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This is a rejected magazine article that I thought I would share with all of you, maybe someone has a use for the information.

 

I sometimes have problems with fabricating very small parts, especially from metal. The edges curl, I drop them and other bad things usually happen. In an effort to make small metal detail parts, I decided to try etching them from metal. I didn't want to put a lot of money into theses parts, so I decided to experiment. I happened upon a technique that works very well for making small parts with for little or no money and only a small time investment. The basic tools for the process are PCB Etchant from Radio Shack, a Sanford Sharpie marker, a scribing tool , some tape and some thin sheet metal.
My scribing tool was made by cutting the head off of a pin and inserting the pin into an Xacto handle.

The basics of the process:

Photoetching is a process that removes metal using a chemical reaction. In this case, ferric chloride is used to erode the unprotected metal. The Sharpie is used as a "resist coating" to make a pattern for a part. The etchant will not erode the protected areas of the metal. Tape is used to protect the back side of the part. Scotch tape or clear packing tape work just fine for this.

Etching:
My favorite source for thin sheet metal is aluminum soft drink cans. After cutting them open (emptying them first helps alot), flatten out a section and cut it into a square or rectangle.

The sheet should be cleaned before etching, I prefer lacquer thinner and steel wool for the cleaning, though fine sandpaper works well too. The reason for cleaning is that the paint and/or the coating on the inside of the can will also resist the etchant, making the process take much longer. K&S sheet brass (.005") or copper will also work very nicely, but they will take longer to etch.

After cleaning, place tape on the side of the metal that will not be etched. This will prevent the pattern from being destroyed from the backside.
Once the backside is completely covered in tape, break out the Sharpie and color in the front side of the sheet. This is going to act as the resist coating.
Color in the whole front of the sheet, unless you are comfortable "freehanding" your part's outline. Drawing the part on the sheet also works, but I find it a bit more difficult.
After the sheet is colored in (or your pattern drawn), a scribing tool is used to draw the part outline or clean up the drawn outline. A drafting template can be helpful for this.
The part shape can simply be scribed into the colored area. Any area not colored will be removed! The finished sheet will look something like this.
The etchant needs to be put into a container for the etching process. Metal containers CANNOT be used, the etchant will destroy them. Glass or plastic is called for here. I use a drinking glass or a shallow bowl for most etching. Be very careful when pouring the etchant from it's bottle into your container.

READ THE LABEL!!!

Always read and understand the labeling on the chemicals you use. Some of this stuff is dangerous! Do not allow the etchant to come into contact with you skin, eyes, clothes or other surfaces which may be damaged. Safety goggles are reccomended, as are rubber gloves. Any tools that will come into contact with the etching solution should be either plastic, or unimportant to you. Even stainless steel is damaged by the etching solution.

For etching aluminum, the ferric chloride is very strong and needs to be diluted at least 1:1 with water. A 2:1 solution usually works even better. Undiluted, the ferric chloride will make a smoking mess of aluminum, though it works just fine on copper or brass.

The sheet can be placed directly into the etchant, with the pattern side down to prevent buildup of the eroded metal. Instead, I generally hang the sheet from a bamboo skewer. The prevents any buildup that would affect the etching, as well as making the sheet easier to handle during the process.
For the thin aluminum of a beverage can, the etching process will take about 10 minutes. You may want to take the sheet out and rinse it with water from time to time to check the progress. Water neutralizes the etchant, stopping the etching process. If the sheet is not etched long enough, the edges of the part will not be sharp and clean.
If the sheet is etched too long, the parts may completely disappear. Stopping the process when, after rinsing, you can see through the tape all around the part will give the best results.

A bit of lacquer thinner can now be used to remove the permanent marker and also free the part from the tape. The results look better than what I've been able to cut from sheet metal with any other process.

 

The parts can now be added to the model, or any other techniques that you would use on metal can be done now.

 

One of my parts is a bracket that needs to have the ends bent.
After the ends were bent, I added a set of footpegs.
This would become a set of "highway pegs" on a 1/25th scale Yamaha Virago motorcycle.