Word Clock

Perspex Enclosure and Vinyl Stencil Construction

Notes

Doug JacksonVK1ZDJ

March 2011

V1.1

Licence

The Word Clock Design, PCB layout, Manual, and Firmware is Copyright 2009, 2010, 2011, by Douglas Jackson, VK1ZDJ.

This Design, PCB layout, Manual and Firmware is licensed under the TAPR Open Hardware Licence (Non-Commercial). www.tapr.org/NCL.

Permission is granted for anybody to:

• Modify the documentation and make products based upon it, provided you do not make more than ten units in any twelve month period.

• Use the products for any legal purpose without limitation. • Distribute unmodified documentation, but you must include the complete package

as you received it. • Distribute only on a non-profit basis, charging no more than the actual cost of parts,

assembly, and shipping. • Distribute products you make to third parties, if you either include the

documentation on which the product is based, or make it available without charge for at least three years to anyone who requests it.

• Distribute modified documentation or products based on it, if you license your modifications under the OHL.

Welcome

Thanks for deciding to make this great little clock project. I have really enjoyed designing and developing it over the last few years.

There are so many ways to construct a word clock. I have broken assembly down into various documents – This document details the construction of a vinyl display (stencil) and a perspex enclosure.

You will find that construction of this clock is very simple and methodical.

Be careful with your measurements, and safety conscious when you are using cutting tools, and you will find that the completed project will be an amazing conversation starter for years to come.

Parts ListThere are two versions of the stencil and enclosure kit – a short form kit that just provides the cut vinyl stencil, requiring you to purchase some Perspex sheets to complete the project, or a full kit containing all of the Perspex as well. Perspex is easily available from many sign writing equipment suppliers. Most suppliers will cut the sheets to the required sizeThe first thing you need to do is to verify that you have all of the necessary components required to assemble your front stencil Here is the complete parts list.

Front

300mm x 300mm Perspex sheet (3mm clear)

1

300mm x 300mm vinyl stencil (In kit)

1

Enclosure

Side Support (3mm Black)

60mm x 270mm 2

Top Supports(3mm Black)

60mm x 264mm 2

Baffles (3mm Black) 25mm x 264mm 10

LED Array Support(3mm White)

264mm x 264mm 1

Rear Cover(3mm Black)

270mm x 270mm 1

Rear Cover Mounts (3mm black)

20mm x 20mm 4

Front stencil mounting strips(3mm Black)

20mm x 260mm 2

Enclosure screws 3mm x 10mm coarse self tapping screw

7

Additionally, you will need some plastic glue which is compatible with your perspex sheets – talk to your perspex supplier for the correct glue. I use "IPS weld-on #16 – Solvent cement for acrylic" for my own projects.

Stencil Construction

Start assembly by making our stencil. You will have been provided with a pre-cut vinyl stencil. This needs to be attached to a clear perspex backing sheet to provide rigidity.

The vinyl stencil as supplied will be larger than required. This is so as to provide extra material for variations in face sizes. We need to cut the vinyl stencil to the final size of your perspex sheet, allowing an extra 10mm allowance around the edges. Lay the Perspex backing on top of the stencil , and mark out a cut line, then using a straight edge and a sharp hobby knife (or scalpel), cut the sheet to size.

NOTICE Ensure that when working with the vinyl sheet, you work in an environment that is clean and relatively dust free. If dust particles are captured between the vinyl and the perspex backing, raised bubbles will appear that can not be resolved, maring the appearance of the front of the clock.I should do all of my vinyl work in the dining room, not in the garage. [Note to self – Thank Mrs Jackson for being accomodating!]

Next, ensure that your working environment is clean – vacuum your table if necessary – or work inside the house, instead of the garage. Lock up your Golden Retriever dog and your cats. If you get small particles between the vinyl and the Perspex, you will have enormous trouble making the surface look flat.Mix up a couple of drops of dish washing liquid with a cup of water, and load that into a spray bottle. We will use this to make applying the vinyl lots easier. Remove the protective cover from the clear perspex, and lay the Perspex to one side, ready for covering. Turn the vinyl sheet over so that the front is against your working surface, and remove the backing sheet from the vinyl stencil, being very careful to ensure that the vinyl does not stick to itself.

DO NOT THROW THE BACKING SHEET AWAY – It contains letter pieces that are important.

Be gentle when you remove the backing to ensure that the bottoms of the letters are not stretched. You may find, for example, that the bottom of the letter R and W stays on the backing. Gently use a sharp instrument to detach them from the backing. This photo shows the base of an 'R' character being loosened. The base of the 'W' has to be loosened as well.

