DIY modular synthesis has become very popular as more and more vendors offer printed circuit boards (PCBs) which can be populated to become synthesizer modules.  Some of these PCBs even come in kit form which includes the board, component parts and a panel. Many, however, come as a standalone board leaving it up to the end user to obtain the rest of the items required to complete the module.  This option is (arguably) the most cost effective method as it gives the builder the choice of component vendors and purchase quantities.  If you are planning on building several modules buying electronic components in bulk a very good way to keep your modules cost down.

Panels, however, are a different story.  Mention panels to many modular builders and they’ll cringe.  Often times, at least for me, obtaining a panel to house your electronics is the hold-up point for the project.  Many fine vendors out there sell finished panels which include the graphics for the potentiometers, jacks, switches, lights, etc… along with the pre-drilled holes to mount your parts into.  This is a great option for builders and while it does add some expense to the project, the convenience of being able to order the panel and then finish the build is worth the cost.

Sometimes, though, with the addition of shipping expenses, taxes and currency conversions a panel which is priced very reasonably by the vendor can end up costing more than the electronics portion of the module itself.

I have gone through a number of options for obtaining panels for my builds;  I’ve purchased panels from vendors who produce them for sale.  I’ve had them screened by a local printing company and I’ve produced them myself through the process of silkscreening.  For me the first two options have been very cost prohibitive.  If building one-off versions of the modules for myself this is sometimes a viable option but if building the modules for sale to others it drives the construction price right out of the market.  Ultimately I discovered that producing the screened panels myself has been the best option for me.

The silkscreening process can seem very daunting and I personally found it that way.  Through trial and error as well as some online support I have managed to work out a process to create my own screens and screen the panels themselves and finally to drill out the panels for installation.  By keeping the items I require on hand I’m able to produce finished panels in a very short time (less than half a day).  This article is meant to share some of my experiences with other builders who wish to screen their own panels.

Before I begin I should note that the process I use is for MU (Moog Unit) format panels.  For MOTM style panels I have used FPD files and Front Panel Express where I have obtained excellent results at reasonable costs (plus they ship gummi-bears with their orders).  Mmmmm gummi-bears.

The Screen

Following my adventures in having a local printing company screen the panels for me (at a very high cost) I decided to screen panels myself.  I purchased panels from Synthesizers.com so I could be sure the size and quality was spot on.  The next step was to obtain the silkscreens with the images of the panels which I produced using Microsoft Visio.  I have been using Visio since it came out and I’m quite familiar with it.  I even created a small library of the shapes I frequently require.  These include knob graphics (0 to 10, -10 to 0 to 10, no numbers) as well as graphics representing jacks, LEDs, switches and more.

I found a company that would produce the screens for me from SVG files (Standard Vector Graphic).  Because of the fine lines and small letters and numbers used on the panels I chose a screen mesh count of 230.  That is 230 threads per inch.  Lower mesh counts work but like lower resolution on monitors, fine images get a chunky, unappealing look.

The trouble I encountered was that the screen production company was manipulating the graphics files I was sending.  This was mainly to fit two panel images on a single screen.  In several cases the graphics were not lined up correctly or some of the text and images were changed or omitted.  Vertical text sometimes had words run together despite the original version being correctly and meticulously laid out. The biggest problem for me, however, was the large cost of shipping the screens.  Some of the screens were used for personal one-off panels and these once again made the process less than cost-effective.

The process of creating my own screens seemed daunting but after a bit of trial and error I’ve been able to do it with good results.  The first step was finding a company to purchase the screens from.  I located a company just outside of Toronto (I live about 100 miles north of the city in a rural area).  They provide ready made screens in the mesh density I desire.  I use a standard 20″ x 24″ framed screen.  They also sell the emulsion, emulsion remover and other supplies necessary to produce the screens.

I should mention that I first tried using my own hand made screens along with a kit I picked up at a local art supply chain (Michaels here in Canada).  The kit was by a company called Speedball and it contained small sizes of emulsion, remover and a screen (110 mesh count).  I had also purchased some squeegees spatulas and a roll of 230 mesh from a mail order house to make my own screens with.  I purchased some small framed canvases at the art store, removed the canvas and stapled the 230 mesh to the empty frame, stretching it tightly.  While this did work out the tension was nowhere near what a good quality screen should be so after making a couple of panels with this setup I switched to professionally stretched screens.

Emulsion

When I made my mail order purchase early on in my learning of the process I also purchased some film emulsion.  This could be cut to size then applied to the screen with a two step spray on adhesive.  I thought this would be easier than the process of using liquid emulsion.  It wasn’t.

