speak up in the comments section with tips, thoughts, etc. It is much appreciated!

Thanks for reading.