Fabricate 3D Shapes From Brass Shim
Much the same way that big milling machines cut away material from a solid block of metal to form a part, you can easily do the same thing, making very complex shapes using only one easy to find “etchant” chemical. Convert any toner image into a fabricated “part” using brass “shim” from .001” on up.
Notice that the black toner image has been transferred to the brass shim using the applicator. Not shown is the same image with the GreenTRF added on top of the toner image to seal the porous toner from unusually long etch times.
1) TRANSFER THE TONER IMAGE ONTO BRASS SHIM:
Cut a piece of brass shim to size and heat-transfer the toner image with an iron. Put the brass in water to remove the TTS paper. Rinse under running water and pat dry. Look at the brass square above that has the toner image fused onto the brass shim.
2) APPLY “GREEN TRF”:
Apply “GreenTRF” over the toner image, let cool, peel back foil and discard. If there are void spots, you can always go back with a new piece of foil to make touch-ups as needed. Toner is porous which makes it easy for etchant to seep into the toner image during long etch times, resulting in heavily “pitted” images. GreenTRF is an accessory item that will prevent all pitting.
3) MOUNT THE BRASS SHIM TO A RIGID CARRIER:
Lay the brass shim image-side down on a square of paper towel and lightly rough up the surface with fine sandpaper. Apply a few coats of KK-2000 adhesive spray. Press the brass shim’s adhesive side onto a piece of rigid acrylic or glass that will fit in a shallow etching tray (plastic or glass is ok). This “carrier” will hold all of the elements of your design from moving while the surrounding brass is etched away.
4) ETCH THE IMAGE:
Place the carrier sheet into the small plastic or glass tray and add a few ounces of Ferric Chloride solution to cover the image. Using a very soft brush, continually wipe over the entire image area in a uniform pattern. Total time to etch will vary widely based on the thickness of the brass, the temperature of the chemical, the aggressiveness of the brushing and saturation level of the etchant. It is common practice to periodically dump the etchant and add fresh chemical to speed up the etching process.
5) CLEAN UP:
Wash the board thoroughly with water to neutralize the etchant and pat dry. Wet a brush or paper towel with acetone and rub over the brass to remove the toner and “GreenTRF”. An X-Acto® knife works well to lift off delicate etched images. The spray adhesive on the brass can be re-used for final placement on your model.