The Speedball emulsion that came with my kit was far easier to use.  The emulsion is mixed with an activator when first opened.  The mixed solution can stay usable for several months if refrigerated and even with the small quantity contained in the kit I was able to produce several screens.  After running out of the Speedball emulsion I switched to Chromaline UDC-HY.  I was able to purchase a larger quantity of it for a much better price.

While the best way to apply the emulsion to the screen is with an emulsion applicator ( a trough-like device that evenly spreads a thin layer of emulsion) I was able to use a 9″ squeegee with a good degree of success.  Remember to keep the layer very thin and very smooth.  Any imperfections will affect your screening process.

Make sure to allow the emulsion to fully dry before proceeding and keep the emulsified screen in a dark place once it’s dry to prevent exposure.  I would apply the emulsion in a lighted room but once the emulsion was applied I would move the screen into a dark room to dry and then transfer it to a closet until needed.  Using a red LED light bulb in that room was handy for avoiding bumping into things in the dark.

It’s also a good idea to have emulsion remover on hand in case your emulsion job goes awry or in case you just want to reuse a screen.  This is typical when making a single screen  for a single, one-off panel.

The Film Positive

To create the image for the screen I printed my graphics onto transparency film.  This is called a Film Positive.  The transparency film is available at your local office supplies store.  It costs a bit of cash but is well worth it.

While there are many types of professional films for Film Positives I’ve found that regular transparency film works fine.  The critical thing to make sure of is that your inkjet printer has a good, full black ink cartridge.  If the image printed is not solid enough light will pass through during exposure causing a poor screen image.  I’ve tried using two copies of the same transparency laid atop one another and taped on the edges but this can cause distortion if the two transparencies aren’t perfectly aligned.  Generally a single well printed transparency will work just fine.  Make sure your inkjet’s black toner is fresh and well topped up and that the print head is clean.  Be sure to let the ink dry before moving around the output as well.

Oh, one last tip;  some transparency film comes with a white strip on one edge for handling the transparency without getting fingerprints on it.  I recommend cutting this off with an Exacto knife (or similar) as it will create a big blank line on your screen into which ink may accidentally seep through.  Not critical though.

Exposure

When reading about the screen creation process I read a lot about light tables and other complex methods of exposing the emulsion to light.  I ended up finding a video that showed me how to create my own exposure lamp using some 2″ x  4″ wood and a halogen work light.  Even this is not fully necessary and exposure can be performed with good old sunlight.

I found this video online which was very helpful for building an exposure unit for an extremely low cost.

This exposure unit has worked great for me.

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My Exposure Unit With Black Cardboard Base

Exposure time is another factor when preparing your screen.  At first I would get exposed screens but the emulsion would not wash out of the printed area.  This was because I was exposing the screen for far too long.  I found that for my exposure unit and the emulsion I was using that four (4) minutes of exposure time was perfect.

I watched the following video to learn a technique to determine exposure time (the whole video is good although I’ve time indexed the exposure section)

Again, when working with the screen in preparation for exposure I had a red LED bulb on in the room just to prevent accidental exposure during handing.

The Ink

Finding the right ink was a challenge which turned out to have a very simple solution.  At first when I was having the screens done by a professional printing company they told me that a big part of the cost was in determining the appropriate paint to screen with as the surface was metal.

Actually the surface of the Dotcom panels is powder coated paint which holds the screened ink quite well.  When obtaining my own screens then experimenting with material I started with acrylic paints.  I chose acrylic because it was easy to handle and washed off with water.  If I messed up a screen I could wash the error away if I got to it within a minute or two.  Warm to hot water was good for this.  The trouble was the different paints I tried were all a bit too runny and yielded poor results.

I finally tried Speedball Screen Printing Ink for Fabric (white).  This turned out to be an excellent choice.  The ink was thick, bright and was easy to handle and to wash off.  Remember to keep your squeegee, spatulas and particularly your screen very clean.

The real trick to ensuring good adhesion with the ink is in the curing process.  More on that later…

The Screening Table

While many sophisticated screening tables are available for big bucks I was looking for a more cost effective system.  Using some scrap wood, a pair of screws and (most importantly) two Butterfly Hinges ($5 each) I fashioned a device which would allow me to screen my panels.  The system works just fine for single colour screens and while I wouldn’t recommend it for high-volume production it works great for small quantity panel creation.

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Some scrap wood, Butterfly Clamps and two screws – that’s it!
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Here is the unit with a screen installed

The screen itself should be about 1 millimetre above the panel itself.  This allows only the portion of the screen under the squeegee to be touching the panel at any given moment and avoids smearing.  I use a pair of screws in the table which the frame of the screen rests on.  They are positioned at a depth allowing this 1 millimetre gap.

