Wednesday, December 18, 2013

Drawknife Rehab - Part 2

As luck would have it, just as I was making great progress on this project, I had to go out to work.  I guess that is how it is when one is semi-retired.  In an attempt to be as thorough as I can this will be a rather lengthy post.

Well I'm back and lets take up where I left off a few weeks ago.  I searched the shop and house for the materials needed to remove the rust using electrolysis and the only thing I had was the baking soda.  I purchased a plastic container to use as the electrolysis tank, 8' of 1/2" rebar to use as sacrificial steel, rebar tie wire to connect the rebar together and to tie to the drawknife so that it could be suspended in the tank, and the total cost was less than $12.  I borrowed the battery charger from my neighbor Rusty (isn't that ironic).

First step was to wire the rebar together as evenly spaced around the tank as possible.  All my research indicated that removing rust using electrolysis is a point to point process.  So to avoid any shadowed or blind spots the drawknife needed to be surrounded by the sacrificial steel.  The longer piece of rebar on the left is where I clamp the positive side of the battery charger making the rebar the anode.

Next I filled the tank with water and added 1 tablespoon of baking soda per gallon of water.  Mix this thoroughly, stirring until the solution is clear.  This is the alkaline solution needed.  Some individuals recommended using sodium bicarbonate NaHCO3 (baking soda) while others recommended using sodium carbonate Na2CO3 (Arm & Hammer Super Wash).  I am not a chemist and I know that there is a difference between the two, but I'm not sure exactly what the difference is in regards to removing rust using electrolysis.  By the way, both camps results were the same, the rust was removed.  So the deciding factor was, the baking soda was in the pantry.  I then wired the drawknife to a piece of wood and submerged it in the tank.  The drawknife will be the cathode once the negative cable of the battery charger is attached.

Take great care to ensure the drawknife or any other parts do not come into contact with the rebar!  Next, I attached the positive cable to the rebar and the negative cable of the battery charger to one of the wires around the drawknife.  I made sure that both cable clamps were out of the water.  Once I ensured that everything was as it should be I plugged it in.  Almost immediately I saw a reaction take place.  Another word of caution: If for any reason you should have to move anything in the tank unplug the battery charger first!

After 32 hours I had to remove the drawknife from the tank.  At that point in time it appeared that 99% of the red rust was removed from the drawknife.  The ferrells and caps however still had a bit of rust remaining, especially on the inside of the ferrells.  I rinsed off the drawknife, ferrells and caps while wire brushing them, then I coated them with a protective layer of oil.

There is a good bit of pitting from the rust, hopefully it will take a good edge.

Red rust is removed and the black rust is stabilized and adhered to good metal.

Name stamped into the drawknife was preserved because electrolysis was used to remove the rust.

Metal Protection from Felder, good stuff!

The sludge that remained in the tank was gnarly looking.  The rebar had collected the rust just like it was supposed to.

Earlier today I cleaned the protective coating off the caps and ferrells.  I then placed them in a glass jar covering them with vinegar (5% acidity).  I will remove them in the morning, rinse them with water, then put them back in the jar covering the pieces with a mixture of water and backing soda.  I will leave them in this mixture for a few minutes to neutralize any remaining vinegar then wire brush them.  Hopefully this will remove the remaining rust and I can apply the protective oil.

If I am unable to get a post made prior to Christmas my family and I would like to wish you a very Merry Christmas and a safe and prosperous New Year.

~ Ray Schwanenberger

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