Electrolysis to Remove Rust: Craftsman King-Seeley 103.23141 Drill Press Restoration, Pt. 2

In Part One of this series, we got the drill press column removed from the base. I had to get the column off to make the base easier to work with and get the rust off in preparation for repainting it.

You can see the rust is bad. I believe at one point there was a mini-flood in my friend's basement where the drill press lived for a few decades.

And you can see the result.

This is the bottom - ironically aside from the parts that touch the floor, it's in good shape.

In pondering how to approach the problem, I did some searching on the interwebs and discovered a popular (and successful) way to remove heavy rust like this is by electrolysis.

There is a whole series of videos on rust removal on YouTube by a poster called "tubalcain" which is very much worth watching. He does a great job demonstrating the electrolysis process.

However, most videos and web sites show how to derust tools, not 80-lb cast iron drill press bases.

The main issue is I needed a tank large enough to hold the base. So I took some measurements, went to my local Despot, and found a suitable storage container.

It's a 17 gallon container. And it's big enough!

Now to connect it all up.

There is a lot on the internet about electrolysis to remove rust, so I'll spare you the details. But in short, you mix a solution of water and washing soda (sodium carbonate), and submerge your rusted part in it.

Then you use a battery charger to provide current. The negative side of the charger connects to the piece itself, which becomes the cathode in electrical terms.

A positive charge is put on rods or plates that are partially submerged in the solution. These, then, are anodes.

When the charger is turned on, the direct current flows from the negative cathode to the positive anode(s). And the rust goes with it!

The process does give off hydrogen gas, so I did this outside. If you do it inside, make sure you have good ventilation.

All of the reading I did said to use a manual battery charger. I do have a nice modern charger, but it's automatic. What this means is that an automatic charger connected to our electrolysis tank will not run because the charger has a sensing circuit to determine the charge state of the battery. No battery, no current.

Hence the manual charger. This is a 'classic' Schumacher 2/6 amp manual unit I procured. You will see many folks using this exact charger (or variations thereof).

I used some steel bar stock in the corners of the tank to serve as anodes. This is a typical connection - the positive lead of the charger (red clip) goes to the bar - I drilled a hole in the bar to facilitate a good connection with a 10 gauge wire (gauge not critical, but it was handy and easy to work with) which ran in turn to the other 3 anodes.

The green clamp just holds the bar to the tank.

You want to ensure the anodes and the cathode (the piece) don't touch each other.

And remember, the piece should be connected to the negative side of the charger.

This picture shows the negative connection to the drill press base. I cleaned up the column mounting screw and used that as a contact point.

Here I used bare galvanized wire for connections. Later I added another 10 gauge wire instead of the wire you see here. (I'll explain this later).

I used a few wires mainly because I saw some of the wire in tubalcain's videos get destroyed by rust during the process!  Although I'm not sure how that happened, since rust should be going away from the cathode side of the setup.

I mixed up about 2 cups of washing soda in a couple gallons of hot water. Hot water just to make the soda dissolve easier. Put that water in the tank, and then used a garden hose (see it in the picture) to fill up the tank the rest of the way.

Make your connections first, then turn the charger on. I had the charger set on the 6 amp setting.

You can see the large clamps on the tank - these are for the 4 bar anodes near each corner. The far-right bar has the positive side of the charger connected to it.

The small black clamp is the negative side of the charger.

After a few minutes, the solution should start to 'cook' - it will bubble as the process starts to work. You should see a current draw on the ammeter on the charger.

In my case, there was a small amount of bubbling, but I didn't get a current reading at all. It was clearly working, but very slowly. I let it run for 24 hours, but there wasn't much happening.

So I did some more reading on the process. Ideally, the anodes should surround the workpiece. Clearly, that wasn't practical for me.

However, I did take some thin (22 gauge) steel sheet and make bigger anodes.

I connected some small pieces of sheet to each of the bars in the corners.

Then I used two 1x1 foot pieces - one lying submerged under the drill press base, and one submerged suspended over the base - I drilled holes to use wire to suspend the plate over the drill press base. You can see that in the picture below.

The other element for me was the sheer size of the tank and the drill press base. I wasn't derusting just a small tool, so more power was needed.

I also read that it IS possible to use a modern automatic battery charger as a power supply. The key is to connect a battery in parallel between the charger and the electrolysis tank.

I took the battery out of Grey Girl, my 900S, and used that. I hadn't driven that car for a few weeks and the battery was nearly flat anyway. So since it needed a charge, the timing was good.

On the connections - just connect the battery to the charger as you usually would - then run leads from the positive battery terminal/charger lead to the anode on the tank, and do the same with the negative going to the workpiece.

And of course, I figured I needed more current, so I put the charger on the 15 amp setting.

Oh yeah.

Immediately I had a bubbling brew of electrolytic solution. You can see this on the left. (Note the top steel sheet suspended over the base - the other sheet is on the bottom of the tank.)

I was definitely cooking now!

I was wary that I'd need to pay close attention to this thing as it worked.

So I kept checking every 15 minutes or so.

After about 45 minutes my charger's readout (told you it was modern) said "Aborted - bad battery." I was concerned, so I unplugged it.

This what the solution looked like at this point - disgusting green, floating hunks of rust.

The anodes were covered with rust (just like those videos).

The charger read "Aborted" because the process had stopped, and most of the rust was gone from the base!

Wow. It's like magic. Forty-five minutes.

Unfortunately I didn't get a good picture of the base post-electrolysis after I took it out of the tank. But we'll see it as I continue to work on it.

I lugged the base down to The Dungeon. After the process, there's light surface rust remaining, but you just take it off by hand with a wire brush.

This is one of the sides - compare this to the shots above. The rust is GONE.

It also took some paint with it - paint was flaking off. But I'm repainting it, so it's not a problem.

I decided to spray some corrosion protectant spray on the base, since I have some areas of bare cast iron and it's going to take a couple weeks to be able to repaint the base.

In the background, you can see how clean the piece is - heavy rust is gone!

I'll continue this in the next post and have some better shots of the base. The polished, finished table part of the base is still covered with black rust - it was transformed during the process and still needs to come off. (You can see that in the picture above).

I'll use a wire cup brush on a grinder to get that off. But I'm thrilled I've gotten so much rust off at this stage.

The complete restoration saga

Part 1 - Beginning

Part 2 - Electrolysis to Remove Rust

Part 3 - Grinding to Remove Rust

Part 4 - Leveling Base Table

Part 5 - Recreating Model Number Label

Part 6 - Refinishing Base

Part 7 - Removing Motor

Part 8 - Motor Disassembly

Part 9 - Motor Bearing Replacement

Part 10 - Start Capacitor and Motor Reassembly

Part 11 - Removing Threaded Jacobs Chuck

Part 12 - Spindle Removal

Part 13 - Quill Disassembly

Part 14 - New Quill and Spindle Bearings

Part 15 - Engine Turned Aluminum Trim Proof of Concept

Part 16 - Engine Turned Aluminum Trim

Part 17 - Cleaning and Polishing Hardware

Part 18 - Jacobs 633C Drill Chuck Restoration

Part 19 - Cleaning and Polishing Column

Part 20 - Reassembly Begins

Part 21 - Restoration Completed