The Process – Part 1: Emulsifying the Screen

Mix the emulsion with the activator according to the instructions for your particular brand of emulsion.  Mark the container with the date so you’ll know when it expires as you don’t need a whole lot of it for each screen.  I use a large Zip-Lok bag to store the container in the fridge after I’m done.  The bag prevents stray emulsion which may have got on the container from dirtying the fridge and getting my wife angry with me.

The emulsion may stain plastic wash sinks if left for any length of time so make sure to have a source of water and scrub brush handy.  Latex gloves are also a good idea.  I have a short length of hose with a garden spray nozzle connected to my sink to add some pressure.

Since I don’t have an emulsion applicator I use a squeegee to apply the emulsion to the screen.  Emulsion is applied to the bottom side of the screen.  That is the side the screen is attached to frame.  The side that makes contact with the panel.  Apply a thin even layer to the screen.  If you have to go back and forth just make sure the layer is even and smooth.  I don’t cover the whole screen as I’m only using a panel-sized graphic (smaller that 8.5″ x 11″).

When I apply the emulsion I squeegee the emulsion right off the edge of the screen into a large aluminum tray that I place in my laundry room work sink (see: keeping the wife happy).  I can then recover the excess emulsion and return it to the container before refrigerating it for storage.  Plastic paint spatulas are ideal for this.

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My Drip Tray With a Handy Warning

Once satisfied with my layer of emulsion I place the screen bottom side up on a table in my dark(ish) room with a fan which gently blows across the surface.  If the layer of emulsion is thin and even it should dry in one to two hours.  If you have a bead of thicker emulsion down the sides of the emulsified area (caused by the edge of the squeegee) I carefully remove it with my paint spatula to avoid a wet thick section which takes longer to dry.  Just make sure not to muck up the smooth centre area where the panel image will ultimately go.

Once dry you can either proceed to the next step or store the screen in a cool, dry, DARK place until you need it.  Sometimes it’s handy to make several screens if you plan to create a bunch of different panels.

The Process – Part 2: Screen Image Creation

Double check, then triple check your image ensuring the spacing is correct, fonts are suitable and that the spelling is correct.  Print on plain paper first and stare at your panel design.  Sometimes mistakes make it through to this stage.  Have someone else check it for you as a fresh pair of eyes can spot errors you miss or see logistical problems you didn’t foresee.  Also remember that you don’t want to print the image of the panel if you included that in your design.  You only want the text / graphics which will be screened onto the panel plus crosshairs for where drilling should be done.

Once the graphic is confirmed ready on your computer  print it onto transparency film.  Let the ink dry thoroughly once printed and avoid bending the transparency so that the ink doesn’t crack.

The next steps involve using the exposure unit I chose so this process may differ from other systems.  First, I place a piece of black cardboard (available at your local office supply store) across the bottom of my exposure unit.  This prevents light from bouncing back up and ruining the exposure.  Next I place the screen, bottom up onto the cardboard and place my film positive UPSIDE DOWN onto the screen.  It is upside down because when the screen is turned over it will be in the correct orientation.  Finally I place a piece of glass over the film positive to ensure firm contact between the film and the emulsion side of the screen.

And now… LET THERE BE LIGHT!  I activate the halogen light and at the same time activate a 4 minute timer.  Actually I have SIRI activate my timer.  At this point I also turn off the red light and turn on the room light.  After all, we are exposing using light so what the heck.

At the end of 4 minutes I immediately remove the glass and Film Positive from the screen and take the screen to sink where my hose and nozzle is set up.  Sometimes in the summer I do this outside.  Whatever you do, don’t dally (who talks like that anymore ; )

First I spray each side of the screen very quickly and for just a second in order to wet it down.  This starts the exposed areas to begin to appear through the emulsion.  Then after 10 to 15 seconds I begin to spray the screen to wash out the exposed areas.  Use only cold or lukewarm water (tending towards cold).  DO NOT USE HOT WATER.  I use the “Flat” setting on my nozzle which generates a wide, flat fan shape from the nozzle which has a good deal of pressure but not the heavy duty maximum pressure.  Spray from the top of the screen through.  You’ll be looking at the correct orientation of the text if you’re looking at the top (providing you didn’t screen the Film Positive backwards : ) You only want to wash out the exposed area, not blow all the emulsion off the other side.  You also don’t want to damage fine areas like lettering, numbers and knob graduations.

When done correctly you should be able to see through the mesh where the exposed areas have been removed.  There should be no emulsion remaining.  Watch for “cloudy” areas where a thin layer of exposed emulsion hasn’t washed off.  Again, be sure not to use too much pressure or to focus your water stream too much in one place or you could damage your work.

Once satisfied with the washed off screen I then place the screen back on my work table with fan to dry it off.  This only takes about 10 minutes.

