This model is a zebra crossing sign to use together with my pole for
traffic signs. It uses 2 LEDs for lighting: a yellow one to light the
street below the sign and a white one to light the
sign itself.
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General info on the materials used |
The material for all my models is called Frosted Ultra Detail
by
shapeways.
It is printed in a process called Multijet Modeling (MJM). The model is
printed in layers which are hardened by UV light. There is also a wax like
material used as support material. Most of it is removed directly after
print, but on some models it is stuck inside the holes and has to be
removed before assembly.
At room temperature the
Frosted Ultra Detail
is inflexible and breaks suddenly without
warning. Thinner parts break off very easily, so please handle all models with
care. It gets more flexible when heated, but still breaks suddenly without
prior warning. It is possible to very carefully bend it into a new position
while warm. The
Frosted Ultra Detail
will retain this position when cooled, but when warmed
again it will bend back to its original position.
The material can be cut with a sharp knife. Often small splinters will break off at the bottom of the cut. It is possible to smoothen the surface by sanding, I usually use a nail file.
The
Frosted Ultra Detail
material can be glued together with all-purpose glue and with
super glue. As super glue I prefer the liquid one since it sets so fast. I use
it mostly on parts which I fix in position before gluing. For stuff that needs
adjusting before the glue has hardened I use all-purpose glue.
For painting the
Frosted Ultra Detail
material
shapeways
recommends acrylic paints. There
are some reports in the user forums where models in
Frosted Ultra Detail
started to melt and
smell when painted with non-acrylic paints, so I decided to follow the
recommendation to be on the safe side.
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Using LEDs for lighting |
A lot of my models are designed to be lighted by 0402 LEDs. To connect them I use emanelled copper wire of 0.1 mm diameter. Any thinner wire I tried dissolved when soldering. For models which use only one LED it is possible to use thicker wires.
To simplify the threading through the model I twist 2 wires together. I take 2-3 meters of the wire and stick both ends to something like a table or cupboard. Then I try to keep both wires parallel until I reach the end of the loop. This I put into a miniature drill and slowly twist the wires together. Be careful when taking the cable out of the drill, it will try to twist back and create a big knot. It is better to make several shorter lengths than 1 extremely long cable.
Soldering the wires to the LED is not an easy task. I try to stick the LED onto double sided adhesive tape, but they are so small that they don't really stick to it. I use a very fine tip and try to solder both wires at once, but it is also possible to solder them one after the other.
| Osram Firefly® LW VH8G | Cold white | A general purpose white LED. This is officially a side LED, put has the soldering pads at the bottom as usual. |
| Victory VS 1WD9M | Cold white | Another general purpose white LED. |
| Everlight 16-213UYC | Yellow | A yellow LED for traffic signs and traffic lights. It is a lot dimmer than
the other LEDs on this page, but I did not find a brighter one. The LED color
amberis no substitute, it is too red. |
| Everlight 16-213SURC | Hyper red | A red LED for traffic lights. The hyper red LEDs are a lot brighter than the normal red ones, but are nearly identical in color. |
| Osram Firefly® LT VH9G | True green | A green LED for traffic lights. Don't use a normal green LED, they are too yellow, the 525 nm true green ones are much better. |
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Cleaning Frosted Ultra Detail |
To remove traces of the support wax and the oil which is used to remove
the wax on the Frosted Ultra Detail
material I use a small
ultrasonic bath filled with water and a drop of dishwashing detergent. I
usually put the models in for 30 minutes with a change of water after
20 minutes when necessary.
Sometimes there is a white powdery stuff on some parts of the surface. This seems to be a mix of the support wax and the material. As far as I know the only way to remove it is by sanding or scraping it off.
Use a small hobby knife to separate the signs by cutting through
the struts holding the 10 signs together. Remove the rest of the struts
either by cutting them off or by sanding the surface.
Put a small piece of double side adhesive tape unto a flat surface.
Stick the lower side of the sign onto it. Thread the cable of a yellow 0402
LED through the top hole. Insert the yellow 0402 LED into the bottom hole
until it sticks to the tape, too. Then add a small drop of liquid superglue
on each side, I use a short piece of emanelled copper wire with a small
opening created by bending and twisting the wire. Let the glue dry.
To prevent the upper LED mounted in the next step from shining through
paint the whole inside in matte black including the yellow LED. The sign
can be unsticked from the tape before painting, I kept it stuck to the tape
only for the photo.
Thread the cable of a white 0402 LED through the top hole, carefully
pull it until the LED has reached the top and glue it into position. The
LED does not have to be perfectly parallel to the bottom. It also does not
matter that parts of it are shadowed be the cable to the bottom LED, this
won't be visible in the finished model.
Print the graphics for the front and back of the sign, I use normal
paper and an inkjet printer. Graphics for German signs (left and right
versions) can be downloaded below. Cut one sign from the paper and
carefully glue it with all-purpose glue onto the sign. I don't use
superglue in this step, it tends to gas out when hardening and may fog the
sign.
Cut the mounting
pole to the desired length. Drill a 0.5-0.6 mm hole with a hand
drill from the underside where you want to mount the sign. I hold the pole
in my hand, I only added the tape to make the photo.
Thread all wires from the sign through the newly drilled hole until they all come out at the base of the pole. For me it works best to start with one pair until it just sticks out at the base. Then I add the second pair and push both until the second one comes through. Then I pull only the second one until both have the same length to go. After that I pull both pairs until there is no more cable left at the sign.
The next step is to glue the sign to the pole. For that I stick the pole
to a flat surface with clear tape. Then I fine tune the position of the
sign with one finger while adding a small drop of liquid super glue. After
the glue has stuck I repeat that on the other side. I also put a very tiny
drop into the hole at the end of the pole to close it.
After the glue has set the model can be painted. Clean it with degreaser just before painting to remove any fingerprints still left. Don't paint over the yellow LED at the bottom. Depending on the color and the LEDs you may need more than one coat of paint. Connect the LEDs to see how much they shine through where they should not and apply another coat when necessary.
