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Making Plane Blades #2: Etching a Logo

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Blog entry by bobasaurus posted 08-17-2015 06:32 AM 1560 reads 12 times favorited 5 comments Add to Favorites Watch
« Part 1: Fabrication and Heat Treatment Part 2 of Making Plane Blades series no next part

(Disclaimer: I take no responsibility for anything done with this information, proceed at your own risk.)

I like to etch my logo onto plane blades using toner transfer and salt water electrolysis. This technique is commonly used by knife makers to put a makers mark on their blades, and is pretty simple to do.

I start by making a logo in a program called Inkscape. This makes a “vector” image that can be scaled to whatever size I want without becoming blurry. I then invert the colors and horizontally mirror the image to get something like this:

This image needs to be printed using a laser printer (NOT an inkjet printer) onto glossy photo paper. I use “Hammermill Color Laser Gloss Paper, 94 Brightness, 32lb” paper and it seems to work okay, but about any shiny paper will work.

Now I use a clothes iron to transfer the printed image to the steel blade (this is called “toner transfer”). I tape one edge down, make sure things are aligned, then iron away:

This will liquefy the plastic toner particles and make them stick to the steel. I use the edge of the iron as a burnisher to push the melted toner onto the steel after everything is heated up. After I feel it has been thoroughly heated and burnished, I fill the sink with cold water and put the blade in. After some soaking, I gently scrub off the paper first with my fingers then with a small toothbrush until the bare metal is shining through the non-toner areas:

Next I coat the non-image parts of the blade with shellac and then wrap them with blue painters tape to prevent accidental etching of random areas, leaving one small bare metal section to connect a wire to later.

For the etching stage, you’ll need a DC voltage supply of some kind. This could be a battery charger or large-capacity “wall wart” dc transformer or a regulated power supply… about any low voltage supply at a few amps capacity will work. Initially I tried connecting the supply directly to the etching, but there was a problem:

There is so little resistance while etching that it forms a “short”, drawing so much current that it either breaks or shuts off the power supply. So you’ll also need a “load” in series with the power supply and your piece being etched to regulate the current being supplied. For a battery charger, put a battery to be charged in series with your etching. For my power supply, I made a “resistive load” by thermally gluing a couple resistors to a big hunk of aluminum so they wouldn’t melt under load. Assuming the worst case of no resistance when etching, make sure that:

(power supply voltage [V]) / (load resistance [ohms]) < (power supply max current [amps])

And check that your load resistance can handle the power involved without melting/exploding (thus my large piece of aluminum). The battery charger method makes this easy, as it’s specifically designed to handle the battery as its load.

Connect a wire from the negative (black) terminal of your power supply to a hunk of steel that will make your “probe”. Wrap some scrap cloth or paper towel around the end of the probe and secure it with a rubber band. Connect a wire from the positive (red) terminal of the power supply to the load, then connect the other side of the load to the blade being etched. You could also have the load on the negative side, it doesn’t matter as long as it’s in series.

Now mix up some salt water in the kitchen until the salt stops dissolving.

Turn on the power supply, dunk the probe’s cloth end into the salt water, then touch the now-wet probe to the area being etched:

You should see some tiny bubbles forming in the salt water around the area being etched as you’re holding the probe. The steel from the uncovered areas of the blade will detach and plate onto the steel of the probe, leaving an etched recess in the blade. This can take quite a while if you have a smaller power supply… it took about 10 minutes using my 24V supply drawing about 4 amps with my load. Keep going until you can feel the etched recess in the blade using a fingernail. You might have to move the probe around if doing a big etch so all areas get equal coverage. Dunk back in the salt water occasionally if the probe dries out.

After you’re finished etching, use sandpaper on a hard surface to remove the toner. I haven’t found any other way to remove the toner, it’s resilient stuff.

Sometimes the etching leaves weird mottled black coloring in the recesses. To even this out, I coat the etched areas with apple cider vinegar and leave them outside for a while:

This oxidizes everything the vinegar touches. I then sand the black/rusty stuff off the top, then hit the recesses with a soft buffing wheel to leave the dark oxidization only around the edges.

Here is the completed etch on my swap plane’s blade:

And another from the previous plane swap, this one came out darker and the head is flipped for some reason:

Soon I plan on doing this on a brass plate to make a custom branding iron. I did a test with a brass probe and brass piece being etched and it worked well.

Here is a similar set of steps I found online:

http://www.instructables.com/id/How-To-Electro-Etch-a-Solid-Metal-Plaque/?ALLSTEPS

-- Allen, Colorado



5 comments so far

View RogerBean's profile

RogerBean

1602 posts in 2415 days


#1 posted 08-17-2015 10:21 AM

Allen,
Cool process. Well done, and thanks for the info.
Roger

-- "Everybody makes mistakes. A craftsman always fixes them." (Monty Kennedy, "The Checkering and Carving of Gunstocks", 1952)

View daddywoofdawg's profile

daddywoofdawg

1010 posts in 1037 days


#2 posted 08-17-2015 12:13 PM

“For a battery charger, put a battery to be charged in series with your etching. For my power supply, I made a “resistive load” by thermally gluing a couple resistors to a big hunk of aluminum so they wouldn’t melt under load. Assuming the worst case of no resistance when etching, make sure that:

(power supply voltage [V]) / (load resistance [ohms]) < (power supply max current [amps])”
Are you saying use a battery charger and hook to the battery,then hook the battery lead to the plane blade and the other lead to the etching probe? if not can you show a better photo of this step.

View MNclone's profile

MNclone

187 posts in 1046 days


#3 posted 08-17-2015 12:50 PM

Interesting, do you think this could this be done with a more typical electrylosis set up in reverse?

View bobasaurus's profile

bobasaurus

2658 posts in 2646 days


#4 posted 08-17-2015 05:14 PM

daddywoof, everything needs to be in series (not parallel). I imagine this would work like so: positive charger terminal to positive battery terminal, negative battery terminal to piece being etched, probe to negative charger terminal. I haven’t used a charger myself, but I hear car battery chargers work well.

MNclone, yes this is like electrolysis rust removal in reverse but with salt instead of washing soda.

-- Allen, Colorado

View Northwest29's profile

Northwest29

1494 posts in 1952 days


#5 posted 08-19-2015 09:32 PM

Very cool process and the blog explains it quite well. Thank you very much for taking the time to put it together. I will have to add this to my shop techniques.

-- Ron, Eugene, OR, "Curiosity is a terrible thing to waste."

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