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Not Totally Pretty But Perfectly Functional

The Process – Part 3: Screening the Panel

With the screen all complete it’s time to put ink to panel.  The frame of the screen must be snugly mounted into the Butterfly Clamps.  The important thing is that everything not move during the process.  Because I don’t use a specific positioning system when preparing the graphic on the silk screen I have to “eye” the location of the panel.

This involves carefully placing the panel beneath the graphic and carefully moving into the correct position.  I also use a pair of aluminum rails to help firm up the position of the panel once it’s in place.  This is a slow and carefully executed procedure.  I use duct tape to hold everything in position.

I’ve also found that if only the panel is used on the table during screening there can be some smearing at the top and bottom of the panel as the squeegee pushes the screen down to the panel at these points.  To prevent this I use 2 blank panels wrapped in cellophane (to protect them from stray ink) positioned at the top and bottom of the panel I’m screening.  This acts as a buffer so the panel is printed more evenly.

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When everything is in place I lower the screen and apply ink over the area of the panel.  This ensures that the ink will cover everything and will not rely alone on the squeegee process to spread the ink.  I also apply a bit more ink along the top of the panel to ensure that there is plenty of ink when the squeegee is used.

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The next part goes smooth and quickly;  firmly grasping the squeegee drag it down the panels (over the top buffer, down the main panel and across the bottom buffer).  Apply even pressure all the way and be deliberate.  Use a slight tilt to the squeegee so the edge of the rubber rather than the flat bit makes contact with the screen.  Don’t use too much of an angle though.  Don’t hesitate or lose your nerve during this portion of the operation.  If a mistake is made you’ll have a minute or two to wash the panel off and try again.  If everything goes ok (which after much trial and error it has been) then I lift the screen to check the panel then use my spatula to remove excess ink and place it back into the ink container.

The next part MUST BE DONE QUICKLY.  Get your screen, squeegee and spatula to your wash area.  Wash the screen thoroughly with cold or cool water.  Make sure to get all the ink out of the exposed areas to ensure the screen can be used again.  A thin scrim of ink will likely stick to a portion of the screen but as long as the exposed areas are clear you’ll be fine.  Warm or even hot water can be used to wash your tools once the screen is clean and out of the way.  If you wait longer than a minute or two to wash your screen there is a good chance it will be ruined so don’t hang around admiring your panel.  Once you check that it’s ok do your clean-up quickly.

But what if it’s not ok?  Something may have moved or perhaps your pressure wasn’t even.  If this is the case first carefully remove the panel from your setup.  You don’t want to mess up your positioning apparatus as you’ll have to put the panel exactly back into position for your next attempt.  After the panel has been removed quickly use your squeegee to cover the exposed area of the screen with a very thin layer of ink.  Don’t press hard with the squeegee as you don’t want the ink to go through the screen.  You only want to cover the exposed area so that the ink doesn’t dry into it while you’re washing your panel.

Take the panel to your wash area and use warm / hot water and even a light scrub brush to remove the ink.  This must be done quickly before the ink dries (on either the panel or the waiting screen).  You must then dry the panel thoroughly, re-install it in your table and repeat the screening process.  If it fails a second or third time you may want to remove the ink and execute the cleaning process on your panel, screen and tools before trying again.

It sounds complicated and takes some practice but with time you’ll find that it’s not that difficult and takes only a few minutes.

The Process – Part 4: The Curing Process

I like to ensure my ink has set firmly by “curing” my panels.  I use a toaster oven dedicated to this process as there is a smell and thin residue produced that I don’t want in my oven where my food is cooked (and again, I don’t want to piss off my wife).  I have found that 15 minutes at 320 degrees Fahrenheit  does the job just fine.  If you cure for too long or at too high a temperature the ink can turn an off-white brownish shade.

Finishing Up

The last part of the process involves drilling the panel, filing off the backside of the panel to remove burrs and then installing the components.  I won’t talk about this too much although I will say I recommend using a drill press and using pilot holes before drilling the actual holes.

So there you have it!

There are a lot of helpful videos on the Net which you may gain tips from which are helpful to your process.  I learned a lot from them.  I also learned a pile of info from Jeff at GuitarFool.com.  It was his site and his support that helped me get my screening project off the ground.  Thanks dude!

Remember that this is just “what works for me”.  There are many ways to skin a cat (sorry Wigglers) and you have to find the right technique to suit your personal needs.

 

Author’s Note:  I posted a link to this article on the Muff Wiggler DIY Forum.  If you’re not already aware, Muff Wiggler is the FINEST resource on the Internet for modular synthesizer enthusiasts.  There are some excellent points being made in relation to this article.  You might find it interesting to follow this link and read them for yourself.

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