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Blade Works Etching Setup

by pamrick





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Download Blade Works Etching Setup


Metal Etching By Bladeworks OK, here is the developer cabinet I built a bunch of years ago, for developing the photo resist stencils. It started out being a mil-surp radio telephone set box. I gutted it, installed two lamp sockets and a single pole switch and power cord. I then put aluminum angle about 8 inches up from the bottom to support a piece of glass for the platen and another piece of glass for the cover plate. It's pretty hard to take pics of the actual developing process as it is done under a yellow light to prevent the photo resist from being developed prematurely. Here's the cabinet... This shows the lamps that are used for the developing process. Two fluorescent screw in bulbs,,,, notice that underneath the bulbs in the bottom of the cabinet are inexpensive plastic mirrors to reflect more light upward. I used the front compartments in the box for storage of my photo resist and developer solution... The platen glass sets over the bulbs. I painted a black window on the underside of the platen to concentrate all the light directly above the bulbs Print out your artwork for your stencil on a clear transparency. Ink jet printer is a must, and print in the highest resolution that you can, to get the ink as dense and dark as possible. Lay the transparency down on the platen. The light should still be off at this point. Once you have the artwork positioned on the glass, cut a piece of photo resist material the size you need for the job and lay it over the transparency. This must be done under a dim yellow light, otherwise the photo resist will be set, and will not be able to be developed. I put a yellow bug light in a lamp across the room and turn all the other lights off in the room and block out all sunlight with curtains on my shop windows. A little light is OK but any direct light on the photo resist will kill it. I also keep my photo resist stencil triple wrapped in heavy black paper to keep light out. Then lay the the top glass cover down to hold them flat together. The top glass has a piece of thin black foam on the underside to block the light from passing through and around to the top of the stencil. Wherever the black artwork blocks light from contacting the photo resist, the photo resist will remain soluble to the developer solution. Once the cover is on, turn on the light to begin setting the photo resist mask. My set up takes about 90 seconds to set the photo resist. In a glass bowl, mix a solution of 1:4 developer and clean water. have it setting close buy and ready for use as soon as you pull the stencil out of the developer. The photo resist has a thin clear protective film on both sides. Once the stencil is pulled out of the cabinet, peel the film off of both sides and immerse the photo resist in the developer solution and swish it around for about three minutes. This will soften the undeveloped photo resist where your transparency blocked the light, and you will then be able to rinse the stencil. When the stencil is complete it should look like this.....Then you tape the stencil to your piece to be etched with electrical tape to make sure it is flat against the surface and will not move around. Another piece of artwork which shows the way you use the transparencies... This is the power unit I use for etching. Mine is a plating rectifier that puts out up to 15 volts. I added a bridge rectifier to it so that I can both etch and mark. The DC setting strips the metal away, and the AC side deposits a black mark on the surface of the etch. I use a graphite head marking wand that has a reservoir in the handle for electrolyte. You can also build your own out of a block of wood and stainless steel plate in place of the graphite. I initially built my own but later opted for this style because it is handier, and keeps a supply of electrolyte in the handle to keep the etching pad wet. The head is wrapped with an etching pad which is held in place with a rubber band. The pad is wetted with electrolyte to begin with and filling the reservoir in the handle with electrolyte keeps the pad from being dried out. You must keep the pad wet at all times during the process or heat will build up and cause damage to your stencil and will make the edges of your etch fuzzy and rough. The work piece you are etching is connected to your ground cable and the positive cable is attached to your wand. Turn on the power unit, adjust the power up to around twelve to fifteen volts and press the wand firmly down on top of the stencil, just hard enough to make good contact, but not so hard that you squeeze all the electrolyte out of the pad. It takes some practice to get a feel for the process. so plan on going through a couple of sheets of photo resist, and some transparencies and etching pads until you get the hang of it. When I do my next etch, I will take some photos of the actual etching process. As far as artwort is concerned, anything black and white with a resolution of over 600 dpi works well, and then on the printing process, select a setting on your printer that gives you the heaviest saturation of black. You really need to make sure you block all the light coming through the transparancy onto the photo resist. High volume etching/marking usually involves what is called a stencil cap which goes onto the end of the marking wand rather than having the stencil applied to the part. Those type of jobs usually don't require a very deep etch, more for part numbers, bar codes etc. Deep etching takes a lot longer because it has to be pulsed or cycled on and off to get deep etching and metal removal without building up too much heat, or drying up the electrolite between the part and the marking head/wand. For marking metals, many manufacturers have switched to laser/chemical marking, a process that involves coating the metal with a chemical which the laser then burns into the surface permanently. That process removes absolutely no metal and leaves the surface perfectly smooth, and is the preferred method for marking stainless