The Home Machinist!

Friends:

Here's how I lettered my first large scale freight car. I created
a set of printing screens by copying a freight car photo off the
internet.

I edited the photo and printed it onto 5 pieces of overhead projector
film which were used to expose the screens which I had coated with
photosensitive polymer.



Areas not exposed to light wash away with water allowing passage of
the printing ink. Back in the day we called this "Silk Screening", but make
no mistake about it, nobody uses silk anymore. This is 105 line/inch
monofilament nylon fabric. The frames were made to fit between hopper ribs.



Each screen was clamped to the side of the car, and the white ink was
forced through the screen with a rubber squeegee. If this looks fun to
you, you are right.

Bill

That's way cool, Bill! [img]/ubb/images/graemlins/cool.gif"%20alt="[/img] Looks like the "big boys" did the job.

I'd be interested in hearing more about how you go about making the screens. Never been there, so I don't have a clue.

Could you suggest sources for the materials necessary to make them?

Thanks for any time you're willing to share with us.

Harold

I will add my interest to this subject as well. [img]/ubb/images/graemlins/grin.gif"%20alt="[/img]

Harold:

When it comes to screen printing, I too am a novice. However, it's
easy to do, and if you mess up you can always wash off and try
again. Some will avoid it because they don't want to learn another
skill, and like any skill it takes a little trial and error.

But there are more books written on the art of screen printing or
"silk screening" than there are about live steam. I'd recommend one
except I don't have any. But for those who do learn, you will then
have a very useful technique which lends itself to other uses, such
as metal etching. (That's how you make HO or N scale ladders, etc.)

Screen printing supplies are available in many craft stores. But the
best bet is to get them from commercial vendors such as Naz Dar.

NazDar.com

There they have a link called "find the nearest location". Most of them
offer unlimited free advice, which is how I got started.

You will need frames, which you can buy or make yourself. Fabric is
abundant and relatively cheap. Photo polymer emulsions, (the blue
stuff in my first photo) comes in quantities that will outlast us all for
$20 to $30. Squeegees are sold by the inch. I needed a 5" squeegee
for this job, as that is the width of each panel. Ink is available in any
color or composition. I used "poster ink" on my hopper car.

Artwork. You can make that on your computer using your favorite paint
program. Make your "films" by printing your artwork on overhead
transparency film for inkjet printers, available at any office supply store.
Expose the screens by placing the film on the screen with a piece of
window glass to hold it down. A 150 watt indoor floodlamp two feet above
the glass for 40 minutes will expose the screen. Develop the screen by
washing it out with water.

Printing. Once the screens dry, clamp one to a panel to be printed.
Place a row of ink inside the screen above the image. Drag the squeegee
(and the ink) over the image. The ink oozes through the screen where the
image is and onto the workpiece. Carefully and gently unclamp and remove
the screen so as not to smear the printed image. If the printed image looks
good, let it dry. If not, wash it off with Xylene (Xylol) and hit it again.

That's pretty much it. But to go into every hint, tip, or detail would run Chaski
out of disk space. Those that want to learn will dig more deeply into it.

Bill

Bill,

The hopper car looks great. Thanks for sharing it with us. The screen printing has my interest also.

Reed [img]/ubb/images/graemlins/grin.gif"%20alt="[/img]

Beautiful results! And thanks for sharing. Charles

Bill;

I noticed that you used some of the panels twice. IE the Minne-apolis are on upside down. Was this because of cost?

-willy-

A very professional looking job! Congratulations!

Willy (noticing I had multiple images on some frames) asks:

Was this because of cost?

No. But obviously you do save some cost by sharing frames. The
overhead projector film is the most expensive part at close to a dollar
a sheet. I stack two sheets per screen to increase the density.

But the real savings is in time. It takes time to make the frames, print
the films, sensitize the screens, expose the screens (40 min). This
doesn't count drying times. The same holds true for cleanup afterwards.

I crammed 7 panels into 5 screens. That's a real timesaver. I learned
this technique back when I made my own printed circuit boards. Also,
the frames and screens are completely reusable. I can remove the
emulsion and use the screens for another hopper, or remove the fabric
and reuse the frames. I will probably do this, in case I ever need to
reprint this car or build another car. Changing the number is easy. You
can masking tape or cardstock over any part of the screen you don't
want printed.

Glad you all enjoyed the post. Thanks for the positive remarks.

Bill

Wonderful Reader's Digest version, Bill, and more than enough information to point me (us) in the right direction.

I fully agree that projects like this are dependant on experience, for without some, a guy generally doesn't have a clue when he's headed in the wrong direction, or what to do about it if he is. The tips you so kindly provided will help all of us avoid some of the pitfalls to which we may be subject in getting started.

Thanks for taking the time, Bill. I'm of the opinion it was well spent, for I noticed several of us are quite envious of your outstanding success.

Happy Holidays!!

Harold

Bill, the car looks great! I can see doing this for fine lettering on a car. Have you tried painting premask? A painting premask is a low stick vinyl kind of like shelving paper. You place it where you want the graphics tape and paper around it, then scuff surface, clean, then paint. I did this with my daugther's engine for the flames( my bio pic) could not get the tape to bend that tight. What is the life of the poster ink?
-Kevin S.

Neat idea! My dad was R&D at a decal making firm for over 30 years and they used silk screen extensively in the late 1950s through the 1960s. IIRC, the presses would take about a 60" x 60" sheet. I watched him do prototype work using a frame that was about a foot square. I don't know why I never thought of using it for the hobby.

Something I didn't see Bill mention is that making designs in two or three colors isn't hard if you plan which color goes in which order and work out a way of registering the layers. Let one color dry and then add the next.