Spray the vinyl sheet with a liberal amount of the water/soap solution - Don't panic - we will be squeegeeing this out later - it simply allows us heaps of extra time and movement to get the vinyl applied easily. Continue by laying the Perspex on the top of the vinyl at an angle, starting with the bottom edge – carefully align the edge so that it is straight, Hold the top of the vinyl sheet taunt (you can have an assistant help you), then, and using a folding, or rolling motion lay the sheet on the vinyl. The folding or rolling motion will help to ensure so that most of the air and soapy water is expelled. (In the photo, I didn't use tension – I have subsequently determined that tension helps ☺ )

Turn the Perspex over and using a squegee, or your hand, gently flatten the stencil out to remove the excess water / soap mix. Use some paper towel to clean and dry the stencil as you expel liquid. As you expel the liquid, you will notice that the stencil locks onto the acrylic sheet. We want this gluing action to happen. Do not rub the front hard, as you will damage the surface. Once you have expelled all of the water/soap mix, and things are looking very flat, marvel at your work, and leave it to adhere for an hour or so.

Cut the vinyl sheet to the final size on the perspex – I love the look of allowing a 3 – 5mm clear edge to frame the black vinyl. You may prefer to cut the vinyl even with the edge.Next, looking at your stencil, you may find that some letters need to be removed, while the centre of other letters (O, A, R, D, etc) need to be transferred from the backing sheet to the Perspex. Use a sharp knife to gently remove the extra vinyl letters, and to transfer the centre of the letters to the Perspex.

In this photo, I removed the air and soapy water before I filled the letters in – you are very welcome to do these steps in the order that you are most comfortable. Remember – Gentle pressure is all that is needed to remove the water / soap mix.

It is unlikely that you will have any bubbles left, but if you do, over the next week or so, any left over tiny air pockets will tend to migrate away by themselves.

That completes the stencil assembly.

Enjoy looking at it, and then put it away somewhere safe where it won't get damaged. Now is a great time to have a break!.

Enclosure Construction

Having finished the face, we need to continue with the assembly of the enclosure.

Our enclosure is made from 3mm Perspex sheets that are held together using a vinyl adhesive. As mentioned in the parts list, you will need some plastic glue which is compatible with your Perspex sheets – talk to your Perspex supplier for the correct glue. It is a solvent that actually dissolves the Acrylic material that the Perspex is made from so it ensures that the joints are extremely strong.

Start by placing the stencil FACE DOWN onto a soft surface to protect the vinyl face. We will be using the stencil as a template to ensure that we place the baffles in the correct positions. You may like to use a piece of tracing paper to mark out the locations of the words on the stencil, and use that to work on instead.

Before anything is glued into position, ensure that everything fits together by 'dry fitting' the pieces together using masking tape as a jointing material.

The 60mm x 270 mm pieces are the sides, while the 60mm x 264mm pieces are the tops and bottoms

Remember that the baffle pieces sit against the back of the face plate.

Once you are happy with the fit of the pieces, remove the protective paper from the Perspex, and glue the outside edges of the enclosure together. When gluing, use a thin bead of glue along the entire edge of the sheet to be attached. Be careful at this stage, to keep the orientation of the sides and top the same as during the dry fitting. Also be careful with the glue to ensure that it does not flow from the tube over everything, making a mess.

Use adhesive tape as a temporary support for the edges of the enclosure while the glue sets.

Once the sides are joined together, it is time to install the baffles. Start by running a strip of masking tape on the inside edges of the enclosure to protect the stencil from excess glue. Centre the enclosure onto either the stencil, or the template you have created, and start by mounting a middle baffle component. When gluing, again be careful to avoid dribbling glue everywhere. Be sure to attach the baffle so that it is at the bottom of the enclosure, touching the stencil. DO NOT GLUE THE BAFFLE TO THE STENCIL. Just glue the ends to the enclosure sides.

WARNING Fumes given off by most Acrylic solvents are not healthy to breathe. Ensure that when working with the glue, adequate ventalation is available.Please read and observe all safety warnings printed on the Acrylic solvent. These solvents can be highly toxic and give off strong fumes.

Continue assembly by gluing the rest of the black perspex baffles. Once glued, hold the frame together for a few minutes while the glue sets.

Complete the baffles, by turning the enclosure over, and attaching some temporary masking tape to hold the assembly together while the glue sets completely – this should take about 4 hours.Enjoy a cup of coffee!

After the glue is dry, test the white perspex LED mounting board for a good fit – It should fit inside the frame, leaving no gaps around the edge of the enclosure.

Once you are happy with the fit, put the stencil some place safe, and liberally apply glue to the edges of the baffles, and the sides of the LED mounting board, and glue the board into place. Again – wait a few hours for the glue to set completely.

This largely completes the assembly of the enclosure..

Once the glue has completely set, we need to install the LEDs on the inside of the newly created light box enclosures.There are two options at this stage – Either, you can use individual LEDs and resistors (Which I feel is a little ugly, but it works), or you can use some of the 'strip lights' that are available from places like eBay.

