7' crosscut saw electrolysis resto WIP

[CedarEater]

So, I got gifted this 7' crosscut saw from the next-door neighbor of our jobsite a few weeks back.
It was a bit rusty but I thought it would be a good candidate for my first electrolysis rust removal project. I figure this will probably lead me to learning how to sharpen it too. Here is what it looked like when I got it.

After a little internet search for 'electrolysis rust removal', reading a few write-ups and watching a couple videos I figured I was all set. This electrolysis thing looked simple enough. Just add 1 tablespoon of sodium carbonate (i.e. washing soda) to each gallon of water, hook up some rebar (anode) to the positive lead and the saw (cathode) to the negative lead of the battery charger, submerse the whole shebang in the electrolytic solution (except extend the rebar out of the solution so the positive lead of your charger doesn't corrode away to nothing), plug in the battery charger and watch the bubbles form and the rust fall off while practicing all the safety precautions. How hard could that be, right?

Well, Saturday morning I spent a couple hours building the box that would be lined with plastic and act as the tub for the saw to bathe in. It took a couple hours to get it all set up and ready to go.

I plugged it in and nothing happened. Pushed some buttons on the battery charger and still nothing.

I figured the connection to the saw was not a good one so I scrapped the clips back and forth on the saw and started to notice little sparks and lots of bubbles forming and the battery charger's charging lights came on. The problem was that the bubbles were only forming right at the negative lead clip and not down the whole length of the saw. Then the charger would shut off every couple minutes or so. I took a little sandpaper to the spot on the saw that I was connecting to in an attempt to get a very good connection. At that point the battery charger would not charge at all and was acting like it was shorting out. After checking and rechecking the set up to make sure the saw was not shorting out to the rebar and that everything was hooked up right and that I used the right ratio of washing soda to water I went and saw a movie.

Eventually, I came to the conclusion that it was something in the battery charger that was switching it off whenever the negative lead even touched the solution while the positive was hooked up to the rebar. I decided to borrow a different battery charger. This borrowed one being a Napa brand "automatic" battery charger. I hooked it up and nothing happened again. Frustrating to say the least. This is not rocket science!

I started draining my 30 gallons of solution with a syphon thinking that somehow my solution was contaminated or something was wrong with it. Then I got the idea to hook up my truck battery. Truck batteries don't care what is happening when anything is hooked up to them. So, I tested it on a carpenter's hatchet head in a 5 gallon bucket before hooking the saw up to it. That hatchet bubbled like crazy and it was time to hook up the saw to the truck.

The battery charger got hooked up to the truck battery too after a little while. It was fine with charging the battery even though the battery was connected to the anode and cathode in the solution. Bubbles were forming like crazy and I was quickly able to disconnect the handle parts so they could be wired up too.

After about 6 hours of electrolysis it was getting dark on Sunday evening and the truck battery was about out of juice even though the battery charger was hooked up to it on the 2 amp setting. Since I need my truck on Monday morning it was time to see what kind of progress was made. Most of the red rust was removed from the handle parts and some red paint was exposed.

I'm thinking its easier to finish them off in a vinegar bath rather than wire them back up for more electrolysis so thats what I did.

The saw will probably get another treatment of electrolysis next weekend. I will flip it over and spin it around to get more of the red rust off that was shadowed from the rebar by the stands that I made to hold the saw away from the rebar. This is what it looks like now.

The electrolysis exposed a stamp that reads "E839" on each end of the saw on opposite sides. I tried to photograph it but it wasn't showing up very well. Maybe I can get a better shot of it later? No visible etching has shown up yet. Maybe I will hit it lightly with a scotch bright pad after the next round of electrolysis?

I have come to the conclusion that if you are going to do this electrolysis thing don't use an "automatic" battery charger. I will be looking for one that sparks if I touch the + and - leads together. Older ones that are not so "automatic" are the way to go IMHO.

 

[Double Ott]

Great write up and pictures.
I think you nailed it..

"I have come to the conclusion that if you are going to do this electrolysis thing don't use an "automatic" battery charger. I will be looking for one that sparks if I touch the + and - leads together. Older ones that are not so "automatic" are the way to go IMHO. "

Several guys that tried this ended up going with the older style charger. It will stay on, the auto ones turn themselves off.

Tom

 

[Square_peg]

Thanks for the very useful WIP.

I'm glad you persisted and got it figured out. You probably just saved me and a bunch of other guys a lot of hassle. I need to do this with my 90" saw.

PS - Hope your truck started OK this morning.

 

[FortyTwoBlades]

Yes--you absolutely want to avoid automatic chargers. A manual one is the way to go. I'm setting up an electrolysis tank for cleaning vintage scythe blades and my tank arrived today. I've got the washing soda ready to go and am just waiting on the charger. Since I plan on using it pretty heavily I went with a USA-made industrial-grade manual charger by Rizk National Industries.

Chatted with a fellow at the company and they suggested this model on the medium setting. Electrolysis works best at around 2 volts and 30-50 amps from what I've read. The amps do the actual work and the voltage is what splits the water, causing the bubbles. While those bubbles let you know stuff is working you want to keep it minimal since it generates flammable hydrogen gas--hence it being preferable to work the tank in a well-ventilated area and to keep sparks away from the anode while it's in operation if possible. Some folks go so far as to build their own power supplies that hit those marks on the dot.

I'm no expert, though. Just getting into it like you are.

 

[FortyTwoBlades]

I just got my electrolysis tank up and running and can already tell you one thing you'll want to fix if possible--you need a bigger anode for that saw. You want an anode that's as close to the same size of the object being cleaned or larger or you're not going to get much cleaning done. I was using a piece of rebar bent into a "V" to make a bipod for the positive clip and even with the two ends in the water it wasn't reaching the full length of the scythe blade I was cleaning. It still ended up cleaning it well, but that's 'cause I had it running all night in fully saturated electrolyte. Picked up a length of mild steel flat stock at Lowe's and bent one end so it would stand with the wide side facing the workpiece, and bent the other side up vertically to give me a good spot to clamp to that wasn't submerged. Much better coverage now.

 

[trailtime]

I have two 6-foot lengths of #4 rebar mounted on either side of my tank with enough room for a saw to fit between them without touching. Works pretty well. I drilled a hole in each piece of rebar to just-fit a loop of heavy gauge copper wire for my (+) lead. You still have to scrub the saw after a day in the tank, but the crud comes off pretty easily, especially all the gunk in the gullets.

 

[FortyTwoBlades]

Yeah I find using a wire wheel really sloughs the rust off after it's been loosened by the electrolysis--it's like kicking mud clods off your boots after they've dried. Nice and easy.

 

[CedarEater]

Thanks for the suggestions. I lengthened the piece of rebar that bent around the end of the saw so that it extended the full length of the saw on both sides and gave it another bath all day today. It worked beautifully with the battery charger hooked up to the truck battery and charging at 6 amps. I pulled it out and it was all black and clean of red rust. I rinsed it off and scrubbed it with dish soap and a scotchbrite pad, dried it off and put some mineral oil on it for now. The next step will be hitting it with a fine brass cup brush.

 

[FortyTwoBlades]

Here's the results of one blade cleaning. I had two of these blades, both in about the same rusted-but-restorable condition, and I did a full restoration on one of them. Electrolysis bath followed by a wipe-down to remove the loose gunk then a once-over with a fine wire brush in a drill. After snapping the photographs I then torched the tang (with the blade wrapped in a soaking rag) and adjusted the pitch for proper lay during use, wire brushed off the discoloration, then applied a couple of clear coats of lacquer.

 

[CedarEater]

Neat 42! That turned out real nice. Thanks for sharing.