steels, tool steels, parkerized and phosphate surfaces etc. Anodized alumium, powder coated or painted steels, plastics and wood can be deep laser engraved and marked in seconds. I do all that in my shop as well. Yes, exactly, the ink jet puts down a denser black that the light will not penetrate. The laser printers put down an opaque cover that the light will shine through. And as far as a depth is concerned, definite detail starts to show up at .001, and if you are going to etch a serial number and manufacturers info, the ATF boys say it needs to be .003" or deeper. .003" is not all that deep, but that's about where electro etching starts to get tricky and requires that you start running the power on and off to keep from getting the surface too hot and drying out the etching pad or running out of solution and burning the resist around the edges. Pulsing keeps the surface cool and allows electrolite to stay flooded in the etch, which is key to getting nice sharp edges. It is pretty hard to get any deeper than .005" with a 12 volt power supply, but .005" is plenty deep for a nice sharp mark in my opinion. Unless you are going to paint over it with something thick, then you loose a little crispness out of it. OK got the final version....and here's how it works... This is on my HK G3 A4 build, the rifle is built from entirely new Hk parts, and an ORF flat. First, you need to have a mask for whatever you are going to etch. Some guys use a photo resist type plastic mask, like I explained in my first post. Some use laser cut vinyl decals that they have a print shop make up. In my case I use the laser. I spray a mask of flat black enamel on the area I'm going to etch and then put the piece under the old laser knife and cut my graphic out. Here's the rifle and receiver in the laser getting the graphic cut out of the mask.... Once the mask is cut out, I add a little extra protection to the surrounding metal surfaces by taping it up with plain old electrical tape. That protects the surrounding surface from spill over electrolyte. There are several different power sources available for doing electro etching. The most popular and affordable is a little deal called the Etch-o-Matic. Or alot of guys build one out of a power supply. All you need is a power supply that puts out 12 to 15 volts AC and 3 to 5 amps. AC current pulses and, when used together with an electrolyte will remove metal. DC current will work but not as well, and is primarily used for marking by depositing oxide onto the surface. I am only going to talk about the etching process here. I use a plating rectifier in my shop that I also use for plating knives, guns and other parts in my shop. It has the capability of AC or DC output and the power on it is adjustable from 1 to 15 volts and 0 to 25 amps. The home made or smaller Etch-oMatic units work just as well for etching. Here's my plating rectifier. The next thing you need is electrolyte, that will etch the metal. You can use a strong solution of salt water and that works, but I use a specific electrolyte made just for deep etching. The advantage is that the electrolyte is cleaner and keeps the etch a more uniform depth. Salt water tends to build up with oxides on the surface. I use a self cleaning electrolyte soultion called SC-44, that I get from a marking company called IMG (more later about that) The other thing you need is a marking head and an absorbant pad that holds the electrolyte. You can buy these or build one out of a flat piece of stainless steel with a stainless steel stud welded on to it, and then just wrap the flat plate with medical cotton. I prefer the little hand held marker because it has a reservoir for electrolyte in the handle and keeps the surface wet with electrolyte. Here's the marking head with pad wrapped around the head and the bottle of electrolyte. Next step is to wet the pad with the electrolyte, attach the positive lead from your etching power supply to the piece you are working on and the negative lead to the marking head. (Pay no attention to the red and black clips in my pics. The negative lead is really attached to the marking wand. I just grabbed two leads and didn't pay attention to the colors.) Turn on the power and apply the pad to the area you want to etch. It will bubble, fizz, sizzle and foam up. Only hold it there for about three seconds at a time. Lift it to let more electrolyte flood the surface and to keep it from getting too hot and melting or burning your mask. It is important not to let the electrolyte dry up from under the pad, and to keep the surface flooded and wet. Pause every little while to let the piece cool off and to check how deep you are getting. On this receiver, I etched it about twenty times letting it cool between etchings till I had it as deep as I wanted it. My power was set at 12 volts and 3 amps. Then I did the other side the same way, here's the mask for the right side... Once you are done, rinse the surface real well to get all the electrolyte off, it is an acid and will continue to corrode the metal if you don't clean it off. Remove the mask and clean the surface again and apply a light coat of oil to prevent rusting until you are ready to park or paint. Here are the final results of this etch....plenty deep to satisfy the minimum .003" depth requirements of the ATF, and I think the quality equals that of machined engraving, without having a CNC machine to do it.... There are several places on the web that have the supplies you need. I buy all of my supplies from a company called IMG. And they have a handbook on the site which explains alot about etching and marking. or here is the link to Etch-O-matic they also have their own phot resist mask and some tutorials on how to use it on the site. and here is a tutorial by a fellow knife maker, Chris Crawford about how to build your own etching unit. You can also make a permanent black mark on stainless in the same manner, by just using a different electrolyte and reversing the polarity on the marking head, using DC current. If you decide to try this, make sure you practice on scrap stuff first to get the hang of it.
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