Strip lights are strips of flexible plastic PCB material that have groups of LEDs and resistors pre-installed. They are designed to run of 12V DC, and have an adhesive backing material already applied. They can normally be cut into set of 3 LEDs, as individual light components. The photo on the right shows a typical strip light.I purchased 2 x 1m Strip Lights for the project.

Start be cutting the strip light into the appropriate length sections for the words to be illuminated. In the case of my strip lights, there is a cut line every 3 LEDs, so I used 3 LEDs for the short words, and 6 LEDs for the longer words.

Once the individual words have been cut out from the strip lights use a small soldering iron to tin the ends – They are plastic coated, but should solder easily.Next, remove the paper backing, exposing the sticky adhesive surface.

Continue by attaching the strips to the back of each small light chamber enclosure. Alignment is not incredibly critical, but try to get the strip centred along the word. Use the stencil as a guide. Be careful when installing the strips to make sure that the + and – connections are uniform (i.e. all + up, or all + down) It doesn't matter which convention you use, just be consistent.Once the strips have been stuck down, use a 3mm diameter drill and drill a small hole beside the strip light for the cable to be wired through. Be careful to not drill a hole in the strip light material.

Next, hold the assembly up to a light, and mark the holes for the controller to be mounted – we use a light behind the assembly to make sure that the holes you will be drilling won't interfere with any of the strip lights.

Next, install 4 sets of short hex standoffs for the controller to be mounted on.

Continue assembly by soldering a wire between all of the '+' connections – Remember that the controller has a common + between all of the words.

Here is a close up of the connection.

Once all of the strip lights have been installed, mount the controller, insert the ribbon and wire each individual LED strip. Keep a copy of the wiring instructions as detailed in the assembly manual for the Arduino or PIC Wordclock controller manual to help you get the wiring right. I wrote the names of the words on the back of the white LED mounting sheet to help me.

The first word wired up! All of the words wired up!

Here is a photo of the finished wiring on the back of the clock. Note the coils at the top of the clock – These are the wires for the two spare words – instead of clipping the wire off, I coiled it up for later.

Mount the power connector socket.

I drilled a hole that was the correct size for the power socket (7.5mm) and mounted the socket and wired it up to the board.

And apply power to test all of the wiring is correct. A self test runs at startup, testing every word by turning it for for half a second. If one of the words fails to light, check your wiring (did you get + and – the correct way round?)

YAY!!! Run inside and show your spouse!

Next, we need to complete the baffles by adding the separators between the words.I can't give you an exact measurement for these, as their size depends on the spacing that you used between the horizontal baffles.

I measured each, and cut them individually, and then glued them in place using the vinyl adhesive.

Here is what the clock looks like with the baffles completed!

Centre the enclosure on the back of the stencil, and mark the edges. Remove the enclosure, tape the sides of the enclosure to protect it from the glue. Attach the mounting strips to the top and bottom as shown in the below diagram. The photos on the next page will help with this step!

Here is a close up of one of the stencil mounts ready for gluing – I set up all four before I glued the stencil in place. I simply used masking tape to hold the mount temporarily for gluing.

Check the fit of the stencil mounts carefully before applying vinyl glue. Note that I have protected the edge of the enclosure using tape to ensure that no glue can accidentally glue the stencil on – the stencil has to be able to be removed (which is why we use mounts).

Here is a close up of one the mounts, waiting to be glued. Note the gap between the enclosure and the stencil!

Once you are happy, apply the glue, and leave it it dry for a few hours.

Once dry, remove the enclosure, and verify that the stencil mounts are correctly positioned! Remove the extra tape, press the stencil back into place, drill the holes for the mounting screws.

Continue assembly by mounting the time setting buttons on the bottom of the enclosure, so that the time is able to be changed.

I assembled the time button board (using a couple of buttons with long shafts), marked a convenient place on the bottom of the clock, drilling the holes for the buttons to go through. Then I attached the buttons with a set of small spacers and screws.

After this is done, you need to add the tabs to the back panel of the enclosure so that it can be attached to the top and bottom walls. Just use a bead of glue to attach the strips.

I used one long strip at the top, and a set of strips at the bottom. Because the strips are all that holds the clock to the wall, I re-enforced the strips with some extra black perspex. Once the back was dry, I placed it on the enclosure, drilled the mounting holes, and screwed it in place.

My back panel has a slot cut into the top to allow the clock to be hung on the wall. This photo shows the long strip at the top of the back, and the wall mounting slot.

While you are waiting for the glue to dry, you need to attach some diffuser material to the back of the stencil – I used strips of light weight tissue held in place using clear tape. You may use paper, but I felt that the paper blocked too much light.

Finally, screw the back onto the enclosure, and screw the enclosure to the stencil, and that's it – Mount the clock on the wall, set the time, and have a party!

:-) There – that was easy!